Investigating the influence of hydrogeomorphic setting on the response of lake sedimentation to climatic changes in the Uinta Mountains, Utah, USA - Corbett, Lee B.; Munroe, Jeffrey S. (Journal of Paleolimnology, 2010)
Reader Lake and Elbow Lake, two high-altitude lakes in the Uinta Mountains of Utah, are located approximately 2 km apart, at similar elevations, and within identical vegetation communities. Loss on ignition, carbon to nitrogen ratios, biogenic silica, and sediment grain size were analyzed throughout percussion cores retrieved from both lakes to construct continuous time series spanning 14 to ca. 2 ka BP. Given the proximity of the lakes, it is assumed that both were subjected to the same climatic forcing over this time. Accordingly, the first goal of this study was to consider these two multiproxy datasets in concert to yield an integrated paleoclimate record for this region. Close inspection of the records identified discrepancies indicating that the lakes responded to climate changes in different ways despite their proximity and similar setting. Clarifying these differences and understanding why the two lakes behaved differently at certain times was the second goal of this study. Overall, the paleoclimatic records document lake formation in the latest Pleistocene following glacier retreat. Buried glacier ice at the location of Reader Lake may have persisted through the Younger Dryas. Both lakes became biologically productive ca. 11.5 ka BP, and the first appearance of conifer needles indicates that trees had replaced alpine tundra in these watersheds by 10.5 ka BP. The interval from 10 to 6 ka BP was marked by a dramatic increase in precipitation, perhaps related to enhanced monsoonal circulation driven by the insolation maximum. The two lakes recorded this event in notably contrasting ways given their differing hydrogeomorphic settings. Precipitation decreased from 6 to 4 ka BP, and low water levels and drought conditions marked the interval from 4.0 to 2.7 ka BP. The integrated paleoclimate record developed from these cores provides a useful point of comparison with other records from the region. The differences between the records from these closely spaced lakes underscore the need to consider hydrogeomorphic setting when evaluating the suitability of a lake for a paleolimnological study.
id: 2013; PT: J; UT: WOS:000277939200023

Late Holocene Evolution of the Mekong Subaqueous Delta, Southern Vietnam - Xue, Z.; Liu, J. P.; DeMaster, D.; Van Nguyen, L.; Ta, T. K. O. (Marine Geology, 2010)
As Asia's third largest river. with regard to sediment load, the Mekong River delivers approximately 160 million tons of sediment per year to the South China Sea. High-resolution seismic profiling and coring during 2006 and 2007 cruises revealed a low gradient, subaqueous delta system, up to 20 m thick, surrounding the modern Mekong River Delta (MRD) in the west of the South China Sea. Based on clinoform structure, grain size Pb-210, AMS C-14, and delta C-13 results, the subaqueous delta is divided into four zones defined by different sedimentary processes and depositional features. Over the past 3000 yr, the evolution of the MRD has shown a morphological asymmetry indicated by a large down-drift area and a rapid progradation around Cape Camau, similar to 200 km downstream from the river mouth. This asymmetric feature is consistent with increased wave influence. The strong southwestward coastal current, strengthened by the Strong NE monsoon, plays an important role locally in longshore transport of resuspended sediments into the Gulf of Thailand. A late Holocene sediment budget for the MRD has been determined, based on the area and thickness of deltaic sediment. Approximately 80% of Mekong delivered sediment has been trapped within the delta area, which, together with a falling sea-level, resulted in a rapidly prograding MRD over the past 3000 yr. (C) 2009 Elsevier B.V. All rights reserved.
id: 848; 560AN Times Cited:0 Cited References Count:53Y

Late Quaternary record of pteropod preservation from the Andaman Sea - Sijinkumar, A. V.; Nath, B. Nagender; Guptha, M. V. S. (Marine Geology, 2010)
In order to understand the glacial to interglacial fluctuations in pteropod preservation and productivity during the late Quaternary (similar to 54 ka BP to present), we investigated pteropod, organic carbon (Cord and Globigerina bulloides abundance in a deep sea core from the western Andaman Sea. Pteropod abundance and preservation is similar to the "Indo-Pacific carbonate preservation type", showing better preservation during glacial and poor preservation during interglacial periods. The core site appears to have remained below the aragonite compensation depth (ACD) throughout the Holocene, indicated by the total absence of pteropods. Maximum abundance and good preservation of pteropods was observed during stadials such as Younger Dryas (YD), Heinrich Events (HEs) and Last Glacial Maxima (LGM) indicating weaker oxygen minimum zone (OMZ) and deeper ACD. Furthermore, the high relative abundance of mesopelagic pteropods over epipelagic forms suggests a well ventilated water column with weak OMZ particularly during LGM, apparently driven by intense winter monsoon. Increased monsoon-driven productivity was observed during 45-40 ka, of early Marine Isotope stage 2 (MIS 2, 24-22 ka), Bolling/Allered (B/A; 15-13.5 ka), YD and late Holocene as evidenced by Cor, content and G. bulloides. Enhanced pteropod preservation of H1 associated with low C(org) content and G. bulloides suggests that reduced monsoonal driven productivity might have influenced pteropod preservation. Deglacial preservation spike in the Andaman Sea is consistent with other northern Indian Ocean records and elsewhere outside the Indian Ocean implying the event is global in nature, marked by deepening of ACD probably driven by enhancement of winter monsoon on local and changes in intermediate water circulation on regional scale. (C) 2010 Elsevier B.V. All rights reserved.
id: 2018; PT: J; UT: WOS:000281217300016

Late-twentieth-century warming in Lake Tanganyika unprecedented since AD 500 - Tierney, Jessica E.; Mayes, Marc T.; Meyer, Natacha; Johnson, Christopher; Swarzenski, Peter W.; Cohen, Andrew S.; Russell, James M. (Nature Geoscience, 2010)
Instrumental observations suggest that Lake Tanganyika, the largest rift lake in East Africa, has become warmer, increasingly stratified and less productive over the past 90 years (refs 1,2). These trends have been attributed to anthropogenic climate change. However, it remains unclear whether the decrease in productivity is linked to the temperature rise(3,4), and whether the twentieth-century trends are anomalous within the context of longer-term variability. Here, we use the TEX(86) temperature proxy, the weight per cent of biogenic silica and charcoal abundance from Lake Tanganyika sediment cores to reconstruct lake-surface temperature, productivity and regional wildfire frequency, respectively, for the past 1,500 years. We detect a negative correlation between lake-surface temperature and primary productivity, and our estimates of fire frequency, and hence humidity, preclude decreased nutrient input through runoff as a cause for observed periods of low productivity. We suggest that, throughout the past 1,500 years, rising lake-surface temperatures increased the stratification of the lake water column, preventing nutrient recharge from below and limiting primary productivity. Our records indicate that changes in the temperature of Lake Tanganyika in the past few decades exceed previous natural variability. We conclude that these unprecedented temperatures and a corresponding decrease in productivity can be attributed to anthropogenic global warming, with potentially important implications for the Lake Tanganyika fishery.
id: 2043; PT: J; UT: WOS:000278134100019

A long history of cloud and forest migration from Lake Consuelo, Peru - Urrego, D. H.; Bush, M. B.; Silman, M. R. (Quaternary Research, 2010)
The complete paleoecological history from Lake Consuelo forest yields a record of ground-level cloud formation and changes in its lower altitudinal limit over the last 46,300 cal yr BP. The timing of early lake level fluctuations prior to 37,000 cal yr BP appears sensitive to North Atlantic temperature oscillations, corresponding to Dansgaard-Oeschger interstadials 11, 10 and 8 recorded in GISP2. After the LGM, the first hint of warming is recorded in Lake Consuelo at 22,000 call yr BP and agrees with other estimates for the region. The mid-Holocene (7400-5000 cal yr BP) was the period of highest rates of change and most significant reorganizations in the Consuelo forest. These community changes resulted from a regionally widespread dry period. Results from Lake Consuelo indicate that moisture availability, mediated through cloud cover, played the most significant role in ecological change in this system. Rates of past climate fluctuations never exceeded the forest capacity to accommodate change. Unfortunately, this might not be the case under predicted scenarios for the end of the current century. (C) 2009 University of Washington. Published by Elsevier Inc. All rights reserved.
id: 1903; 564VS Times Cited:8 Cited References Count:85Y

Long-term stability in the production of a NW Mediterranean Posidonia oceanica (L.) Delile meadow - Mateo, M. A.; Renom, P.; Michener, R. H. (Palaeogeography Palaeoclimatology Palaeoecology, 2010)
Long-term changes in leaf net production of the seagrass Posidonia oceanica (L) Defile. and in the irradiance arriving at the meadow canopy, were investigated in a NW Mediterranean meadow using a palaeoecological approach. We conducted in situ shade experiments to find the relationships between the carbon stable isotope ratio (delta(13)C) of plant tissues, leaf net production, and ambient irradiance. The relationships were highly significant and fitted the Michaelis-Menten equation and power functions. These functions were used to reconstruct light and net production using the delta(13)C of P. oceanica detritus as a palaeoecological proxy along a 150 cm core of P. oceanica matte (a peat-like deposit formed by this endemic seagrass species). The delta(13)C values of sheath detritus along the core (i.e.. the net leaf production) showed a weak but significant decrease towards the present time (R = 0.308: P = 0.02) probably as a result of (1) an increase in DIC availability, and/or (2) a progressive change in the carbon isotopic signature of DIC, both of which are consistent with a rise in anthropogenic atmospheric CO(2). The canopy irradiance, reconstructed for the last 1200 years, showed a mean value of 128 mu E m(-2) s(-1) with a range of 12.5-280 mu E m(-2) s(-1). The reconstruction of the net leaf production for the same period yielded a mean value of 2.5 mg dw day(-1) shoot(-1) with a range of 2.0-2.7 mg dw day(-1) shoot(-1). Both ranges are within the values reported in the literature for present day studies. The absence of significant fluctuations or sudden changes through time suggests remarkable ecosystem stability during the last millennium. (C) 2010 Elsevier B.V. All rights reserved.
id: 1911; 611AI Times Cited:3 Cited References Count:116Y

Megadroughts and late Holocene dune activation at the eastern margin of the Great Plains, north-central Kansas, USA - Hanson, P. R.; Arbogast, A. F.; Johnson, W. C.; Joeckel, R. M.; Young, A. R. (Aeolian Research, 2010)
Optical and radiocarbon dating indicates that alluvium underlying dunes near Abilene was deposited at or before similar to 45 ka, and that the overlying dunes were active at similar to 1.1-0.5 ka. Geochemical data indicate that the Abilene dune sand is immature and was derived from the underlying Pleistocene alluvium, and not from Holocene age Smoky Hill River deposits. These findings suggest that dune activation was a response to increased aridity and local reduction in vegetation cover as opposed to changes in sediment availability from nearby rivers. The time interval of dune activation at Abilene overlaps Medieval Warm Period megadroughts, similar to the larger and more westerly dune fields on the Great Plains, including the Nebraska Sand Hills and the Great Bend Sand Prairie. The activation of smaller dune fields such as the Abilene dunes near the more humid eastern margin of the Great Plains shows the geographic extent and severity of paleodrought events. Unlike the Duncan dunes, another plains-marginal dune field, however, the Abilene dunes show no evidence for multiple drought events during the Holocene. This difference in dune activity, if it is not a result of sampling or preservation bias, indicates variations in the extent and severity of older drought events at the eastern margin of the Great Plains. Published by Elsevier B.V.
851alTimes Cited:20Cited References Count:35

Microbial carbon cycling in oligotrophic regional aquifers near the Tono Uranium Mine, Japan as inferred from delta(13)C and Delta(14)C values of in situ phospholipid fatty acids and carbon sources - Mills, Christopher T.; Amano, Yuki; Slater, Gregory F.; Dias, Robert F.; Iwatsuki, Teruki; Mandernack, Kevin W. (Geochimica et Cosmochimica Acta, 2010)
Microorganisms are ubiquitous in deep subsurface environments, but their role in the global carbon cycle is not well-understood. The natural abundance delta(13)C and Delta(14)C values of microbial membrane phospholipid fatty acids (PLFAs) were measured and used to assess the carbon sources of bacteria in sedimentary and granitic groundwaters sampled from three boreholes in the vicinity of the Tono Uranium Mine, Gifu, Japan. Sample storage experiments were performed and drill waters analyzed to characterize potential sources of microbial contamination. The most abundant PLFA structures in all waters sampled were 16:0,16:1 omega 7c, cy17:0, and 18:1 omega 7c. A PLFA biomarker for type 11 methanotrophs, 18:1 omega 8c, comprised 3% and 18% of total PLFAs in anoxic sedimentary and granitic waters, respectively, sampled from the KNA-6 borehole. The presence of this biomarker was unexpected given that type II methanotrophs are considered obligate aerobes. However, a bacterium that grows aerobically with CH(4) as the sole energy source and which also produces 56% of its total PLFAs as 18:1 omega 8c was isolated from both waters, providing additional evidence for the presence of type II methanotrophs. The Delta(14)C values determined for type II methanotroph PLFAs in the sedimentary (-86 parts per thousand) and granite (-867 parts per thousand) waters were very similar to the Delta(14)C values of dissolved inorganic carbon (DIC) in each water (similar to-850 parts per thousand). This suggests that type II methanotrophs ultimately derive all their carbon from inorganic sources, whether directly from DIC and/or from CH4 produced by the reduction of DIC. In contrast, delta(13)C values of type II PLFAs in the sedimentary (-93 parts per thousand) and granite (-60 parts per thousand) waters indicate that these organisms use different carbon assimilation schemes in each environment despite very similar delta(13)C(CH4) values (-similar to 95 parts per thousand) for each water. The delta(13)C(PLFA) values (-28 parts per thousand to -45 parts per thousand) of non-methanotrophic bacteria in the KNA-6 LTL water do not clearly distinguish between heterotrophic and autotrophic metabolisms, but Delta(14)C(PLFA) values indicate that >65% of total bacteria filtered from the KNA-6 LTL water are heterotrophs. Ancient Delta(14)C values (similar to-1000 parts per thousand) of some PLFAs suggest that many heterotrophs utilize ancient organic matter, perhaps from lignite seams within the sedimentary rocks. The more negative range of delta(13)C(PLFA) values determined for the KNA-6 granitic water (-42 parts per thousand to -66 parts per thousand) are likely the result of a microbial ecosystem dominated by chemolithoautotrophy, perhaps fuelled by abiogenic H(2). Results of sample storage experiments showed substantial shifts in microbial community composition and delta(13)C(PLFA) values (as much as 5 parts per thousand) during 2-4 days of dark, refrigerated, aseptic storage. However, water samples collected and immediately filtered back in the lab from freshly drilled MSB-2 borehole appeared to maintain the same relative relationships between delta(13)C(PLFA) values for sedimentary and granitic host rocks as observed for samples directly filtered under artesian flow from the KNA-6 borehole of the Tono Uranium Mine. (C) 2010 Elsevier Ltd. All rights reserved.
id: 2057; PT: J; UT: WOS:000278510300008

Mid-Brunhes strengthening of the Indian Ocean Dipole caused increased equatorial East African and decreased Australasian rainfall - Gupta, Anil K.; Sarkar, Sudipta; De, Soma; Clemens, Steven C.; Velu, Angamuthu (Geophysical Research Letters, 2010)
The tropical Indian Ocean is an important component of the largest warm pool, marked by changes in sea surface temperatures and depths of thermocline and mixed layer in its western and eastern extremities leading to the development of a dipole mode - the Indian Ocean Dipole (IOD). A narrow band of westerlies (7 degrees N to 7 degrees S) sweep the equatorial Indian Ocean during the April - May and October - November transitions between the summer - and winter-monsoon seasons. These Indian Ocean equatorial westerlies (IEW) are closely related to the IOD, intensifying the upper ocean Eastward Equatorial current also known as Wyrtki jets. The strength of the IOD/IEW determines the moisture content in East Africa. A major decrease in the strength of the IEW (strengthening or positive mode of the IOD) during the mid-Brunhes epoch (similar to 300-250 Kyr BP) coincides with a wetter equatorial East Africa, a drier Australasia and a stronger Indian summer monsoon, indicating that the IOD/IEW play a significant role in driving climate change in East Africa, Australasia and South Asia. Citation: Gupta, A. K., S. Sarkar, S. De, S. C. Clemens, and A. Velu (2010), Mid-Brunhes strengthening of the Indian Ocean Dipole caused increased equatorial East African and decreased Australasian rainfall, Geophys. Res. Lett., 37, L06706, doi: 10.1029/2009GL042225.
id: 1966; PT: J; UT: WOS:000276025100002

Millennial-aged organic carbon subsidies to a modern river food web - Caraco, Nina; Bauer, James E.; Cole, Jonathan J.; Petsch, Steven; Raymond, Peter (Ecology, 2010)
Recent studies indicate that highly aged material is a major component of organic matter transported by most rivers. However, few studies have used natural (14)C to trace the potential entry of this aged material into modern river food webs. Here we use natural abundance (14)C, (13)C, and deuterium ((2)H) to trace the contribution of aged and contemporary organic matter to an important group of consumers, crustacean zooplankton, in a large temperate river (the Hudson River, New York, USA). Zooplankton were highly (14)C depleted (mean Delta(14)C = -240 parts per thousand) compared to modern primary production in the river or its watershed (Delta(14)C = -60 parts per thousand to +50 parts per thousand). In order to account for the observed (14)C depletion, zooplankton must be subsidized by highly aged particulate organic carbon. IsoSource modeling suggests that the range of the aged dietary subsidy is between similar to 57%, if the aged organic matter source was produced 3400 years ago, and similar to 21%, if the organic carbon used is >= 50 000 years in age, including fossil material that is millions of years in age. The magnitude of this aged carbon subsidy to river zooplankton suggests that modern river food webs may in some cases be buffered from the limitations set by present-day primary production.
id: 2032; PT: J; UT: WOS:000280153500022

Millennial-scale climate variability during the Last Glacial period in the tropical Andes - Fritz, S. C.; Baker, P. A.; Ekdahl, E.; Seltzer, G. O.; Stevens, L. R. (Quaternary Science Reviews, 2010)
Millennial-scale climate variation during the Last Glacial period is evident in many locations worldwide, but it is unclear if such variation occurred in the interior of tropical South America. and, if so, how the low-latitude variation was related to its high-latitude counterpart A high-resolution record, derived from the deep drilling of sediments on the floor of Lake Titicaca in the southern tropical Andes, is presented that shows clear evidence of millennial-scale climate variation between similar to 60 and 20 ka BP This variation is manifested by alternations of two interbedded sedimentary units The two units have distinctive sedimentary, geochemical, and paleobiotic properties that are controlled by the relative abundance of terrigenous or nearshore components versus pelagic components The sediments of more terrigenous or nearshore nature likely were deposited during regionally wetter climates when river transport of water and sediment was higher, whereas the sediments of more pelagic character were deposited during somewhat drier climates regionally. The majority of the wet periods inferred from the Lake Titicaca sediment record are correlated with the cold events in the Greenland ice cores and North Atlantic sediment cores. indicating that increased intensity of the South American summer monsoon was part of near-global scale climate excursions (C) 2010 Elsevier Ltd All rights reserved
id: 1886; 584JY Times Cited:5 Cited References Count:59Y

Mineral carbonation in peridotite and basalt for CO2 capture and storage - Kelemen, P. B.; Matter, J. M.; Streit, L. (Annual Reviews of Earth & Planetary Sciences, 2010)
id: 845not submitted

Modern sediment dispersal and accumulation on the outer Poverty continental margin - Alexander, C. R.; Walsh, J. P.; Orpin, A. R. (Marine Geology, 2010)
The Poverty margin was sampled in 2005 and 2006 as part of an international initiative to examine the terrestrial and marine sedimentary response to natural and human impacts on dispersal systems at mud-dominated coasts: the NSF MARGINS Source-to-Sink Initiative. Pb-210 accumulation rates generally decrease from similar to 1 g/cm(2) y in the mid-shelf depocenter on the outer shelf to similar to 0.1 g/cm2 y on the mid-slope plateau (range 0.04-2.53 g/cm(2) y). Higher accumulation rates are observed all along the outer Poverty shelf, extending over the shelf break onto the upper Poverty slope in canyons and gullies. Rates are fast in gullies that incise into the shelf edge (0.75-1 g/cm(2) y), particularly in the area between Waipaoa Canyon and Poverty Canyon, and in the axis of Poverty Canyon (1.29-1.89 g/cm(2) y). Below similar to 1200 m water depth, rates in the axis of Poverty Canyon are no more rapid than those found at open slope cores in similar water depths (0.12-0.15 g/cm(2) y). Excess Pb-210 profiles generally exhibit steady state characteristics, except in the axis of Poverty Canyon, where non-steady-state Pb-210 profiles are observed. Cs-137 was not found above minimum detection limits or above statistical background levels in any cores from the Poverty margin. Be-7 was found distributed widely along and across the margin during both summer and winter periods, observed to depths of up to 4cm. Widespread presence of Be-7 on the margin in both winter and summer suggests that terrestrially derived sediment is reaching the outer shelf and upper slope throughout the year. A sediment budget based on Pb-210 accumulation rate data shows that approximately 13-18% of the Waipaoa annual discharge is accumulating on the outer Poverty margin as a whole, and approximately 11-15% of the annual discharge is accumulating on the continental slope alone. Notably, approximately 28% of the sediment annually accumulating in the outer margin is being sequestered in slope gullies and canyons, although they represent only 6% of the area of the outer margin. (C) 2009 Elsevier B.V. All rights reserved.
id: 792; Sp. Iss. SI 576IF Times Cited:4 Cited References Count:72Y

Molecular and Isotopic Analysis of Motor Oil from a Biodiesel-Driven Vehicle - Peacock, E. E.; Arey, J. S.; DeMello, J. A.; McNichol, A. P.; Nelson, R. K.; Reddy, C. M. (Energy & Fuels, 2010)
Biodiesel, a mixture of fatty acid methyl esters (FAMEs), is increasingly recognized as a renewable fuel. While some environmental impacts of biodiesel usage have been investigated, accumulation of organic compounds in motor oil, which can subsequently leak onto roads, has not been studied. Because studies have shown that toxic polycyclic aromatic hydrocarbons (PAHs) accumulate in the motor oil of engines fueled with fossil diesel or gasoline, the objective of this study was to determine if this also occurs for engines fueled with biodiesel. Here, we sampled and analyzed motor oil of a biodiesel-powerd 2005 Volkswagen Passat Wagon over 3240 km for personal-use driving. Using gas chromatography with flame ionization detection (GC-FID), we found a total of 0.5% FAMEs in the motor oil after 3240 km. We also used gas chromatography-mass spectrometry and comprehensive two-dimensional gas chromatography and did not detect PAHs or other organic compounds not present in the initial motor oil. Using natural radiocarbon analysis, a powerful technique capable of detecting biodiesel-derived carbon that would be otherwise undetectable by gas chromatography, we found a total of 0.68% biodiesel-derived carbon after 3240 km. This is similar to the amount of FAMEs found in these samples with GC-FID, indicating that the primary source of biodiesel-derived carbon in the motor oil is FAMEs (and not PAHs or other carbonaceous species). This result suggests that used motor oil of biodiesel vehicles can be less toxic based on PAH content than vehicles fueled with fossil diesel or gasoline.
id: 816; 555MH Times Cited:0 Cited References Count:63; YY

A molecular perspective on Late Quaternary climate and vegetation change in the Lake Tanganyika basin, East Africa - Tierney, J. E.; Russell, J. M.; Huang, Y. S. (Quaternary Science Reviews, 2010)
Characterizing the nature of past hydrological change and its interactions with vegetation is fundamental to acquiring a better understanding of continental tropical climate dynamics. Here, we outline major shifts in the climate and ecosystem of tropical East Africa for the past 60,000 years (60 ka) by examining molecular records of hydrology, vegetation, and temperature from a sediment sequence from Lake Tanganyika. We demonstrate, via comparison with pollen spectra, that stable carbon isotopes measured on higher plant leaf waxes (delta C-13(wax)) are a reliable proxy for vegetation change. In addition we argue that the D/H ratio of higher plant leaf waxes (delta D-wax) is a robust and independent indicator of past changes in aridity, and is not affected by regional vegetation change directly. Our paired, compound-specific isotope data show that shifts in vegetation lead major changes in hydrology in the Tanganyika basin at several major climate transitions during the past 60,000 years, suggesting that vegetation in the Tanganyika basin is not as sensitive to aridity as previous studies have suggested and that variations in carbon dioxide, temperature, and internal ecosystem dynamics are equally, if not more, important. We hypothesize that regional vegetation change may exert a positive feedback on regional hydrology, thus partially accounting for the abrupt threshold behavior evident in our paleohydrological data. Furthermore, we find that past changes in Tanganyika basin climate and ecology are closely linked to concentrations of atmospheric trace gases, highlighting the paramount influence of global climatic shifts upon regional tropical climate over glacial/interglacial timescales. (C) 2009 Elsevier Ltd. All rights reserved.
id: 1850; 574XV Times Cited:0 Cited References Count:111Y

No signature of abyssal carbon n intermediate waters off Chile during deglaciation - dePol-Holz, R.; Keigwin, L.; Southon, J.; Hebbeln, D.; Mohtadi, M. (Nature Geosciences, 2010)
id: 772; YY

The Passage of the Bomb Radiocarbon Pulse into the Pacific Ocean - Jenkins, W. J.; Elder, K. L.; McNichol, A. P.; von Reden, K. (Radiocarbon, 2010)
We report and compare radiocarbon observations made on 2 meridional oceanographic sections along 150 degrees W in the South Pacific in 1991 and 2005. The distributions reflect the progressive penetration of nuclear weapons-produced (14)C into the oceanic thermocline. The changes over the 14 yr between occupations are demonstrably large relative to any possible drift in our analytical standardization. The computed difference field based on the gridded data in the upper 1600 m of the section exhibits a significant decrease over time (approaching 40 to 50 parts per thousand in Delta(14)C) in the upper 200-300 m, consistent with the decadal post-bomb decline in atmospheric (14)C levels. A strong positive anomaly (increase with time), centered on the low salinity core of the Antarctic Intermediate Water (AAIW), approaches 50-60 parts per thousand in Delta(14)C, a clear signature of the downstream evolution of the (14)C transient in this water mass. We use this observation to estimate the transit time of AAIW from its "source region" in the southeast South Pacific and to compute the effective reservoir age of this water mass. The 2 sections show small but significant changes in the abyssal (14)C distributions. Between 1991 and 2005, Delta(14)C has increased by 9 parts per thousand below 2000 m north of 55 degrees S. This change is accompanied overall by a modest increase in salinity and dissolved oxygen, as well as a slight decrease in dissolved silica. Such changes are indicative of greater ventilation. Calculation of "phosphate star" also indicates that this may be due to a shift from the Southern Ocean toward North Atlantic Deep Water as the ventilation source of the abyssal South Pacific.
Sp. Iss. 2696jo Times Cited:7 Cited References Count:38
Keywords: AMS; antarctic intermediate water; anthropogenic co2; atlantic; c-14 data; carbon; distributions; graphite; south-pacific; tritium

Photosynthetic isotope biosignatures in laminated micro-stromatolitic and non-laminated nodules associated with modern, freshwater microbialites in Pavilion Lake, BC RID B-8520-2011 - Brady, A. L.; Slater, G. F.; Omelon, C. R.; Southam, G.; Druschel, G.; Andersen, D. T.; Hawes, I.; Laval, B.; Lim, D. S. S. (Chemical Geology, 2010)
The influence of microbial activity on carbonate precipitation was investigated within micro-stromatolitic nodules associated with modem, freshwater microbialites located in Pavilion Lake, B.C. Observed carbonate delta(13)C values enriched by up to +3.6 parts per thousand as compared to predicted abiotic carbonate delta(13)C values from measured dissolved inorganic carbon (mean -1.2 parts per thousand, n=13) were consistent with microbial photosynthetic influence on in situ precipitation within the nodule microenvironment. Estimated carbonate precipitation temperatures within the nodules based on delta(18)O were consistent with recorded summertime temperatures, indicative of precipitation during the period of highest levels of photosynthetic activity. Low delta(13)C values of organic matter within the nodules (-30.6 to 21.1 parts per thousand) and an average inorganic to organic carbon Delta delta(13)C value of 26.8 parts per thousand reflected the preferential uptake of (12)C during non-CO(2) limited photosynthesis, supporting the generation of (13)C-enriched DIC. Microelectrode profiles through the nodules showed oxygen supersaturation of up to similar to 275%, elevated pH compared to ambient water and a lack of any observable dissolved sulphide, Mn or Fe further indicated that photosynthetic activity was the predominant metabolic process within the nodule during light exposure. Microbial phospholipid fatty acid profiles of the nodule communities were indicative of bacteria rather than eukaryotes and PLFA delta(13)C values were depleted relative to the bulk cell by 2.6-6.6 parts per thousand, consistent with a predominance of photosynthetic microbes. Scanning electron microscopy images of the relationship between carbonate minerals and filaments indicated that carbonate precipitation had occurred in situ due to microbial influences on the geochemistry within the nodule microenvironment rather than due to cell surface effects or trapping and binding. The observation of photosynthetically induced (13)C-enrichment of in situ precipitated carbonate within the nodule microenvironment is thus a biosignature of the activity of these surface communities and is consistent with the hypothesized role of biology in the formation of microbialites. (C) 2010 Elsevier B.V. All rights reserved.
id: 2056; PT: J; UT: WOS:000279094700005

Postglacial changes in El Nino and La Nina behavior - Makou, Matthew C.; Eglinton, Timothy I.; Oppo, Delia W.; Hughen, Konrad A. (Geology, 2010)
Paleoclimate reconstructions suggest distinctive changes in the Ell Nino-Southern Oscillation (ENSO), the dominant mode of tropical climate variability, over the last glacial cycle and throughout the Holocene. However, to the best of our knowledge, no studies provide parallel reconstructions of warm (El Nino) and cold (La Nina) phase variability, thus precluding distinction between variations in ENSO activity and the mean state of the tropical Pacific. Here we provide the first such records, generated using molecular organic geochemical proxies in a sediment core from the Peru margin region. The opposing influences of El Nino and La Nina on coastal upwelling and phytoplankton community structure produce distinct sedimentary sterol records describing the evolution of each ENSO phase. We document changes in surface ocean productivity on the Peru margin over the past 16 ka that indicate enhanced La Nina-like conditions alone during deglaciation, but concomitant increases in both El Nino and La Nina activity during the past 2 ka. We propose that the preponderance of La Nina-like conditions prior to 11.5 ka reflects the influence of waning glacial boundary conditions. By contrast, warm and cold phase covariability during the late Holocene suggests centennial-scale changes in ENSO activity, rather than the Pacific mean state, driven by tropical insolation.
id: 1985; PT: J; UT: WOS:000273346200011

The potential of New Zealand kauri (Agathis australis) for testing the synchronicity of abrupt climate change during the Last Glacial Interval (60,000-11,700 years ago) - Turney, Chris S. M.; Fifield, L. Keith; Hogg, Alan G.; Palmer, Jonathan G.; Hughen, Konrad; Baillie, Mike G. L.; Galbraith, Rex; Ogden, John; Lorrey, Andrew; Tims, Stephen G.; Jones, Richard T. (Quaternary Science Reviews, 2010)
The latter part of the Last Glacial Interval (LGI; 60,000 to 11,700 years ago) experienced a range of climatic and environment extremes. To elucidate the mechanisms of these changes requires records of past variability that are precisely dated and correlated on the same absolute timescale. However, despite decades of research, it is still not possible to align most marine and terrestrial records of past change with ice-core records, largely because of ongoing uncertainties over the conversion of pre-Holocene (14)C ages on to a calendar timescale and uncertainties with in ice-core chronologies. As a result, it is equivocal whether climate changes in both hemispheres during the LGI led, lagged or were synchronous with one another. A decadally-resolved radiocarbon calibration is urgently required to test these models of the Earth system. Here we report radiocarbon measurements obtained from subfossil New Zealand kauri (Agathis australis) spanning a collective 3500 years dated between 25,000 and 45,000 years ago. The results are compared to the recently published international calibration curve IntCal09 and to the marine Cariaco Basin datasets. We show that kauri have considerable potential for development of a Southern Hemisphere component of a unified global calibration curve suite, and that tree-ring sequences can be superposed on other radiocarbon records to constrain atmospheric marine offsets and precisely test the synchronicity of abrupt climate change. (C) 2010 Elsevier Ltd. All rights reserved.
id: 1982; PT: J; UT: WOS:000285222000001

The radiocarbon age of organic carbon in marine surface sediments - Griffith, David R.; Martin, William R.; Eglinton, Timothy I. (GEOCHIMICA ET COSMOCHIMICA ACTA, 2010)
Long-term carbon cycling and climate change are strongly dependent on organic carbon (OC) burial in marine sediments. Radiocarbon ((14)C) has been widely used to constrain the sources, sinks, and processing of sedimentary OC. To elucidate the dominant controls on the radiocarbon content of total organic carbon ((14)C(TOC)) accumulating in surface sediments we construct a box model that predicts (14)C(TOC) in the sediment mixed layer (measured as fraction modern, Fm). Our model defines three distinct OC pools ({''}degradable,{''} ``semi-labile,{''} and ``refractory{''}) and assumes that (14)C(TOC) flux to sediments is exclusively derived from surface ocean primary productivity, and hence follows a ``generic{''} surface ocean dissolved inorganic carbon (DIC) bomb curve. Model predictions are compared to a set of 75 surface sediment samples, which span a wide geographic range and reflect diverse water column and depositional conditions, and for which sedimentation rate and mixed-layer depth are well characterized. Our model overestimates the Fm value for a majority (65%) of these sites, especially at shallow water depths and for sites characterized by depleted delta(13)C(TOC) values. The model is most sensitive to sedimentation rate and mixed-layer depth. Therefore, slight changes to these parameters can lead to a match between modeled and measured Fm values at many sites. Yet, in some cases, we find that measured Fm values cannot be simulated without large and unrealistic changes to sedimentation rate and mixed-layer depth. These results point to sources of pre-aged OC to surface sediments and implicate soil-derived terrestrial OC, reworked marine OC, and/or anthropogenic carbon as important components of the organic matter present in surface sediments. This approach provides a valuable framework within which to explore controls on sedimentary organic matter composition and carbon burial over a range of spatial and temporal scales. (C) 2010 Elsevier Ltd. All rights reserved.

