Sedimentary iron cycling and the origin and preservation of magnetization in platform carbonate muds, Andros Island, Bahamas - Maloof, A. C.; Kopp, R. E.; Grotzinger, J. P.; Fike, D. A.; Bosak, T.; Vali, H.; Poussart, P. M.; Weiss, B. P.; Kirschvink, J. L. (Earth and Planetary Science Letters, 2007)
Carbonate muds deposited on continental shelves are abundant and well-preserved throughout the geologic record because shelf strata are difficult to subduct and peritidal carbonate units often form thick, theologically strong units that resist penetrative deformation. Much of what we know about pre-Mesozoic ocean chemistry, carbon cycling, and global change is derived from isotope and trace element geochemistry of platform carbonates. Paleomagnetic data from the same sediments would be invaluable, placing records of paleolatitude, paleogeography, and perturbations to the geomagnetic field in the context and relative chronology of chemostratigraphy. To investigate the depositional and early diagenetic processes that contribute to magneitzation in carbonates, we surveyed over 500 core and surface samples of peritidal, often microbially bound carbonate muds spanning the last similar to 1000 yr and deposited on top of Pleistocene aeolianites in the Triple Goose Creek region of northwest Andros Island, Bahamas. Sedimentological, geochemical, magnetic and ferromagnetic resonance properties divide the sediment columns into three biogeochemical zones. In the upper sediments, the dominant magnetic mineral is magnetite, produced by magnetotactic bacteria and dissimiliatory microbial iron metabolism. At lower depths, above or near mean tide level, microbial iron reduction dissolves most of the magnetic particles in the sediment. In some cores, magnetic iron sulfides precipitate in a bottom zone of sulfate reduction, likely coupled to the oxidation of decaying mangrove roots. The remanent magnetization preserved in all oriented samples appears indistinguishable from the modem local geomagnetic field, which reflects the post-depositional origin of magnetic particles in the lower zone of the parasequence. While we cannot comment on the effects of late-stage diagenesis or metamorphism on remanence in carbonates, we postulate that early-cemented, thin-laminated parasequence tops in ancient peritidal carbonates are mostly likely to preserve syn-depositional paleomagnetic directions and magnetofossil stratigraphies. (c) 2007 Published by Elsevier B.V.
id: 787; 197DX Times Cited:9 Cited References Count:47Y

Selective degradation of organic compounds in sediments from the California Borderland Basins: evidence from compound specific Delta 14C and delta 13C analyses - Mollenhauer, Gesine; Eglinton, Timothy I. (Limnology and Oceanography, 2007)
id: 544

Source apportionment of atmospheric PAHs in the western Balkans by natural abundance radiocarbon analysis - Zencak, Zdenek; Klanova, Jana; Holoubek, Ivan; Gustafsson, Örjan (Environmental Science and Technology, 2007)
id: 519

Source, transport and fate of terrestrial organic carbon on the western Mediterranean Sea, Gulf of Lions, France - Tesi, T.; Miserocchi, S.; Goñi, M. A.; Langone, L. (Marine Chemistry, 2007)
As part of the EuroSTRATAFORM project, a multi-proxy study was conducted in order to investigate origin, transport and deposition of riverine organic matter in the Gulf of Lions. Surface sediments (0-1 cm) from the Rhone prodelta area and along the sediment dispersal system were collected in September 2004 and in April 2005. Lignin, elemental and stable carbon isotopic analyses were carried out to characterize the source of sedimentary organic material and to facilitate evaluation of temporal and spatial variability. Large contrasts in the organic matter composition of prodelta sediments were observed as a result of the preferential transport of the finest material. In our hypothesis, woody debris, rich in organic matter, hydraulically behaves like very fine sand and is retained within the prodelta area. In contrast, the organic matter adsorbed onto finer particles is selectively transported away from the prodelta along the sediment dispersal system, explaining the distinct organic matter composition observed in the offshore regions. (c) 2007 Elsevier B.V. All rights reserved.
id: 825; 176SJ Times Cited:15 Cited References Count:70Y

Spatial complexity of 'Little Ice Age' climate in East Africa: sedimentary records from two crater lake basins in western Uganda - Russell, J. M.; Verschuren, D.; Eggermont, H. (Holocene, 2007)
Lithostratigraphic analyses of the sedimentary record from two contrasting crater lake basins in western Uganda, Africa, provide evidence for three major century-scale and intervals during the last 2000 year. Variations in sedimentation and salt mineralogy of hypersaline Lake Kitagata, and a succession of fine-grained lake sediments and peat in the freshwater Lake Kibengo, suggest century-scale droughts centred on AD 0, similar to 1100, similar to 1550 and 1750. These results broadly support data from nearby Lake Edward on the timing of drought in western Uganda, but contrast with lake sediment records from eastern equatorial Africa. In particular, our results suggest regional variability of East African climate during the main phase of the 'Little Ice Age' (AD similar to 1500 to 1800), with westernmost East Africa experiencing drought while areas farther east were wet. This spatial pattern highlights the strongly regional nature of century-scale climate changes over the African continent, and holds implications for the mechanisms governing African rainfall during the 'Little Ice Age'.
144ztTimes Cited:36Cited References Count:55