Radiocarbon Dating of Individual Lignin Phenols: A New Approach for Establishing Chronology of Late Quaternary Lake Sediments - Hou, Juzhi; Huang, Yongsong; Brodsky, Corynn; Alexandre, Marcelo R.; McNichol, Ann P.; King, John W.; Hu, Feng Sheng; Shen, Ji (ANALYTICAL CHEMISTRY, 2010)
The reliability of chronology is a prerequisite for meaningful paleoclimate reconstructions from sedimentary archives. The conventional approach of radiocarbon dating bulk organic carbon in lake sediments is often hampered by the old carbon effect, i.e., the assimilation of ancient dissolved inorganic carbon (DIC) derived from carbonate bedrocks or other sources. Therefore, radiocarbon dating is ideally performed on organic compounds derived from land plants that use atmospheric CO(2) and rapidly delivered to sediments. We demonstrate that lignin phenols isolated from lake sediments using reversed phase high performance liquid chromatography (HPLC) can serve as effective (14)C dating materials for establishing chronology during the late Quaternary. We developed a procedure to purify lignin phenols, building upon a published method. By isolating lignin from standard wood reference substances, we show that our method yields pure lignin phenols and consistent ages as the consensus ages and that our procedure does not introduce radiocarbon contamination. We further demonstrate that lignin phenol ages are compatible with varve counted and macrofossil dated sediment horizons in Steel Lake and Fayetteville Green Lake. Applying the new method to lake sediment cores from Lake Qinghai demonstrates that lignin phenol ages in Lake Qinghai are consistently younger than bulk total organic carbon (TOC) ages which are contaminated by old carbon effect. We also show that the age offset between lignin and bulk organic carbon differs at different Lake Qinghai sedimentary horizons, suggesting a variable hard water effect at different times and that a uniform age correction throughout the core is inappropriate.

Radiocarbon in the Canada Basin: Carbon Transfer Processes in the Changing Arctic - McNichol, A P; Xu, L; Griffith, D R; Eglinton, T I; Macdonald, R; McLaughlin, F A (Proceedings from the 2010 AGU Ocean Sciences Meeting, 2010)
We are developing full water column depth [delta]14C profiles for dissolved inorganic carbon (DIC), dissolved organic carbon (DOC) and suspended particulate organic carbon (POC) collected in 2008 from the Canada Basin in the Arctic Ocean. These samples provide an opportunity to study the current distribution of radiocarbon in different carbon pools and set a baseline for future investigations of the carbon cycle in this key oceanic region where climate change is anticipated to have a major and imminent impact on carbon storage and cycling. Our first DI14C depth profile from 75, 150 is similar to one taken in 1992 (Jones et al. 1994) in demonstrating a well-ventilated surface layer overlying an older but recently ventilated deeper basin. Significant increases in DI14C, up to 30 ppt, are observed in the mid-depth region between 500 to 1500 m, roughly coincident with a warm layer underlying cold surface waters. The differences that have occurred over 16 years may lend insight to the observed warming of Atlantic water in the Canada Basin over the past decades. We will present the first DO14C profile from the central Canada Basin. Measurements are being made using a UV oxidation system established at NOSAMS. Most of the samples collected for DO14C measurement were acidified to preserve them. Results from frozen duplicates for a few of the samples will be compared to validate the preservation technique. In most regions of the ocean, the shape of DO14C depth profiles parallel those of DI14C profiles but are shifted to significantly older values. This reflects the fact that general oceanographic circulation and remineralization processes dominate the overall profile, but that the sources of carbon to the DOC pool are more complex than those of DIC. It is unknown whether this will be the case in the Arctic Ocean which, while representing only ~1% of the worlds ocean volume, receives approximately 13% of the global flux of terrigeneous DOC. Jones, G. A. et al. (1994). NIMS B, 92, 426-430.
Date revised - 2010-09-01SuppNotes - Abstracts AvailableLast updated - 2016-12-22
Keywords: and modeling; Biogeochemical cycles; carbon cycling; processes; Radioactivity and radioisotopes

Rapid Climatic Signal Propagation from Source to Sink in a Southern California Sediment-Routing System - Covault, J. A.; Romans, B. W.; Fildani, A.; McGann, M.; Graham, S. A. (Journal of Geology, 2010)
Terrestrial source areas are linked to deep-sea basins by sediment-routing systems, which only recently have been studied with a holistic approach focused on terrestrial and submarine components and their interactions. Here we compare an extensive piston-core and radiocarbon-age data set from offshore southern California to contemporaneous Holocene climate proxies in order to test the hypothesis that climatic signals are rapidly propagated from source to sink in a spatially restricted sediment-routing system that includes the Santa Ana River drainage basin and the Newport deep-sea depositional system. Sediment cores demonstrate that variability in rates of Holocene deep-sea turbidite deposition is related to complex ocean-atmosphere interactions, including enhanced magnitude and frequency of the North American monsoon and El Nino-Southern Oscillation cycles, which increased precipitation and fluvial discharge in southern California. This relationship is evident because, unlike many sediment-routing systems, the Newport submarine canyon-and-channel system was consistently linked to the Santa Ana River, which maintained sediment delivery even during Holocene marine transgression and highstand. Results of this study demonstrate the efficiency of sediment transport and delivery through a spatially restricted, consistently linked routing system and the potential utility of deep-sea turbidite depositional trends as paleoclimate proxies in such settings.
id: 875; 574IR Times Cited:0 Cited References Count:55Y

Recent shoaling of the nutricline and thermocline in the western tropical Pacific - Williams, Branwen; Grottoli, Andrea G. (Geophysical Research Letters, 2010)
Long records of subsurface ocean observations are key to constrain our understanding of the climate response of the tropical Pacific to increasing greenhouse gases. Due to the lack of continuous ocean observations, proxies become essential to estimate changes in the tropical thermocline related to changes in Walker circulation. Here, we present high resolution stable nitrogen (delta(15)N) and carbon (delta(13)C) isotope records from three proteinaceous corals spanning the top 105 m of the euphotic zone from an offshore Palauan reef in the western tropical Pacific. Dated with radiocarbon-derived growth chronologies, these isotope records indicate a shoaling of the mean nutricline and thus the thermocline as well, and a likely increase in primary productivity in the western tropical Pacific since the mid-to-late 1970s. Thus, these are the first subsurface proxy data extending below 20 m to support a slowdown of the tropical Pacific Walker circulation during the 20th Century. Citation: Williams, B., and A. G. Grottoli (2010), Recent shoaling of the nutricline and thermocline in the western tropical Pacific, Geophys. Res. Lett., 37, L22601, doi:10.1029/2010GL044867.
id: 1961; PT: J; UT: WOS:000284479000002

Reconnaissance dating A new radiocarbon method applied to assessing the temporal distribution of Southern Ocean deep-sea corals - Burke, Andrea; Robinson, Laura F.; McNichol, Ann P.; W. J. Jenkins; Scanlon, Kathryn M.; Gerlach, Dana S. (Deep-Sea Research Part I-Oceanographic Research Papers, 2010)
We have developed a rapid reconnaissance method of preparing graphite for (14)C/(12)C analysis Carbonate (similar to 15 mg) is combusted using an elemental analyzer and the resulting CO(2) is converted to graphite using a sealed tube zinc reduction method Over 85% (n=45 replicates on twenty-one individual corals) of reconnaissance ages measured on corals ranging in age from 500 to 33 000 radiocarbon years (Ryr) are within two standard deviations of ages generated using standard hydrolysis methods on the same corals and all reconnaissance ages are within 300 Ryr of the standard hydrolysis ages Replicate measurements on three individual aragonitic corals yielded ages of 1076 +/- 35 Ryr (standard deviation n=5) 10 739 +/- 47 Ryr (n=8) and 40 146 +/- 3500 Ryr (n=9) No systematic biases were found using different cleaning methods or variable sample sizes Analysis of (13)C/(12)C was made concurrently with the (14)C/(12)C measurement to correct for natural fractionation and for fractionation during sample processing and analysis This technique provides a new rapid method for making accurate percent-level (14)C/(12)C analyses that may be used to establish the rates and chronology of earth system processes where survey-type modes of age estimation are desirable For example applications may include creation of sediment core-top maps preliminary age models for sediment cores and growth rate studies of marine organisms such as corals or mollusks We applied the reconnaissance method to more than 100 solitary deep-sea corals collected in the Drake Passage in the Southern Ocean to investigate their temporal and spatial distribution The corals used in this study are part of a larger sample set and the subset that was dated was chosen based on species as opposed to preservation state so as to exclude obvious temporal biases Similar to studies in other regions the distribution of deep-sea corals is not constant through time across the Drake Passage Most of the corals from the Burdwood Bank (continental shelf of Argentina) have ages ranging between 0 and 2500 calendar years whereas most of the corals from the Sars Seamount in the Drake Passage have ages between 10 000 and 12 500 calendar years Such differences may be caused in part by sampling biases but may also be caused by changes in larval transport nutrient supply or other environmental pressures (C) 2010 Elsevier Ltd All rights reserved
id: 1924; PT: J; UT: WOS:000284750700012

Reconstructing Holocene conditions under the McMurdo Ice Shelf using Antarctic barnacle shells - Burgess, S. N.; Henderson, G. M.; Hall, B. L. (Earth and Planetary Science Letters, 2010)
This study evaluates the potential of barnacles for paleoceanographic reconstruction and, in particular, of the Antarctic species Bathylasma corolliforme to reconstruct past under ice shelves Like other barnacle species, this Antarctic barnacle secretes a robust low-Mg calcite shell with distinct growth increments on the external surface indicating growth over a number of years (30-50 in samples studied here). The Bathylasma samples used in this study grew in the Ross Sea and became entrained at the grounding line of a coastal ice shelf in McMurdo Sound, offering potential as an archive of changing conditions in this difficult to access environment under the McMurdo ice shelf. Nine barnacle shells were subsampled at high resolution (60 pun) for delta(18)O and delta(13)C analysis. These samples were dated with (14)C and U-Th techniques, although the later did not yield useful age information due to open-system behaviour of barnacle calcite. Measured delta(18)O values indicate that Bathylasma calcifies close to equilibrium with ambient seawater. One older sample (approximate to 200 ka) has similar delta(18)O and delta(13)C values as the eight Holocene samples, suggesting that barnacle calcite is not prone to significant diagenesis in this setting. Apparent isotope equilibrium and lack of diagenesis make barnacles a promising archive for reconstruction of past ocean conditions. Cycles of delta(18)O observed within each sample sometimes correlate with the external growth ridges, but not always, and have amplitudes of typically 0.6 parts per thousand. This magnitude of variation suggests shell growth during a significant portion of the year. although it remains unclear whether growth continues throughout the year. However, the prominent growth bands suggest at least a signficant seasonal slowing in growth rate. Variations in barnacle delta(18)O within each plate and between plates are too large to be caused by temperature. and instead reflect changes in delta(18)O of the seawater, allowing some assessment of seawater salinity under the ice shelf. Salinities are lowered by addition of meltwaters, but the barnacle delta(18)O data suggest values do not go below 33 parts per thousand.. These data indicate that Bathylasma has potential as an archive of paleoclimate information for shallow/intermediate water depths and, in particular, for difficult to reach environments such as below ice-shelves of Antarctica. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved
id: 1960; PT: J; UT: WOS:000283756600013

Reduced ice extent on the western Antarctic Peninsula at 700–970 cal. yr B.P. - Hall, B.L.; Koffman, T.; Denton, G.H. (Geology, 2010)
Rapid warming and consequent ice-shelf collapse have focused attention on the glacial record of the Antarctic Peninsula. Here, we present the first record of terrestrial organic material exposed by recently retreating ice that bears on past glacier extent and climate in this sensitive region. Radiocarbon dates show that ice on Anvers Island was at or behind its present position at 700–970 cal. yr B.P., coincident with ice reduction elsewhere in the Southern Hemisphere. Moreover, the data indicate that present reduced ice extent on the western Antarctic Peninsula is not unprecedented and is similar to that experienced during at least three periods in the last 5600 yr.

Reduced North Atlantic Central Water formation in response to early Holocene ice-sheet melting - Bamberg, A.; Rosenthal, Y.; Paul, A.; Heslop, D.; Mulitza, S.; Ruhlemann, C.; Schulz, M. (Geophysical Research Letters, 2010)
Central waters of the North Atlantic are fundamental for ventilation of the upper ocean and are also linked to the strength of the Atlantic Meridional Overturning Circulation (AMOC). Here, we show based on benthic foraminiferal Mg/Ca ratios, that during times of enhanced melting from the Laurentide Ice Sheet (LIS) between 9.0-8.5 thousand years before present (ka) the production of central waters weakened the upper AMOC resulting in a cooling over the Northern Hemisphere. Centered at 8.54 +/- 0.2 ka and 8.24 +/- 0.1 ka our dataset records two similar to 150-year cooling events in response to the drainage of Lake Agassiz/Ojibway, indicating early slow-down of the upper AMOC in response to the initial freshwater flux into the subpolar gyre (SPG) followed by a more severe weakening of both the upper and lower branches of the AMOC at 8.2 ka. These results highlight the sensitivity of regional North Atlantic climate change to the strength of central-water overturning and exemplify the impact of both gradual and abrupt freshwater fluxes on eastern SPG surface water convection. In light of the possible future increase in Greenland Ice Sheet melting due to global warming these findings may help us to better constrain and possibly predict future North Atlantic climate change. Citation: Bamberg, A., Y. Rosenthal, A. Paul, D. Heslop, S. Mulitza, C. Ruhlemann, and M. Schulz (2010), Reduced North Atlantic Central Water formation in response to early Holocene ice-sheet melting, Geophys. Res. Lett., 37, L17705, doi: 10.1029/2010GL043878.
id: 874; 649FZ Times Cited:3 Cited References Count:32submittedY

Regional seismic stratigraphy and controls on the Quaternary evolution of the Cape Hatteras region of the Atlantic passive margin, USA - Mallinson, D. J.; Culver, S. J.; Riggs, S. R.; Thieler, E. R.; Foster, D.; Wehmiller, J.; Farrell, K. M.; Pierson, J. (Marine Geology, 2010)
Seismic and core data, combined with amino acid racemization and strontium-isotope age data, enable the definition of the Quaternary stratigraphic framework and recognition of geologic controls on the development of the modern coastal system of North Carolina, U.S.A. Seven regionally continuous high amplitude reflections are defined which bound six seismic stratigraphic units consisting of multiple regionally discontinuous depositional sequences and parasequence sets, and enable an understanding of the evolution of this margin. Data reveal the progressive eastward progradation and aggradation of the Quaternary shelf. The early Pleistocene inner shelf occurs at a depth of ca. 20-40 m beneath the western part of the modern estuarine system (Pamlico Sound). A mid- to outer shelf lowstand terrace (also early Pleistocene) with shelf sand ridge deposits comprising parasequence sets within a transgressive systems tract, occurs at a deeper level (ca. 45-70 m) beneath the modern barrier island system (the Outer Banks) and northern Pamlico Sound. Seismic and foraminiferal paleoenvironmental data from cores indicate the occurrence of lowstand strandplain shoreline deposits on the early to middle Pleistocene shelf. Middle to late Pleistocene deposits occur above a prominent unconformity and marine flooding surface that truncates underlying units, and contain numerous filled fluvial valleys that are incised into the early and middle Pleistocene deposits. The stratigraphic framework suggests margin progradation and aggradation modified by an increase in the magnitude of sea-level fluctuations during the middle to late Pleistocene. expressed as falling stage, lowstand, transgressive and highstand systems tracts. Thick stratigraphic sequences occur within the middle Pleistocene section, suggesting the occurrence of high capacity fluvial point sources debouching into the area from the west and north. Furthermore, the antecedent topography plays a significant role in the evolution of the geomorphology and stratigraphy of this marginal system. (C) 2009 Elsevier B.V. All rights reserved.
id: 1862; 556RX Times Cited:0 Cited References Count:71Y

Relative sea-level changes, Schuchert Dal, East Greenland, with implications for ice extent in late-glacial and Holocene times - Hall, B. L.; Baroni, C.; Denton, G. H. (Quaternary Science Reviews, 2010)
The chronology of late-glacial and Holocene ice fluctuations in East Greenland is important for documenting glacier response to climate change and for determining the mechanisms behind abrupt climate switches. Raised marine sediments and landforms suggest culmination of the late-glacial Milne Land Stade in Schuchert Dal alongside Scoresby Sund before similar to 11,900-12,300 cal yr B.P. Ice in Schuchert Dal apparently receded during the later part of the Younger Dryas, consistent with the idea that this period was characterized by strong seasonality. A stillstand or slight readvance probably interrupted overall recession just prior to 11,000 cal yr B.P. In many locations, ice was back close to present positions by the start of the Holocene. The most extensive glacier advance of the Holocene occurred during the Little Ice Age and was restricted to within a few kilometers of present-day ice margins. (C) 2010 Elsevier Ltd. All rights reserved.
id: 1953; PT: J; SI: SI; UT: WOS:000284724400003

The role of glacio-eustasy in sequence formation: Mid-Atlantic Continental Margin, USA - McHugh, Cecilia M.; Hartin, Corinne A.; Mountain, Gregory S.; Gould, Helene M. (Marine Geology, 2010)
Previous studies of the Mid-Atlantic Continental Margin had shown the lack of correlation between Pleistocene glacio-eustatic oscillations and sequence boundaries. This study documents late Pleistocene to Holocene paleoenvironments within a seismic stratigraphic sequence in order to characterize sequence formation and the development of unconformities in response to glacio-eustatic oscillations. The data, high-resolution CHIRP subbottom profiling and 28 vibracores, were collected in water depths of 38 m to 145 m as part of the R/V Endeavor cruise 370 survey to the Mid-Atlantic Continental Margin. Sediment sources, sedimentary and seismic facies associated with the last major glaciation, and oxygen isotope stages OIS 5 to OIS 1 were examined and a chronology was constructed from mollusk assemblages of intertidal origin that allowed tracking the paleoshoreline from 19 to 6 ka BP. The maximum extent of the Last Glacial Maximum (LGM) paleoshoreline at 17 ka BP was documented near the 120 m modern isobath. The shoreline was marked by sediment mounds up to 5 m high and troughs 15 m deep and 1 km wide (interpreted as shoreface and tidal inlet or lagoons) formed from 17 to 15 ka BP. Five kilometers seaward from the LGM shoreline and the head of the Hudson Canyon is a wedge-shaped feature interpreted as a lowstand delta. Sediments older than the last glacial, possibly OIS 3 or OIS 5, onlap a basal unconformity. We correlate this unconformity to a previously identified sequence boundary. Approximately 20 m to 30 m of sediment accumulated on the outer shelf NE of the Hudson Canyon during the last glacial and little deposition has occurred since ~ 11 ka BP. The modern outershelf is covered by ~ 1 m of mollusk-rich glauconitic sand deposited from latest Pleistocene to early Holocene, 15 to 11 ka BP. These results showed a close correspondence between depositional environments and glacio-eustasy but sequence development and sequence boundary formation appeared to be influenced by the incomplete filling of accommodation space due to poor preservation during OIS 2 and low accumulation during the Holocene.
Keywords: Hudson Canyon; Hudson Shelf Valley; Last glacial maximum; Mid-Atlantic Continental Margin; paleoshoreline; sequence stratigraphy

Search for a glacial-age (14)C-depleted ocean reservoir - Broecker, Wally; Clark, Elizabeth (Geophysical Research Letters, 2010)
Measurements of the radiocarbon age difference between mixed benthic foraminifera and several coexisting planktic entities were made in hopes of finding evidence for the existence of an isolated glacial-age abyssal ocean reservoir whose demise would explain the large drops in the (14)C to C ratio in atmosphere and surface ocean carbon which occurred during the period of deglaciation. Forty-six new radiocarbon results were obtained at seven depths covering the full range of glacial time (i.e., similar to 27 to 15 (14)C kyrs) from an equatorial Pacific sediment core at 4.4-km water depth. Even though age reversals for foraminifera (but not for coccoliths) at two of the eight depths and large age differences between G. sacculifer and three submixed-layer planktic species mar this data set, there remains little likelihood that such a reservoir existed. Citation: Broecker, W., and E. Clark (2010), Search for a glacial-age (14)C-depleted ocean reservoir, Geophys. Res. Lett., 37, L13606, doi: 10.1029/2010GL043969.
id: 1923; PT: J; UT: WOS:000280043800003

Selective preservation of old organic carbon fluvially released from sub-Arctic soils - Vonk, J. E.; van Dongen, B. E.; Gustafsson, O. (Geophysical Research Letters, 2010)
Amplified climate warming in the Arctic may cause thaw-remobilization of its large soil organic carbon (SOC) pool. Here we assess the remobilization and preservation of old SOC by the watershed-integrated radiocarbon signature of molecular SOC markers released from northernmost Scandinavia. The radiocarbon analyses revealed a remarkable fractionation for identical vascular plant markers (similar to 420 parts per thousand or similar to 6000 (14)C years) upon settling from surface water to the underlying sediments. From this, we infer fluvial export of two SOC pools; a young surface peat component, and an old deep mineral soil component. The young pool exists as an easily degradable humic suspension, while the old pool is matrix protected from degradation and ballasted for preferential settling. The two soil types with highest OC in Arctic permafrost evidently exhibit different susceptibilities to degradation. Hence, a significant part of the thaw-released OC may simply be fluvially relocated to sediments instead of being emitted to the atmosphere. Citation: Vonk, J.E., B.E. van Dongen, and. Gustafsson (2010), Selective preservation of old organic carbon fluvially released from sub-Arctic soils, Geophys. Res. Lett., 37, L11605, doi:10.1029/2010GL042909.
id: 886; 610KU Times Cited:7 Cited References Count:30Y

Shifting Perceptions of Sacred Spaces: Ceremonial Reuse of Maya Architecture and Monuments at San Bartolo, Guatemala - Craig, Jessica (University of Kansas, 2010)

Sources of CO2 evasion from two subtropical rivers in North America - Zeng, F. W.; Masiello, C. A. (Biogeochemistry, 2010)
We directly measured the partial pressure of dissolved CO2 (pCO(2)) in two humid subtropical rivers in coastal Texas, one highly urbanized (Buffalo Bayou) and one relatively undeveloped (Spring Creek), and analyzed carbon isotopic signatures (Delta C-14 and delta C-13) of riverine dissolved inorganic carbon (DIC) to determine carbon sources sustaining river respiration. Both rivers were highly supersaturated with CO2 at all study sites and on all dates sampled from June 2007 to February 2009. Mean riverine pCO(2) values are 3,052 +/- A 1,364 and 4,702 +/- A 1,980 mu atm for Buffalo Bayou and Spring Creek, respectively. Calculated CO2 emission fluxes per ha of water surface area from these rivers are intermediate between those in tropical and temperate rivers, indicating that globally, humid subtropical rivers may be a significant source of atmospheric CO2. Carbon isotopic signatures revealed that CO2 supersaturation is supported by different carbon sources for the two rivers. In the relatively undeveloped river (Spring Creek), young terrestrial organic matter (OM) is the predominant C source fueling river heterotrophic respiration. In the highly urbanized river (Buffalo Bayou), the high concentration of riverine CO2 is additionally supported by dissolution of CaCO3 likely from pedogenic carbonate, and crushed limestone/dolomite and oyster shells imbedded in old roads in the watershed. Because urban sources of acidity can include HNO3 and H2SO4, whether the limestone/dolomite and shells used by humans act as a net sink or source of atmospheric CO2 needs further study.
646uoTimes Cited:17Cited References Count:55

A Source-to-Sink Study of the Mekong River Delta: Hydrology, Delta Evolution, and Sediment Transport Modeling - Xue, Z. (North Carolina State University, 2010)

The southern Svalbard Margin sedimentary system: preliminary results from EGLACOM cruise 2008 - Melis, R.; Lucchi, R. G.; Giorgetti, G.; Persico, D.; BÁRcena, M. A. A.; Caburlotto, A.; MacrÌ, P.; Villa, G.; Sagnotti, L.; Rebesco, M. (European Geosciences Union, General Assembly 2010, 2010)
id: 873

Sr-Nd-Os evidence for a stable erosion regime in the Himalaya during the past 12 Myr - Galy, Valier; France-Lanord, Christian; Peucker-Ehrenbrink, Bernhard; Huyghe, Pascale (EARTH AND PLANETARY SCIENCE LETTERS, 2010)
Modern erosion of the Himalaya, the world's largest mountain range, transfers huge dissolved and particulate loads to the ocean. It plays an important role in the long-term global carbon cycle, mostly through enhanced organic carbon burial in the Bengal Fan. To understand the role of past Himalayan erosion, the influence of changing climate and tectonic on erosion must be determined. Here we use a 12 Myr sedimentary record from the distal Bengal Fan (Deep Sea Drilling Project Site 218) to reconstruct the Mio-Pliocene history of Himalayan erosion. We use carbon stable isotopes (delta(13)C) of bulk organic matter as paleo-environmental proxy and stratigraphic tool. Multi-isotopic - Sr, Nd and Os - data are used as proxies for the source of the sediments deposited in the Bengal Fan over time. delta(13)C values of bulk organic matter shift dramatically towards less depleted values, revealing the widespread Late Miocene (ca. 7.4 Ma) expansion of C4 plants in the basin. Sr, Nd and Os isotopic compositions indicate a rather stable erosion pattern in the Himalaya range during the past 12 Myr. This supports the existence of a strong connection between the southern Tibetan plateau and the Bengal Fan. The tectonic evolution of the Himalaya range and Southern Tibet seems to have been unable to produce large re-organisation of the drainage system. Moreover, our data do not suggest a rapid change of the altitude of the southern Tibetan plateau during the past 12 Myr. Variations in Sr and Nd isotopic compositions around the late Miocene expansion of C4 plants are suggestive of a relative increase in the erosion of High Himalaya Crystalline rock (i.e. a simultaneous reduction of both Transhimalayan batholiths and Lesser Himalaya relative contributions). This could be related to an increase in aridity as Suggested by the ecological and sedimentological changes at that time. A reversed trend in Sr and Nd isotopic compositions is observed at the Plio-Pleistocene transition that is likely related to higher precipitation and the development of glaciers in the Himalaya. These almost synchronous moderate changes in erosion pattern and climate changes during the late Miocene and at the Plio-Pleistocene transition support the notion of a dominant control of climate on Himalayan erosion during this time period. However, stable erosion regime during the Pleistocene is suggestive of a limited influence of the glacier development on Himalayan erosion. (C) 2010 Elsevier B.V. All rights reserved.
Keywords: Bengal Fan; climate; erosion; Himalaya; Miocene; radiogenic isotopes

Stable isotopes reveal Holocene changes in the diet of Ad,lie penguins in Northern Victoria Land (Ross Sea, Antarctica) - Lorenzini, Sandra; Baroni, Carlo; Fallick, Anthony E.; Baneschi, Ilaria; Salvatore, Maria Cristina; Zanchetta, Giovanni; Dallai, Luigi (Oecologia, 2010)
Ad,lie penguin (Pygoscelis adeliae) modern and fossil eggshells and guano samples collected from ornithogenic soils in Terra Nova Bay (Victoria Land, Ross Sea) were processed for carbon and nitrogen isotopic ratios with the aim of detecting past penguin dietary changes. A detailed and greatly expanded Ad,lie penguin dietary record dated back to 7,200 years BP has been reconstructed for the investigated area. Our data indicate a significant dietary shift between fish and krill, with a gradual decrease from past to present time in the proportion of fish compared to krill in Ad,lie penguin diet. From 7,200 to 2,000 years BP, delta(13)C and delta(15)N values indicate fish as the most eaten prey. The dietary contribution of lower-trophic prey in penguin diet started becoming evident not earlier than 2,000 years BP, when the delta(13)C values reveal a change in the penguin feeding behavior. Modern eggshell and guano samples reveal a major dietary contribution of krill but not a krill-dominated diet, since delta(13)C values remain much too high if krill prevail in the diet. According to the Holocene environmental background attested for Victoria Land, Ad,lie penguin dietary shifts between fish and krill seem to reflect penguin paleoecological responses to different paleoenvironmental settings with different conditions of sea-ice extension and persistence. Furthermore, Ad,lie penguin diet appears to be particularly affected by environmental changes in a very specific period within the breeding season, namely the egg-laying period when penguin dietary and feeding habit shifts are clearly documented by the delta(13)C of eggshell carbonate.
id: 2350; PT: J; TC: 6; UT: WOS:000284271900007

Stable nitrogen and carbon isotope (delta(15)N and delta(13)C) variability in shallow tropical Pacific soft coral and black coral taxa and implications for paleoceanographic reconstructions - Williams, Branwen; Grottoli, Andrea G. (Geochimica et Cosmochimica Acta, 2010)
Soft corals and black corals are useful proxy tools for paleoceanographic reconstructions. However, most work has focused on deep-water taxa and few studies have used these corals as proxy organisms in shallow water (
id: 1963; PT: J; UT: WOS:000281094900009

Submarine Mass Transport Within Monterey Canyon: Benthic Disturbance Controls on the Distribution of Chemosynthetic Biological Communities - Paull, C. K.; Schlining, B.; Ussler, W.; Lundste, E.; Barry, J. P.; Caress, D. W.; Johnson, J. E.; McGann, M. (Submarine mass movements and their consequences, 4th International Symposium:, 2010)
Documenting mass transport within Monterey Canyon and Fan has been a focus of remotely operated vehicle (ROV) observations, sampling, monitoring, and multibeam mapping studies. These efforts indicate that major mass transport events occur within upper Monterey Canyon (2 km water depths) and onto Monterey Fan for ~100 years. Simultaneous efforts to document the distribution of benthic taxa observed in the video records from 668 ROV dives conducted by the Monterey Bay Aquarium Research Institute (MBARI) provide a uniquely detailed record of the occurrence of chemosynthetic biological communities (CBC). The combined results of these studies provide an understanding of the relationship between disturbance caused by episodic mass wasting events and the distribution of CBC. CBC are common within the canyon's axis below ~2.5 km water depth, but have not been found within the canyon's axis at depths shallower than 2 km. Moreover, CBC occur on the canyon walls at essentially any depth, primarily within young (~hundreds of years old) slump scars. The distribution of CBC provides evidence about the disturbance history of the seafloor. Major mass transport events will destroy communities that lie in their path. Erosion associated with major mass transport events can create environments to support CBC by exposing methane-bearing strata. This can happen as a result of slumping events on the sidewalls of the canyon or where major gravity flow events have excavated the base of canyon walls. Once fresh strata are exposed, geochemical conditions to support CBC will persist for a few centuries. Because CBC are composed of slow-growing and long-lived organisms, it will take decades for these communities to be established. Their existence indicates that environmental stability has occurred over a similar time scale.
id: 879

Synchronous Deglacial Overturning and Water Mass Source Changes - Roberts, N. L.; Piotrowski, A. M.; McManus, J. F.; Keigwin, L. D. (Science, 2010)
Understanding changes in ocean circulation during the last deglaciation is crucial to unraveling the dynamics of glacial-interglacial and millennial climate shifts. We used neodymium isotope measurements on postdepositional iron-manganese oxide coatings precipitated on planktonic foraminifera to reconstruct changes in the bottom water source of the deep western North Atlantic at the Bermuda Rise. Comparison of our deep water source record with overturning strength proxies shows that both the deep water mass source and the overturning rate shifted rapidly and synchronously during the last deglacial transition. In contrast, any freshwater perturbation caused by Heinrich event 1 could have only affected shallow overturning. These findings show how changes in upper-ocean overturning associated with millennial-scale events differ from those associated with whole-ocean deglacial climate events.

Temperature and salinity changes in the deglacial North Atlantic - Benway, H.M.; McManus, J.F.; Oppo, D.W.; Cullen, J.F. (Quaternary Science Reviews, 2010)

The Ties That Bind: 3000 Years of Fabric Production and Fiber Use in the Ozark Plateau - Horton, Elizabeth T. (75th annual Conference of the Society for American Archaeology, 2010)
id: 776

Timescales of lateral sediment transport in the Panama Basin as revealed by radiocarbon ages of alkenones, total organic carbon and foraminifera - Kusch, Stephanie; Eglinton, Timothy I.; Mix, Alan C.; Mollenhauer, Gesine (Earth and Planetary Science Letters, 2010)
id: 882Y

Unique Baltic Outcrops Reveal Millennia of Ecological Changes - Buynevich, I. V.; Bitinas, A.; Damušytė, A.; Pupienis, D. (EOS, TRANSACTIONS AMERICAN GEOPHYSICAL UNION, 2010)
Throughout Earth's history, tectonic forces, often violent and unpredictable, have been responsible for exposing geological formations to scientific scrutiny. But forces of uplift are not restricted to plate boundaries. For example, when looking at forested coastal dunes bordering placid Curonian Lagoon along the Lithuanian coast of the Baltic Sea, one hardly suspects that any powerful forces are at work. Yet this is a site where massive migrating hills of sand have put pressure on the deep strata of the ancient lagoon, forcing its sediments to the surface and offering rare access to fossils of the Holocene, which spans the past 10,000 years.
id: 1978

Using proglacial-threshold lakes to constrain fluctuations of the Jakobshavn Isbræ ice margin, western Greenland, during the Holocene - Briner, J.P.; Stewart, H.A.M.; Young, N.E.; Philipps, W.; Losee, S. (Quaternary Science Reviews, 2010)
The future response of the Greenland Ice Sheet (GIS) and its potential contribution to sea level rise are uncertain. Rapid changes of Greenland’s outlet glaciers over the past decade have made it difficult to extrapolate ice sheet change into the future. This significant short-term variability highlights the need for longer-term, geologic (e.g., Holocene) records of ice margin fluctuations. However, a major challenge with reconstructing the GIS during the Holocene stems from it having been smaller than it is at present, thus traditional glacial geologic approaches are not suitable. We use radiocarbon-dated sediment sequences from seven proglacial-threshold lakes spanning ∼50 km of the western GIS margin near Jakobshavn Isbræ to constrain the timing of early Holocene deglaciation, the duration that this sector of the western GIS was smaller than its present configuration, and the timing of its advance during Neoglaciation. Our reconstructions suggest deglaciation ∼7300 cal yr BP, minimum ice extent ∼6000–5000 cal yr BP and smaller-than-present ice configuration until at least ∼2300 cal yr BP for the ice margin south of Jakobshavn Isbræ, and until ∼400 cal yr BP for the ice margin north of Jakobshavn Isbræ. One relatively large proglacial lake that became briefly ice-free during the middle Holocene lies in a catchment that likely extends 10s of km inland beneath the GIS, suggesting significant middle Holocene retreat of this portion of the GIS. The overall pattern of ice sheet change is inconsistent with existing ice sheet model reconstructions for this region, but is consistent with numerous paleoclimate proxy and relative sea level data. These continuous lacustrine records corroborate, but provide closer age control than, existing non-continuous records of radiocarbon-dated reworked bivalves from historical moraines in the region. Reconstructing ice margin change from proglacial-threshold lakes is one of few approaches with the potential to constrain smaller-than-present ice sheet extent.

Variations in the distribution and radiocarbon age of lignin phenols exported by large river systems - Feng, X. J.; Montlucon, D. B.; Eglinton, T. I. (Geochimica Et Cosmochimica Acta, 2010)
Suppl. 1676tl Times Cited:0 Cited References Count:0

Were last glacial climate events simultaneous between Greenland and France? A quantitative comparison using non-tuned chronologies RID E-4539-2011 RID A-2643-2010 - Blaauw, Maarten; Wohlfarth, Barbara; Christen, J. Andres; Ampel, Linda; Veres, Daniel; Hughen, Konrad A.; Preusser, Frank; Svensson, Anders (Journal of Quaternary Science, 2010)
Several large abrupt climate fluctuations during the last glacial have been recorded in Greenland ice cores and archives from other regions. Often these Dansgaard-Oeschger events are assumed to have been synchronous over wide areas, and then used as tie-points to link chronologies between the proxy archives. However, it has not yet been tested independently whether or not these events were indeed synchronous over large areas. Here, we compare Dansgaard-Oeschger-type events in a well-dated record from southeastern France with those in Greenland ice cores. Instead of assuming simultaneous climate events between both archives, we keep their age models independent. Even these well-dated archives possess large chronological uncertainties that prevent us from inferring synchronous climate events at decadal to multi-centennial time scales. If possible, comparisons between proxy archives should be based on independent, non-tuned time-scales. Copyright (C) 2009 John Wiley & Sons, Ltd.
id: 1986; PT: J; UT: WOS:000276090800014

Year-round probing of soot carbon and secondary organic carbon contributions and sources to the South Asian Atmospheric Brown Cloud using radiocarbon (14C) measurements - Kirillova, Elena; Sheesley, Rebecca J.; Andersson, August; Kruså, Martin; Safai, P. D.; Budhavant, Krishnakant; Rao, P. S. P.; Praveen, P. S.; Gustafsson, Örjan (EGU General Assembly 2010, held 2-7 May, 2010 in Vienna, Austria, 2010)
South Asia is one region of vital importance for assessing human impact on radiative forcing by atmospheric aerosols. Previous research in the region has indicated that black carbon is a significant component of the regional aerosol load. In contrast, there is more ambiguous information regarding the contribution of secondary organic aerosols (SOA) to the total carbonaceous (TC) aerosol composition. Here we primarily address the SOA component of the South Asian Atmospheric Brown Cloud (ABC) by a combination of measurements of SOA concentrations and the 14C signature of TC. Atmospheric particulate matter was collected during fourteen-month continuous sampling campaigns Jan 2008 - March 2009 at both the Maldives Climate Observatory at Hannimaadho (MCO-H) and at the Sinhagad hilltop sampling site of the Indian Institute of Tropical Meteorology (SIN) in central-western India. The radiocarbon method is an ideal approach to identify fossil sources (14C "dead") compared to biogenic and biomass combustion products (with a contemporary 14C signal). The radiocarbon source apportionment of TC revealed very similar contribution from biogenic/biomass combustion (60-70%) for Indian SIN site and the MCOH receptor regions for much of the year. However, during the summer monsoon season biomass contribution to TC at the Indian Ocean site increases to 70-80%, while it decreases to 40-50% at the Indian site. Source apportionment of a soot carbon (SC) isolate (CTO-375 method; a tracer of black carbon) shows a similar trend. According to preliminary data in summer biomass contribution is higher at the MCOH receptor site (70%) compared to the SIN background site (45%). These unique year-round 14C data will be interpreted in view of the SOA concentration and the varying origin of the air masses.
id: 870Y

Younger Dryas Event and formation of peat layers in the northern Yellow Sea - Li, Tiegang; Chang, Fengming; Yu, Xinke (Earth Science Frontiers, 2010)
Peat layer, which formed under the humid climatic conditions and during the stagnated phase of sea level changes, is an important vehicle for information of paleoenvironmental evolution. Results of study on four sections of peat layer from the northern Yellow Sea indicate that all of them are located on the mouth of Bohai Sea strait between 50 and 54 meters water depth. The AMS 14C ages of peat layer are in the range between 10650 and 10100 a BP, which are highly coincident with the age of the Younger Dryas event that was the most significant cold climatic event during the last deglacial warming and occurred between 11000 and 10000 14C a BP. This coincidence indicates that the formation of peat layers in the northern Yellow Sea may be closely correlated with the global impact of Younger Dryas event and can be regard as an evidence of the response of the northern Yellow Sea area to it. The mass appearance of peat layer implies that during the Younger Dryas event a few stagnated periods existed in the postglacial process of sea level rising, the sea level had reached the outside of Bohai Sea strait and may have lingered for about thousand years. The above results and records of pollen suggest that during the period from 10600 to 10200 14C a BP, the northern Yellow Sea was in a cold and humid environment. The humid condition in the northern Yellow Sea area during the Younger Dryas event was distinctly different from the most terrestrial and oceanic records of Younger Dryas event in the global, which shows distinctive effect of Younger Dryas event in different region, and it is irresponsible to diagnose the characteristics of response to Younger Dryas events in different regions based on a single dry and cold mode.
id: 1969
Keywords: northern Yellow Sea; peat layer; sea level; Younger Dryas Event

A 2000 year midge-based paleotemperature reconstruction from the Canadian Arctic archipelago - Porinchu, D.; MacDonald, G.; Rolland, N. (Journal of Paleolimnology, 2009)
A lake sediment core recovered from Lake V57 on Victoria Island, Nunavut, Canada, spanning the last 2000 years, was analyzed for sub-fossil midge remains and organic-matter content (estimated by loss-on-ignition (LOI)). Significant changes in midge community composition occurred during the last 2000 years, with a distinct midge community appearing after 1600 AD. The chironomid community between 0 and 1600 AD was dominated by Heterotrissocladius, Tanytarsus, Abiskomyia, and Paracladius. At approximately 1600 AD, Heterotrissocladius decreased in relative abundance and taxa such as Corynocera ambigua, C. oliveri, Psectrocladius sordidellus type, and Pentanneurini increased in relative abundance. Previously published midge-based inference models for average July air temperature (AJAT) and summer surface-water temperature (SSWT) were applied to the subfossil midge stratigraphy. The AJAT reconstruction indicates relatively cool conditions existed between 1100 and 1600 AD, with exceptional warming occuring after 1600 AD, as lake productivity inferred from organic-matter content increased concomitantly with midge-inferred AJAT and SSWT. The cooler conditions between 1200 and 1600 AD, and the pattern of warming over recent centuries inferred from Lake V57 is broadly consistent with temperature-sensitive biogenic silica records from other sites in the central Canadian Arctic and the treeline zone to the south suggesting a regionally synchronous response to climate forcing.
id: 1863; 395EF Times Cited:3 Cited References Count:57Y

2,000-year-long temperature and hydrology reconstructions from the Indo-Pacific warm pool - Oppo, D. W.; Rosenthal, Y.; Linsley, B. K. (Nature, 2009)
Northern Hemisphere surface temperature reconstructions suggest that the late twentieth century was warmer than any other time during the past 500 years and possibly any time during the past 1,300 years (refs 1, 2). These temperature reconstructions are based largely on terrestrial records from extra-tropical or high-elevation sites; however, global average surface temperature changes closely follow those of the global tropics(3), which are 75% ocean. In particular, the tropical Indo-Pacific warm pool (IPWP) represents a major heat reservoir that both influences global atmospheric circulation(4) and responds to remote northern high-latitude forcings(5,6). Here we present a decadally resolved continuous sea surface temperature (SST) reconstruction from the IPWP that spans the past two millennia and overlaps the instrumental record, enabling both a direct comparison of proxy data to the instrumental record and an evaluation of past changes in the context of twentieth century trends. Our record from the Makassar Strait, Indonesia, exhibits trends that are similar to a recent Northern Hemisphere temperature reconstruction(2). Reconstructed SST was, however, within error of modern values from about AD 1000 to AD 1250, towards the end of the Medieval Warm Period. SSTs during the Little Ice Age ( approximately AD 1550-1850) were variable, and similar to 0.5 to 1 degrees C colder than modern values during the coldest intervals. A companion reconstruction of delta O-18 of sea water-a sea surface salinity and hydrology indicator-indicates a tight coupling with the East Asian monsoon system and remote control of IPWP hydrology on centennial-millennial timescales, rather than a dominant influence from local SST variation.
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A 24,900-year paleolimnological history from the Peruvian Andes - Hillyer, R.; Valencia, B. G.; Bush, M. B.; Silman, M. R.; Steinitz-Kannan, M. (Quaternary Research, 2009)
id: 1902

5000 year sedimentary record of hurricane strikes on the central coast of Belize - McCloskey, T. A.; Keller, G. (Quaternary International, 2009)
The central coast of Belize has been subject to hurricane strikes throughout recorded history with immense human and material cost to the Belizean people. What remains unknown is the long-term frequency of hurricane strikes and the effects such storms may have had on the ancient Maya civilization. Our sedimentary study of major hurricane strikes over the past 5000 years provides preliminary insights. We calculate that over the past 500 years major hurricanes have struck the Belize coast on average once every decade. One giant hurricane with probably particularly catastrophic consequences struck Belize sometime before AD 1500. A temporal clustering of hurricanes suggests two periods of hyperactivity between similar to 4500 and 2500 (14)Cyr BP, which supports a regional model of latitudinal migration of hurricane strike zones. Our preliminary hurricane data, including the extreme apparent size of the giant event, suggest that prehistoric hurricanes were capable of having exerted significant environmental stress in Maya antiquity. (c) 2008 Elsevier Ltd and INQUA. All rights reserved.
id: 2008; PT: J; CT: Workshop on Hurricanes and Typhoons - From the Field Records to the Forecast; CY: SEP 25-28, 2006; CL: Lafayette, LA; SP: United Nat Int Geosci Program, Int Geosphere-Biosphere Programme Past Global Changes; UT: WOS:000263692000006

8000 Years of Human Settlement and Land Use in Old Ranch Canyon, Santa Rosa Island, California - Rick, Torben C. (Proceedings of the Seventh California Islands Symposium, 2009)
id: 2074

Abrupt climate change as an important agent of ecological change in the Northeast US throughout the past 15,000 years - Shuman, B. N.; Newby, P.; Donnelly, J. P. (Quaternary Science Reviews, 2009)
We use a series of tests to evaluate two competing hypotheses about the association of climate and vegetation trends in the northeastern United States over the past 15 kyrs. First, that abrupt climate changes on the scale of centuries had little influence on long-term vegetation trends, and second, that abrupt climate changes interacted with slower climate trends to determine the regional sequence of vegetation phases. Our results support the second. Large dissimilarity between temporally close fossil pollen samples indicates large vegetation changes within 500 years across >4 degrees of latitude at ca 13.25-12.75, 12.0-11.5, 10.5, 8.25, and 5.25 ka. The evidence of vegetation change coincides with independent isotopic and sedimentary indicators of rapid shifts in temperature and moisture balance. In several cases, abrupt changes reversed long-term vegetation trends, such as when spruce (Picea) and pine (Pinus) pollen percentages rapidly declined to the north and increased to the south at ca 13.25-12.75 and 8.25 ka respectively. Abrupt events accelerated other long-term trends, such as a regional increase in beech (Fagus) pollen percentages at 8.5-8.0 ka. The regional hemlock (Tsuga) decline at ca 5.25 ka is unique among the abrupt events, and may have been induced by high climatic variability (i.e., repeated severe droughts from 5.7 to 2.0 ka); autoregressive ecological and evolutionary processes could have maintained low hemlock abundance until ca 2.0 ka. Delayed increases in chestnut (Castanea) pollen abundance after 5.8 and 2.5 ka also illustrate the potential for multi-century climate variability to influence species' recruitment as well as mortality. Future climate changes will probably also rapidly initiate persistent vegetation change, particularly by acting as broad, regional-scale disturbances. (C) 2009 Published by Elsevier Ltd.
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Newby, Paige Donnelly, Jeffrey P. Pergamon-elsevier science ltd Oxford Sp. Iss. SI; YY

Abrupt mid-Holocene onset of centennial-scale climate variability on the Peru-Chile Margin - Chazen, C. R.; Altabet, M. A.; Herbert, T. D. (Geophysical Research Letters, 2009)
Understanding the natural climate variations in the eastern tropical Pacific (ETP) is crucial for predicting the evolution of the El Nino-Southern Oscillation (ENSO). Here we present the first continuous, decadal-resolution Holocene climate record from the Peru-Chile Margin, near the epicenter of the modern ENSO system. Geochemical proxies allow us to reconstruct sea surface temperature, phytoplankton productivity, and thermocline ventilation, variables that are tightly correlated to ENSO events today. Despite the observation that the mean state of all three variables did not change over the past 10,000 years, our data reveal a dramatic increase in climate variability near 5 ka; represented by prolonged periods (50-200 yrs) of climate extremes, which are absent in the early Holocene. These centennial-scale oscillations do not show typical El Nino-La Nina correlations between proxies. We therefore posit that a significant fraction of super-ENSO variance may originate outside the tropics, through processes that ventilate the ETP subsurface waters. Citation: Chazen, C. R., M. A. Altabet, and T. D. Herbert (2009), Abrupt mid-Holocene onset of centennial-scale climate variability on the Peru-Chile Margin, Geophys. Res. Lett., 36, L18704, doi:10.1029/2009GL039749.
id: 1890; 499OY Times Cited:0 Cited References Count:41Y

Age Validation of Freshwater Drum using Bomb Radiocarbon - Davis-Foust, S. L.; Bruch, R. M.; Campana, S. E.; Olynyk, R. P.; Janssen, J. (Transactions of the American Fisheries Society, 2009)
The ages of freshwater drum Aplodinotus grunniens have typically been estimated by counting the growth increments on their scales or otoliths, but the accuracy of these estimates has not been validated. We used accelerator mass spectrometry (AMS) bomb radiocarbon dating to validate age estimates from sagittal otoliths of freshwater drum from the Lake Winnebago system, Wisconsin. The freshwater drum Delta C-14 chronology from the AMS assay closely reflects the timing and shape of other bomb radiocarbon chronologies, thus validating the accuracy of otolith growth increments to at least age 52 +/- 2 years. The progression of a strong 1983 year-class, which was detected every year sampled over the course of the study (1986, 2003-2007), and indices of year-class abundance calculated from trawling assessments on Lake Winnebago (1986-2007) corroborated otolith ages. Age estimate comparisons between scales, anal spines, dorsal spines, and otoliths showed scales and spines to be completely unreliable as aging structures after age 2. Freshwater drum live to very old ages relative to most other Great Lakes fishes; our oldest specimen based on an otolith age estimate was 58 years old.
id: 802; 477EI Times Cited:1 Cited References Count:58Y

Atlantic hurricanes and climate over the past 1,500 years - Mann, M. E.; Woodruff, J. D.; Donnelly, J. P.; Zhang, Z. H. (Nature, 2009)
Atlantic tropical cyclone activity, as measured by annual storm counts, reached anomalous levels over the past decade(1). The short nature of the historical record and potential issues with its reliability in earlier decades, however, has prompted an ongoing debate regarding the reality and significance of the recent rise(2-5). Here we place recent activity in a longer-term context by comparing two independent estimates of tropical cyclone activity over the past 1,500 years. The first estimate is based on a composite of regional sedimentary evidence of landfalling hurricanes, while the second estimate uses a previously published statistical model of Atlantic tropical cyclone activity driven by proxy reconstructions of past climate changes. Both approaches yield consistent evidence of a peak in Atlantic tropical cyclone activity during medieval times (around AD 1000) followed by a subsequent lull in activity. The statistical model indicates that the medieval peak, which rivals or even exceeds (within uncertainties) recent levels of activity, results from the reinforcing effects of La-Nina-like climate conditions and relative tropical Atlantic warmth.
id: 1893; ISI Document Delivery No.: 483CB Times Cited: 2 Cited Reference Count: 37 Cited References: BOLDT K, MAR GEOL UNPUB COBB KM, 2003, NATURE, V424, P271, DOI 10.1038/nature01779 DONNELLY JP, 2001, GEOL SOC AM BULL, V113, P714 DONNELLY JP, 2001, GEOLOGY, V29, P615 DONNELLY JP, 2004, MAR GEOL, V210, P107, DOI 10.1016/j.margeo.2004.05.005 DONNELLY JP, 2007, NATURE, V447, P465, DOI 10.1038/nature05834 ELSNER JB, 2008, J APPL METEOROL CLIM, V47, P368, DOI 10.1175/2007JAMC1692.1 GARCIAHERRERA R, 2005, J GEOPHYS RES-ATMOS, V110, ARTN D03109 GRAHAM NE, 2007, CLIMATIC CHANGE, V83, P241, DOI 10.1007/s10584-007-9239-2 HIPPENSTEEL SP, 2005, GEOL SOC AM BULL, V117, P250, DOI 10.1130/B25535.1 HOLLAND GJ, 2007, PHIL T R SOC A, DOI 10.1098/RSTA.2007.2083 JONES PD, 1997, INT J CLIMATOL, V17, P1433 KAPLAN A, 1998, J GEOPHYS RES-OCEANS, V103, P18567 KEIGWIN LD, 1996, SCIENCE, V274, P1504 KNUTSON TR, 2008, NAT GEOSCI, V1, P359, DOI 10.1038/ngeo202 LAMBERT WJ, 2003, T GULF COAST ASS GEO, V53, P443 LANDSEA CW, 2007, EOS T AGU, V88, P197, DOI 10.1029/2007E0180001 LIU KB, 2000, QUATERNARY RES, V54, P238 LUTERBACHER J, 2002, ATMOS SCI LETT, V2, P114, DOI 10.1006/ASLE.2001.0044 MANN ME, SCIENCE UNPUB MANN ME, 2005, J CLIMATE, V18, P447 MANN ME, 2007, EOS, V88, P349, DOI 10.1029/2007E0360002 MANN ME, 2007, GEOPHYS RES LETT, V34, ARTN L22707 MANN ME, 2008, GEOPHYS RES LETT, V35, DOI 10.1029/2008GL034716 NEU U, 2008, NATURE, V451, E5, DOI 10.1038/nature06576 NYBERG J, 2007, NATURE, V447, P698, DOI 10.1038/nature05895 OTVOS EG, 2002, QUATERNARY RES, V57, P425 RAYNER NA, 2003, J GEOPHYS RES-ATMOS, V108, ARTN 4407 RICHEY JN, 2007, GEOLOGY, V35, P423, DOI 10.1130/G23507A.1 SABBATELLI TA, J GEOPHYS RES UNPUB SABBATELLI TA, 2007, J GEOPHYS RES-ATMOS, V112, ARTN D17114 SCILEPPI E, 2007, GEOCHEM GEOPHY GEOSY, V8, P1 SCOTT DB, 2003, GEOL SOC AM BULL, V115, P1027 SMITH TM, 2003, J CLIMATE, V16, P1495 VECCHI GA, 2007, GEOPHYS RES LETT, V34, ARTN L08702 WOODRUFF JD, 2008, GEOCHEM GEOPHY GEOSY, V9, DOI 10.1029/2008GC002043 WOODRUFF JD, 2008, GEOLOGY, V36, P391, DOI 10.1130/G24731A.1 Mann, Michael E. Woodruff, Jonathan D. Donnelly, Jeffrey P. Zhang, Zhihua National Science Foundation [ATM-0542356, EAR-0519118, OCE-0402746]; YY

Bioturbation artifacts in zero-age sediments - Keigwin, L. D.; Guilderson, T. P. (Paleoceanography, 2009)
Most seafloor sediments are dated with radiocarbon, and the sediment is assumed to be zero-age (modern) when the signal of atmospheric testing of nuclear weapons is present (Fraction modern (Fm) > 1). Using a simple mass balance, we show that even with Fm > 1, half of the planktonic foraminifera at the seafloor can be centuries old, because of bioturbation. This calculation, and data from four core sites in the western North Atlantic indicate that, first, during some part of the Little Ice Age (LIA) there may have been more Antarctic Bottom Water than today in the deep western North Atlantic. Alternatively, bioturbation may have introduced much older benthic foraminifera into surface sediments. Second, paleo-based warming of Sargasso Sea surface waters since the LIA must lag the actual warming because of bioturbation of older and colder foraminifera.
id: 1826; 535DQ Times Cited:0 Cited References Count:18; YY

Black carbon in marine particulate organic carbon: Inputs and cycling of highly recalcitrant organic carbon in the Gulf of Maine - Flores-Cervantes, D. X.; Plata, D. L.; MacFarlane, J. K.; Reddy, C. M.; Gschwend, P. M. (Marine Chemistry, 2009)
To increase our understanding of the roles of black carbon (BC), a highly sorptive and recalcitrant material, we measured BC concentrations and fluxes in marine particulate organic carbon (POC) out of the water column in the Gulf of Maine (GoM), a representative coastal area downwind of important BC sources of the Northeastern United States. Concentrations ranged from
id: 1865; 440SC Times Cited:0 Cited References Count:85; YY

Bomb dating and age determination of skates (family Rajidae) off the eastern coast of Canada - McPhie, R. P.; Campana, S. E. (Ices Journal of Marine Science, 2009)
Recent declines in abundance of skates off the eastern coast of Canada have heightened the need for validated age and growth estimates in the region. In all, 502 winter (Leucoraja ocellata), little (Leucoraja erinacea), thorny (Amblyraja radiata), and smooth (Malacoraja senta) skate vertebral centra collected seasonally between 1999 and 2004 were sectioned using a mass processing method, then used to reconstruct growth in each species. Bomb rediocarbon (Delta C-14) analysis was used to provide evidence of annual band-pair deposition in thorny skates. Estimates of L-infinity from traditional von Bertalanffy growth models (VBGM) ranged from 60.6 cm (little skate) to 89.7 cm (thorny skate), and K estimates from 0.07 (thorny skate) to 0.19 (little skate). A modified two-parameter VBGM (L-MAX = 94.1 cm) fitted to winter skate lenght-at-age data yielded a value of K to 0.15. Maximum observed ages ranged from 12 (little skate) to 19 years in both winter and thorny skates. The year-specific incorporation of Delta C-14 milled from thorny and winter skate vertebral sections closely resembled shark-derived reference chronology values from the Northwest Atlantic. Pre-bomb Delta C-14 in a thorny skate collected in 1988 and aged at 23 years appeared to validate age interpretations and suggested that thorny skate reach an absolute age of at least 28 years, the oldest validated age reported for any species of batoid.
id: 1856; 421XR Times Cited:3 Cited References Count:82Y

Brown Clouds over South Asia: Biomass or Fossil Fuel Combustion? - Gustafsson, O.; Krusa, M.; Zencak, Z.; Sheesley, R. J.; Granat, L.; Engstrom, E.; Praveen, P. S.; Rao, P. S. P.; Leck, C.; Rodhe, H. (Science, 2009)
Carbonaceous aerosols cause strong atmospheric heating and large surface cooling that is as important to South Asian climate forcing as greenhouse gases, yet the aerosol sources are poorly understood. Emission inventory models suggest that biofuel burning accounts for 50 to 90% of emissions, whereas the elemental composition of ambient aerosols points to fossil fuel combustion. We used radiocarbon measurements of winter monsoon aerosols from western India and the Indian Ocean to determine that biomass combustion produced two- thirds of the bulk carbonaceous aerosols, as well as one- half and two- thirds of two black carbon subfractions, respectively. These constraints show that both biomass combustion ( such as residential cooking and agricultural burning) and fossil fuel combustion should be targeted to mitigate climate effects and improve air quality.
id: 1867; 396JL Times Cited:8 Cited References Count:33Y

Carbonaceous aerosol over a Pinus taeda forest in Central North Carolina, USA - Geron, Chris (Atmospheric Environment, 2009)
Organic aerosol is the least understood component of ambient fine particulate matter (PM(2.5)). In this study, organic and elemental carbon (OC and EC) within ambient PM(2.5) over a three-year period at a forested site in the North Carolina Piedmont are presented. EC exhibited significant weekday/weekend effects and less significant seasonal effects, in contrast to OC, which showed strong seasonal differences and smaller weekend/weekday effects. Summer OC concentrations are about twice as high as winter concentrations, while EC was somewhat higher in the winter. OC was highly correlated with EC during cool periods when both were controlled by primary combustion sources. This correlation decreased with increasing temperature, reflecting higher contributions from secondary organic aerosol, likely of biogenic origin. PM(2.)5 radiocarbon data from the site confirms that a large fraction of the carbon in PM(2.5) is indeed of biogenic origin, since modern (non-fossil fuel derived) carbon accounted for 80% of the PM(2.5) carbon over the course of a year. OC and EC exhibited distinct diurnal profiles, with summertime OC peaking in late evening and declining until midday, During winter, DC peaked during the early morning hours and again declined until midday. Summertime EC peaked during late morning hours except on weekends. Wintertime EC often peaked in late PM or early AM hours due to local residential wood combustion emissions. The highest short term peaks in OC and EC were associated with wildfire events. These data corroborate recent source apportionment Studies conducted within 20 km of our site, where oxidation products of isoprene, alpha-pinene, and beta-caryophyllene were identified as important precursors to organic aerosols. A large fraction of the carbon in rural southeastern ambient PM(2.5), appears to be of biogenic origin, which is probably difficult to reduce by anthropogenic controls. Published by Elsevier Ltd.
id: 1958; PT: J; UT: WOS:000263188100024

Changes in sediment and organic carbon accumulation in a highly-disturbed ecosystem: The Sacramento-San Joaquin River Delta (California, USA) - Canuel, E. A.; Lerberg, E. J.; Dickhut, R. M.; Kuehl, S. A.; Bianchi, T. S.; Wakeham, S. G. (Marine Pollution Bulletin, 2009)
We used the Sacramento-San Joaquin River Delta CA (Delta, hereafter) as a model system for understanding how human activities influence the delivery of sediment and total organic carbon (TOC) over the past 50-60 years. Sediment cores were collected from sites within the Delta representing the Sacramento River (SAC), the San Joaquin River (SJR), and Franks Tract (FT), a flooded agricultural tract. A variety of anthropogenic tracers including (CS)-C-137, total DDE (Sigma DDE) and brominated diphenyl ether (BDE) congeners were used to quantify sediment accumulation rates. This information was combined with total organic carbon (TOC) profiles to quantify rates of TOC accumulation. Across the three sites, sediment and TOC accumulation rates were four to eight-fold higher prior to 1972. Changes in sediment and TOC accumulation were coincident with completion of several large reservoirs and increased agriculture and urbanization in the Delta watershed. Radiocarbon content of TOC indicated that much of the carbon delivered to the Delta is "pre-aged" reflecting processing in the Delta watershed or during transport to the sites rather than an input of predominantly contemporary carbon (e.g., 900-1400 years BP in surface sediments and 2200 yrs BP and 3610 yrs BP at the base of the SJR and FT cores, respectively). Together, these data suggest that human activities have altered the amount and age of TOC accumulating in the Delta since the 1940s. (C) 2009 Elsevier Ltd. All rights reserved.
id: 1845; Sp. Iss. SI 477XX Times Cited:1 Cited References Count:49Y

Chemical and isotopic characterization of size-fractionated organic matter from cryoturbated tundra soils, northern Alaska - Xu, C. H.; Guo, L. D.; Ping, C. L.; White, D. M. (Journal of Geophysical Research-Biogeosciences, 2009)
Recent studies indicate a second layer of organic matter often accumulates in the lower active layer and upper permafrost in arctic tundra soils as a result of cryoturbation. In this study, cryoturbated organic matter was characterized using a combination of physical size fractionation and modern analytical techniques for elemental composition (C and N), stable isotopes (delta(13) C and delta N-15), radiocarbon content (Delta C-14), and molecular fingerprinting (pyrolysis-gas chromatography/mass spectrometry, Py-GC/MS). The results indicated that cryoturbated organic matter could be highly bioavailable. Soil organic matter (SOM) associated with fine sand particles was considered to be the organic carbon pool most sensitive to the changing climate. More organic matter is stabilized on clay minerals in arctic tundra soils compared to those in temperate and tropical soils. The bioavailable soluble organic matter extracted from cryoturbated soil was found to have significant long-term effects on carbon cycling. The similar molecular composition between cryoturbated and surface soil organic matter suggests that the vegetation cover has not significantly changed since the early Holocene. Furthermore, the SOM quality in moist acidic tundra was found to be higher than that of wet nonacidic tundra. With thawing permafrost and a deepening of the active layer, cryotrubated organic matter could reenter the biogeochemical cycles in the Arctic, resulting in a positive feedback to climate change.
id: 1828; 475IS Times Cited:0 Cited References Count:61Y

Chemical and isotopic composition of high-molecular-weight dissolved organic matter from the Mississippi River plume - Guo, L. D.; White, D. M.; Xu, C.; Santschi, P. H. (Marine Chemistry, 2009)
In order to examine the source and transformation of high-molecular-weight dissolved organic matter (HMW-DOM) in the mixing zone of the Mississippi River plume, HMW-DOM with sizes between 1 kDa and 0.2 mu m was collected along a salinity gradient using cross-flow ultrafiltration. Isolated OM samples were desalted, freeze-dried and characterized for elemental (C and N) and biochemical composition (proteins, carbohydrates and uronic acids), stable isotopic (delta C-13 and delta N-15) and radiocarbon (Delta C-14) signatures, and relative molecular composition using pyrolysis-gas chromatography/mass spectrometry. The organic carbon content of HMW-DOM samples ranged from 31 to 36 wt.%, indicating that isolated colloids are mostly organic in nature. Contents of N ranged from 1.9% to 3.3%, resulting in a C/N ratio of 19-20 at lower salinity stations with a strong influence by terrestrial DOM and 12-15 at higher salinity stations with more freshly photosynthesized marine DOM. While OC-normalized protein contents decreased with increasing salinity, both carbohydrate and uronic acid contents increased with increasing salinity. Variations of pyrograms demonstrated that the proportion of furfural (an indicator of polysaccharides) in HMW-DOM also increased with increasing salinity, while the proportion of phenols decreased with increasing salinity. Changes in carbohydrate, (acid) polysaccharide and phenol contents of HMW-DOM samples reflect the variation in DOM sources along the salinity gradient, with higher phenol and low polysaccharide contents in lower salinity areas but higher polysaccharide and low phenol contents in coastal waters. Values of delta C-13 increased from -25.24 parts per thousand at the Mississippi River fresh water end-member station to -21.86 parts per thousand at an offshore station in the Gulf of Mexico. Changes in stable isotope composition resemble the changes in molecular composition from freshwater to coastal waters. Values of delta N-15, on the other hand, varied little, from 3.5 parts per thousand to 4.9 parts per thousand without a consistent trend, indicating that delta N-15 is a less sensitive source tracer. Measured radiocarbon signatures (Delta C-14) expressed as apparent C-14 ages ranged from > modern at lower salinity stations to 400-800 y BP at coastal stations. Results of isotopic mass balance revealed that, in addition to end-member organic matter from river and marine sources, at least 10-25% of the HMW-DOM could derive from reworked or regenerated DOM in the Mississippi River plume, most likely through sediment-water interactions and lateral transport. Thus, reworking processes are important in governing the chemical and isotopic composition of DOM in the estuarine mixing zone. (C) 2009 Elsevier B.V. All rights reserved.
id: 1827; 465CM Times Cited:1 Cited References Count:51Y

Chemical and isotopic signature of old groundwater and magmatic solutes in a Costa Rican rain forest: Evidence from carbon, helium, and chlorine - Genereux, David P.; Webb, Mathew; Solomon, D. Kip (WATER RESOURCES RESEARCH, 2009)
C, He, and Cl concentrations and isotopes in groundwater and surface water in a lowland Costa Rican rain forest are consistent with the mixing of two distinct groundwaters: (1) high-solute bedrock groundwater representing interbasin groundwater flow (IGF) into the rain forest and (2) low-solute local groundwater recharged in the lowlands. In bedrock groundwater, high delta(13)C (-4.89%), low (14)C (7.98 pM), high R/R(A) for He (6.88), and low (36)Cl/Cl (17 x 10(-15)) suggest that elevated tracer concentrations are derived from magmatic outgassing and/or weathering of volcanic rock beneath nearby Volcan Barva. In local groundwater, the magmatic signature is absent, and data suggest atmospheric sources for He and Cl and a biogenic soil gas CO(2) source for dissolved inorganic carbon. Dating of (14)C suggests that the age of bedrock groundwater is 2400-4000 years (most likely at the lower end of the range). Local groundwater has (14)C > 100 pM, indicating the presence of ``bomb carbon'' and thus ages less than similar to 55 years. Overall, data are consistent with a conceptual hydrologic model originally proposed on the basis of water budget and major ion data: (1) large variation in solute concentrations can be explained by mixing of the two distinct groundwaters, (2) bedrock groundwater is much older than local groundwater, (3) elevated solute concentrations in bedrock groundwater are derived from volcanic fluids and/or rock, and (4) local groundwater has not interacted with volcanic rock. Tracers with different capabilities converge on the same hydrologic interpretation. Also, transport of magmatic CO(2) into the lowland rain forest via IGF seems to be significant relative to other large ecosystem-level carbon fluxes.