Stable carbon isotope compositions of Eastern Beringian grasses and sedges: Investigating their potential as paleoenvironmental indicators - Wooller, M. J.; Zazula, G. D.; Edwards, M.; Froese, D. G.; Boone, R. D.; Parker, C.; Bennett, B. (Arctic Antarctic and Alpine Research, 2007)
The nature of vegetation cover present in Beringia during the last glaciation remains unclear. Uncertainty rests partly with the limitations of conventional paleoecological methods. A lack of sufficient taxonomic resolution most notably associated with the grasses and sedges restricts the paleoccological inferences that can be made. Stable isotope measurements of subfossil plants are frequently used to enhance paleoenvironmental reconstructions. We present an investigation of the stable carbon isotope composition (delta C-13) of modern and subfossil grasses and sedges (graminoids) from Eastern Beringia. Modern grasses from wet habitats had a mean delta C-13 of -29.1 parts per thousand. (standard deviation [SD] = 2.1 parts per thousand, n = 75), while those from dry habitats had a mean of -26.9 parts per thousand (SD = 1.19, n = 27). Sedges (n = -50) from dry, wet, marsh, and sand dune habitats had specific habitat ranges. Four modern C-4 grasses had delta C-13 values typical Of C4 plants. Analyses were also conducted using subfossil graminoid remains from several sedimentary paleoecological contexts (e.g., arctic ground squirrel nests, loess, permafrost, and paleosols) in Eastern Beringia. Results from these subfossil samples, ranging in age from > 40,000 to ca. 11,000 cal. yr BP, illustrate that the delta C-13 of graminoid remains has altered during the past. The range of variation in the subfossil samples is within the range from modern graminoid specimens from dry and wet habitats. The results indicate that stable isotopes could contribute to a comprehensive and multiproxy reconstruction of Beringian paleoenvironments.
170fwTimes Cited:20Cited References Count:73

Stable-and radiocarbon isotopes in corals and adjacent natural waters: reconstructing land-use change and the land-ocean carbon cycle - Moyer, R. P.; Grottoli, A. G. (ASLO, 2007)
id: 654

Status of the Black Sea flood hypothesis - Ryan, W. B. F. (The Black Sea Flood Question: Changes in Coastline, Climate and Human Settlement, 2007)
id: 854

Strandplain evolution along the southern coast of Santa Caterina, Brazil - FitzGerald, D. M.; Cleary, W. J.; Buynevich, I. V.; Hein, C. J.; Kleins, A. H. F.; Asp, N.; Angulo, R. (Journal of Coastal Research, 2007)
id: 1099

Stratigraphy and environmental reconstruction at the middle Wisconsinan Gilman Canyon Formation type locality, Buzzard's Roost, southwestern Nebraska, USA - Johnson, W. C.; Willey, K. L.; Mason, J. A.; May, D. W. (Quaternary Research, 2007)
The middle Wisconsinan Gilman Canyon Formation at the Buzzard's Roost type locality in southwestern Nebraska was investigated to document the stratigraphy and to reconstruct the environmental and climate record. The Gilman Canyon Formation was subdivided into three loess units and three soils, with radiocarbon ages constraining it between about 40 ka and 25 ka. Stable carbon isotope ratios, magnetic susceptibility, and carbon content were used to define and characterize soils within both the Gilman Canyon Formation and underlying Illinoian Loveland Loess. At the height of soil development within the Gilman Canyon Formation, climate was supporting C-4-dominated grassland, with July temperatures equal to or exceeding those of today. Soil-forming intervals within the Loveland Loess, including the Sangamon Soil, also exhibited relative increases in C-4 biomass. Climate, as recorded in the Gilman Canyon Formation, is corroborated by regional proxy data. The formation accumulated during MIS 3, and concurrent soil formation coincided with a summer insolation maximum. (c) 2007 University of Washington. All rights reserved.
160ruTimes Cited:17Cited References Count:115