A chronology of hurricane landfalls at Little Sippewissett Marsh, Massachusetts, USA, using optical dating - Madsen, A. T.; Duller, G. A. T.; Donnelly, J. P.; Roberts, H. M.; Wintle, A. G. (Geomorphology, 2009)
Optical dating has been applied to sediments preserved in Little Sippewissett Marsh, Massachusetts, USA, which are associated with overwashing of the beach barrier during hurricane strikes on the coast. The aims were to determine the hurricane landfall frequency, and make comparisons with independent age control and the historical record. Written sources of hurricane activity along the American east coast are only considered reliable back to the mid 19th century, but the sedimentary record is potentially much longer. Optical dating was applied to quartz grains extracted from thirteen samples within a sediment core from the salt-marsh. Variability in the luminescence characteristics between aliquots was observed and similar to 33% of the measured aliquots were discarded based upon the ratio of the fast component to the medium component. The majority of the samples gave normal dose distributions implying homogeneous resetting of the luminescence signal at the time of deposition, but three of the samples required application of the minimum age model (MAM). Ages ranging between 20 +/- 2 and 594 +/- 38 years were obtained and are broadly in agreement with independent chronologies, thus demonstrating the potential of optical dating in this setting. The hurricane record based upon optical dating extends approximately 300 years further back in time than the official National Oceanic Atmospheric Administration (NOAA) record. The localised nature of hurricane landfalls means that it will be necessary to collect multiple cores from a number of different sites in order to build up a complete hurricane record for this part of the coast. (C) 2009 Elsevier B.V. All rights reserved.
id: 861; ISI Document Delivery No.: 465RS Times Cited: 1 Cited Reference Count: 47 Cited References: *NOAA NOS COOPS, 2006, VER HIST WAT LEV DAT AITKEN MJ, 1985, THERMOLUMINESCENCE D ANDERSON TW, 1974, CAN J EARTH SCI, V11, P678 BAILEY RM, 1997, RADIAT MEAS, V27, P123 BAILEY SD, 2001, QUATERNARY SCI REV, V20, P701 BALLARINI M, 2003, QUATERNARY SCI REV, V22, P1011, DOI 10.1016/S0277-3791(03)00043-X BERGER GW, 2003, QUATERNARY SCI REV, V22, P1043, DOI 10.1016/S0277-3791(03)00017-9 BOOSE ER, 2001, ECOL MONOGR, V71, P27 BOSSAK BH, 2003, EARLY 19 CENTURY US BOTTERJENSEN L, 1988, NUCL TRACKS RAD MEAS, V14, P187 BOTTERJENSEN L, 1997, RADIAT MEAS, V27, P749 CHOI JH, 2003, QUATERNARY SCI REV, V22, P407 DIVIGALPITIYA WMR, 1982, THESIS S FRASER U BU DONNELLY JP, 2001, GEOL SOC AM BULL, V113, P714 DONNELLY JP, 2001, GEOLOGY, V29, P615 DONNELLY JP, 2004, HURRICANES TYPHOONS, P58 DONNELLY JP, 2004, MAR GEOL, V210, P107, DOI 10.1016/j.margeo.2004.05.005 DULLER GAT, 2004, J QUATERNARY SCI, V19, P183, DOI 10.1002/jqs.809 EMANUEL K, 2005, NATURE, V436, P686, DOI 10.1038/nature03906 GALBRAITH RF, 1999, ARCHAEOMETRY 2, V41, P339 GOLDENBERG SB, 2001, SCIENCE, V293, P474 HENDERSONSELLERS A, 1998, B AM METEOROL SOC, V79, P19 HUNTLEY DJ, 1994, ANCIENT TL, V12, P41 JAGGER TH, 2006, J CLIMATE, V19, P3220 JAIN M, 2005, RADIAT MEAS, V39, P309 LANDSEA CW, 2004, HURRICANES TYPHOONS, P177 LANDSEA CW, 2006, SCIENCE, V313, P452, DOI 10.1126/science.1128448 LIAN OB, 2006, QUATERNARY SCI REV, V25, P2449, DOI 10.1016/j.quascirev.2005.11.013 LIU KB, 1993, GEOLOGY, V21, P793 LIU KB, 2000, QUATERNARY RES, V54, P238 LUDLUM DM, 1963, EARLY AM HURRICANES MADSEN AT, 2005, MAR GEOL, V214, P251, DOI 10.1016/j.margeo.2004.10.034 MADSEN AT, 2007, J COASTAL RES, V23, P1259, DOI 10.2112/05-0471.1 MADSEN AT, 2007, MAR GEOL, V242, P221, DOI 10.1016/j.margeo.2007.03.001 MANN ME, 2006, EOS, V87, P233 MURRAY AS, 2000, RADIAT MEAS, V32, P57 MURRAY AS, 2002, GEOCHRONOMETRIA, V21, P1 MURRAY AS, 2003, RADIAT MEAS, V37, P377, DOI 10.1016/S1350-4487(03)00053-2 NEUMANN CJ, 1993, NCDC NHC HIST CLIMAT, V6 PIELKE RA, 1998, WEATHER FORECAST 2, V13, P621 PRESCOTT JR, 1988, NUCL TRACKS RAD MEAS, V14, P223 PRESCOTT JR, 1994, RADIAT MEAS, V23, P497 RHODES EJ, 2000, RADIAT MEAS, V32, P595 STUIVER M, 1998, RADIOCARBON, V40, P1041 TRENBERTH KE, 2006, GEOPHYS RES LETT, V33, ARTN L12704 WEBSTER PJ, 2005, SCIENCE, V309, P1844, DOI 10.1126/science.1116448 WINTLE AG, 2006, RADIAT MEAS, V41, P369, DOI 10.1016/j.radmeas.2005.11.001 Madsen, A. T. Duller, G. A. T. Donnelly, J. P. Roberts, H. M. Wintle, A. G. National Science Foundation [0519118] The authors wish to acknowledge Dana MacDonald for pollen analysis. This work was supported by National Science Foundation award #0519118. Elsevier science bv Amsterdam Sp. Iss. SI; YY

Coarse-grained sediment delivery and distribution in the Holocene Santa Monica Basin, California: Implications for evaluating source-to-sink flux at millennial time scales - Romans, B. W.; Normark, W. R.; McGann, M. M.; Covault, J. A.; Graham, S. A. (Geological Society of America Bulletin, 2009)
Utilizing accumulations of coarse-grained terrigenous sediment from deep-marine basins to evaluate the relative contributions of and history of controls on sediment flux through a source-to-sink system has been difficult as a result of limited knowledge of event timing. In this study, six new radiocarbon (C-14) dates are integrated with five previously published dates that have been recalibrated from a 12.5-m-thick turbidite section from Ocean Drilling Program (ODP) Site 1015 in Santa Monica Basin, offshore California. This borehole is tied to high-resolution seismic-reflection profiles that cover an 1100 km(2) area of the middle and lower Hueneme submarine fan and most of the basin plain. The resulting stratigraphic framework provides the highest temporal resolution for a thick-bedded Holocene turbidite succession to date, permitting an evaluation of source-to-sink controls at millennial (1000 yr) scales. The depositional history from 7 ka to present indicates that the recurrence interval for large turbidity-current events is relatively constant (300-360 yr), but the volume of sediment deposited on the fan and in the basin plain has increased by a factor of 2 over this period. Moreover, the amount of sand per event on the basin plain during the same interval has increased by a factor of 7. Maps of sediment distribution derived from correlation of seismic-reflection profiles indicate that this trend cannot be attributed exclusively to autogenic processes (e.g., progradation of depocenters). The observed variability in sediment accumulation rates is thus largely controlled by allogenic factors, including: (1) increased discharge of Santa Clara River as a result of increased magnitude and frequency of El Nino-Southern Oscillation (ENSO) events from ca. 2 ka to present, (2) an apparent change in routing of coarse-grained sediment within the staging area at ca. 3 ka (i.e., from direct river input to indirect, littoral cell input into Hueneme submarine canyon), and (3) decreasing rates of sea-level rise (i.e., rate of rise slowed considerably by ca. 3 ka). The Holocene history of the Santa Clara River-Santa Monica Basin source-to-sink system demonstrates the ways in which varying sediment flux and changes in dispersal pathways affect the basinal stratigraphic record.
id: 876; 478QZ Times Cited:1 Cited References Count:90Y

Comparing glacial and Holocene opal fluxes in the Pacific sector of the Southern Ocean - Bradtmiller, L. I.; Anderson, R. F.; Fleisher, M. Q.; Burckle, L. H. (Paleoceanography, 2009)
The silicic acid leakage hypothesis (SALH) predicts that during glacial periods excess silicic acid was transported from the Southern Ocean to lower latitudes, which favored diatom production over coccolithophorid production and caused a drawdown of atmospheric CO2. Downcore records of Th-230-normalized opal (biogenic silica) fluxes from 31 cores in the Pacific sector of the Southern Ocean were used to compare diatom productivity during the last glacial period to that of the Holocene and to examine the evidence for increased glacial Si export to the tropics. Average glacial opal fluxes south of the modern Antarctic Polar Front (APF) were less than during the Holocene, while average glacial opal fluxes north of the APF were greater than during the Holocene. However, the magnitude of the increase north of the APF was not enough to offset decreased fluxes to the south, resulting in a decrease in opal burial in the Pacific sector of the Southern Ocean during the last glacial period, equivalent to approximately 15 Gt opal ka(-1). This is consistent with the work of Chase et al. (2003a), and satisfies the primary requirement of the SALH, assuming that the upwelled supply of Si was approximately equivalent during the Holocene and the glacial period. However, previous results from the equatorial oceans are inconsistent with the other predictions of the SALH, namely that either the C-org:CaCO3 ratio or the rate of opal burial should have increased during glacial periods. We compare the magnitudes of changes in the Southern Ocean and the tropics and suggest that Si escaping the glacial Southern Ocean must have had an alternate destination, possibly the continental margins. There is currently insufficient data to test this hypothesis, but the existence of this sink and its potential impact on glacial pCO(2) remain interesting topics for future study.
id: 836; 455GX Times Cited:0 Cited References Count:97Y

Compound-specific radiocarbon analysis – analytical challenges and applications - Mollenhauer, G.; Rethemeyer, Janet (IOP conference proceedings: Earth and Environmental Sciences, 2009)
id: 884Y

Constraining carbon sources and growth rates of freshwater microbialites in Pavilion Lake using 14C analysis - Brady, A. L.; Slater, G.; Laval, B.; Lim, D. S. (Geobiology, 2009)
This study determined the natural abundance isotopic compositions (13C, 14C) of the primary carbon pools and microbial communities associated with modern freshwater microbialites located in Pavilion Lake, British Columbia, Canada. The Delta 14C of dissolved inorganic carbon (DIC) was constant throughout the water column and consistent with a primarily atmospheric source. Observed depletions in DIC 14C values compared with atmospheric CO(2) indicated effects due either to DIC residence time and/or inputs of 14C-depleted groundwater. Mass balance comparisons of local and regional groundwater indicate that groundwater DIC could contribute a maximum of 9-13% of the DIC. 14C analysis of microbial phospholipid fatty acids from microbialite communities had Delta 14C values comparable with lake water DIC, demonstrating that lake water DIC was their primary carbon source. Microbialite carbonate was also primarily derived from DIC. However, some depletion in microbialite carbonate 14C relative to lake water DIC occurred, due either to residence time or mixing with a 14C-depleted carbon source. A detrital branch covered with microbialite growth was used to estimate a microbialite growth rate of 0.05 mm year-1 for the past 1000 years, faster than previous estimates for this system. These results demonstrate that the microbialites are actively growing and that the primary carbon source for both microbial communities and recent carbonate is DIC originating from the atmosphere. While these data cannot conclusively differentiate between abiotic and biotic formation mechanisms, the evidence for minor inputs of groundwater-derived DIC is consistent with the previously hypothesized biological origin of the Pavilion Lake microbialites.
id: 2055; PT: J; UT: WOS:000271633500006

Coral growth rates from the Holocene Canada Honda fossil reef, Southwestern Dominican Republic: Comparisons with modern counterparts in high sedimentation settings - Cuevas, D. N.; Sherman, C. E.; Ramírez, W.; Hubbard, D. K. (Caribbean Journal of Science, 2009)
The Holocene Canada Honda fossil reef, located in southwestern Dominican Republic, provides a unique opportunity to examine a well-preserved fossil coral reef that thrived in a high-sedimentation environment between 9,000 to 5,000 years ago. Measurements of coral growth rates from the corals Montastraea faveolata and Siderastrea siderea were conducted and comparisons made with growth rate data of these same species from modern coral reefs throughout the Caribbean. Also, assessments of coral species abundance, morphology, age, and distribution, as well as reef sediment composition, were made to determine the paleoenvironment of reef accretion. This reef is characterized by a high relative abundance of sediment-tolerant coral species that have a tendency to form almost monospecific stands. Individual colonies have a propensity to grow as encrusting, dome-shaped, platy-like forms and specimens of Montastraea faveolata commonly contain bands of sediment incorporated into the skeleton. Calibrated radiocarbon ages of fossil corals range from 9,256 +/- 137 to 6,737 +/- 94.5 BP. Correlation of radiocarbon ages with well-established Holocene sea-level curves indicates that most corals on this reef developed at depths >15m. Measured growth rates in Siderastrea siderea (0.2-0.4 cm/yr) and Montastraea faveolata (0.09-0.44 cm/yr) are relatively low compared with growth rates from modern reef sites, indicating reduced light intensity caused by coral growth at depths greater than 15 m. Reef sediment is characterized by more than 85% carbonate material. A significant portion of the carbonate is allochtonous and was derived from nearby Neogene limestones. The reef was able to survive under high-sedimentation conditions because the high carbonate content of incoming terrigenous sediment would have allowed better light penetration and probable sporadic storms would provide intervening low-sedimentation periods during which reef corals could respond and grow back, keeping-up with sedimentation.
695voTimes Cited:0 Cited References Count:47
Keywords: australia; Belize; Caribbean; community; degradation; enriquillo valley; florida; great-barrier-reef; linear extension; montastraea-annularis; paluma shoals; record; siltation stress; skeletal extension; turbidity

Developments in Radiocarbon Technologies: From the Libby Counter to Compound-Specific Ams Analyses - Povinec, P. P.; Litherland, A. E.; von Reden, K. F. (Radiocarbon, 2009)
We review developments in radiocarbon measuring techniques from the Libby counter through proportional gas counters and liquid scintillation spectrometers to the more recent developments of accelerator mass spectrometry (AMS), followed by a coupling of gas chromatography with AMS for compound-specific (14)C analyses. While during the first 60 yr of (14)C measurements beta counting, specifically gas counting, was the dominant technique, in the future of (14)C science AMS will be the dominant technology.
453wfTimes Cited:15 Cited References Count:273
Keywords: accelerator mass-spectrometry; black-sea shelf; liquid scintillation techniques; low-level c-14; natural-abundance radiocarbon; negative-ion source; polycyclic aromatic-hydrocarbons; proportional counter; salt-marsh sediments; sedimentary organic-carbon

Distribution of artificial radionuclides in deep sediments of the Mediterranean Sea - Garcia-Orellana, J.; Pates, J. M.; Masque, P.; Bruach, J. M.; Sanchez-Cabeza, J. A. (Science of the Total Environment, 2009)
Artificial radionuclides enter the Mediterranean Sea mainly through atmospheric deposition following nuclear weapons tests and the Chernobyl accident, but also through the river discharge of nuclear facility effluents. Previous studies of artificial radionuclides impact of the Mediterranean Sea have focussed on shallow, coastal sediments. However, deep sea sediments have the potential to store and accumulate pollutants, including artificial radionuclides. Deep sea marine sediment cores were collected from Mediterranean Sea abyssal plains (depth >2000 m) and analysed for Pu-239,Pu-240 and Cs-137 to elucidate the concentrations, inventories and sources of these radionuclides in the deepest areas of the Mediterranean. The activity - depth profiles of Pb-210, together with 14 C dating, indicate that sediment mixing redistributes the artificial radionuclides within the first 2.5 cm of the sedimentary column. The excess Pb-210 inventory was used to normalize Pu-239,Pu-240 and Cs-137 inventories for variable sediment fluxes. The Pu-239,Pu-240/Pb-210(xs) ratio was uniform across the entire sea, with a mean value of 1.24 x 10(-3), indicating homogeneous fallout of Pu-239,Pu-240. The Cs-137/Pb-210(xs) ratio showed differences between the eastern (0.049) and western basins (0.030), clearly significant impact of deep sea sediments from the Chernobyl accident. The inventory ratios of Pu-239,Pu-240/Cs-137 were 0.041 and 0.025 in the western and eastern basins respectively, greater than the fallout ratio, 0.021, showing more efficient scavenging of Pu-231,Pu-210 in the water column and major sedimentation of Cs-137 in the eastern basin. Although areas with water depths of >2000 m constitute around 40% of the entire Mediterranean basin, the sediments in these regions only contained 2.7% of the Pu-239,Pu-240 and 0.95% of the Cs-137 deposited across the Sea in 2000. These data show that the accumulation of artificial radionuclides in deep Mediterranean environments is much lower than predicted by other studies from the analysis of continental shelf sediments. (C) 2008 Elsevier B.V, All rights reserved.
id: 871; 389FH Times Cited:2 Cited References Count:63Y

DNA and lipid molecular stratigraphic records of haptophyte succession in the Black Sea during the Holocene - Coolen, M. J. L.; Saenz, J. P.; Giosan, L.; Trowbridge, N. Y.; Dimitrov, P.; Dimitrov, D.; Eglinton, T. I. (Earth and Planetary Science Letters, 2009)
Previous studies suggest that the coccolithophorid haptophyte Emiliania huxleyi entered the Black Sea similar to 3400 yrs ago and since then a coccolith ooze defined as Unit I has developed. Unit I sediments contain long-chain alkenones derived from E huxleyi whereas the alkenone distribution of the deeper coccolith-free sapropel (Unit II) is rather unusual. Alkenone-derived past sea surface temperature (SST) estimates suggest a large difference between Unit II and Unit I, which is likely a result of unusual biological precursors of the alkenones in Unit II. Here, we report a high-resolution stratigraphic analysis of ancient haptophyte DNA to establish the Holocene succession of haptophytes as sources of the alkenones in the Black Sea. Haptophytes related to brackish Isochrysis spp. were the initial sources of alkenones, and appeared immediately after the onset of sapropel deposition (similar to 7550 yrs before present [a BP]). As salinity increased, Isochrysis-related haptophytes were slowly replaced by a complex suite of huxleyi strains as sources of alkenones. Our paleogenetic data showed that E. huxleyi colonized the Black Sea shortly after the onset of sapropel deposition, similar to 4000 yrs earlier than previously recognized based on their preserved coccoliths. E. huxleyi strains were the most likely source of the previously reported abundant and unusual C-36 di-unsaturated "Black Sea alkenone". Strong haptophyte species and strain-specific effects were observed on the level of unsaturation of alkenones which resulted in spurious alkenone-derived SST estimates before 5250 a BP. In contrast, from similar to 5250 a BP onwards a relatively stable haptophyte assemblage dominated by a different suite of E. huxleyi strains yielded robust alkenone-SST values and indicated a gradual cooling from 19 degrees C to similar to 15 degrees C at the top of the record (similar to 450 a BP). Published by Elsevier B.V.
id: 1853; 487NY Times Cited:1 Cited References Count:78; YY

Dynamics and Vulnerability of Delta Systems - Overeem, I.; Syvitski, J. P. M.; al, et (LOICZ Reports & Studies, 2009)
id: 1898; 35; Y

Dynamics of particle export on the Northwest Atlantic margin - Hwang, J.; Manganini, S. J.; Montlucon, D. B.; Eglinton, T. I. (Deep-Sea Research Part I-Oceanographic Research Papers, 2009)
The Northwest Atlantic margin is characterized by high biological productivity in shelf and slope surface waters. In addition to carbon supply to underlying sediments, the persistent, intermediate depth nepheloid layers emanating from the continental shelves, and bottom nepheloid layers maintained by strong bottom currents associated with the southward flowing Deep Western Boundary Current (DWBC), provide conduits for export of organic carbon over the margin and/or to the interior ocean. As a part of a project to understand dynamics of particulate organic carbon (POC) cycling in this region, we examined the bulk and molecular properties of time-series sediment trap samples obtained at 968 m, 1976 m, and 2938 m depths from a bottom-tethered mooring on the New England slope (water depth, 2988 m). Frequent occurrences of higher fluxes in deep relative to shallower sediment traps and low Delta C-14 values of sinking POC together provide strong evidence for significant lateral transport of aged organic matter over the margin. Comparison of biogeochemical properties such as aluminum concentration and flux, and iron concentration between samples intercepted at different depths shows that particles collected by the deepest trap had more complex sources than the shallower ones. These data also suggest that at least two modes of lateral transport exist over the New England margin. Based on radiocarbon mass balance, about 30% (+/- 10%) of sinking POC in all sediment traps is estimated to be derived from lateral transport of resuspended sediment. A strong correlation between Delta C-14 values and aluminum concentrations suggests that the aged organic matter is associated with lithogenic particles. Our results suggest that lateral transport of organic matter, particularly that resulting from sediment resuspension, should be considered in addition to vertical supply of organic matter derived from primary production, in order to understand carbon cycling and export over continental margins. (C) 2009 Elsevier Ltd. All rights reserved.
id: 1829; 490AT Times Cited:0 Cited References Count:61Y

Evidence for calcification depth change of Globorotalia truncatulinoides between deglaciation and Holocene in the Western Atlantic Ocean - Cleroux, C.; Lynch-Stieglitz, J.; Schmidt, M. W.; Cortijo, E.; Duplessy, J. C. (Marine Micropaleontology, 2009)
Measurements of the delta O-18 in tests of planktonic and benthic foraminifera in the Florida Straits are used to reconstruct the properties of the water column through time over the last 12 ka (Lynch-Stieglitz et al., in press). The isotopic composition of the foraminifera largely reflects the vertical density gradient. We use this reconstruction and delta O-18 measurements on Globorotalia truncatulinoides in a nearby core to track the depth habitat of this species from the last deglaciation to 1.6 ka B.P. Around 9 ka, G. truncatulinoides was calcifying in much shallower water than during the late Holocene. The downward migration toward its modem habitat is a regional phenomenon over the western tropical Atlantic continental slope. The cause is still unclear but we hypothesize that the shallower calcification depth may be a response to the presence of glacial melt water or to circulation changes. This study points to the value of further study of the ecology, life cycle and calcification depth for G. truncatulinoides and other planktonic foraminifera that are used to reconstruct the history of the thermocline and upper water column structure. Published by Elsevier B.V.
id: 1883; 514BR Times Cited:0 Cited References Count:33Y

Evidence of centennial-scale drought from southeastern Massachusetts during the Pleistocene/Holocene transition - Newby, P. E.; Donnelly, J. P.; Shuman, B. N.; MacDonald, D. (Quaternary Science Reviews, 2009)
A principal method for studying past hydroclimatic change is the reconstruction of paleo-lake levels. Here, we provide high-resolution lake-level records from New Long Pond and Rocky Pond in southeastern Massachusetts, which each contain evidence for multiple, sub-centennial-to-millennial scale low stands during the transition between the Late Pleistocene (15.0 ka) and Middle Holocene (ca 7.0 ka). Data from New Long Pond also demonstrate sedimentary evidence for a drop in water levels in the early to mid AD 20th century, when long-term trends in instrumental data show lower-than-average precipitation in the northeastern United States. Local data show the most precipitous declines in precipitation and groundwater levels are concurrent with the most severe drought in the AD 1960s, which occurred during a period of low sea-surface temperatures in the western North Atlantic. Ground penetrating radar and sediment core data indicate five intervals with numerous paleo-shoreline deposits between ca 15.0 and 7.0 ka, similar to the layer deposited in the AD 1960s. Many of the intervals of low lake levels coincide with proposed meltwater release events or abrupt climate oscillations in the circum North Atlantic. For example, we document at least three low stands during the Younger Dryas (12.9-11.6 ka) and in association with the "9.2" and "8.2" ka events. The combined evidence of (1) concurrent paleo-droughts in southeastern New England with documented North Atlantic abrupt cooling events and (2) recent drought with the modern association of low sea-surface temperatures indicates that freshening and cooling of the western North Atlantic is a viable mechanism for decreasing moisture within the region. Large-scale changes in seasonality and ice sheet extent also may have increased the susceptibility of the northeast to dry conditions triggered by changes in the North Atlantic. (C) 2009 Elsevier Ltd. All rights reserved.
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Donnelly, Jeffrey P. Shuman, Bryan N. MacDonald, Dana Pergamon-elsevier science ltd Oxford Sp. Iss. SI; YY

Evidence of paleo-cold seep activity from the Bay of Bengal, offshore India - Mazumdar, A.; Dewangan, P.; Joao, H. M.; Peketi, A.; Khosla, V. R.; Kocherla, M.; Badesab, F. K.; Joshi, R. K.; Roxanne, P.; Ramamurty, P. B.; Karisiddaiah, S. M.; Patil, D. J.; et al. (Geochemistry Geophysics Geosystems, 2009)
We report evidence of paleo-cold seep associated activities, preserved in methane-derived carbonates in association with chemosynthetic clams (Calyptogena sp.) from a sediment core in the Krishna-Godavari basin, Bay of Bengal. Visual observations and calculations based on high-resolution wet bulk density profile of a core collected on board R/V Marion Dufresne (May 2007) show zones of sharp increase in carbonate content (10-55 vol%) within 16-20 meters below seafloor (mbsf). The presence of Calyptogena clam shells, chimneys, shell breccias with high Mg calcite cement, and pyrite within this zone suggest seepage of methane and sulfide-bearing fluid to the seafloor in the past. Highly depleted carbon isotopic values (delta C-13 ranges from -41 to -52% VPDB) from these carbonates indicate carbon derived via anaerobic oxidation of methane. Extrapolated mean calendar age (similar to 58.7 ka B. P.) of the clastic sediments at a depth of 16 mbsf is close to the upper limit of the U-Th based depositional age (46.2 +/- 3.7 and 53.0 +/- 1.6 ka) of authigenic carbonates sampled from this level, thereby constraining the younger age limit of the carbonate deposition/methane expulsion events. The observed carbonate deposition might have resulted from the flow of methane-enriched fluids through the fracture network formed because of shale diapirism.
id: 794; 458FC Times Cited:0 Cited References Count:80Y

Exploring typhoon variability over the mid-to-late Holocene: evidence of extreme coastal flooding from Kamikoshiki, Japan - Woodruff, J. D.; Donnelly, J. P.; Okusu, A. (Quaternary Science Reviews, 2009)
Sediment cores from two coastal lakes located on the island of Kamikoshiki in southwestern Japan (Lake Namakoike and Lake Kaiike) provide evidence for the response of a backbarrier beach system to episodic coastal inundation over the last 6400 years. Sub-bottom seismic surveys exhibit acoustically laminated, parallel to subparallel seismic reflectors, intermittently truncated by erosional unconformities. Sediment cores collected from targeted depocenters in both lakes contain finely laminated organic mud interbedded with coarse-grained units, with depths of coarse deposits concurrent with prominent seismic reflectors. The timing of the youngest deposit at Kamikoshiki correlates to the most recently documented breach in the barrier during a typhoon in 1951 AD. Assuming that this modern deposit provides an analog for identifying past events, paleo-typhoons may be reconstructed from layers exhibiting an increase in grain-size, a break in fine-scale stratigraphy, and elevated Sr concentrations. Periods of barrier breaching are concurrent with an increase in El Nino frequency, indicating that the El Nino/Southern Oscillation has potentially played a key role in governing typhoon variability during the mid-to-late Holocene. An inverse correlation is observed between tropical cyclone reconstructions from the western North Atlantic and the Kamikoshiki site, which may indicate an oscillating pattern in tropical cyclone activity between the western Northern Atlantic and the western North Pacific, or at least between the western Northern Atlantic and regions encompassing southern Japan. The two kamikaze typhoons which contributed to the failed Mongol invasions of Japan in 1274 AD and 1281 AD occur during a period with more frequent marine-sourced deposition at the site, suggesting that the events took place during a period of greater regional typhoon activity. (C) 2009 Elsevier Ltd. All rights reserved.
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Donnelly, Jeffrey P. Okusu, Akiko Pergamon-elsevier science ltd Oxford Sp. Iss. SI; YY

Field Survey and Geological Effects of the 15 November 2006 Kuril Tsunami in the Middle Kuril Islands - MacInnes, B. T.; Pinegina, T. K.; Bourgeois, J.; Razhigaeva, N. G.; Kaistrenko, V. M.; Kravchunovskaya, E. A. (Pure and Applied Geophysics, 2009)
The near-field expression of the tsunami produced by the 15 November 2006 Kuril earthquake (M-w 8.1-8.4) in the middle Kuril Islands, Russia, including runup of up to 20 m, remained unknown until we conducted a post-tsunami survey in the summer of 2007. Because the earthquake occurred between summer field expeditions in 2006 and 2007, we have observations, topographic profiles, and photographs from three months before and nine months after the tsunami. We thoroughly surveyed portions of the islands of Simushir and Matua, and also did surveys on parts of Ketoi, Yankicha, Ryponkicha, and Rasshua. Tsunami runup in the near-field of the middle Kuril Islands, over a distance of about 200 km, averaged 10 m over 130 locations surveyed and was typically between 5 and 15 m. Local topography strongly affected inundation and somewhat affected runup. Higher runup generally occurred along steep, protruding headlands, whereas longer inundation distances occurred on lower, flatter coastal plains. Sediment transport was ubiquitous where sediment was available-deposit grain size was typically sand, but ranged from mud to large boulders. Wherever there were sandy beaches, a more or less continuous sand sheet was present on the coastal plain. Erosion was extensive, often more extensive than deposition in both space and volume, especially in areas with runup of more than 10 m. The tsunami eroded the beach landward, stripped vegetation, created scours and trim lines, cut through ridges, and plucked rocks out of the coastal plain.
id: 831; 418XP Times Cited:2 Cited References Count:46Y

Fine-scale relief related to Late Holocene channel shifting within the floor of the upper Redondo Fan, offshore Southern California - Normark, William R.; Paull, Charles K.; Caress, David W.; Ussler Iii, William; Sliter, Ray (Sedimentology, 2009)
AbstractErosional and depositional bedforms have been imaged at outcrop scale in the upper Redondo Fan, in the San Pedro Basin of offshore Southern California in greater than or equal to 600 m water depths, using an Autonomous Underwater Vehicle developed by the Monterey Bay Aquarium Research Institute. The Autonomous Underwater Vehicle is equipped with multibeam and chirp sub-bottom sonars. Sampling and photographic images using the Monterey Bay Aquarium Research Institute Remotely Operated Vehicle Tiburon provide groundtruth for the Autonomous Underwater Vehicle survey. The 0.3 m vertical and 1.5 m lateral bathymetric resolution and 0.1 m sub-bottom profile resolution provide unprecedented detail of bedform morphology and structure. Multiple channels within the Redondo Fan have been active at different times during the Late Holocene (0 to 3000 yr bp). The currently active channel extending from Redondo Canyon makes an abrupt 90 degree turn at the canyon mouth before resuming a south-easterly course along the east side of the Redondo Fan. This channel is floored by sand and characterized by small steps generally
id: 2216; Source type: scholarlyjournals; Object type: Article; Object type: Feature; CSAUnique: OB-MD-0010477140; AccNum: 11022775; DOI: 10.1111/j.1365-3091.2009.01052.x; ISSN: 0037-0746; Peer Reviewed: true

Fish scales in sediments from off Callao, central Peru - Diaz-Ochoa, J. A.; Lange, C. B.; Pantoja, S.; De lange, G. J.; Gutierrez, D.; Munoz, P.; Salamanca, M. (DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 2009)
We study fish scales as a proxy of fish abundance and preservation biases together with phosphorus from fish remains (P(fish)) in a sediment core retrieved off Callao, Peru (12 degrees 1'S, 77 degrees 42'W; water depth = 179 m; core length = 52 cm). We interpret our results as a function of changing redox conditions based on ratios of redox-sensitive trace elements (Cu/Al, Mo/Al, Ni/Al, Zn/Al, V/Al), terrigenous indicators (Fe in clays, Ti, Al), and biogenic proxies (CaCO(3), biogenic opal, total nitrogen, organic carbon, barite Ba). The core covers roughly 700 years of deposition, based on (210)Pb activities extrapolated downcore and (14)C dating at selected intervals. Our fish-scale record is dominated by anchovy (Engraulis ringens) scales followed by hake (Merluccius gayii) scales. The core presented an abrupt lithological change at 17 cm (corresponding to the early 19th century). Above that depth, it was laminated and was more organic-rich (10-15% organic carbon) than below, where the core was partly laminated and less organic-rich (< 10%). The lithological shift coincides with abrupt changes in dry bulk density and in the contents of terrigenous and redox-sensitive trace elements, biogenic proxies, and fish scales. The remarkable increase in redox-sensitive trace elements in the upper 17 cm of the core suggests more reducing conditions when compared with deeper and older horizons, and is interpreted as an intensification of the oxygen minimum zone off Peru beginning in the early 19th century. Higher fish-scale contents and higher P(fish)/P(total) ratios were also observed within the upper 17 cm of the core. The behavior of biogenic proxies and redox-sensitive trace elements was similar; more reduced conditions corresponded to higher contents of CaCO(3), C(org), total nitrogen and fish scales, suggesting that these proxies might convey an important preservation signal. (C) 2008 Elsevier Ltd. All rights reserved.
Keywords: Callao; Clupeoid fish; Molybdenum; Oxygen minimum zone; Peru; Redox-sensitive trace elements

Fishing from past to present: continuity and resilience of red abalone fisheries on the Channel Islands, California - Braje, Todd J.; Erlandson, Jon M.; Rick, Torben C.; Dayton, Paul K.; Hatch, Marco B. A. (Ecological Applications, 2009)
Archaeological data from coastal shell middens provide a window into the structure of ancient marine ecosystems and the nature of human impacts on fisheries that often span millennia. For decades Channel Island archaeologists have studied Middle Holocene shell middens visually dominated by large and often whole shells of the red abalone (Haliotis rufescens). Here we use modern ecological data, historical accounts, commercial red abalone catch records, and zooarchaeological data to examine long-term spatial and temporal variation in the productivity of red abalone fisheries on the Northern Channel Islands, California (USA). Historical patterns of abundance, in which red abalone densities increase from east to west through the islands, extend deep into the Holocene. The correlation of historical and archaeological data argue for long-term spatial continuity in productive red abalone fisheries and a resilience of abalone populations despite dramatic ecological changes and intensive human predation spanning more than 8000 years. Archaeological, historical, and ecological data suggest that California kelp forests and red abalone populations are structured by a complex combination of top-down and bottom-up controls.
id: 2060; PT: J; UT: WOS:000266281400008

Fishing up the Food Web?: 12,000 Years of Maritime Subsistence and Adaptive Adjustments on California's Channel Islands - Erlandson, Jon M.; Rick, Torben C.; Braje, Todd J. (Pacific Science, 2009)
Archaeologists working on California's northern Channel Islands have produced an essentially continuous record of Native American fishing and nearshore ecological changes spanning die last 12,000 years. To search for evidence of Pauly's "fishing down the foodweb" pattern typical of recent historical fisheries, we analyzed variation in the dietary importance of major marine faunal classes (shellfish, fish, marine mammals) on the islands through time. Faunal data suggest that the Island Chumash and their predecessors focused primarily on low-trophic-level shellfish during the Early and Middle Holocene, before shifting their economic focus to finfish and pinnipeds during the Late Holocene. Replicated in faunal sequences from the adjacent mainland, this trans-Holocene pattern suggests that Native Americans fished Lip the food web, a strategy that may have been more sustainable and had fewer ecological repercussions. Emerging technological data suggest, however, that some of the earliest Channel Islanders focused more heavily on higher-trophic-level animals, including marine mammals, seabirds, and waterfowl. These data emphasize the differences between the primarily subsistence-based foraging strategies of ancient Channel Islanders and the globalized market-based fisheries of modern and historic times, with important implications for understanding the long-term evolution and historical ecology of marine ecosystems.
id: 2059; PT: J; UT: WOS:000270849400011

Florida Straits density structure and transport over the last 8,000 years - Lynch-Stieglitz, J.; Curry, W. B.; Lund, D. C. (Paleoceanography, 2009)
id: 837; YY

Formal definition and dating of the GSSP (Global Stratotype Section and Point) for the base of the Holocene using the Greenland NGRIP ice core, and selected auxiliary records RID B-5560-2008 RID F-1111-2011 - Walker, Mike; Johnsen, Sigfus; Rasmussen, Sune Olander; Popp, Trevor; Steffensen, Jorgen-Peder; Gibbard, Phil; Hoek, Wim; Lowe, John; Andrews, John; Bjorck, Svante; Cwynar, Les C.; Hughen, Konrad; et al. (Journal of Quaternary Science, 2009)
The Greenland ice core from NorthGRIP (NGRIP) contains a proxy climate record across the Pleistocene-Holocene boundary of unprecedented clarity and resolution. Analysis of an array of physical and chemical parameters within the ice enables the base of the Holocene, as reflected in the first signs of climatic warming at the end of the Younger Dryas/Greenland Stadial 1 cold phase, to be located with a high degree of precision. This climatic event is most clearly reflected in an abrupt shift in deuterium excess values, accompanied by more gradual changes in delta(18)O, dust concentration, a range of chemical species, and annual layer thickness. A timescale based on multi-parameter annual layer counting provides an age of 11 700 calendar yr b2k (before AD 2000) for the base of the Holocene, with a maximum counting error of 99 yr. A proposal that an archived core from this unique sequence should constitute the Global Stratotype Section and Point (GSSP) for the base of the Holocene Series/Epoch (Quaternary System/Period) has been ratified by the International Union of Geological Sciences. Five auxiliary stratotypes for the Pleistocene-Holocene boundary have also been recognised. Copyright (C) 2008 John Wiley & Sons, Ltd.
id: 1989; PT: J; UT: WOS:000262615700002

Fragmentary Evidence of Great-Earthquake Subsidence during Holocene Emergence, Valdivia Estuary, South Central Chile - Nelson, Alan R.; Kashima, Kaoru; Bradley, Lee-Ann (Bulletin of the Seismological Society of America, 2009)
A reconnaissance of Holocene stratigraphy beneath fringing marshes of the Valdivia estuary, where an M 9.5 earthquake caused 1-2 m of regional coseismic subsidence in 1960, shows only fragmentary evidence of prehistoric coseismic subsidence. In most of the 150 hand-driven cores that were examined, a distinct unconformity separates 0.5-1.5 m of late Holocene tidal and floodplain mud, peat, and sand from underlying middle Holocene subtidal mud and sand. At the Las Coloradas site, where stratigraphy is best preserved, two A horizons of marsh and meadow soils abruptly overlain by sand and mud probably record coseismic subsidence shortly followed by tsunamis. The amount of subsidence during the earthquakes proved difficult to reconstruct with a diatom transfer function because of differences between modern and fossil diatom assemblages. Maximum (14)C ages on macrofossils from the two A horizons at the Las Coloradas site of 1.7-1.3 ka and 2.7-1.7 ka allow correlation of the younger horizon with either of two of six (14)C-dated A horizons buried by tsunami sand or post-tsunami tidal sand 200 km to the south at Maullin, and with a lake-wide mass wasting event in Lago Puyehue, 100 km to the southeast. Tidal records of prehistoric coseismic subsidence at Valdivia are scarce because of a sea-level fall of 3-8 m over the past 6000 years, erosion of marsh and meadow soils during subsidence-induced flooding of the estuary, and largely complete land-level recovery during cycles of coseismic subsidence and postseismic uplift.
id: 2020; PT: J; UT: WOS:000266181100006

From Sheep To (Some) Horses: 4500 Years Of Herd Structure At The Pastoralist Settlement of Begash (southeastern Kazakhstan) - Frachetti, M. D.; Benecke, N. (Antiquity, 2009)
id: 834

A Gendered Model of Prehistoric Resource Depression: A Case Study on the Northwest Coast of North America - Daniels, Phoebe (University of Washington, 2009)

Growth and sexual maturity of the northern propellerclam (Cyrtodaria siliqua) in Eastern Canada, with bomb radiocarbon age validation - Kilada, R. W.; Campana, S. E.; Roddick, D. (Marine Biology, 2009)
The northern propellerclam Cyrtodaria siliqua is a common bycatch in the Arctic surfclam, Mactromeris polynyma fishery on Banquereau Bank in Eastern Canada. Samples of the propellerclam from this exploited fishery were used to determine the life history characteristics of the population. The age structure of the population is dominated by old animals to ages exceeding 100 years. We validated the age estimates for the propellerclam through analysis of bomb-produced radiocarbon in the shell growth increments deposited before, during and after the atmospheric atomic bomb testing periods of the 1950s and 1960s. Radiocarbon from shells with presumed birth dates between the late 1950s and 1970s clearly reflected the sharp increase in oceanic radiocarbon attributable to previous nuclear testing, indicating that age estimates based on shell increment counts are accurate. Estimates of von Bertalanffy growth parameters revealed that the growth rate of the population was relatively rapid for the first 20 years of life, slowing down to very low growth rates thereafter. Sexual maturity was estimated as being reached at 28.6 mm in length and 4.7 years in age. Size-weight morphometric relationships were also calculated.
id: 803; 413YA Times Cited:0 Cited References Count:45Y

High mitogenomic evolutionary rates and time dependency - Subramanian, Sankar; Denver, Dee R.; Millar, Craig D.; Heupink, Tim; Aschrafi, Angelique; Emslie, Steven D.; Baroni, Carlo; Lambert, David M. (Trends in Genetics, 2009)
Using entire modern and ancient mitochondrial genomes of Adelie penguins (Pygoscelis adeliae) that are up to 44000 years old, we show that the rates of evolution of the mitochondrial genome are two to six times greater than those estimated from phylogenetic comparisons. Although the rate of evolution at constrained sites, including nonsynonymous positions and RNAs, varies more than twofold with time (between shallow and deep nodes), the rate of evolution at synonymous sites remains the same. The time-independent neutral evolutionary rates reported here would be useful for the study of recent evolutionary events.
id: 1917; PT: J; NR: 27; TC: 19; J9: TRENDS GENET; PG: 5; GA: 518TW; UT: WOS:000271717800004

High-sensitivity measurement of diverse vascular plant-derived biomarkers in high-altitude ice cores - Makou, Matthew C.; Thompson, Lonnie G.; Montluçon, Daniel B.; Eglinton, Timothy I. (GEOPHYSICAL RESEARCH LETTERS, 2009)
Semi-volatile organic compounds derived from burned and fresh vascular plant sources and preserved in high-altitude ice fields were detected and identified through use of recently developed analytical tools. Specifically, stir bar sorptive extraction and thermal desorption coupled with gas chromatography/time-of-flight mass spectrometry allowed measurement of multiple biomarkers in small sample volumes (<= 30 ml). Among other compounds of interest, several diterpenoids, which suggest inputs from conifers and conifer burning, were identified in post-industrial era and older Holocene ice from the Sajama site in the Bolivian Andes, but not in a glacial period sample, consistent with aridity changes. Differences in biomarker assemblages between sites support the use of these compounds as regionally constrained recorders of vegetation and climate change. This study represents the first application of these analytical techniques to ice core research and the first indication that records of vegetation fires may be reconstructed from diterpenoids in ice. Citation: Makou, M. C., L. G. Thompson, D. B. Montlucon, and T. I. Eglinton (2009), High-sensitivity measurement of diverse vascular plant-derived biomarkers in high-altitude ice cores, Geophys. Res. Lett., 36, L13501, doi: 10.1029/2009GL037643.

Historic sediment accretion rates in a Louisiana coastal marsh and implications for sustainability - Smith, Rebekah P. (Louisiana State University, 2009)

Holocene Adelie penguin diet in Victoria Land, Antarctica - Lorenzini, Sandra; Olmastroni, Silvia; Pezzo, Francesco; Salvatore, Maria Cristina; Baroni, Carlo (Polar Biology, 2009)
Ornithogenic soils (N = 97) dated up to 7000 Before Present (Ebp) were sampled in 16 relict and modern breeding colonies of Ad,lie penguin along the Victoria Land coast (Ross Sea, Antarctica). Taxonomic identification of fish otoliths (N = 677) recovered in these soils allowed to identify the Antarctic silverfish as the most eaten prey (90.1%) throughout the investigated period. A morphometric analysis of the otoliths revealed that the Ad,lie penguin primarily selected prey averaging 67.23 +/- A 23 mm of standard length. Temporal distribution of Pleuragramma antarcticum showed a peak between 2,000 and 4,000 years bp, a period corresponding to the maximum spread of Ad,lie penguin in the Victoria Land. Possible explanations of the variations of the abundance of the fish prey in the diet are discussed in the context of the paleoclimatic events and as possible consequences of dietary shifts due to the temporal variation of prey availability in the Ross Sea ecosystem.
id: 1916; PT: J; NR: 60; TC: 2; J9: POLAR BIOL; PG: 10; GA: 457FQ; UT: WOS:000266914300013

Holocene sea-level changes along the North Carolina Coastline and their implications for glacial isostatic adjustment models - Horton, B. P.; Peltier, W. R.; Culver, S. J.; Drummond, R.; Engelhart, S. E.; Kemp, A. C.; Mallinson, D.; Thieler, E. R.; Riggs, S. R.; Ames, D. V.; Thomson, K. H. (Quaternary Science Reviews, 2009)
We have synthesized new and existing relative sea-level (RSL) data to produce a quality-controlled, spatially comprehensive database from the North Carolina coastline. The RSL database consists of 54 sea-level index points that are quantitatively related to an appropriate tide level and assigned an error estimate, and a further 33 limiting dates that confine the maximum and minimum elevations of RSL The temporal distribution of the index points is very uneven with only five index points older than 4000 cal a BP, but the form of the Holocene sea-level trend is constrained by both terrestrial and marine limiting dates. The data illustrate RSL rapidly rising during the early and mid Holocene from an observed elevation of -35.7 +/- 1.1 m MSL at 11062-10576 cal a BP to -4.2 m +/- 0.4 m MSL at 4240-3592 cal a BP. We restricted comparisons between observations and predictions from the ICE-5G(VM2) with rotational feedback Glacial Isostatic Adjustment (GIA) model to the Late Holocene RSL (last 4000 cal a BP) because of the wealth of sea-level data during this time interval. The ICE-5G(VM2) model predicts significant spatial variations in RSL across North Carolina, thus we subdivided the observations into two regions. The model forecasts an increase in the rate of sea-level rise in Region 1 (Albemarle, Currituck, Roanoke, Croatan, and northern Pamlico sounds) compared to Region 2 (southern Pamlico, Core and Bogue sounds, and farther south to Wilmington). The observations show Late Holocene sea-level rising at 1.14 +/- 0.03 mm year(-1) and 0.82 +/- 0.02 mm year(-1) in Regions 1 and 2, respectively. The ICE-5G(VM2) predictions capture the general temporal trend of the observations, although there is an apparent misfit for index points older than 2000 cal a BR It is presently unknown whether these misfits are caused by possible tectonic uplift associated with the mid-Carolina Platform High or a flaw in the CIA model. A comparison of local tide gauge data with the Late Holocene RSL trends from Regions 1 and 2 support the spatial variation in RSL across North Carolina, and imply an additional increase of mean sea level of greater than 2 mm year(-1) during the latter half of the 20th century; this is in general agreement with historical tide gauge and satellite altimetry data. (C) 2009 Elsevier Ltd. All rights reserved.
id: 814; Sp. Iss. SI 484ZD Times Cited:1 Cited References Count:108Y

Human impacts, climate change, and aquatic ecosystem response during the past 2000 yr at Lake Wandakara, Uganda - Russell, James M.; McCoy, S. J.; Verschuren, D.; Bessems, I.; Huang, Y. (Quaternary Research, 2009)
Analyses of carbon and hydrogen isotope ratios of terrestrial leaf waxes and the carbon and nitrogen abundance. ratio, and isotopic composition of bulk sediments from Like Wandakara, a crater lake in western Uganda, East Africa. document human and climatic controls on the aquatic system and oil the Surrounding terrestrial vegetation during the past two millennia Our data indicate that Wandakara was a relatively stable, productive lake Surrounded by C(3) vegetation from AD 70 to 1000. Abrupt changes in the delta(13)C of terrestrial leaf waxes indicate a series of abrupt shifts in the relative abundance of C(3) and C(4) vegetation caused by a combination of climate change and human activities around Wandakara beginning at AD 1000. Abrupt shifts in bulk sediment organic geochemistry. particularly C/N ratios and delta(15)N, indicate that human activities at this time caused permanent changes in the limnology of Lake Wandakara. including eutrophication Our results suggest that the biogeochemistry of Like Wandakara was more sensitive to shifting human impacts than to climate variations during the past millennium, highlighting the importance of understanding the intensity of pre-colonial human impacts on Africa's aquatic ecosystems (C) 2009 University of Washington Published by Elsevier Inc All rights reserved
id: 2052; PT: J; UT: WOS:000271254000002

Implications of Radiocarbon Dates from Potter Creek Cave, Shasta County, California, USA - Feranec, R. S. (Radiocarbon, 2009)
New dates obtained from the bone collagen of mammals from the deposits in Potter Creek Cave, Shasta County, California, USA, show that these fossils were emplaced over the last 30,000 yr. The dates support the assignment of the fauna in the cave to the late Pleistocene and are contemporaneous to the dates obtained from the fauna of Samwel Cave located 5 km to the north. These new dates do not support previous radiocarbon dates suggesting a Holocene extinction of the extinct bovid Euceratherium collinum, and demonstrate that this and other megafauna were not present in the vicinity after the terminal Pleistocene.
544peTimes Cited:1 Cited References Count:16
Keywords: account; bone; pretreatment

In situ cosmogenic 10Be production-rate calibration from the Southern Alps, New Zealand - Putnam, A. E.; Schaefer, J. M.; Barrell, D. J. A.; Vandergoes, M.; Denton, G. H.; Kaplan, M. R.; Finkel, R. C.; Schwartz, R.; Goehring, B. M.; Kelley, S. E. (Quaternary Geochronology, 2009)
id: 840In pressY

Initial source evaluation of archaeological obsidian from the Kuril Islands of the Russian Far East using portable XRF - Phillips, S. C.; Speakman, R. J. (Journal of Archaeological Science, 2009)
Obsidian artifacts recently have been recovered from 18 archaeological sites on eight islands across the Kuril Island archipelago in the North Pacific Ocean, suggesting a wide-ranging distribution of obsidian throughout the island chain over the last 2,500 years. Although there are no geologic sources of obsidian in the Kurils that are known to have been used prehistorically, sources exist in Hokkaido, Japan, and Kamchatka, Russia, the southern and northern geographic regions respectively from which obsidian may have entered the Kuril Islands. This paper reports on the initial sourcing attempt of Kuril Islands obsidian through the analysis of 131 obsidian artifacts. Data from this research were generated through the application of portable XRF technology, and are used to address research questions concerning prehistoric mobility, exchange, and social networking in the Kuril Islands. (C) 2009 Elsevier Ltd. All rights reserved.
id: 832; 433GY Times Cited:2 Cited References Count:66Y

Inputs of Fossil Carbon from Wastewater Treatment Plants to US Rivers and Oceans - Griffith, D. R.; Barnes, R. T.; Raymond, P. A. (Environmental Science & Technology, 2009)
Every day more than 500 million cubic meters of treated wastewater are discharged into rivers, estuaries, and oceans, an amount slightly less than the average flow of the Danube River. Typically, wastewaters have high organic carbon [OC) concentrations and represent a large fraction of total river flow and a higher fraction of river OC in densely populated watersheds. Here, we report the first direct measurements of radiocarbon (C-14) in municipal wastewater treatment plant (WWTP) effluent. The radiocarbon ages of particulate and dissolved organic carbon (POC and DOC) in effluent are old and relatively uniform across a range of WWTPs in New York and Connecticut. Wastewater DOC has a mean radiocarbon age of 1630 +/- 500 years B.P. and a mean delta C-13 of -26.0 +/- 1 parts per thousand. Mass balance calculations indicate that 25% of wastewater DOC is fossil carbon, which is likely derived from petroleum-based household products such as detergents and pharmaceuticals. These findings warrant reevaluation of the "apparent age" of riverine DOC, the total flux of petroleum carbon to U.S. oceans, and OC source assignments in waters impacted by sewage.
id: 1833; 476XR Times Cited:0 Cited References Count:51Y

Intcal09 and Marine09 Radiocarbon Age Calibration Curves, 0-50,000 Years Cal Bp Rid F-4952-2011 Rid B-7298-2008 - Reimer, P. J.; Baillie, M. G. L.; Bard, E.; Bayliss, A.; Beck, J. W.; Blackwell, P. G.; Ramsey, C. Bronk; Buck, C. E.; Burr, G. S.; Edwards, R. L.; Friedrich, M.; Grootes, P. M.; et al. (Radiocarbon, 2009)
The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the (14)C and calendar timescales as established in 2002. No change was made to the curves from 0-12 cal kBP. The curves were constructed using a Markov chain Monte Carlo (MCMC) implementation of the random walk model used for IntCal04 and Marine04. The new curves were ratified at the 20th International Radiocarbon Conference in June 2009 and; ire available in the Supplemental Material at www.radiocarbon.org.
id: 1983; PT: J; UT: WOS:000274407500002

Interhemispheric Atlantic seesaw response during the last deglaciation - Barker, S.; Diz, P.; Vautravers, M. J.; Pike, J.; Knorr, G.; Hall, I. R.; Broecker, W. S. (Nature, 2009)
The asynchronous relationship between millennial-scale temperature changes over Greenland and Antarctica during the last glacial period has led to the notion of a bipolar seesaw which acts to redistribute heat depending on the state of meridional overturning circulation within the Atlantic Ocean. Here we present new records from the South Atlantic that show rapid changes during the last deglaciation that were instantaneous (within dating uncertainty) and of opposite sign to those observed in the North Atlantic. Our results demonstrate a direct link between the abrupt changes associated with variations in the Atlantic meridional overturning circulation and the more gradual adjustments characteristic of the Southern Ocean. These results emphasize the importance of the Southern Ocean for the development and transmission of millennial-scale climate variability and highlight its role in deglacial climate change and the associated rise in atmospheric carbon dioxide.
id: 856; Barker, Stephen Diz, Paula Vautravers, Maryline J Pike, Jennifer Knorr, Gregor Hall, Ian R Broecker, Wallace S England Nature. 2009 Feb 26;457(7233):1097-102.Y

Interpreting Nd isotope and Pa-231/Th-230 records in the deep Western North Atlantic - Roberts, N. L.; Piotrowski, A. M.; McManus, J. F.; Keigwin, L. D. (Geochimica Et Cosmochimica Acta, 2009)
Suppl. S460ys Times Cited:0 Cited References Count:3
Keywords: circulation

Lake Sturgeon Age Validation using Bomb Radiocarbon and Known-Age Fish - Bruch, R. M.; Campana, S. E.; Davis-Foust, S. L.; Hansen, M. J.; Janssen, J. (Transactions of the American Fisheries Society, 2009)
Pectoral fin spines have been the accepted structure for estimating the age of various sturgeon species for nearly 100 years, though other structures have also been used (otoliths, pectoral girdle, scutes, and caudal fulcra). Accuracy of age estimates using any of these structures has not been validated, so we report the first use of bomb radiocarbon (C-14) assays to assess the validity of ages estimated using growth increments on pectoral fin spine and otolith frontal cross sections from lake sturgeon Acipenser fulvescens: we also assessed age estimates from pectoral fin spines of known-age lake sturgeon. Growth increments on pectoral fin spine cross sections underestimated true age of fish older than 14 years and error increased with age, whereas otoliths accurately estimated true age up to at least 52 years. Increment formation on pectoral fin spine and otolith cross sections from juvenile lake sturgeon (ages 2-11) was similar, although pectoral spines were clearer and easier to interpret. A power function (true age = [estimated age](1.054796), where estimated age was determined from pectoral spines; r(2) = 0.98) provides a means for correcting existing age estimates obtained from lake sturgeon pectoral fin spines.
id: 1855; 477EI Times Cited:1 Cited References Count:33Y

Land-sea linkage of Holocene paleoclimate on the Southern Bering Continental Shelf - Katsuki, K.; Khim, B. K.; Itaki, T.; Harada, N.; Sakai, H.; Ikeda, T.; Takahashi, K.; Okazaki, Y.; Asahi, H. (Holocene, 2009)
Detailed diatom records within surface and core sediments from the Southern Bering Continental Shelf (SBCS) reveal that the Holocene evolution of sea-ice distribution is associated with low pressure patterns. Holocene sea-ice distribution over the SBCS was mainly controlled by the location of the Aleutian Low. The corresponding paleoceanographic and paleoclimate conditions can be divided into three stages. (1) the early Holocene K before 7000 cal. yr BP) was characterized by extensive sea-ice distribution under two low-pressure cells, which covered the western Bering-Sea and the Gulf of Alaska, respectively. (2) Between 3000 and 7000 cal. yr BP, the low-pressure system over the Gulf of Alaska became weak, causing total sea-ice mass over the SBCS to retreat. (3) In the past 3000 years, prevailing southwesterly winds over the SBCS due to the developing Aleutian Low have reduced further sea-ice cover on the SBCS. These paleoclimatic changes were probably a response to ENSO variation. The timings of water mass exchanges on the SBCS coincided with sea-level change along the Alaskan Peninsula. As a result, subsequent morphologic alterations have also influenced the paleoceanographic condition of the SBCS. The effect of the surface coastal water and bottom marine water on the SBCS intensified about 6000 cal. yr BP when sea level increased.
id: 1878; 470HQ Times Cited:1 Cited References Count:76Y

Late Holocene Hydrologic and Vegetation Changes at Turneffe Atoll, Belize, Compared with Records from Mainland Central America and Mexico - Wooller, M. J.; Behling, H.; Guerrero, J. L.; Jantz, N.; Zweigert, M. E. (Palaios, 2009)
We present pollen and stable isotope (delta C-13, delta O-18, delta N-15) data from a similar to 4 in core (TNF-1) of primarily mangrove peat taken from Turneffe Atoll, Belize. Radiocarbon (accelerator mass spectrometry) dates show that the record represents ca. 5000 years of sediment accumulation. Vegetation composition varied between dominant mangroves (primarily Rhizophora mangle) and Chenopodiaceae-Amaranthaceae, most likely Salicornia bigelovii. The pollen data, along with inferences from stable isotope analyses of bulk peat and fossil leaf fragments, indicate that marked environmental changes occurred at this location over the past ca. 5000 years. There was a transition between ca. 4100 and 2900 cal yr BP, from vegetation dominated by relatively tall mangroves (R. mangle) to one dominated by Chenopodiaceae-Amaranthaceae and then Myrica, most likely wax myrtle (M. cerifera). These changes bracket a period centered at ca. 3500 calibrated years before present, where there is a peak in the delta O-18 of mangrove leaf fragments. This timing corresponds with other paleoenvironmental records of climate drying in Central America and increases the geographic and habitat scope (i.e., mangrove habitat) of records documenting these changes. Interpretations of shifts in mangrove habitat, however, require consideration of additional environmental influences, including changes in groundwater hydrology and relative inputs of seawater and freshwater (i.e., precipitation) during the Holocene.
id: 1835; 506UH Times Cited:1 Cited References Count:34Y

A late Holocene paleo-productivity record in the western Gulf of Maine, USA, inferred from growth histories of the long-lived ocean quahog (Arctica islandica) - Wanamaker, Alan D. Jr.; Kreutz, Karl J.; Schoene, Bernd R.; Maasch, Kirk A.; Pershing, Andrew J.; Borns, Harold W.; Introne, Douglas S.; Feindel, Scott (INTERNATIONAL JOURNAL OF EARTH SCIENCES, 2009)
To investigate environmental variability during the late Holocene in the western Gulf of Maine, USA, we collected a 142-year-old living bivalve (Arctica islandica) in 2004, and three fossil A. islandica shells of the Medieval Warm Period (MWP) and late MWP / Little Ice Age (LIA) period (corrected C-14(AMS) = 1030 +/- A 78 ad; 1320 +/- A 45 ad; 1357 +/- A 40 ad) in 1996. We compared the growth record of the modern shell with continuous plankton recorder (CPR) time-series (1961-2003) from the Gulf of Maine. A significant correlation (r (2) = 0.55; p < 0.0001) exists between the standardized annual growth index (SGI) of the modern shell and the relative abundance of zooplankton species Calanus finmarchicus. We therefore propose that SGI data from A. islandica is a valid proxy for paleo-productivity of at least one major zooplankton taxa. SGIs from these shells reveal significant periods of 2-6 years (NAO-like) based on wavelet analysis, multitaper method (MTM) analysis and singular spectrum analysis (SSA) during the late Holocene. Based on established physical oceanographic observation in the Gulf of Maine, we suggest that slope water variability coupled with North Atlantic Oscillation (NAO) dynamics is primarily responsible for the observed SGI variability.
Keywords: Arctica islandica; Climate variability; Gulf of Maine; North Atlantic Oscillation (NAO); Paleo-productivity; Shell growth

Late Holocene sea-surface temperature and precipitation variability in northern Patagonia, Chile (Jacaf Fjord, 44 degrees S) - Sepulveda, J.; Pantoja, S.; Hughen, K. A.; Bertrand, S.; Figueroa, D.; Leon, T.; Drenzek, N. J.; Lange, C. (Quaternary Research, 2009)
A high-resolution multi-proxy study including the elemental and isotopic composition of bulk organic matter, land plant-derived biomarkers, and alkenone-based sea-surface temperature (SST) from a marine sedimentary record obtained from the Jacaf Fjord in northern Chilean Patagonia (similar to 44 degrees 20'S) provided a detailed reconstruction of continental runoff, precipitation, and summer SST spanning the last 1750 yr We observed two different regimes of climate variability in our record a relatively dry/warm period before 900 cal yr BP (lower runoff and average SST 1 degrees C warmer than present day) and a wet/cold period after 750 cal yr BP (higher runoff and average SST 1 degrees C colder than present clay). Relatively colder SSTs were found during 750-600 and 450-250 cal yr BP, where the latter period roughly corresponds to the interval defined for the Little Ice Age (LIA) Similar climatic swings have been observed previously in continental and marine archives of the last two millennia from central and southern Chile, suggesting a strong latitudinal sensitivity to changes in the Southern Westerly Winds, the main Source Of precipitation in southern Chile, and validating the regional nature of the LIA Our results reveal the importance of the Chilean fjord system for recording climate changes of regional and global significance (C) 2009 University of Washington Published by Elsevier Inc All rights reserved.
id: 1858; 512MQ Times Cited:0 Cited References Count:53Y

Late Pleistocene-Holocene evolution of the northern shelf of the Sea of Marmara - Cagatay, M. N.; Eris, K.; Ryan, W. B. F.; Sancar, U.; Polonia, A.; Akcer, S.; Biltekin, D.; Gasperini, L.; Gorur, N.; Lericolais, G.; Bard, E. (Marine Geology, 2009)
Chirp sub-bottom profiling, multibeam bathymetric mapping and a combination of faunal and isotopic analysis of molluscs and foraminifera in sediment cores on the northern shelf of the Sea of Marmara (SoM) provide evidence of sea-level excursions, water exchanges between the adjacent Mediterranean and Black Seas, and oscillating salinity over the last 160 ka bp. During the marine isotope stages MIS-2, MIS-3, MIS-4 and MIS-6 the SoM disconnected from the Mediterranean Sea and evolved into a lake. During MIS-1, MIS-5 and MIS-7, the SoM reconnected and became salty once again. Sapropels formed shortly after each invasion of Mediterranean saltwater observed in our cores. Concurrent suboxic-dysoxic conditions prevailed over quite shallow substrates on the shelf. Ancient shorelines are pervasive at -85 m on the northern shelf and in the region of Prince Islands coincident with the elevation of the modern bedrock sill in the Canakkale (Dardanelles) Strait. At times when global (eustatic) sea level dropped below this sill, the surface of the SoM stabilized at its outlet and freshened. Thus this particular shoreline is interpreted as the edge of the most recent SoM lake that existed from about 75 ka bp to 12 ka bp. The freshening is observed in very light (-6 parts per thousand) values of delta O-18 measured on freshwater molluscs and the complete absence of foraminifera. Two brief lacustrine episodes during MIS-5 suggest that the level of the Canakkale outlet might have been as shallow as -50 m in the past, a likelihood supported by submerged terraces along its margins bounding the modern central channel and the presence of an euryhaline biofacies in Unit L4.1 corresponding to MIS-5b. delta O-18 profiles and carbon-14 dating show that salinification of the SoM and the blossoming of bioherms evolved rapidly after the latest connection with the Mediterranean at 12 ka bp. However, freshening proceeded more slowly once the connection was severed. (C) 2009 Elsevier B.V. All rights reserved.
id: 1843; 500UN Times Cited:1 Cited References Count:80Y

A Late Prehistoric Bison Processing Camp in the Central Plains: Montana Creek East (14JW46) - Ritterbush, Lauren W.; Logan, Brad (Plains Anthropologist, 2009)
id: 1999

Late Quaternary benthic foraminifera from Ocean Drilling Program Hole 716A, Maldives Ridge, southeastern Arabian Sea - Sarkar, S.; De, S.; Gupta, A. K. (Micropaleontology, 2009)
A study on deep-sea benthic foraminifera from the interval similar to 445 ka BP to the Present of the Ocean Drilling Program (ODP) Hole 716A (4 degrees 56.0'N, 73 degrees 17.0'E; preser t water depth 533.3m), Maldives Ridge. southeastern Arabian Sea, documented 201 species belonging to 105 genera. These taxa were examined under scanning electron microscope (SEM) to illustrate their interspecific morphological variations. Several of these species are dominant showing significant down core fluctuations in their abundances whereas some are rare and sporadic.
424cdTimes Cited:5 Cited References Count:47
Keywords: benthonic foraminifera; equatorial indian-ocean; Holocene; late neogene; monsoon; Oxygen minimum zone; productivity; red-sea; south atlantic-ocean; Water masses

Late Quaternary foraminiferal assemblages from western Ross Sea (Antarctica) in relation to the main glacial and marine lithofacies - Melis, R.; Salvi, G. (Marine Micropaleontology, 2009)
investigations oil foraminifers from Upper Pleistocene-Holocene sediments were carried Out On twelve cores from the western Ross Sea continental margin (Drygalski, Joides, North Victoria Land Basins) as part of a "Progetto Nazionale di Ricerche in Antartide" (P.N.R.A.) multidisciplinary project. Data on the foraminiferal frequency, species diversity, tests abundance and their state of preservation were presented as a synthesis of 404 core samples to establish their relationships with the main glacial and marine lithofacies of this area. A total of 126 benthic species. pertaining to 73 genera have been identified; just few taxa, such as Cibicides spp., Globocassidulina spp., Trifarina angulosa and Miliammina spp. being the most ubiquitous and in some cases the dominant species of these paleoenvironments. Two variants of Neogloboquadrina pachyderma, including thin and thick-shelled forms have been recovered. We propose to use these results to provide the degree of glacial control during the Last Glacial Maximum and the following Holocene retreat of the ice sheets. High test fragmentation, low diversity and density tests reflect higher glacial influence of the ice sheet in the Drygalski Basin, whereas the decreasing percentage of fragmentation and a relative increase of density and diversity in Drygalski, Joides and North Victoria Land Basins indicate the paleoenvironmental passage from the ice sheet to the ice shelf condition. The ice shelf retreat is well evidenced in the Joides Basin by a succession of levels barren of foraminifers alternating with high-density levels, rich in T angulosa, followed by a total disappearance of the calcareous foraminifers. Open-marine settings indicative of lower glacial influence and increased corrosiveness of the water masses is testified by the Miliammina foraminiferal assemblage during the Holocene in Drygalski and Joides Basins cores. On the contrary, rich and abundant benthic and planktonic assemblages characterize the Holocene paleoenvironment of the North Victoria Land area, indicating that the water masses were less corrosive with respect to the other areas. In addition to the glacial reworking of the tests, and the dissolution due to the corrosive water mass conditions, the volcaniclastic sediments recovered in the North Victoria Land Basin cores also affected the condition of test preservation. In volcaniclastic sediments, older than about 20 ka BP, the foraminifers concentration tends to zero and, when present, their tests are highly damaged or completely broken. (c) 2008 Elsevier B.V. All rights reserved.
id: 1879; 405HR Times Cited:0 Cited References Count:66Y

Late Quaternary sediment-accumulation rates within the inner basins of the California Continental Borderland in support of geologic hazard evaluation - Normark, William R.; McGann, Mary; Sliter, Ray W. (Geological Society of America Special Papers, 2009)
An evaluation of the geologic hazards of the inner California Borderland requires determination of the timing for faulting and mass-movement episodes during the Holocene. Our effort focused on basin slopes and turbidite systems on the basin floors for the area between Santa Barbara and San Diego, California. Dating condensed sections on slopes adjacent to fault zones provides better control on fault history where high-resolution, seismic-reflection data can be used to correlate sediment between the core site and the fault zones. This study reports and interprets 147 radiocarbon dates from 43 U.S. Geological Survey piston cores as well as 11 dates from Ocean Drilling Program Site 1015 on the floor of Santa Monica Basin. One hundred nineteen dates from 39 of the piston cores have not previously been published. Core locations were selected for hazard evaluation, but despite the nonuniform distribution of sample locations, the dates obtained for the late Quaternary deposits are useful for documenting changes in sediment-accumulation rates during the past 30 ka. Cores from basins receiving substantial sediment from rivers, i.e., Santa Monica Basin and the Gulf of Santa Catalina, show a decrease in sediment supply during the middle Holocene, but during the late Holocene after sea level had reached the current highstand condition, rates then increased partly in response to an increase in El Ni√±o‚ÄìSouthern Oscillation events during the past 3.5 ka.
id: 1906; 10.1130/2009.2454(2.6)

Mangrove ecosystem changes during the Holocene at Spanish Lookout Cay, Belize - Monacci, N. M.; Meier-Grunhagen, U.; Finney, B. P.; Behling, H.; Wooller, M. J. (Palaeogeography Palaeoclimatology Palaeoecology, 2009)
Mangroves are halophytic plants living at the land-sea interface and are therefore natural trackers of sea-level. Multiple proxies of a continuous (8 m) mangrove peat core (BT-79) from Spanish Lookout Cay, Belize illustrate mangrove ecosystem changes during the Holocene. Radiocarbon measurements show this site was colonized by mangroves similar to 8000 cal. yrs BP, with a significant decrease in the peat accumulation rate from similar to 6000 to 1000 cal. yrs BR Stratigraphic characteristics of this peat core such as bulk density, magnetic susceptibility, and loss on ignition show relative uniformity, inferring an uninterrupted mangrove ecosystem during a majority of the Holocene. This is supported by pollen data from BT-79 that show that the site has been consistently dominated by Rhizophora mangle (red mangrove), with Avicennia germinans (black mangrove) and Laguncularia racemosa (white mangrove) present as well. Subfossil R. mangle leaves are used for stable nitrogen, carbon, and oxygen isotope (delta N-15, delta C-13, and delta O-18) analyses. delta N-15 and delta C-13 values provide a proxy of this plant's past physiology and stand structure showing that dwarf (delta N-15
id: 1834; 496QP Times Cited:1 Cited References Count:50Y

Marine shellfish harvest on Middle and Late Holocene Santa Barbara Island, California - Rick, Torben C.; Erlandson, Jon M.; Horton, Kristina (California Archaeology, 2009)
id: 2077

Methane accumulation and release from deep peat: Measurements, conceptual models, and biogeochemical significance - Glaser, Paul H.; Chanton, Jeffrey P. (Carbon Cycling in Northern Peatlands, 2009)
Northern peatlands account for more than half the world's wetlands but are currently estimated to contribute only about a third of the total methane emissions from all wetlands. Increasing data on the dynamics of methane gas bubbles in peat deposits now suggest that these estimates may need to be scaled upward. Rates of methanogenesis may remain high in deep peat strata because of the downward transport of labile root exudates permitting the widespread production of gas bubbles. Recent investigations using an array of methods have reported free-phase gas volumes of 10–20% within both deep and shallow peat strata and episodic ebullition fluxes exceeding 35 g CH4 m−2 per event. Gas bubbles accumulate in overpressured pockets that episodically rupture in response to steep declines in atmospheric pressure or declining water tables. Although these ebullition fluxes are highly variable in both time and space, they appear to dominate the annual methane emissions from northern peatlands and represent a major and underappreciated element of the global methane cycle.
id: 1972
Keywords: Carbon cycle (Biogeochemistry)—Northern Hemisphere; Carbon sequestration—Northern Hemisphere; Greenhouse gases—Northern Hemisphere; Peatlands—Environmental aspects—Northern Hemisphere

Millennial time scale changes in surface to intermediate-deep layer circulation recorded in the sediment cores from the northwestern North Pacific - Harada, N.; Kimoto, K.; Okazaki, Y.; Nagashima, K.; Timmermann, A.; Abe-Ouchi, A. (The Quaternary Research, 2009)
id: 1877

Moderate rates of late Quaternary slip along the northwestern margin of the Basin and Range Province, Surprise Valley fault, northeastern California - Personius, Stephen F.; Crone, Anthony J.; Machette, Michael N.; Mahan, Shannon A.; Lidke, David J. (Journal of Geophysical Research-Solid Earth, 2009)
The 86-km-long Surprise Valley normal fault forms part of the active northwestern margin of the Basin and Range province in northeastern California. We use trench mapping and radiocarbon, luminescence, and tephra dating to estimate displacements and timing of the past five surface-rupturing earthquakes on the central part of the fault near Cedarville. A Bayesian OxCal analysis of timing constraints indicates earthquake times of 18.2 +/- 2.6, 10.9 +/- 3.2, 8.5 +/- 0.5, 5.8 +/- 1.5, and 1.2 +/- 0.1 ka. These data yield recurrence intervals of 7.3 +/- 4.1, 2.5 +/- 3.2, 2.7 +/- 1.6, and 4.5 +/- 1.5 ka and an elapsed time of 1.2 +/- 0.1 ka since the latest surface-rupturing earthquake. Our best estimate of latest Quaternary vertical slip rate is 0.6 +/- 0.1 mm/a. This late Quaternary rate is remarkably similar to long-term (8-14 Ma) minimum vertical slip rates (>0.4-0.5 +/- 0.3 mm/a) calculated from recently acquired seismic reflection and chronologic and structural data in Surprise Valley and the adjacent Warner Mountains. However, our slip rate yields estimates of extension that are lower than recent campaign GPS determinations by factors of 1.5-4 unless the fault has an unusually shallow (30 degrees-35 degrees) dip as suggested by recently acquired seismic reflection data. Coseismic displacements of 2-4.5 +/- 1 m documented in the trench and probable rupture lengths of 53-65 km indicate a history of latest Quaternary earthquakes of M 6.8-7.3 on the central part of the Surprise Valley fault.
id: 2021; PT: J; UT: WOS:000270058200001

Molecular and isotopic constraints on the sources of suspended particulate organic carbon on the northwestern Atlantic margin - Hwang, J.; Montlucon, D.; Eglinton, T. I. (Deep-Sea Research Part I-Oceanographic Research Papers, 2009)
The abundance, carbon isotopic composition (Delta C-14 and delta C-13), and lipid biomarker (alkenones and saturated fatty acids) distributions of suspended particulate organic matter were investigated at three stations centered on the 2000, 3000, and 3500 m isobaths over the New England slope in order to assess particulate carbon sources and dynamics in this highly productive and energetic region. Transmissometry profiles reveal that particle abundances exhibit considerable fine structure, with several distinct layers of elevated suspended particulate matter concentration at intermediate water depths in addition to the presence of a thick bottom nepheloid layer at each station. Excluding surface water samples, the Delta C-14 values of particulate organic carbon (POC) indicated the presence of a pre-aged component in the suspended POC pool (Delta C-14
id: 774; 471WJ Times Cited:1 Cited References Count:73Y

Molluscs and mass harvesting in the Middle Holocene: Prey size and resource ranking on San Miguel Island, Alta California - Braje, Todd J.; Erlandson, Jon M. (California Archaeology, 2009)
id: 2070

Monsoons, Quaternary - Gupta, A. K. (Encyclopedia of Paleoclimatology and Ancient Environments, 2009)
id: 1971

A multi-proxy paleolimnological reconstruction of Holocene climate conditions in the Great Basin, United States - Reinemann, Scott A.; Porinchu, David F.; Bloom, Amy M.; Mark, Bryan G.; Box, Jason E. (Quaternary Research, 2009)
A sediment core spanning ~†7000†cal yr BP recovered from Stella Lake, a small sub-alpine lake located in Great Basin National Park, Nevada, was analyzed for subfossil chironomids (non-biting midges), diatoms, and organic content (estimated by loss-on-ignition (LOI)). Subfossil chironomid analysis indicates that Stella Lake was characterized by a warm, middle Holocene, followed by a cool "Neoglacial" period, with the last two millennia characterized by a return to warmer conditions. Throughout the majority of the core the Stella Lake diatom-community composition is dominated by small, periphytic taxa which are suggestive of shallow, cool, alkaline, oligotrophic waters with extensive seasonal ice cover. A reconstruction of mean July air temperature (MJAT) was developed by applying a midge-based inference model for MJAT (two-component WA-PLS) consisting of 79 lakes and 54 midge taxa (rjack2†=†0.55, RMSEP†=†0.9∞C). Comparison of the chironomid-inferred temperature record to existing regional paleoclimate reconstructions suggests that the midge-inferred temperatures correspond well to regional patterns. This multi-proxy record provides valuable insight into regional Holocene climate and environmental conditions by providing a quantitative reconstruction of peak Holocene warmth and aquatic ecosystem response to these changes in the Great Basin, a region projected to experience increased aridity and higher temperatures.
id: 880Y

The Mysterious C-14 Decline - Broecker, W. (Radiocarbon, 2009)
Fundamental to the field of radiocarbon dating is not only the establishment of the temporal record of the calendar age-radiocarbon age offsets but also the development of an understanding of their cause. Although part of the decline in the magnitude of this offset over the past 40,000 can be explained by a drop in C-14 production rate associated with a progressive increase in the strength of the Earth's magnetic shielding, it is clear that changes in the distribution of C-14 among the Earth's active carbon reservoirs are also required. In particular, the steep 15% decline in the C-14 to C ratio in atmospheric CO2 and surface ocean Sigma CO2,. which occurred in a 3 kyr-duration interval marking the onset of the last deglaciation, appears to require that a very large amount (at least 5000 gigatons) of C-14-deficient carbon was transferred to or within the ocean during this time interval. As no chemical or stable isotope anomaly associated with this injection appears in either the marine sediment or polar ice records, this injection must involve a transfer within the ocean (i.e. a mixing of 2 ocean reservoirs, one depleted in C-14 and the other enriched in C-14). Although evidence for the existence of a salt-stabilized glacial-age abyssal ocean reservoir exists, a search based on benthic-planktic age differences and C-13 measurements appears to place a limit on its size well below that required to account for the steep C-14 decline.
453wfTimes Cited:18Cited References Count:30

The nature and origin of decadal to millennial scale climate variability in the southern tropics of South America - Baker, P. A.; Fritz, S. C.; Burns, S. J.; Ekdahl, E.; Rigsby, C. A. (Past Climate Variability from the Last Glacial Maximum to the Holocene in South America and Surrounding Regions, 2009)
id: 843

A new look at old carbon in active margin sediments RID F-1809-2010 - Drenzek, Nicholas J.; Hughen, Konrad A.; Montluçon, Daniel B.; Southon, John R.; dos Santos, Guaciara M.; Druffel, Ellen R. M.; Giosan, Liviu; Eglinton, Timothy I. (Geology, 2009)
Recent studies suggest that as much as half of the organic carbon (OC) undergoing burial in the sediments of tectonically active continental margins may be the product of fossil shale weathering. These estimates rely on the assumption that vascular plant detritus spends little time sequestered in intermediate reservoirs such as soils, freshwater sediments, and river deltas, and thus only minimally contributes to the extraneously old (14)C ages of total organic matter often observed on adjacent shelves. Here we test this paradigm by measuring the (14)C and delta(13)C values of individual higher plant wax fatty acids as well as the d13C values of extractable alkanes isolated from the Eel River margin (California). The isotopic signatures of the long chain fatty acids indicate that vascular plant material has been sequestered for several thousand years before deposition. A coupled molecular isotope mass balance used to reassess the sedimentary carbon budget indicates that the fossil component is less abundant than previously estimated, with pre-aged terrestrial material instead composing a considerable proportion of all organic matter. If these findings are characteristic of other continental margins proximal to small mountainous rivers, then the importance of petrogenic OC burial in marine sediments may need to be reevaluated.
id: 1987; PT: J; UT: WOS:000263842200012

Oceanographic and climatologic controls on the compositions and fluxes of biogenic materials in the water column and sediments of the Cariaco Basin over the Late Holocene - Goñi, M. A.; Aceves, H.; Benitez-Nelson, B.; Tappa, E.; Thunell, R.; Black, D. E.; Muller-Karger, F.; Astor, Y.; Varela, R. (Deep-Sea Research Part I-Oceanographic Research Papers, 2009)
Materials collected by sediment traps over a 3-y period and sedimentary horizons from a gravity core covering the last 6000y were used to investigate the effects of climate-related processes such as wind-driven upwelling and regional rainfall on the production, export and burial of particulate organic matter in the Cariaco Basin. A variety of chemical analyses, including organic carbon and nitrogen, biogenic opal, calcite, lithogenic contents, stable carbon isotopic ratios of organic matter and the yields of CuO reaction products derived from distinct biochemicals such as amino acids, fatty acids and lignins, were carried out for this purpose. Principal component analyses were used to investigate the trends in this multivariate data set. These analyses reveal marked temporal differences in the composition of the materials sinking through the water column, which were related to distinct oceanographic and climatic forcings. For example, autorchthonous fluxes, characterized by elevated contents of organic carbon and opal as well as high yields of amino acid and fatty acid reaction products, displayed peaks during periods of intense wind-driven upwelling. In contrast, allochthonous materials, characterized by elevated lithogenic contents and elevated yields of lignin-derived products, were more important during periods of high rainfall, low wind and enhanced stratification. In addition to the strong seasonal contrasts, there was significant temporal variability at both shorter (monthly) and longer (inter-annual) time scales. Hence, other factors, such as zooplankton grazing and El Nino effects on local climatology, may also be important. Examination of the gravity core record yielded several significant trends. For example, there was a marked increase in sediment accumulation rates from 5000 to ca. 700 y before present with concomitant increases in the concentrations of organic carbon, opal and most biomarkers. These results suggest that the Cariaco Basin experienced a marked increase in primary productivity and particle flux to the underlying sediments since the Holocene Thermal Maximum. Also within the sedimentary record, we observed distinct variations in the relative contributions of autochthonous and allochthonous organic matter. The frequency of these variations is roughly 1500y and appears to match ice-rafted debris records from the North Atlantic. Such coincidence indicates cold periods within the Holocene, which are related to minima in insolation, may have led to the southern migration of the inter-tropical convergence zone and the enhancement of wind-driven upwelling, primary productivity and autochthonous organic matter flux to the seabed in the Cariaco Basin. Alternatively, during warm periods, the opposite climatic conditions would have increased both the thermal stratification of the water column and average rainfall in the Cariaco Basin, leading to elevated inputs of allochthonous materials. (C) 2008 Elsevier Ltd. All rights reserved.
id: 1871; 430SK Times Cited:0 Cited References Count:69Y

Palaeoecological potential of the marine organic deposits of Posidonia oceanica: A case study in the NE Iberian Peninsula - López-Sáez, J. A.; Lopez-Merino, L.; Mateo, M. A.; Serrano, O.; Perez-Diaz, S.; Serrano, L. (Palaeogeography Palaeoclimatology Palaeoecology, 2009)
A high-resolution sedimentary sequence sampled from the Portlligat Bay (NE Iberian Peninsula) has been studied in order to assess its palaeoecological potential. This sedimentary sequence is considered a very particular one, as it is a peat-like deposit derived from the accumulation of the belowground dead parts of the marine phanerogam Posidonia oceanica through the last 1600 years. This study represents the first attempt to explore the palaeoecological potential of such deposits from a palynological point of view, and has allowed the reconstruction of the vegetation dynamics and changes, human impact and the palaeoclimatic characteristics, demonstrating the value of these sedimentary records in palaeopalynological studies. (C) 2008 Elsevier B.V. All rights reserved.
402ksTimes Cited:20Cited References Count:55

Palaeoenvironmental changes from pollen record in deep sea core PC-1 from northern Okinawa Trough, East China Sea during the past 24 ka - Xu, HongYan; Chang, Fengming; Luo, YunLi; Sun, XiangJun (Chinese Science Bulletin, 2009)
A pollen record of core PC-1 from the northern Okinawa Trough, East China Sea (ECS), provides information on vegetation and climate changes since 24 cal. kaBP. A total of 103 samples were palynologically analyzed at 8 cm intervals with a time resolution of 230 a. Four pollen zones are recognized: zone I (812-715 cm, 24.2-21.1 cal. kaBP), zone II (715-451 cm, 21.1-15.2 cal. kaBP), zone III (451-251 cm, 15.2-10.8 cal. kaBP), zone IV (251-0 cm, 10.8-0.3 cal. kaBP), corresponding to Late MIS 3, Last Glacial Maximum (LGM), deglaciation and Holocene, respectively. The LGM is characterized by the dominance of herbs, mainly Artemisia, and high pollen influx, implying an open vegetation on the exposed continental shelf and a cool and dry climate. The deglaciation is a climate warming stage with Pinus percentage increased and Artemisia percentage decreased and a rapid sea-level rise. The Holocene is characterized by predominance of tree pollen with rapid increase in Castanea-Castanopsis indicating the development of mixed evergreen and deciduous broad-leaved forest and a warm, humid climate. Low pollen influx during the Holocene probably implies submergence of the continental shelf and retreat of the pollen source area. The vegetation indicated by pollen assemblage found in this upper zone is consistent with the present vegetation found in Kyushu, Japan. Originating from the humid mountain area of North Luzon of the Philippines, Tasmania and New Zealand, Phyllocladus with sporadic occurrence throughout PC-1 core probably suggests the influence of Palaeo-Kuroshio Current or intense summer monsoon. The observed changes in Pinus and Herbs percentage indicate fluctuations of the sea level, and high Pinus percentage corresponds to high sea level. Spectrum analysis of the pollen percentage record reveals many millennial-scale periodicities, such as periodicities of 6.8, 3.85 2.2, 1.6 ka.
id: 1931; PT: J; UT: WOS:000271175500023

Palaeohydrology of Kangerlussuaq (Soendre Stroemfjord), West Greenland during the last similar to 8000 years - Aebly, F. A.; Fritz, S. C. (Holocene, 2009)
Major fluctuations of hydroclimate in West Greenland are recorded in palaeoshoreline terraces that encircle several lakes near Kangerlussuaq, Greenland (67 degree 01'N, 50 degree 40'W). Geomorphic and stratigraphic analyses were used to construct a lake-level curve for Hunde S0, a large closed-basin lake in this region. Changes in lake volume associated with lake-level fluctuations were calculated, and a water-balance model was used to determine the primary factors influencing lake volume and the changes in those factors necessary to affect reconstructed lake-level change. Sensitivity tests suggest that mean annual precipitation and the relative proportion of summer versus winter precipitation are the primary climate drivers of lake-level change. Temperature effects are less important unless coupled with changes in one of the other variables. Two pluvial periods occurred centred around 4600 and 2000 cal. yr BP, with mean annual precipitation estimated at 130 mm and 70 mm higher than modern, respectively. In contrast, a low-stand prior to 6070 cal. yr BP with water levels as much as 18 m below modern was a result of summer temperatures similar to 2-3 degree above modern, coupled with a 14 day increase in the length of the ice-off period and a reduction in mean annual precipitation of similar to 80 mm relative to modern.
id: 2218; Source type: scholarlyjournals; Object type: Article; Object type: Feature; CSAUnique: OB-MD-0009349512; AccNum: 9048978; InputCenter: CS0919076; DOI: 10.1177/0959683608096601; ISSN: 0959-6836; ElecISSN: 1477-0911; Peer Reviewed: true

A Paleocoastal Shell Midden at Seal Cave (CA-SMI-604), San Miguel Island, California - Erlandson, Jon M.; Braje, Todd J.; Rick, Torben C.; Davis, Troy; Southon, Troy (Proceedings of the Seventh California Islands Symposium, 2009)
id: 2075

Paleolimnological records of recent glacier recession in the Rwenzori Mountains, Uganda-D. R. Congo - Russell, J.; Eggermont, H.; Taylor, R.; Verschuren, D. (Journal of Paleolimnology, 2009)
The status of tropical glaciers is enormously important to our understanding of past, present, and future climate change, yet lack of continuous quantitative records of alpine glacier extent on the highest mountains of tropical East Africa prior to the 20th century has left the timing and drivers of recent glacier recession in the region equivocal. Here we investigate recent changes (the last 150-700 years) in lacustrine sedimentation, glacier extent, and biogeochemical processes in the Rwenzori Mountains (Uganda- Democratic Republic of Congo) by comparing sedimentological (organic and siliciclastic component determined by loss-on-ignition; LOI) and organic geochemical profiles (carbon and nitrogen abundance, ratio, and isotopic composition of sedimentary organic matter) from lakes occupying presently glaciated catchments against similar profiles from lakes located in catchments lacking glaciers. The siliciclastic content of sediments in the 'glacial lakes' significantly decreases towards the present, whereas 'non-glacial lakes' generally show weak trends in their siliciclastic content over time, demonstrating that changes in the siliciclastic content of glacial lake sediments primarily record fluctuations in glacier extent. Radiometric dating of our sediment cores indicates that prior to their late 19th-century recession Rwenzori glaciers stood at expanded 'Little Ice Age' positions for several centuries under a regionally dry climate regime, and that recession was underway by 1870 AD, during a regionally wet episode. These findings suggest that the influence of late 19th century reductions in precipitation in triggering Rwenzori glacier recession is weaker than previously thought. Our organic geochemical data indicate that glacier retreat has significantly affected carbon cycling in Afroalpine lakes, but trends in aquatic ecosystem functioning are variable among lakes and require more detailed analysis.
id: 2048; PT: J; UT: WOS:000262651500002

Partitioning of organic matter in continental margin sediments among density fractions - Wakeham, S. G.; Canuel, E. A.; Lerberg, E. J.; Mason, P.; Sampere, T. P.; Bianchi, T. S. (Marine Chemistry, 2009)
Hydrodynamic processes sort and redistribute organic matter (OM) and minerals on continental margins. Density fractionations were conducted on sediments from diverse margins (Mexico margin, Gulf of Mexico, Mississippi River delta, Eel River margin) to investigate the nature, provenance and age of OM among density fractions. Mass. elemental (C and N), lignin, and surface area distributions, as well as stable carbon and radiocarbon isotopic compositions were measured, The lowest density fractions (2.5 g cm(-3)) were OC-poor (%OC -200 parts per thousand). Ratios of vanillic acid to vanillin (Ad/Al)v among lignin oxidation products increase with increasing particle density suggesting variable lignin sources or selective degradation of lignin among the different density fractions. (C) 2009 Elsevier B.V. All rights reserved.
id: 1844; 521ZI Times Cited:0 Cited References Count:99Y

Permanent storage of carbon dioxide in geological reservoirs by mineral carbonation - Matter, J. M.; Kelemen, P. B. (Nature Geoscience, 2009)
Anthropogenic greenhouse-gas emissions continue to increase rapidly despite efforts aimed at curbing the release of such gases. One potentially long-term solution for offsetting these emissions is the capture and storage of carbon dioxide. In principle, fluid or gaseous carbon dioxide can be injected into the Earth's crust and locked up as carbonate minerals through chemical reactions with calcium and magnesium ions supplied by silicate minerals. This process can lead to near-permanent and secure sequestration, but its feasibility depends on the ease and vigour of the reactions. Laboratory studies as well as natural analogues indicate that the rate of carbonate mineral formation is much higher in host rocks that are rich in magnesium-and calcium-bearing minerals. Such rocks include, for example, basalts and magnesium-rich mantle rocks that have been emplaced on the continents. Carbonate mineral precipitation could quickly clog up existing voids, presenting a challenge to this approach. However, field and laboratory observations suggest that the stress induced by rapid precipitation may lead to fracturing and subsequent increase in pore space. Future work should rigorously test the feasibility of this approach by addressing reaction kinetics, the evolution of permeability and field-scale injection methods.
id: 844; 525TO Times Cited:10 Cited References Count:49Y

Photochemical changes in chemical markers of sedimentary organic matter source and age - Mayer, L. M.; Schick, L. L.; Bianchi, T. S.; Wysocki, L. A. (Marine Chemistry, 2009)
Several chemical markers of organic matter source and age are shown to be susceptible to light-induced alteration. To test for the photochemical lability of markers previously employed for sediments from the Louisiana Coastal zone, we subjected sediments under resuspension conditions to Simulated Sunlight, and monitored changes in ON and Br:OC ratios, delta C-13, Delta C-14, and lignin composition. Markers of terrigenous origin (high C:N, lignin) decreased and delta C-13 became enriched in sediments containing primarily terrigencrus organic matter, while a marker of marine organic matter (Br:OC) decreased in samples containing significant contributions from this source. Preferential loss of C-14 from all sediments indicated enhanced photochemical lability of organic matter of relatively recent origin, consistent with the changes in chemical markers. Most, but not all, experimental alterations are consistent with field distributions of these markers. Relatively small experimental changes in the markers in combination with confounding processes in the environment, however. prevent these parallel trends from providing any more than a consistency test for the importance of photochemical reactions in this region. (C) 2009 Elsevier B.V. All rights reserved.
id: 793; 425QO Times Cited:0 Cited References Count:40Y

Pleistocene Megafaunal Collapse, Novel Plant Communities, and Enhanced Fire Regimes in North America - Gill, J. L.; Williams, J. W.; Jackson, S. T.; Lininger, K. B.; Robinson, G. S. (Science, 2009)
Although the North American megafaunal extinctions and the formation of novel plant communities are well-known features of the last deglaciation, the causal relationships between these phenomena are unclear. Using the dung fungus Sporormiella and other paleoecological proxies from Appleman Lake, Indiana, and several New York sites, we established that the megafaunal decline closely preceded enhanced fire regimes and the development of plant communities that have no modern analogs. The loss of keystone megaherbivores may thus have altered ecosystem structure and function by the release of palatable hardwoods from herbivory pressure and by fuel accumulation. Megafaunal populations collapsed from 14,800 to 13,700 years ago, well before the final extinctions and during the Bolling-Allerod warm period. Human impacts remain plausible, but the decline predates Younger Dryas cooling and the extraterrestrial impact event proposed to have occurred 12,900 years ago.
id: 769; 521UW Times Cited:4 Cited References Count:30Y

Pre-Columbian settlement of Carriacou, West Indies - Fitzpatrick, S. M.; Kappers, M.; Kaye, Q.; Giovas, C. M.; LeFebvre, M. J.; Harris, M. H.; Burnett, S.; Pavia, J. A.; Marsaglia, K.; Feathers, J. (Journal of Field Archaeology, 2009)
id: 830

Processes That Initiate Turbidity Currents and Their Influence on Turbidites: A Marine Geology Perspective - Piper, D. J. W.; Normark, W. R. (Journal of Sedimentary Research, 2009)
How the processes that initiate turbidity currents influence turbidite deposition is poorly understood, and many discussions in the literature rely on concepts that are overly simplistic. Marine geological studies provide information on the initiation and flow path of turbidity currents, including their response to gradient. In case studies of late Quaternary turbidites on the eastern Canadian and western U.S. margins, initiation processes are inferred either from real-time data for historical flows or indirectly from the age and contemporary paleogeography, erosional features, and depositional record. Three major types of initiation process are recognized: transformation of failed sediment, hyperpycnal flow from rivers or ice margins, and resuspension of sediment near the shelf edge by oceanographic processes. Many high-concentration flows result from hyperpycnal supply of hyperconcentrated bedload, or liquefaction failure of coarse-grained sediment, and most tend to deposit in slope conduits and on gradients
id: 877; 451YQ Times Cited:2 Cited References Count:124Y

Proxy Records of Paleohurricanes for the Western and Southern Caribbean - McCloskey, T. A. (Louisiana State University, 2009)

Radiocarbon Analysis of Atmospheric Formaldehyde Using Cystamine Derivatization - Shen, Haiwei; McNichol, Ann P.; Xu, Li; Gagnon, Alan; Heikes, Brian G. (ANALYTICAL CHEMISTRY, 2009)
A compound specific radiocarbon analysis method was developed to evaluate the C-14 composition of atmospheric formaldehyde. In this method, gaseous formaldehyde was collected with a high-volume air sampler using glass-fiber filters pretreated with sodium bisulfite. Collected formaldehyde was then released into water and derivatized with cysteamine to thiazolidine. The thiazolidine was extracted into dichloromethane and concentrated by evaporation. Concentrated thiazolidine was separated from other compounds using preparative capillary gas chromatography and uniquely collected as a phosphate salt with a fraction collector. The C-14 composition of the salt was analyzed by accelerator mass spectrometry after combustion to CO2 and subsequent reduction to graphite. In a pilot study, ambient formaldehyde samples collected on the roof of the CACS building at Narragansett Bay Campus, Narragansett, RI, showed a significantly larger fraction of fossil carbon than modern carbon.

Rapid Response of a Marine Mammal Species to Holocene Climate and Habitat Change - de Bruyn, Mark; Hall, Brenda L.; Chauke, Lucas F.; Baroni, Carlo; Koch, Paul L.; Hoelzel, A. Rus (Plos Genetics, 2009)
Environmental change drives demographic and evolutionary processes that determine diversity within and among species. Tracking these processes during periods of change reveals mechanisms for the establishment of populations and provides predictive data on response to potential future impacts, including those caused by anthropogenic climate change. Here we show how a highly mobile marine species responded to the gain and loss of new breeding habitat. Southern elephant seal, Mirounga leonina, remains were found along the Victoria Land Coast (VLC) in the Ross Sea, Antarctica, 2,500 km from the nearest extant breeding site on Macquarie Island (MQ). This habitat was released after retreat of the grounded ice sheet in the Ross Sea Embayment 7,500-8,000 cal YBP, and is within the range of modern foraging excursions from the MQ colony. Using ancient mtDNA and coalescent models, we tracked the population dynamics of the now extinct VLC colony and the connectivity between this and extant breeding sites. We found a clear expansion signal in the VLC population similar to 8,000 YBP, followed by directional migration away from VLC and the loss of diversity at similar to 1,000 YBP, when sea ice is thought to have expanded. Our data suggest that VLC seals came initially from MQ and that some returned there once the VLC habitat was lost, similar to 7,000 years later. We track the founder-extinction dynamics of a population from inception to extinction in the context of Holocene climate change and present evidence that an unexpectedly diverse, differentiated breeding population was founded from a distant source population soon after habitat became available.
id: 1914; PT: J; NR: 58; TC: 11; J9: PLOS GENET; PG: 11; GA: 486SZ; UT: WOS:000269219500031

Recent occurrence of large jokulhlaups at Lake Tuborg, Ellesmere Island, Nunavut - Lewis, Ted; Francus, Pierre; Bradley, Raymond S. (Journal of Paleolimnology, 2009)
The varved sediment record from glacially-fed Lake Tuborg, Ellesmere Island, Nunavut, shows that only three large jokulhlaups have occurred there in the last millennium: 2003, 1993, and 1960. Detailed analyses of sediment microstructure and particle size, combined with in-situ hydrometeorological and limnological process studies, allowed jokulhlaup facies identification and discrimination from deposits from other processes. Deposits from large jokulhlaups are anomalously thick, typically lack internal structure, have sharp bases, and fine upwards. The ice-dammed lake above Lake Tuborg (the source of the jokulhlaups) likely changed its drainage style in 1960, from ice-dam overtopping to ice-dam flotation and glacial tunnel enlargement by melt widening, which allowed the lake to drain completely and catastrophically. Complete drainage of ice-dammed lakes by ice-dam flotation is rare in the region is due to the pervasiveness of cold-based ice. Twentieth century warming is likely responsible for some combination of dam thinning, lake expansion and deepening, and changing the thermal regime at the base of the dam. Anomalously thick individual varves were periodically deposited beginning in the nineteenth century, and their thickness increased with time. This likely reflects a combination of increased ice dam overtopping, subaqueous slope failures, sediment availability and rising air temperature. The varve record presented here significantly correlates with a previous, shorter record from Lake Tuborg. However, generally weak correlations are found between the new varve time series, regional records of air temperature, and glacial melt from ice cores on the Agassiz Ice Cap. It is hypothesized that on short timescales, sedimentation at the coring location reflects a complex and varying integration of multiple hydroclimatic, geomorphic and limnologic influences.
id: 1998; PT: J; UT: WOS:000263543300006

Recently exposed vegetation reveals Holocene changes in the extent of the Quelccaya Ice Cap, Peru - Buffen, Aron M.; Thompson, Lonnie G.; Mosley-Thompson, Ellen; Huh, Kyung In (QUATERNARY RESEARCH, 2009)
Radiocarbon dating of well-preserved, in-place vegetation exposed by the retreating Quelccaya Ice Cap of southeastern Peru constrains the last time the ice cap's extent was smaller than at present. Seventeen plant samples from two sites along the central western margin collectively date to 4700 and 5100 cal yr BP and strongly indicate that current ice cap retreat is unprecedented over the past similar to 5 millennia. Seventeen vegetation samples interbedded in a nearby clastic sedimentary sequence suggest ice-free conditions at this site from similar to 5200 to at least similar to 7000 cal yr BP, and place minimum constraint on early- to mid-Holocene ice cap extent. (C) 2009 University of Washington. Published by Elsevier Inc. All rights reserved.
Keywords: 14C dating; Andes; Climate change; Glacier retreat; Holocene; Peru; Quelccaya Ice Cap; South America; Tropical glaciers

A record of Lateglacial and early Holocene environmental and ecological change from southwestern Connecticut, USA - Oswald, W. W.; Foster, D. R.; Doughty, E. D.; Faison, E. K. (Journal of Quaternary Science, 2009)
Analyses of a sediment core from Highstead Swamp in southwestern Connecticut, USA, reveal Lateglacial and early Holocene ecological and hydrological changes. Lateglacial pollen assemblages are dominated by Picea and Pinus subg. Pinus, and the onset of the Younger Dryas (YD) cold interval is evidenced by higher abundance of Abies and Alnus viridis subsp. crispa. As climate warmed at the end of the YD, Picea and Abies declined and Pinus strobus became the dominant upland tree species. A shift from lacustrine sediment to organic peat at the YD-Holocene boundary Suggests that the lake that existed in the basin during the Lateglacial interval developed into a swamp in response to reduced effective moisture. A change in wetland vegetation from Myrica gale to Alnus incana subsp. rugosa and Sphagnum is consistent with this interpretation of environmental changes at the beginning of the Holocene. Copyright (C) 2009 John Wiley & Sons, Ltd.
id: 783; 494LO Times Cited:0 Cited References Count:27Y

Regional beryllium-10 production rate calibration for late-glacial northeastern North America - Balco, Greg; Briner, Jason; Finkel, Robert C.; Rayburn, John A.; Ridge, John C.; Schaefer, Joerg M. (Quaternary Geochronology, 2009)
The major uncertainty in relating cosmogenic-nuclide exposure ages to ages measured by other dating methods comes from extrapolating nuclide production rates measured at globally scattered calibration sites to the sites of unknown age that are to be dated. This uncertainty can be reduced by locating production rate calibration sites that are similar in location and age to the sites to be dated. We use this strategy to reconcile exposure age and radiocarbon deglaciation chronologies for northeastern North America by compiling (10)Be production rate calibration measurements from independently dated late-glacial and early Holocene ice-marginal landforms in this region. 10Be production rates measured at these sites are 6-12% lower than predicted by the commonly accepted global 10Be calibration data set used with any published production rate scaling scheme. In addition, the regional calibration data set shows significantly less internal scatter than the global calibration data set. Thus, this calibration data set can be used to improve both the precision and accuracy of exposure dating of regional late-glacial events. For example, if the global calibration data set is used to calculate exposure ages, the exposure-age deglaciation chronology for central New England is inconsistent with the deglaciation chronology inferred from radiocarbon dating and varve stratigraphy. We show that using the regional data set instead makes the exposure age and radiocarbon chronologies consistent. This increases confidence in correlating exposure ages of ice-marginal landforms in northeastern North America with glacial and climate events dated by other means. (c) 2008 Elsevier Ltd. All rights reserved.
id: 2034; PT: J; UT: WOS:000265163500003

Relationship between Holocene climate variations over southern Greenland and eastern Baffin Island and synoptic circulation pattern - Frechette, B.; de Vernal, A. (Climate of the Past, 2009)
Lake pollen records from southwest Greenland and eastern Baffin Island show strong regionalism in climate trends of the last 7000 cal years. July surface air temperature reconstructions from pollen indicate larger amplitude cooling in southwest Greenland (>3.0 degrees C) than in eastern Baffin Island (<1.0 degrees C). This west-east gradient in climate change is consistent with August sea-surface temperature reconstructions from dinocyst records that indicate decreasing temperature and/or strength of the North Atlantic Current to the east during the Holocene while the eastern Canadian margins under the Labrador Current influence display slight warming. Complementary to air and sea-surface temperature records, the lake pollen data led to reconstruct increased cloudiness in southern Greenland, which points to increasing cyclonic activity since 7000 cal years BP west of Greenland. Together, the terrestrial and marine records of the northwest North Atlantic therefore suggest a shift from a dominant NAO+ during the early-mid Holocene to dominant NAO- in the late Holocene.
500rkTimes Cited:18 Cited References Count:64
Keywords: arctic canada; cal kyr bp; data-base; dinoflagellate cyst assemblages; high-latitudes; modern analogs; north-atlantic; pollen spectra; radiocarbon age calibration; sea-surface temperatures

Report from the International Permafrost Association: Carbon Pools in Permafrost Regions - Kuhry, Peter; Ping, Chien-Lu; Schuur, Edward A. G.; Tarnocai, Charles; Zimov, Sergey (Permafrost and Periglacial Processes, 2009)
id: 2027; PT: J; UT: WOS:000267409000012

Sediment accumulation on the Southern California Bight continental margin during the twentieth century - Alexander, Clark R.; Lee, Homa J. (Special Paper - Geological Society of America, 2009)
Sediment discharged into the portion of the Southern California Bight extending from Santa Barbara to Dana Point enters a complex system of semi-isolated coastal cells, narrow continental shelves, submarine canyons, and offshore basins. On both the Santa Monica and San Pedro margins, (super 210) Pb accumulation rates decrease in an offshore direction (from approximately 0.5 g cm (super -2) yr (super -1) to 0.02 g cm (super -2) yr (super -1) ), in concert with a fining in sediment grain size (from 4.50phi to 8.50phi ), suggesting that offshore transport of wave-resuspended material occurs as relatively dilute nepheloid layers and that hemipalegic sedimentation dominates the supply of sediment to the outer shelf, slope, and basins. Together, these areas are effectively sequestering up to 100% of the annual fluvial input. In contrast to the Santa Monica margin, which does not display evidence of mass wasting as an important process of sediment delivery and redistribution, the San Pedro margin does provide numerous examples of failures and mass wasting, suggesting that intraslope sediment redistribution may play a more important role there. Basin deposits in both areas exhibit evidence of turbidites tentatively associated with both major floods and earthquakes, sourced from either the Redondo Canyon (San Pedro Basin) or Dume Canyon (Santa Monica Basin). On the Palos Verdes shelf, sediment-accumulation rates decrease along and across the shelf away from the White's Point outfall, which has been a major source of contaminants to the shelf deposits. Accumulation rates prior to the construction of the outfall were approximately 0.2 g cm (super -2) yr (super -1) and increased 1.5-3.7 times during peak discharges from the outfall in 1971. The distal rate of accumulation has decreased by approximately 50%, from 0.63 g cm (super -2) yr (super -1) during the period 1971-1992 to 0.29 g cm (super -2) yr (super -1) during the period 1992-2003. The proximal rate of accumulation, however, has only decreased approximately 10%, from 0.83 g cm (super -2) yr (super -1) during the period 1971-1992 to 0.73 g cm (super -2) yr (super -1) during the period 1992-2003. Effluent-affected sediment layers on the Palos Verdes shelf can be identified in seabed profiles of naturally occurring (super 238) U, which is sequestered in reducing sediments. The Santa Clara River shelf, just north and west of the Santa Monica and San Pedro margins, is fine-grained and flood-dominated. Core profiles of excess (super 210) Pb from sites covering the extent of documented major flood deposition exhibit evidence of rapidly deposited sediment up to 25 cm thick. These beds are developing in an active depocenter in water depths of 30-50 m at an average rate of 0.72 g cm (super -2) yr (super -1) . Budget calculations for annual and 50-yr timescale sediment storage on this shelf shows that 20%-30% of the sediment discharge is retained on the shelf, leaving 70%-80% to be redistributed to the outer shelf, slope, Santa Barbara Basin, and Santa Monica Basin.
id: 855; Editor: Lee, Homa J; Normark, William R References: 52; illus. incl. 2 tables, sketch maps Latitude:N332000,N340000 Longitude:W1183000,W1193000Y

Sedimentation rates and provenance analysis in the Southwestern Okinawa Trough since the mid-Holocene - Li, ChuanShun; Jiang, Bo; Li, Anchun; Li, Tiegang; Jiang, FuQing (Chinese Science Bulletin, 2009)
As a high-sedimentation rate depocenter along the path of the Kuroshio Current, the southwesternmost part of the Okinawa Trough is a key area to understand the Kuroshio history and sediments transportation. A 34.17-m-long sediment core was obtained by the advanced piston corer of Marco Polo/IMAGES XII MARION DUFRESNE during the May 2005 from the Southern Okinawa Trough at site MD05-2908. The recovered sediments were analyzed by AMS (14)C dating, coarse size fraction (> 63 mu m) extraction and moisture content determination in order to study its sedimentation flux and provenance. The depth-age relationship of core MD05-2908 was well constrained by 17 (14)C dating points. The sediments span across the mid-Holocene (6.8 ka B.P.) and have remarkablely high sedimentation rates between 1.8 and 21-2 m/ka, which is well consistent with the modern observations from sediment traps. We identified five 70-200 a periods of abnormally rapid sedimentation events at 6790-6600 a B.P., 5690-5600 a B.P., 4820-4720 a B.P., 1090-880 a B.P., and 260-190 a B.P., during which the highest sedimentation rate is up to 21-2 m/ka. In general, the lithology of the sediments were dominated by silt and clay, associated with less than 5% coarse size fraction (a parts per thousand
id: 1930; PT: J; UT: WOS:000264842600017

Sinking deltas due to human activities - Syvitski, J. P. M.; Kettner, A. J.; Overeem, I.; Hutton, E. W. H.; Hannon, M. T.; Brakenridge, G. R.; Day, J.; Vorosmarty, C.; Saito, Y.; Giosan, L.; Nicholls, R. J. (Nature Geoscience, 2009)
Many of the world's largest deltas are densely populated and heavily farmed. Yet many of their inhabitants are becoming increasingly vulnerable to flooding and conversions of their land to open ocean. The vulnerability is a result of sediment compaction from the removal of oil, gas and water from the delta's underlying sediments, the trapping of sediment in reservoirs upstream and floodplain engineering in combination with rising global sea level. Here we present an assessment of 33 deltas chosen to represent the world's deltas. We find that in the past decade, 85% of the deltas experienced severe flooding, resulting in the temporary submergence of 260,000 km(2). We conservatively estimate that the delta surface area vulnerable to flooding could increase by 50% under the current projected values for sea-level rise in the twenty-first century. This figure could increase if the capture of sediment upstream persists and continues to prevent the growth and buffering of the deltas.
id: 799; 501BW Times Cited:2 Cited References Count:38; YY

Source apportionment of elevated wintertime PAHs by compound-specific radiocarbon analysis - Sheesley, R. J.; Krusa, M.; Krecl, P.; Johansson, C.; Gustafsson, O. (Atmospheric Chemistry and Physics, 2009)
Natural abundance radiocarbon analysis facilitates distinct source apportionment between contemporary biomass/biofuel ((14)C "alive") versus fossil fuel ((14)C "dead") combustion. Here, the first compound-specific radiocarbon analysis (CSRA) of atmospheric polycyclic aromatic hydrocarbons (PAHs) was demonstrated for a set of samples collected in Lycksele, Sweden a small town with frequent episodes of severe atmospheric pollution in the winter. Renewed interest in using residential wood combustion (RWC) means that this type of seasonal pollution is of increasing concern in many areas. Five individual/paired PAH isolates from three pooled fortnight-long filter collections were analyzed by CSRA: phenanthrene, fluoranthene, pyrene, benzo[b+k] fluoranthene and indeno[cd]pyrene plus benzo[ghi]perylene; phenanthrene was the only compound also analyzed in the gas phase. The measured Delta(14)C for PAHs spanned from -138.3% to 58.0%. A simple isotopic mass balance model was applied to estimate the fraction biomass (fbiomass) contribution, which was constrained to 71-87% for the individual PAHs. Indeno[cd]pyrene plus benzo[ghi]perylene had an fbiomass of 71%, while fluoranthene and phenanthrene (gas phase) had the highest biomass contribution at 87%. The total organic carbon (TOC, defined as carbon remaining after removal of inorganic carbon) fbiomass was estimated to be 77%, which falls within the range for PAHs. This CSRA data of atmospheric PAHs established that RWC is the dominating source of atmospheric PAHs to this region of the boreal zone with some variations among RWC contributions to specific PAHs.
452qjTimes Cited:22 Cited References Count:52
Keywords: air-pollution sources; atmospheric aerosols; BLACK CARBON; emissions; northern sweden; organic-compounds; particulate matter; polycyclic aromatic-hydrocarbons; positive matrix factorization; residential wood combustion

Southern Ocean evidence for reduced export of North Atlantic Deep Water during Heinrich event 1 - Robinson, L. F.; van de Flierdt, T. (Geology, 2009)
Deep-sea corals form unique, high-resolution archives of ocean circulation that can be dated using the decay of uranium to thorium. They are abundant in the Southern Ocean, and can provide unprecedented insights into ocean circulation and ocean chemistry on sub-millennial time scales in areas where application of traditional paleoceanographic proxies is difficult. Here we present the first coupled neodymium (Nd) isotope and radiocarbon data from deep-sea corals in the Drake Passage (Southern Ocean) adding new constraints on ocean circulation during the last Heinrich event (H1; 16.7 ka). The modern-day Drake Passage water column is homogeneous with respect to Nd isotopes (expressed in epsilon units, e Nd). Its isotopic value of close to -9 is largely controlled by the mixture of North Atlantic Deep Water and Pacific Deep Water. The aragonite of modern Drake Passage corals reflects this water-column value, whereas a fossil coral from H1 is significantly higher at -6.4 +/- 0.4. We interpret this similar to 2.5 epsilon unit shift as a reduction in the influence of North Atlantic-sourced Nd in the Southern Ocean during H1. This interpretation is supported by a series of radiocarbon analyses on the same sample, and is consistent with a twofold or greater reduction in export of North Atlantic waters from the Atlantic Basin. Combining analyses of radiocarbon and Nd isotopes on U-series dated deep-sea coral skeletons holds great potential for quantification of past ocean ventilation rates.
id: 817; 414CT Times Cited:2 Cited References Count:40; YY

Southward movement of the Pacific intertropical convergence zone AD 1400-1850 - Sachs, J. P.; Sachse, D.; Smittenberg, R. H.; Zhang, Z. H.; Battisti, D. S.; Golubic, S. (Nature Geoscience, 2009)
Tropical rainfall patterns control the subsistence lifestyle of more than one billion people. Seasonal changes in these rainfall patterns are associated with changes in the position of the intertropical convergence zone, which is characterized by deep convection causing heavy rainfall near 10 degrees N in boreal summer and 3 degrees N in boreal winter. Dynamic controls on the position of the intertropical convergence zone are debated, but palaeoclimatic evidence from continental Asia, Africa and the Americas suggests that it has shifted substantially during the past millennium, reaching its southernmost position some time during the Little Ice Age (AD 1400-1850). However, without records from the meteorological core of the intertropical convergence zone in the Pacific Ocean, quantitative constraints on its position are lacking. Here we report microbiological, molecular and hydrogen isotopic evidence from lake sediments in the Northern Line Islands, Galapagos and Palau indicating that the Pacific intertropical convergence zone was south of its modern position for most of the past millennium, by as much as 500 km during the Little Ice Age. A colder Northern Hemisphere at that time, possibly resulting from lower solar irradiance, may have driven the intertropical convergence zone south. We conclude that small changes in Earth's radiation budget may profoundly affect tropical rainfall.
id: 847; 497LS Times Cited:5 Cited References Count:45Y

Spatial variability of late Holocene and 20th century sea-level rise along the Atlantic coast of the United States - Engelhart, Simon E.; Horton, Benjamin P.; Douglas, Bruce C.; Peltier, W. Richard; Törnqvist, Torbjörn E. (Geology, 2009)
id: 1872Y

Submarine canyon and fan systems of the California Continental Borderland - Normark, William R.; Piper, David J. W.; Romans, Brian W.; Covault, Jacob A.; Dartnell, Peter; Sliter, Ray W. (Geological Society of America Special Papers, 2009)
Late Quaternary turbidite and related gravity-flow deposits have accumulated in basins of the California Borderland under a variety of conditions of sediment supply and sea-level stand. The northern basins (Santa Barbara, Santa Monica, and San Pedro) are closed and thus trap virtually all sediment supplied through submarine canyons and smaller gulley systems along the basin margins. The southern basins (Gulf of Santa Catalina and San Diego Trough) are open, and, under some conditions, turbidity currents flow from one basin to another. Seismic-reflection profiles at a variety of resolutions are used to determine the distribution of late Quaternary turbidites. Patterns of turbidite-dominated deposition during lowstand conditions of oxygen isotope stages 2 and 6 are similar within each of the basins. Chronology is provided by radiocarbon dating of sediment from two Ocean Drilling Program sites, the Mohole test-drill site, and large numbers of piston cores. High-resolution, seismic-stratigraphic frameworks developed for Santa Monica Basin and the open southern basins show rapid lateral shifts in sediment accumulation on scales that range from individual lobe elements to entire fan complexes. More than half of the submarine fans in the Borderland remain active at any given position of relative sea level. Where the continental shelf is narrow, canyons are able to cut headward during sea-level transgression and maintain sediment supply to the basins from rivers and longshore currents during highstands. Rivers with high bedload discharge transfer sediment to submarine fans during both highstand and lowstand conditions.
id: 878; 10.1130/2009.2454(2.7)

Surculichnus bifurcauda n. igen., n. isp., a trace fossil from Late Pleistocene glaciolacustrine varves of the Connecticut River Valley, USA, attributed to notostracan crustaceans based on neoichnological experimentation - Knecht, Richard J.; Benner, Jacob S.; Rogers, Christopher; Ridge, John C. (Palaeogeography Palaeoclimatology Palaeoecology, 2009)
New trace fossils found in the Late Pleistocene glaciolacustrine varves of the Connecticut River Valley, Vermont, USA represent the first known notostracan presence in glacial Lake Hitchcock. These unique trace fossils warrant a new ichnogenus and ichnospecies Surculichnus bifurcauda. The New England Varve Chronology (NEVC) constrains the initial presence of S. bifurcauda at similar to 13.3-13.2 kyr. The morphology of S. bifurcauda correlates well with notostracan characteristics and behavior. Sieving of bedding planes that contained S. bifurcauda produced one chitinous fossil that is suggestive of a notostracan telson. Neoichnological experimentation was conducted with the species Triops longicaudatus. During the subadult stage, T longicaudatus produced traces representative of locomotion and feeding behaviors, and at the adult stage reproduced S. bifurcauda, as well as Rusophycus. Possible explanations for the productions of these traces are egg laying or predation behaviors that are both related to maturity. Further research in the paleo- and modern ecology of glacial and nearctic lakes may shed more light on the maker of S. bifurcauda. (C) 2008 Elsevier B.V. All rights reserved.
id: 2036; PT: J; UT: WOS:000264010000008

Terminal Report: Nutrient and Carbon Biogeochemistry of the Sulu Sea (Project No. 96/01/CW) - Jacinto, G. S.; David, L. T.; Peleo-Alampay, A. M.; San Diego-McGlone, M. L.; Siringan, F. P.; Villanoy, C. L. (Southeast Asia Regional Committee for START (SARCS), 2009)
id: 872

Timing and magnitude of recent accelerated sea-level rise (North Carolina, United States) - Kemp, A. C.; Horton, B. P.; Culver, S. J.; Corbett, D. R.; van de Plassche, O.; Gehrels, W. R.; Douglas, B. C.; Parnell, A. C. (Geology, 2009)
We provide records of relative sea level since A. D. 1500 from two salt marshes in North Carolina to complement existing tide-gauge records and to determine when recent rates of accelerated sea-level rise commenced. Reconstructions were developed using foraminifera-based transfer functions and composite chronologies, which were validated against regional twentieth century tide-gauge records. The measured rate of relative sea-level rise in North Carolina during the twentieth century was 3.0-3.3 mm/a, consisting of a background rate of similar to 1 mm/a, plus an abrupt increase of 2.2 mm/a, which began between A. D. 1879 and 1915. This acceleration is broadly synchronous with other studies from the Atlantic coast. The magnitude of the acceleration at both sites is larger than at sites farther north along the U. S. and Canadian Atlantic coast and may be indicative of a latitudinal trend.
id: 829; 512AY Times Cited:15 Cited References Count:30Y

Timing of post-glacial reinhabitation and ecological development of two New England, USA, drainages based on trace fossil evidence - Benner, Jacob S.; Ridge, John C.; Knecht, Richard J. (Palaeogeography Palaeoclimatology Palaeoecology, 2009)
Trace fossils as paleoecological and paleobiogeographical tools in Pleistocene glaciolacustrine sediments have been largely ignored. Combining high resolution varve stratigraphy with trace fossil data can lead to refined paleoenvironmental interpretations during times of rapid climate change. Based on trace fossils from glaciolacustrine varves in the Connecticut and Merrimack River valleys, a new timeline for the reinhabitation of New England by fish and associated invertebrates has been constructed. In addition, it appears that colonization of the recently deglaciated environments occurred in at least four successional stages. If these stages can be recognized elsewhere, it may be possible to accurately model other postglacial migrations using trace fossils and varve chronostratigraphy. (C) 2008 Elsevier B.V. All rights reserved.
id: 2035; PT: J; UT: WOS:000264010000007

Towards a quantitative and independent reconstruction of Holocene temperature and precipitation in Northern Great Plains using novel organic proxies - Toney, J. L.; Huang, Y.; Fritz, S. C.; Baker, P.; Grimm, E. C.; Nyren, P. E. (Eos, Transactions, American Geophysical Union, 2009)
id: 891

A trans-Holocene archaeological record of Guadalupe fur seals (Arctocephalus townsendi) on the California coast - Rick, Torben C.; DeLong, Robert L.; Erlandson, Jon M.; Braje, Todd J.; Jones, Terry L.; Kennett, Douglas J.; Wake, Thomas A.; Walker, Phillip L. (Marine Mammal Science, 2009)
id: 2061; PT: J; UT: WOS:000265228700018

Using foraminifera to recognize former flood-tide deltas in the Holocene stratigraphic record: examples from the Outer Banks, North Carolina - Smith, C. G.; Culver, S. J.; Mallinson, D. J.; Riggs, S. R.; Corbett, D. R. (Stratigraphy, 2009)
id: 851

Validation of yellowedge grouper, Epinephelus flavolimbatus, age using nuclear bomb-produced radiocarbon - Cook, Melissa; Fitzhugh, Gary R.; Franks, James S. (ENVIRONMENTAL BIOLOGY OF FISHES, 2009)
Age validation and estimates of longevity of yellowedge grouper (Epinephelus flavolimbatus) from the Gulf of Mexico (GOM) are needed to inform fishery management decisions. Yellowedge grouper sagittal otoliths (n = 100) were collected, aged using conventional means, and cores were submitted for radiocarbon ((14)C) measurement. Radiocarbon values of yellowedge grouper otoliths were compared to established radiocarbon chronologies in the region to validate the age and ageing methodology of this species. The yellowedge grouper chronology displayed a similar sigmoidal trend as previously published chronologies. In addition to the core analysis, multiple areas on otolith sections from eight specimens were analyzed for Delta(14)C to validate age estimates for fish born prior to the (14)C increase. Our results indicate that yellowedge grouper live longer than previously reported (minimum of 40 years based on radiocarbon measurements). The validated ageing methodology supported an estimated maximum longevity of 85 years and established that yellowedge grouper have the longest lifespan currently known for any species of grouper in the GOM. Results also indicate a depth-age interaction in that material extracted from adult otolith sections assigned to post-bomb dates exhibited lower Delta(14)C values than cores (juvenile material) assigned to the same post-bomb dates. This finding is likely explained by lower (14)C levels reported from water masses at deeper depths (> 100 m) which are inhabited by adults.
Keywords: Age determination; Age validation; Gulf of Mexico; Longevity; RADIOCARBON ANALYSIS; Yellowedge grouper

Variations of terrigenous material discharges in the South Okinawa trough and its relation to the East Asian summer monsoon since the last millennium - Chen, Jinxia; Li, Tiegang; Qingyun, Nan (Journal of China University of Geosciences, 2009)
The top part of a giant IMAGE core MD05-2908 taken from the South Okinawa Trough was investigated for the sake of understanding the climate evolution in Donghai seacoast areas since the last millennium. Sporopollen and organic carbon isotope records of bulk sediments were used as proxies to trace the climate variations and terrigenous materials discharges. Time series were demarcated by 4 AMS 14 C dating ages. Comprehensive data of sporopollen and carbon isotopic composition, together with the paleoenvironmental records show that in the South Okinawa Trough the terrigenous material discharges fluctuated obviously for the past 1000 years. Three relatively high terrigenous material discharge periods, corresponding to 1100-1040 a BP, 960-880 a BP and 800-480 a BP respectively and two quite low terrigenous material discharge periods, namely, 1040-960 a BP and 480-230 a BP, can be identified from our records. In comparison with the stalagmite delta (super 13) C records(which were used to trace the East Asian Summer Monsoon) from Buddha Cave, Shaanxi Province, we found that the variations of terrigenous material discharges might be related closely to variations of the East Asian Summer Monsoon(EASM). Weaker EASM resulted in a convergence rain belt and longer residence time in the South China regions, which increased the efficiency of weathering and denudation of the source area. Moreover, increased rainfall enhanced the land runoff and as a result more terrigenous materials were transported to the South Okinawa Trough.
id: 1948; Source type: scholarlyjournals; Object type: Article; Copyright: GeoRef in Process, Copyright 2011, American Geosciences Institute. After editing and indexing, this record will be added to Georef.; CSAUnique: 600756-13; AccNum: 600756-13; ISSN: 1000-2383; Peer Reviewed: true

Vast laminated diatom mat deposits from the west low-latitude Pacific Ocean in the last glacial period - Zhai, Bin; Li, Tiegang; Chang, Fengming; Cao, QiYuan (Chinese Science Bulletin, 2009)
Diatoms are one of the predominant contributors to global carbon fixation by accounting for over 40% of total oceanic primary production and dominate export production. They play a significant role in marine biogeochemistry cycle. The diatom mat deposits are results of vast diatoms bloom. By analysis of diatom mats in 136 degrees 00'-140 degrees 00'E, 15 degrees 00'-21 degrees 00'N, Eastern Philippines Sea, we identified the species of the diatoms as giant Ethmodiscus rex (Wallich) Hendey. AMS (14)C dating shows that the sediments rich in diatom mats occurred during 16000-28600 a B.P., which means the bloom mainly occurred during the last glacial period, while there are no diatom mat deposits in other layers. Preliminary analysis indicates that Antarctic Intermediate Water (AAIW) expanded northward and brought silicate-rich water into the area, namely, silicon leakage processes caused the bloom of diatoms. In addition, the increase of iron input is one of the main reasons for the diatom bloom.
id: 1928; PT: J; UT: WOS:000272622100036

Was the Black Sea catastrophically flooded in the early Holocene? - Giosan, L.; Filip, F.; Constatinescu, S. (Quaternary Science Reviews, 2009)
A catastrophic flooding of the Black Sea basin was proposed to have occurred during its reconnection to the ocean in the early Holocene. Possible cultural consequences of the flood include the migration of Neolithic farmers from around the Black Sea towards central Europe as well as the creation of flood myths. Stratigraphic and paleo-geomorphologic information from Danube delta aided by radiocarbon ages on articulated mollusks constrain the level in the Black Sea before the marine reconnection to ca 30 m below the present sea level rather than 80 m or lower. If the flood occurred at all, the sea level increase and the flooded area during the reconnection were significantly smaller than previously proposed. (C) 2008 Elsevier Ltd. All rights reserved.
id: 866; 399HK Times Cited:0 Cited References Count:56; YY

Wind-Driven Upwelling in the Southern Ocean and the Deglacial Rise in Atmospheric CO2 - Anderson, R. F.; Ali, S.; Bradtmiller, L. I.; Nielsen, S. H. H.; Fleisher, M. Q.; Anderson, B. E.; Burckle, L. H. (Science, 2009)
Wind-driven upwelling in the ocean around Antarctica helps regulate the exchange of carbon dioxide (CO2) between the deep sea and the atmosphere, as well as the supply of dissolved silicon to the euphotic zone of the Southern Ocean. Diatom productivity south of the Antarctic Polar Front and the subsequent burial of biogenic opal in underlying sediments are limited by this silicon supply. We show that opal burial rates, and thus upwelling, were enhanced during the termination of the last ice age in each sector of the Southern Ocean. In the record with the greatest temporal resolution, we find evidence for two intervals of enhanced upwelling concurrent with the two intervals of rising atmospheric CO2 during deglaciation. These results directly link increased ventilation of deep water to the deglacial rise in atmospheric CO2.
id: 835; 417TP Times Cited:18 Cited References Count:69Y

3500 yr record of centennial-scale climate variability from the Western Pacific Warm Pool - Langton, S. J.; Linsley, B. K.; Robinson, R. S.; Rosenthal, Y.; Oppo, D. W.; Eglinton, T. I.; Howe, S. S.; Djajadihardja, Y. S.; Syamsudin, F. (Geology, 2008)
We use geochemical data from a sediment core in the shallow-silled and intermittently dysoxic Kau Bay in Halmahera (Indonesia, lat 1 degrees N, long 127.5 degrees E) to reconstruct century-scale climate variability within the Western Pacific Warm Pool over the past similar to 3500 yr. Downcore variations in bulk sedimentary delta N-15 appear to reflect century-scale variability in basin ventilation, attributed to changes in oceanographic conditions related to century-scale fluctuations in El Nino Southern Oscillation (ENSO). We infer an increase in century-scale El Nino activity beginning ca. 1700 yr B.P. with peaks in El Nino activity ca. 1500 yr B.P., 1150 yr B.P., and ca. 700 yr B.P. The Kau Bay results suggest that there was diminished ENSO amplitude or frequency, or a departure from El Nino-like conditions during the Medieval Warm Period, and distinctive, but steadily decreasing, El Nino activity during and after the Little Ice Age.
id: 1894; ISI Document Delivery No.: 357HB Times Cited: 1 Cited Reference Count: 36 Cited References: ALDRIAN E, 2003, INT J CLIMATOL, V23, P1435, DOI 10.1002/joc.950 ALTABET MA, 1994, GLOBAL BIOGEOCHEM CY, V8, P103 ALTABET MA, 2001, LIMNOL OCEANOGR, V46, P368 ARRUDA WZ, 2003, J PHYS OCEANOGR, V33, P2815 BRANDES JA, 1998, LIMNOL OCEANOGR, V43, P1680 BRANDES JA, 2002, GLOBAL BIOGEOCHEMICA, V16 CASCIOTTI KL, 2002, ANAL CHEM, V74, P4905, DOI 10.1021/ac020113w CHRISTIAN JR, 2004, DEEP-SEA RES PT II, V51, P209, DOI 10.1016/j.dsr2.2003.06.002 DEUTSCH C, 2007, NATURE, V445, P163, DOI 10.1038/nature05392 GANESHRAM RS, 2000, PALEOCEANOGRAPHY, V15, P361 GRANGER J, 2004, EOS T AM GEOPHYS U S, V85 GRANGER J, 2004, LIMNOL OCEANOGR, V49, P1763 HAUG GH, 1998, PALEOCEANOGRAPHY, V13, P427 HAUG GH, 2001, SCIENCE, V293, P1304 HODELL DA, 2005, QUATERNARY SCI REV, V24, P1413, DOI 10.1016/j.quascirev.2004.10.013 LIU KK, 1989, LIMNOL OCEANOGR, V34, P820 MAKOU MC, 2007, ORG GEOCHEM, V38, P1680, DOI 10.1016/j.orggeochem.2007.06.003 MARIOTTI A, 1981, PLANT SOIL, V62, P413 MASUMOTO Y, 2001, GEOPHYS RES LETT, V28, P1631 MIDDELBURG JJ, 1990, GEOL ULTRIECTIN, V71, P177 MOY CM, 2002, NATURE, V420, P162 NEWTON A, 2006, GEOPHYS RES LETT, V33, ARTN L19710 REIN B, 2004, GEOPHYS RES LETT, V31, ARTN L17211 REIN B, 2005, PALEOCEANOGRAPHY, V20, ARTN PA4003 REYNOLDS RW, 1994, J CLIMATE, V7, P929 RODBELL DT, 1999, SCIENCE, V283, P516 SIGMAN DM, 2003, GEOCHEM GEOPHY GEOSY, V4, ARTN 1040 SIGMAN DM, 2005, GLOBAL BIOGEOCHEM CY, V19, ARTN GB4022 STOTT L, 2004, NATURE, V431, P56, DOI 10.1038/nature02903 STREETPERROTT FA, 1997, SCIENCE, V278, P1422 THUNELL R, 2004, GLOBAL BIOGEOCHEMICA, V18, UNSP GB3001 UEKI I, 2003, J GEOPHYS RES-OCEANS, V108, ARTN 3243 VANAKEN HMV, 1988, NETHERLANDS J SEA RE, V22, P403, DOI 10.1016/0077-7579(88)90011-7 VANDERWEIJDEN CH, 1989, NETH J SEA RES, V24, P583 VANRIEL PM, 1943, OCEANOGRAPHIC RESU 5, V2 WYRTKI K, 1961, NAGA REPORT, V2 Langton, S. J. Linsley, B. K. Robinson, R. S. Rosenthal, Y. Oppo, D. W. Eglinton, T. I. Howe, S. S. Djajadihardja, Y. S. Syamsudin, F. U.S. National Science Foundation [OCE-0502550, OCE-0502504, OCE-052960] This work was supported by the U.S. National Science Foundation (grants OCE-0502550, OCE-0502504, and OCE-052960). We thank the captain, crew, technicians, and the scientific crew who helped with sample collection on the R/V Baruna Jaya VIII. Geological soc amer, inc Boulder; YY

A 5000-year history of Caribbean environmental change and hurricane activity reconstructed from coastal lake sediments of the West Indies - Knowles, J. T. (Louisiana State University, 2008)

Abrupt changes in Antarctic Intermediate Water circulation over the past 25,000 years - Pahnke, Katharina; Goldstein, Steven L.; Hemming, Sidney R. (Nature Geoscience, 2008)
The circulation of Antarctic Intermediate Water is thought to make an important contribution to the global ocean-climate system, but the details of this interaction are not fully understood. Furthermore, the behaviour of Antarctic Intermediate Water under glacial and interglacial conditions is not well constrained. Here we present a 25,000-year-long record of neodymium isotopic variations-a tracer of water-mass mixing-from the middle depths of the tropical Atlantic Ocean. Our data reveal abruptly enhanced northward advection of Antarctic Intermediate Water during periods of reduced North Atlantic overturning circulation during the last deglaciation. These events coincide with an increase in the formation of Antarctic Intermediate Water and warming in the southwest Pacific Ocean, which suggests a tight link with Southern Hemisphere climate. In contrast, the initial incursion of southern source water into the North Atlantic similar to 19,000 years ago coincided with weak Antarctic Intermediate Water formation in the Pacific and reduced overturning in the North Atlantic. We conclude that reduced competition at intermediate water depth at this time allowed expansion of Antarctic Intermediate Water into the North Atlantic. This early incursion of Antarctic Intermediate Water may have contributed to freshening of the North Atlantic, perhaps spurring the subsequent collapse of North Atlantic deep convection.
id: 2026; PT: J; UT: WOS:000261278700021

Abrupt climate change and collapse of deep-sea ecosystems - Yasuhara, M.; Cronin, T. M.; deMenocal, P. B.; Okahashi, H.; Linsley, B. K. (Proceedings of the National Academy of Sciences of the United States of America, 2008)
We investigated the deep-sea fossil record of benthic ostracodes during periods of rapid climate and oceanographic change over the past 20,000 years in a core from intermediate depth in the northwestern Atlantic. Results show that deep-sea benthic community "collapses" occur with faunal turnover of up to 50% during major climatically driven oceanographic changes. Species diversity as measured by the Shannon-Wiener index falls from 3 to as low as 1.6 during these events. Major disruptions in the benthic communities commenced with Heinrich Event 1, the Inter-Allerod Cold Period (IACP: 13.1 ka), the Younger Dryas (YD: 12.9-11.5 ka), and several Holocene Bond events when changes in deep-water circulation occurred. The largest collapse is associated with the YD/IACP and is characterized by an abrupt two-step decrease in both the upper North Atlantic Deep Water assemblage and species diversity at 13.1 ka and at 12.2 ka. The ostracode fauna at this site did not fully recover until approximate to 8 ka, with the establishment of Labrador Sea Water ventilation. Ecologically opportunistic slope species prospered during this community collapse. Other abrupt community collapses during the past 20 ka generally correspond to millennial climate events. These results indicate that deep-sea ecosystems are not immune to the effects of rapid climate changes occurring over centuries or less.
id: 1884; 261KQ Times Cited:12 Cited References Count:71Y

Accelerator Mass Spectrometry and Bayesian Data Analysis - Palonen, Vesa (University of Helsinki, 2008)

Accelerator mass spectrometry C-14 determination in CO2 produced from laser decomposition of aragonite - Rosenheim, B. E.; Thorrold, S. R.; Roberts, M. L. (Rapid Communications in Mass Spectrometry, 2008)
The determination of C-14 in aragonite (CaCO3) decomposed thermally to CO2 using an yttrium-aluminum-garnet doped neodymium laser is reported. Laser decomposition accelerator mass spectrometry (LD-AMS) measurements reproduce AMS determinations of C-14 from the conventional reaction of aragonite with concentrated phosphoric acid. The lack of significant differences between these sets of measurements indicates that LD-AMS radiocarbon dating can overcome the significant fractionation that has been observed during stable isotope (C and O) laser decomposition analysis of different carbonate minerals. The laser regularly converted nearly 30% of material removed into CO2 despite it being optimized for ablation, where laser energy breaks material apart rather than chemically altering it. These results illustrate promise for using laser decomposition on the front-end of AMS systems that directly measure CO2 gas. The feasibility of such measurements depends on (1) the improvement of material removal and/or CO2 generation efficiency of the laser decomposition system and (2) the ionization efficiency of AMS systems measuring continuously flowing CO2 Copyright (C) 2008 John Wiley & Sons, Ltd.
id: 1891; 370OU Times Cited:1 Cited References Count:16Y

Age validation of Dover sole (Microstomus pacificus) by means of bomb radiocarbon - Kastelle, C. R.; Anderl, D. M.; Kimura, D. K.; Johnston, C. G. (Fishery Bulletin, 2008)
We used bomb radiocarbon (C-14) in this age validation study of Dover sole (Microstomus pacificus). The otoliths of Dover sole, a commercially important fish in the North Pacific, are difficult to age and ages derived from the current break-and-burn method were not previously validated. The otoliths used in this study were chosen on the basis of estimated birth year and for the ease of interpreting growth zone patterns. Otolith cores, material representing years 0 through 3, were isolated and analyzed for C-14. Additionally, a small number of otoliths with difficult-to-interpret growth patterns were analyzed for C-14 to help determine age interpretation. The measured Dover sole C-14 values in easier-to-interpret otoliths were compared with a C-14. reference chronology for Pacific halibut (Hippoglossus stenolepis) in the North Pacific, We used an objective statistical analysis where sums of squared residuals between otolith C-14 values of Dover sole and the reference chronology were examined. Our statistical analysis also included a procedure where the Dover sole C-14 values were standardized to the reference chronology. These procedures allowed an evaluation of aging error. The C-14 results indicated that the Dover sole age estimates from the easier-to-interpret otoliths with the break-and-burn method are accurate. This study validated Dover sole ages from 8 to 47 years.
371ygTimes Cited:4 Cited References Count:34
Keywords: alaska; gulf; lead-radium; north pacific; otoliths; paucispinis; pleuronectids; pollock theragra-chalcogramma; quality-control; rockfish sebastes-pinniger

Antarctic sediment chronology by programmed-temperature pyrolysis: Methodology and data treatment - Rosenheim, B. E.; Day, M. B.; Domack, E.; Schrum, H.; Benthien, A.; Hayes, J. M. (Geochemistry Geophysics Geosystems, 2008)
We report a detailed programmed-temperature pyrolysis/ combustion methodology for radiocarbon (C-14) dating of Antarctic sub-ice shelf sediments. The method targets the autochthonous organic component in sediments that contain a distribution of acid-insoluble organic components from several sources of different ages. The approach has improved sediment chronology in organic-rich sediments proximal to Antarctic ice shelves by yielding maximum age constraints significantly younger than bulk radiocarbon dates from the same sediment horizons. The method proves adequate in determining isotope ratios of the pre-aged carbon end-member; however, the isotopic compositions of the low-temperature measurements indicate that no samples completely avoided mixing with some proportion of pre-aged organic material. Dating the unresolved but desired young end-member must rely on indirect methods, but a simple mixing model cannot be developed without knowledge of the sedimentation rate or comparable constraints. A mathematical approach allowing for multiple mixing components yields a maximum likelihood age, a first-order approximation of the relative proportion of the autochthonous component, and the temperature at which allochthonous carbon begins to volatilize and mix with the autochthonous component. It is likely that our estimation of the cutoff temperature will be improved with knowledge of the pyrolysis kinetics of the major components. Chronology is improved relative to bulk acid-insoluble organic material ages from nine temperature interval dates down to two, but incorporation of inherently more pre-aged carbon in the first division becomes more apparent with fewer and larger temperature intervals.
id: 1847; 284ON Times Cited:5 Cited References Count:27Y

Assessing sedimentary records of paleohurricane activity using modeled hurricane climatology - Woodruff, J. D.; Donnelly, J. P.; Emanuel, K.; Lane, P. (Geochemistry Geophysics Geosystems, 2008)
Patterns of overwash deposition observed within back-barrier sediment archives can indicate past changes in tropical cyclone activity; however, it is necessary to evaluate the significance of observed trends in the context of the full range of variability under modern climate conditions. Here we present a method for assessing the statistical significance of patterns observed within a sedimentary hurricane-overwash reconstruction. To alleviate restrictions associated with the limited number of historical hurricanes affecting a specific site, we apply a recently published technique for generating a large number of synthetic storms using a coupled ocean- atmosphere hurricane model set to simulate modern climatology. Thousands of overwash records are generated for a site using a random draw of these synthetic hurricanes, a prescribed threshold for overwash, and a specified temporal resolution based on sedimentation rates observed at a particular site. As a test case we apply this Monte Carlo technique to a hurricane- induced overwash reconstruction developed from Laguna Playa Grande (LPG), a coastal lagoon located on the island of Vieques, Puerto Rico in the northeastern Caribbean. Apparent overwash rates in the LPG overwash record are observed to be four times lower between 2500 and 1000 years B. P. when compared to apparent overwash rates during the last 300 years. However, probability distributions based on Monte Carlo simulations indicate that as much as 65% of this drop can be explained by a reduction in the temporal resolution for older sediments due to a decrease in sedimentation rates. Periods of no apparent overwash activity at LPG between 2500 and 3600 years B. P. and 500-1000 years B. P. are exceptionally long and are unlikely to occur (above 99% confidence) under the current climate conditions. In addition, breaks in activity are difficult to produce even when the hurricane model is forced to a constant El Nino state. Results from this study continue to support the interpretation that the western North Atlantic has exhibited significant changes in hurricane climatology over the last 5500 years.
id: 1895; ISI Document Delivery No.: 351AC Times Cited: 2 Cited Reference Count: 46 Cited References: BOVE MC, 1998, B AM METEOROL SOC, V79, P2477 DEMUTH JL, 2006, J APPL METEOROL CLIM, V45, P1573 DONNELLY JP, 2001, GEOL SOC AM BULL, V113, P714 DONNELLY JP, 2001, GEOLOGY, V29, P615 DONNELLY JP, 2001, P NATL ACAD SCI USA, V98, P14218 DONNELLY JP, 2004, GEOPHYS RES LETT, V31, ARTN L05203 DONNELLY JP, 2004, HURRICANES TYPHOONS, P58 DONNELLY JP, 2004, MAR GEOL, V210, P107, DOI 10.1016/j.margeo.2004.05.005 DONNELLY JP, 2005, J COAST RES S, V142, P201 DONNELLY JP, 2007, NATURE, V447, P465, DOI 10.1038/nature05834 ELSNER JB, 2001, GEOPHYS RES LETT, V28, P4123 ELSNER JB, 2001, J CLIMATE, V14, P4341 ELSNER JB, 2008, J APPL METEOROL CLIM, V47, P368, DOI 10.1175/2007JAMC1692.1 EMANUEL K, 2004, J ATMOS SCI, V61, P843 EMANUEL K, 2006, B AM METEOROL SOC, V87, P299, DOI 10.1175/BAMS-87-3-299 EMANUEL K, 2008, B AM METEOROL SOC, V89, P347, DOI 10.1175/BAMS-89-3-347 FRAPPIER A, 2007, TELLUS A, V59, P529, DOI 10.1111/j.1600-0870.2007.00250.x FRAPPIER AB, 2007, GEOLOGY, V35, P111, DOI 10.1130/G23145A.1 GEHRELS WR, 2005, QUATERNARY SCI REV, V24, P2083, DOI 10.1016/j.quascirev.2004.11.016 GOLDENBERG SB, 2001, SCIENCE, V293, P474 GONZALEZ JL, 2006, EOS, V87, P493, DOI 10.1029/2006EO450001 GRAY WM, 1984, MON WEATHER REV, V112, P1649 JELESNIANSKI CP, 1992, NOAA TECH REP NWS, V48 KALNAY E, 1996, B AM METEOROL SOC, V77, P437 LAMBERT WJ, 2008, J PALEOLIMNOL, V39, P117, DOI 10.1007/s10933-007-9101-6 LIGHTY RG, 1982, CORAL REEFS, V1, P125 LIU KB, 1993, GEOLOGY, V21, P793 LIU KB, 2000, QUATERNARY RES, V54, P238 MALMQUIST DL, 1997, 22 C HURR TROP MET A MERCADO A, 1994, NAT HAZARDS, V10, P235, DOI 10.1007/BF00596144 MILLER DL, 2006, P NATL ACAD SCI USA, V103, P14294, DOI 10.1073/pnas.0606549103 MOY CM, 2002, NATURE, V420, P162 NGUETSOP VF, 2004, QUATERNARY SCI REV, V23, P591, DOI 10.1016/j.quascirev.2003.10.007 NOTT J, 2001, NATURE, V413, P508 NOTT J, 2004, ENVIRON INT, V30, P433, DOI 10.1016/j.cnvint.2003.09.010 NOTT J, 2007, EARTH PLANET SC LETT, V255, P367, DOI 10.1016/j.epsl.2006.12.023 NYBERG J, 2002, PALAEOGEOGR PALAEOCL, V183, P25 PIELKE RA, 1999, B AM METEOROL SOC, V80, P2027 PIELKE RA, 2008, NAT HAZARDS REV, V9, P29, DOI 10.1061/(ASCE)1527-6988(2008)9:1(29) RICHEY JN, 2007, GEOLOGY, V35, P423, DOI 10.1130/G23507A.1 SCILEPPI E, 2007, GEOCHEM GEOPHY GEOSY, V8, ARTN Q06011 SIMPSON RH, 1981, HURRICANE ITS IMPACT STOCKDON HF, 2006, COAST ENG, V53, P573, DOI 10.1016/j.coastaleng.2005.12.005 TORNQVIST TE, 2004, GEOL SOC AM BULL, V116, P1026, DOI 10.1130/B2525478.1 WOODRUFF JD, 2008, VIEQUES PUERTO RICO, V36, P391, DOI 10.1130/G24731A.1 WRIGHT CW, 2001, J PHYS OCEANOGR, V31, P2472 Woodruff, Jonathan D. Donnelly, Jeffrey P. Emanuel, Kerry Lane, Philip National Science Foundation ; Risk Prediction Initiative ; National Geographic Society ; Coastal Ocean Institute at WHOI ; Andrew W. Mellon Foundation Endowed Fund for Innovative Research Funding for this research was provided by the Earth Systems History Program of the National Science Foundation, Risk Prediction Initiative, National Geographic Society, Coastal Ocean Institute at WHOI, and the Andrew W. Mellon Foundation Endowed Fund for Innovative Research. We are grateful to E. Bryant, M. Gomes, E. Scileppi, and J. Tierney, who assisted with the field and lab work, and thank A. Solow for informative discussions. Special thanks to J. Elsner for providing the POT modeling code and documentation. This article benefited through constructive reviews by three anonymous referees. Amer geophysical union Washington; YY

A Be-10 chronology of lateglacial and Holocene mountain glaciation in the Scoresby Sund region, east Greenland: implications for seasonality during lateglacial time - Kelly, M. A.; Lowell, T. V.; Hall, B. L.; Schaefer, J. M.; Finkel, R. C.; Goehring, B. M.; Alley, R. B.; Denton, G. H. (Quaternary Science Reviews, 2008)
Thirty-eight new cosmogenic (Be-10) exposure ages from the Scoresby Sund region of east Greenland indicate that prominent moraine sets deposited by mountain glaciers date from 780 to 310 yr, approximately during the Little Ice Age, from 11660 to 10 630 yr, at the end of the Younger Dryas cold interval or during Preboreal time, and from 13 010 to 11630 yr, during lateglacial time. Equilibrium line altitudes (ELAs) interpreted from lateglacial to Early Holocene moraines indicate summertime cooling between similar to 3.9 and 6.6 degrees C relative to today's value, much less than the extreme Younger Dryas cooling registered by Greenland ice cores (mean-annual temperatures of similar to 15 degrees C colder than today's value). This apparent discrepancy between paleotemperature records supports the contention that Younger Dryas cooling was primarily a wintertime phenomenon. Be-10 ages of lateglacial and Holocene moraines show that mountain glaciers during the Little Ice Age were more extensive than at any other time since the Early Holocene Epoch. In addition, 10Be ages of lateglacial moraines show extensive reworking of boulders with cosmogenic nuclides inherited from prior periods of exposure, consistent with our geomorphic observations and cosmogenic-exposure dating studies in other Arctic regions. (C) 2008 Elsevier Ltd. All rights reserved.
id: 1868; 389XX Times Cited:7 Cited References Count:75Y

Benthic foraminiferal faunal and isotopic changes as recorded in Holocene sediments of the northwest Indian Ocean - Gupta, Anil K.; Das, Moumita; Clemens, Steven C.; Mukherjee, Baidehi (Paleoceanography, 2008)
Historically, the Holocene has been considered an interval of relatively stable climate. However, recent studies from the northern Arabian Sea (Netherlands Indian Ocean Program 905) suggested high-amplitude climate shifts in the early and middle Holocene based on faunal and benthic isotopic proxy records. We examined benthic foraminiferal faunal and stable isotopic data from Ocean Drilling Program (ODP) Site 723 and total organic carbon data from ODP Site 724, Oman Margin (808 and 593 m water depths, respectively). At Site 723 the mid-Holocene shift in delta(18)O values of infaunal benthic species Uvigerina peregrina (1.4 parts per thousand) is 3 times larger than that of epifaunal benthic species Cibicides kullenbergi recorded at Site NIOP 905 off Somalia. However, none of the five other benthic species we measured at Hole 723A exhibits such a shift in delta(18)O. We speculate that the late Holocene delta(18)O decrease in U. peregrina represents species-specific changes in ecological habitat or food preference in response to changes in surface and deep ocean circulation. While the stable isotopic data do not appear to indicate a middle Holocene climatic shift, our total organic carbon and benthic faunal assemblage data do indicate that the early Holocene deep Arabian Sea was influenced by increased ventilation perhaps by North Atlantic Deep Water and/or Circumpolar Deep Water incursions into the Indian Ocean, leading to remineralization of organic matter and a relatively weak early Holocene oxygen minimum zone in the northwest Arabian Sea in spite of strong summer monsoon circulation.
id: 1964; PT: J; UT: WOS:000256362400001

Biodiesel effects on particulate radiocarbon (C-14) emissions from a diesel engine - Bennett, Maren; Volckens, John; Stanglmaier, Rudy; McNichol, Ann P.; Ellenson, William D.; Lewis, Charles W. (JOURNAL OF AEROSOL SCIENCE, 2008)
The relative amount of C-14 in a sample of atmospheric particulate matter (PM), defined as percent modern carbon (pMC), allows the Environmental Protection Agency (EPA) to infer the fraction of PM derived from anthropogenic pollution sources. With increased use of biofuels that contain C-14, the main assumption of the two-source model, that C-14 is solely derived from biogenic emissions, may become invalid. The goal of this study was to determine the C-14 content of PM emitted from an off-highway diesel engine running on commercial grade biodiesel. Tests were conducted with an off-highway diesel engine running at 80% load fueled by various blends of soy-based biodiesel. A dilution tunnel was used to collect PM10 emissions on quartz filters that were analyzed for their C-14 content using accelerator mass spectrometry. A mobility particle sizer and 5-gas analyzer provided supporting information on the particle size distribution and gas-phase emissions. The pMC of PM10 aerosol increased linearly with the percentage of biodiesel present in the fuel. Therefore, PM emissions resulting from increased combustion of biodiesel fuels will likely affect contemporary C-14 apportionment efforts that attempt to split biogenic vs. anthropogenic emissions based on aerosol C-14 content. Increasing the biodiesel fuel content also reduced emissions of total hydrocarbons (THC), PM10 mass, and particulate elemental carbon. Biodiesel had variable results on oxides of nitrogen (NOx) emissions. (C) 2008 Elsevier Ltd. All rights reserved.
Keywords: biofuel; EC; OC; PM; source apportionment

Biogeochemical characterization of carbon sources in the strickland and fly rivers, Papua New Guinea - Alin, S. R.; Aalto, R.; Goñi, M. A.; Richey, J. E.; Dietrich, W. E. (Journal of Geophysical Research-Earth Surface, 2008)
[1] The highstanding islands of Oceania are recognized as a source of significant particulate organic carbon delivered to nearshore marine environments. The existing data on carbon export in Oceania are largely derived from small mountainous watersheds (
id: 1870; 251HH Times Cited:4 Cited References Count:75Y

Bomb radiocarbon age validation of Pacific ocean perch (Sebastes alutus) using new statistical methods - Kastelle, C. R.; Kimura, D. K.; Goetz, B. J. (Canadian Journal of Fisheries and Aquatic Sciences, 2008)
We used bomb-produced radiocarbon (C-14) to validate ages of Pacific ocean perch (Sebastes alutus), which are routinely estimated with the cut-and-burn method at the Alaska Fisheries Science Center (Seattle, Washington, USA). New statistical methods to compare Delta C-14 in validation samples with a reference chronology are introduced: (i) calculating confidence intervals around the LOESS-smoothed Delta C-14 reference chronology using simultaneous inference; (ii) purposely adding biases to the validation sample ages and then analyzing the sum of squared residuals of the validation samples' Delta C-14 about the LOESS-smoothed reference chronology; and (iii) standardizing the Delta C-14 measurements from the validation sample to better fit the reference chronology. Standardized Delta C-14 measurements are particularly useful when researchers suspect that environmental and biological differences between the validation samples and the reference chronology may exist that affect the level, but not the timing, of Delta C-14 in the samples. These new methods can be applied simultaneously. Two previous bomb radiocarbon studies on canary rockfish (Sebastes pinniger) and black drum (Pogonias cromis) were reanalyzed, further illustrating the usefulness of these new methods.
id: 1832; 322ER Times Cited:1 Cited References Count:35Y

Bomb radiocarbon chronologies in the Arctic, with implications for the age validation of lake trout (Salvelinus namaycush) and other Arctic species - Campana, S. E.; Casselman, J. M.; Jones, C. M. (Canadian Journal of Fisheries and Aquatic Sciences, 2008)
Radiocarbon generated by atmospheric testing of nuclear weapons (bomb radiocarbon) produced a strong signal with an abrupt onset in the 1950s, which serves as a dated marker for tracing oceanic circulation and confirming age in animals forming growth bands. Here, we report the first prebomb and postbomb radiocarbon chronologies for marine and freshwater environments in the Canadian Arctic, extend the radiocarbon chronology for the northwest Atlantic Ocean, and use the onset of the bomb signal to validate our age interpretations of lake trout (Salvelinus namaycush) in Arctic lakes. Both surface and deepwater Arctic chronologies became detectable on or around 1958, similar to the year of onset elsewhere in the world. In contrast, the freshwater Arctic chronology increased sharply in 1957, with a peak value sixfold higher than the adjacent marine environment. The radiocarbon content of the adult otolith core validated our age interpretation criteria for Arctic lake trout to an age of at least 50 years. Otolith growth in such slow-growing fish was so low as to be unresolvable under conventional examination with a dissecting microscope. With these new radiocarbon reference chronologies, age validation of a large number of Arctic organisms should now be possible.
id: 804; 285MD Times Cited:7 Cited References Count:41Y

C-14 as a tracer of labile organic matter in Antarctic benthic food webs - Purinton, B. L.; DeMaster, D. J.; Thomas, C. J.; Smith, C. R. (Deep-Sea Research Part Ii-Topical Studies in Oceanography, 2008)
C-14 measurements were made on surface plankton, particle-trap material, surface sediment, benthic invertebrate gut contents, and body tissue samples to assess the effectiveness of this radioisotope as a tracer of labile organic carbon in Antarctic benthic food webs. Samples were collected on five cruises to the West Antarctic Peninsula (WAP) shelf between November 1999 and March 2001 as part of the Food for Benthos on the ANtarctic Continental-Shelf (FOODBANCS) Project. The 14C contents of the body tissues from a variety of deposit feeders (-126 +/- 13 per mil) were substantially enriched relative to the surface sediment (-234 +/- 13 per mil) and statistically similar to the organic matter collected in plankton tows (-135 +/- 10 per mil), indicating that recently produced marine plankton are the primary source of nutrition for these deposit feeders on the West Antarctic shelf. Selective ingestion was the primary feeding strategy used by echiuran worms and certain holothurians (i.e. Peniagone vignoni) for incorporating labile organic carbon into their tissues as demonstrated by the large differences (105 +/- 13 per mil) between surface sediment and gut content C-14 activities. In contrast, digestive and/or assimilatory, selection was the predominant strategy used by an irregular urchin (Amphipneustes lorioli) and several other holothurians (Protelpidia murrayi, Bathyplotes fuscivinculum and the head-clown conveyor belt feeder, Molpadia musculus), as demonstrated by large differences (42 +/- 7 per mil) between the 14C activities of their foregut or whole-gut organic contents and their body tissues. Despite large fluctuations in carbon export from the euphotic zone, benthic feeding strategies remained essentially constant over the 15-month sampling period. No seasonal variation was evident in either the 14C abundance of the deposit-feeder body tissues, or in the 14C abundance of their gut contents. The mean C-14 abundance in the body tissues of the two sub-surface deposit feeders (A. lorioli and M. musculus; mean = -136.2 +/- 8.5 per mil) was distinct (p = 0.0008) from the mean 14C abundance in the body tissues of the four surface deposit feeders (echiuran worm, P vignoni, P. murrayi, and B. fusciviculum; -122.6 +/- 12.3 per mil). The mean 14 C abundance of the gut contents from the sub-surface deposit feeders (-178.0 +/- 18.6 per mil) also was significantly depleted (p = 0.0009) relative to that of the surface deposit feeders (-149.5 +/- 26.6 per mil). The 14C measurements proved to be a much more sensitive tracer for tracking labile organic carbon during ingestive and assimilatory processes than the stable isotopes of carbon or nitrogen. (C) 2008 Elsevier Ltd. All rights reserved.
id: 1854; 386VU Times Cited:7 Cited References Count:98Y

A canyon through time : archaeology, history, and ecology of the Tecolote Canyon area, Santa Barbara County, California - Erlandson, Jon M.; Rick, Torben C.; Vellanoweth, Ren L. (University of Utah Press, 2008)
id: 1907

Carbonate cycle and its control factors in Kuroshio source region during the last 190ka BP - Jingtao, Zhao; Chang, Fengming; Li, Tiegang; Qingyun, Nan; Li, Qing (Yanshi Xuebao = Acta Petrologica Sinica, 2008)
Two deep sea cores (Ph05-5, 16.05 degrees N, 124.34 degrees E, water depth 3382m and WP3:22.15 degrees N, 122.95 degrees E, water depth 2700m) retrieved from the Kuroshio source region of the western Philippine Sea were selected to carry out the CaCO
id: 1934; NO: Source type: scholarlyjournals; Object type: Article; Copyright: GeoRef in Process, Copyright 2011, American Geosciences Institute. After editing and indexing, this record will be added to Georef.; CSAUnique: 577070-23; AccNum: 577070-23; ISSN: 1000-0569; Peer Reviewed: true

Catastrophic hurricane history revealed by organic geochemical proxies in coastal lake sediments: a case study of Lake Shelby, Alabama (USA) - Lambert, W. Joe; Aharon, Paul; Rodriguez, Antonio B. (Journal of Paleolimnology, 2008)
We developed a new method for reconstructing millennia-long hurricane records from coastal environments that uses Organic Geochemical Proxies (OGPs) of organic carbon and nitrogen concentrations and their delta C-13 and delta N-15 compositions. The new method is independent of presence/absence of sand layers and improves significantly the severe-storm history resolution. The subject of this investigation is a 1.5 m long sediment core raised at 2.8 m water depth from the center of Lake Shelby, Alabama, a freshwater lake located approximately 250 m from the Gulf of Mexico, from which an overwash sand-layer based record was previously derived. The core contains two distinct sediment units; an upper 62 cm thick, fine-grained, organic-rich lacustrine sapropel (gyttja) that shows no visible structures except one sand lamina at 23.7 cm depth, and an underlying 90 cm thick, organic-poor lagoon/estuary clay unit. The sapropel unit was deposited over a 682 +/- 30 cal year time interval (1320-2002 A.D.) with a mean sedimentation rate of 0.79 +/- 0.04 mm/year. Lake Shelby's water column exhibits two contrasting states based on water chemistry surveys (i) an "isolated", stratified, mode under calm weather conditions with a relatively low trophic state, and (ii) a "flooded" mode occurring during storm surges when nutrient-rich seawater floods the lake. Statistically significant delta C-13 and delta N-15 positive excursions in organic matter, up to maximum values of -25 (parts per thousand PDB) and 4 (parts per thousand Air N-2), respectively, are interpreted as geochemical responses to the marine intrusions that fertilize the lake, increase light availability, and cause eutrophication spikes. Detailed OGPs analyses crossing a sand layer that offers visual evidence of a catastrophic hurricane overwash event at 1717 A.D. exhibit large delta C-13 and delta N-15 positive shifts bounded by rapid returns to base values, thus confirming the validity of the hurricane identification by the OGPs model. Our data indicate that 11 catastrophic hurricanes hit the Alabama coast over the past 682 years with a rough recurrence interval of one in 62 years.
id: 2037; PT: J; UT: WOS:000251730600010

Changes in the composition of organic matter from prodeltaic sediments after a large flood event (Po River, Italy) - Tesi, T.; Langone, L.; Goñi, M. A.; Miserocchi, S.; Bertasi, F. (Geochimica et Cosmochimica Acta, 2008)
The Po River (Italy) experienced a 100-year flood in October 2000. Surface sediments (0-1 cm) from cross-shelf transects were collected in the Po prodelta area (Adriatic Sea) in December 2000, in order to describe the distribution of organic matter (OM) along the main sediment dispersal system immediately after the flood event. Stations were subsequently reoccupied in October 2001 and April 2002. This sampling program provided a special opportunity to characterize the initial surficial flood deposit and the evolution of its associated OM over the course of 2 years. CuO oxidation, elemental, delta C-13, Delta C-14, and grain-size analyses were carried out to characterize the source, age, and spatial variability of sedimentary OM. Statistical analysis (PERMANOVA) was then applied to investigate temporal changes in different portions of the Po prodelta area. Isotopic and biomarker data suggest that the sedimentary OM in the flood deposit was initially dominated by aged (Delta C-14(Dec-00) = -298.7 +/- 56.3%,), lignin-poor OM (Lambda(Dec-00) = 1.96 +/- 0.33 mg/100 mg OC), adsorbed on the fine material (clay(Dec-00) = 72.1 +/- 4.8%) delivered by the flood. In the 2 years following the flood, post-depositional processes significantly increased the content of lignin (Lambda(Oct-01) = 2.19 +/- 0.51 mg/100 mg OC; Lambda(Apr-02) = 2.61 +/- 0.63 mg/100 mg OC); and coarse material (silt and sand), while decreasing the contributions from aged OC (Delta C-14(Oct-01) = -255.7 +/- 32.8%.; Delta C-14(Apr-02) = -213.2 +/- 30.4%.) and fine fraction (clay(Oct-01) = 54.8 +/- 9.5%; clay(Apr-02) = 44.6 +/- 13.3%). The major changes were observed in the northern and central portions of the prodelta. (c) 2008 Elsevier Ltd. All rights reserved.
id: 888; 290IO Times Cited:4 Cited References Count:66Y

Constraints on the Pleistocene chronology of sediments from the Lomonosov Ridge - O'Regan, M.; King, J.; Backman, J.; Jakobsson, M.; Palike, H.; Moran, K.; Heil, C.; Sakamoto, T.; Cronin, T. M.; Jordan, R. W. (Paleoceanography, 2008)
[1] Despite its importance in the global climate system, age-calibrated marine geologic records reflecting the evolution of glacial cycles through the Pleistocene are largely absent from the central Arctic Ocean. This is especially true for sediments older than 200 ka. Three sites cored during the Integrated Ocean Drilling Program's Expedition 302, the Arctic Coring Expedition ( ACEX), provide a 27 m continuous sedimentary section from the Lomonosov Ridge in the central Arctic Ocean. Two key biostratigraphic datums and constraints from the magnetic inclination data are used to anchor the chronology of these sediments back to the base of the Cobb Mountain subchron ( 1215 ka). Beyond 1215 ka, two best fitting geomagnetic models are used to investigate the nature of cyclostratigraphic change. Within this chronology we show that bulk and mineral magnetic properties of the sediments vary on predicted Milankovitch frequencies. These cyclic variations record "glacial'' and "interglacial'' modes of sediment deposition on the Lomonosov Ridge as evident in studies of ice-rafted debris and stable isotopic and faunal assemblages for the last two glacial cycles and were used to tune the age model. Potential errors, which largely arise from uncertainties in the nature of downhole paleomagnetic variability, and the choice of a tuning target are handled by defining an error envelope that is based on the best fitting cyclostratigraphic and geomagnetic solutions.
id: 868; 281YL Times Cited:22 Cited References Count:55; YY

Contrasting lipid biomarker composition of terrestrial organic matter exported from across the Eurasian Arctic by the five great Russian Arctic rivers - van Dongen, B. E.; Semiletov, I.; Weijers, J. W. H.; Gustafsson, O. R. (Global Biogeochemical Cycles, 2008)
Surface sediments outside the great Russian Arctic rivers (GRARs; Ob, Yenisey, Lena, Indigirka, and Kolyma) were investigated for their lipid biomarker composition to elucidate compositional distinctions of the exported organic matter (OM) across this continent-scale climosequence of the Siberian Arctic. The lipid biomarker composition is dominantly terrestrial (high molecular weight (HMW) n-alkanols, n-alkanoic acids, n-alkanes; branched glycerol dialkyl glycerol tetraethers (GDGTs), beta-sitosterol, other sterols, and triterpenoids) with only minor marine contributions (e. g., the ratio of terrigenous-to-aquatic n-alkanes was 17-80, the TOC/TN ratio was 10-16, and the branched and isoprenoid tetraether (BIT) index > 0.88). There is a large contribution of C-23 and C-25 homologues relative to other long-chained n-alkanes, suggesting substantial contribution of probably Sphagnum-derived OM. The C-23 and C-25 contribution decreases eastward, signaling either a decrease in the potential contribution of Sphagnum or a shift within the n-alkane distribution of Sphagnum species or increased aeolian input, due to more arid conditions in the east. Other distinctions in molecular OM composition across the climosequence include increased concentrations of both HMW n-alkanoic acids and beta-sitosterol relative to HMW n-alkanes in the eastern sediments. This suggests that the OM exported by the eastern GRARs is, despite their higher bulk radiocarbon ages, less degraded, which is consistent with increasing permafrost and a shorter annual thaw period in eastern Siberia. Taken together, this benchmark study of the current composition of terrestrially exported OM suggests distinguishing continent-scale trends in molecular composition of the OM across the west-east set of GRARs, which reflects both differences in vegetation and climate. If the climate in the eastern Russian Arctic region becomes more like the current state in the western part, these results would predict a greater degree of decomposition of the old terrestrial OM released by the eastern GRARs and thus greater remineralization and release as CO2 and methane.
id: 819; 261FT Times Cited:10 Cited References Count:112Y

Cooling and changing seasonality in the Southern Alps, New Zealand during the Antarctic Cold Reversal - Vandergoes, M. J.; Dieffenbacher-Krall, A. C.; Newnham, R. M.; Denton, G. H.; Blaauw, M. (Quaternary Science Reviews, 2008)
A comprehensively C-14 AMS dated pollen and chironomid record from Boundary Stream Tarn provides the first chironomid-derived temperature reconstruction to quantify temperature change during Lateglacial times (17,500-10,000 cal yr BP) in the Southern Alps, New Zealand. The records indicate a ca 1000-year disruption to the Lateglacial warming trend and an overall cooling consistent with the Antarctic Cold Reversal (ACR). The main interval of chironomid-inferred summer temperature depression (similar to 2-3 degrees C) lasted about 700 years during the ACR. Following this cooling event, both proxies indicate a warming step to temperatures slightly cooler than present during the Younger Dryas chronozone (12,900-11,500 cal yr BP). These results highlight a direct linkage between Antarctica and mid-latitude terrestrial climate systems and the largely asynchronous nature of the interhemispheric climate system during the last glacial transition. The greater magnitude of temperature changes shown by the chironomid record is attributed to the response of the proxies to differences in seasonal climate with chironomids reflecting summer temperature and vegetation more strongly controlled by duration of winter or by minimum temperatures. These differences imply stronger seasonality at times during the Lateglacial, which may explain some of the variability between other paleoclimate records from New Zealand and have wider implications for understanding differences between proxy records for abrupt climate change. (C) 2007 Elsevier Ltd. All rights reserved.
293rhTimes Cited:27Cited References Count:64

Coupled North Atlantic slope water forcing on Gulf of Maine temperatures over the past millennium - Wanamaker, Alan D.; Kreutz, Karl J.; öne, Bernd R.; Pettigrew, Neal; Borns, Harold W.; Introne, Douglas S.; Belknap, Daniel; Maasch, Kirk A.; Feindel, Scott (Climate Dynamics, 2008)
To investigate ocean variability during the last millennium in the Western Gulf of Maine (GOM), we collected a 142-year-old living bivalve (Arctica islandica L.) in 2004, and three fossil A. islandica shells (calibrated 14CAMS = 1030 ± 78 ad; 1320 ± 45 ad; 1357 ± 40 ad) for stable isotope and growth increment analysis. A statistically significant relationship exists between modern GOM temperature records [shell isotope-derived (30 m) (r = −0.79; P < 0.007), Prince 5 (50 m) (r = −0.72; P < 0.019), Boothbay Harbor SST (r = −0.76; P < 0.011)], and Labrador Current (LC) transport data from the Eastern Newfoundland Slope during 1993–2003. In all cases, as LC transport increased, GOM water temperatures decreased the following year. Decadal trends in the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO) influence GOM water temperatures in the most recent period, with water temperatures decreasing during NAO and AMO negative modes most likely linked to LC transport and Gulf Stream interaction. Mean shell-derived isotopic changes (δ18Oc) during the last 1,000 years were +0.47‰ and likely reflect a 1–2°C cooling from 1000 ad to present. Based on these results, we suggest that observed cooling in the GOM during the last millennium was due to increased transport and/or cooling of the LC, and decreased Gulf Stream influence on the GOM.

Deepwater circulation on Blake Outer Ridge (western North Atlantic) during the Holocene, Younger Dryas, and Last Glacial Maximum - Evans, H. K.; Hall, I. R. (Geochemistry Geophysics Geosystems, 2008)
Three depth transects containing a total of 33 sediment cores were investigated along the Blake Outer Ridge in the western subtropical North Atlantic. Sortable silt mean ((SS) over bar) grain size and stable isotope records were used to assess the position and relative intensity of the Western Boundary Undercurrent (WBUC) during the Holocene, the Last Glacial Maximum (LGM), and the Younger Dryas (YD) intervals. The Holocene reconstruction is consistent with modern physical and chemical hydrographic measurements in the area, suggesting a deep position for the fast flowing core of the WBUC (3000-4000 m, deepening to similar to 4500 m water depth on the ridge flanks) and a water column dominated by North Atlantic Deep Water (NADW). The LGM and YD reconstructions show that a comparable hydrographic regime was present during both these intervals, suggesting a similar mode of circulation that was appreciably different from the Holocene reconstruction. The WBUC's zone of maximum flow speed during these intervals is suggested to have shifted above 2500 m water depth, consistent with nutrient depleted Glacial North Atlantic Intermediate Water formation with an increasing influence of Southern Source Water (SSW) beneath. Below 4000 m water depth, (SS) over bar results hint at increased SSW flow vigor during both the LGM and YD with higher flow speeds than during the Holocene. This study provides a framework for aiding the interpretation of time series records of paleocurrent flow speed changes in the region of the WBUC.
id: 839; 281XG Times Cited:1 Cited References Count:84Y

Deglacial variability in the surface return flow of the Atlantic meridional overturning circulation - Came, R. E.; Oppo, D. W.; Curry, W. B.; Lynch-Stieglitz, J. (Paleoceanography, 2008)
[1] Benthic foraminiferal Cd/Ca from a Florida Current sediment core documents the history of the northward penetration of southern source waters within the surface return flow of the Atlantic meridional overturning circulation (AMOC). Cd seawater estimates (Cd-W) indicate that intermediate-depth southern source waters crossed the equator and contributed to the Florida Current during the Bolling-Allerod warm period of the last deglaciation, consistent with evidence of only a modest AMOC reduction compared to today. The Cd-W estimates also provide the first paleoceanographic evidence of a reduction in the influence of intermediate-depth southern source waters within the Florida Current during the Younger Dryas, a deglacial cold event characterized by a weak North Atlantic AMOC. Our results reveal a close correspondence between the northward penetration of intermediate-depth southern source waters and the influence of North Atlantic Deep Water, suggesting a possible link between intermediate-depth southern source waters and the strength of the Atlantic AMOC.
id: 838; 281YL Times Cited:4 Cited References Count:41; YY

Determination of biodiesel blending percentages using natural abundance radiocarbon analysis: Testing the accuracy of retail biodiesel blends - Reddy, C. M.; DeMello, J. A.; Carmichael, C. A.; Peacock, E. E.; Xu, L.; Arey, J. S. (Environmental Science & Technology, 2008)
Blends of biodiesel and petrodiesel are being used increasingly worldwide. Due to several factors, inaccurate blending of these two mixtures can occur. To test the accuracy of biodiesel blending, we developed and validated a radiocarbon-based method and then analyzed a variety of retail biodiesel blends. Error propagation analysis demonstrated that this method calculates absolute blend content with +/- 1% accuracy, even when real-world variability in the component biodiesel and petrodiesel sources is taken into account. We independently confirmed this accuracy using known endmembers and prepared mixtures. This is the only published method that directly quantifies the carbon of recent biological origin in biodiesel blends. Consequently, it robustly handles realistic chemical variability in biological source materials and provides unequivocal apportionment of renewable versus nonrenewable carbon in a sample fuel blend. Analysis of retail biodiesel blends acquired in 2006 in the United States revealed that inaccurate blending happens frequently. Only one out of ten retail samples passed the specifications that the United States Department of Defense requires for blends that are 20% biodiesel (v/v; referred to as B20).
id: 1864; 281JN Times Cited:3 Cited References Count:39; YY

Differences in sediment organic matter composition and PAH weathering between non-vegetated and recently vegetated fuel oiled sediments - Gregory, Samuel T., III; Nichols, Elizabeth Guthrie (International Journal of Phytoremediation, 2008)
We examined polycyclic aromatic hydrocarbon (PAH) attenuation in contaminated field sediments after only 2 years of plant growth. We collected sediments from vegetated and non-vegetated areas at the Indiana Harbor Canal (IHC), an industrialized area with historic petroleum contamination of soils and sediments. PAH concentrations, PAH weathering indices, and organic matter composition in sediments colonized by Phragmites, cattails, or willow trees were compared to the same indices for non-vegetated sediments. We hypothesized that bulk sediment and humin fractions with measurable increases in plant organic matter content would show measurable changes to PAH attenuation as indicated by more weathered PAH diagnostic ratios or reduced PAH concentrations. Carbon-normalized PAH concentrations were lower in vegetated bulk sediments but higher in vegetated humin fractions relative to non-vegetated sediment fractions. Total organic carbon content was not indicative of more weathered N(3)/P(2) ratios or reduced PAH concentrations in vegetated sediment fractions. More weathered N(3)/P(2) ratios were observed with increased modern carbon (plant carbon) content of vegetated sediment fractions. Phragmites sediments contained more modern carbon (plant carbon) and more weathered PAH ratios [C(3)-naphthalenes and C(2)-phenanthrenes (N(3)/P(2))] than willow, cattail, and non-vegetated sediments.
id: 2025; PT: J; UT: WOS:000258774100001