A study of secondary organic aerosol formation in the anthropogenic-influenced southeastern United States - Weber, R. J.; Sullivan, A. P.; Peltier, R. E.; Russell, A.; Yan, B.; Zheng, M.; de Gouw, J.; Warneke, C.; Brock, C.; Holloway, J. S.; Atlas, E. L.; Edgerton, E. (Journal of Geophysical Research-Atmospheres, 2007)
[1] The formation of secondary organic aerosol (SOA) in an anthropogenic-influenced region in the southeastern United States is investigated by a comparison with urban plumes in the northeast. The analysis is based on measurements of fine-particle organic compounds soluble in water (WSOC) as a measure of secondary organic aerosol. Aircraft measurements over a large area of northern Georgia, including the Atlanta metropolitan region, and in plumes from New York City and surrounding urban regions in the northeast show that fine-particle WSOC are spatially correlated with vehicle emission tracers (e.g., CO), yet the measurements indicate that vehicles do not directly emit significant particulate WSOC. In addition to being correlated, WSOC concentrations were in similar proportions to anthropogenic tracers in both regions, despite biogenic volatile organic compounds (VOCs) that were on average 10-100 times higher over northern Georgia. In contrast, radiocarbon analysis on WSOC extracted from integrated filters deployed in Atlanta suggests that roughly 70-80% of the carbon in summertime WSOC is modern. If both findings are valid, the combined results indicate that in northern Georgia, fine-particle WSOC was secondary and formed through a process that involves mainly modern biogenic VOCs but which is strongly linked to an anthropogenic component that may largely control the mass of SOA formed. Independent of the radiocarbon results, a strong association between SOA and anthropogenic sources has implications for control strategies in urban regions with large biogenic VOC emissions.
id: 788; 187XB Times Cited:47 Cited References Count:39Y

A study of secondary organic aerosol formation in the anthropogenic-influenced southeastern United States - Weber, R. J.; Sullivan, A. P.; Peltier, R. E.; Russell, A.; Yan, B.; Zheng, M.; de Gouw, J.; Warneke, C.; Brock, C.; Holloway, J. S.; Atlas, E. L.; Edgerton, E. (Journal of Geophysical Research-Atmospheres, 2007)
[1] The formation of secondary organic aerosol (SOA) in an anthropogenic-influenced region in the southeastern United States is investigated by a comparison with urban plumes in the northeast. The analysis is based on measurements of fine-particle organic compounds soluble in water (WSOC) as a measure of secondary organic aerosol. Aircraft measurements over a large area of northern Georgia, including the Atlanta metropolitan region, and in plumes from New York City and surrounding urban regions in the northeast show that fine-particle WSOC are spatially correlated with vehicle emission tracers (e.g., CO), yet the measurements indicate that vehicles do not directly emit significant particulate WSOC. In addition to being correlated, WSOC concentrations were in similar proportions to anthropogenic tracers in both regions, despite biogenic volatile organic compounds (VOCs) that were on average 10-100 times higher over northern Georgia. In contrast, radiocarbon analysis on WSOC extracted from integrated filters deployed in Atlanta suggests that roughly 70-80% of the carbon in summertime WSOC is modern. If both findings are valid, the combined results indicate that in northern Georgia, fine-particle WSOC was secondary and formed through a process that involves mainly modern biogenic VOCs but which is strongly linked to an anthropogenic component that may largely control the mass of SOA formed. Independent of the radiocarbon results, a strong association between SOA and anthropogenic sources has implications for control strategies in urban regions with large biogenic VOC emissions.
263D13302
Keywords: AMBIENT AEROSOL; atmosphere; C-14; emissions; evolution; GASOLINE; OXIDATION; PARTICLES; RATIOS; ZURICH

Submarine canyon and fan systems of the California Continental Borderland, Chapter 3-7 - Normark, W. R.; Piper, D. J. W.; Romans, B. W.; Covault, J. A.; Dartnell, P.; Sliter, R. W. (Earth Science in the Urban Ocean: The Southern California Contental Borderlands, 2007)
id: 992

Surface currents in the western North Atlantic during the Last Glacial Maximum - LeGrande, A. N.; Lynch-Stieglitz, J. (Geochemistry Geophysics Geosystems, 2007)
[1] During the last ice age, the density gradient across the Florida Current was reduced, implying a reduction in the flow of the Gulf Stream through the Florida Straits. Here we investigate the possibility that a significant portion of this wind-driven western boundary flow bypassed the Florida Straits during glacial times due to either changes in bathymetry induced by the sea level drop or changes in wind patterns. Down core records of the oxygen isotope ratios of the planktonic foraminifer Globorotalia truncatulinoides are used to locate the density gradients and thus the locations of upper ocean currents in the western North Atlantic. We find that western boundary flow was largely confined within the Florida Straits during the Last Glacial Maximum as it is today. This finding supports the idea that the reduced density gradient across the Florida Current represents a reduction in the surface branch of the surface to deep meridional overturning circulation in the Atlantic rather than a reduction in the proportion of the wind-driven flow carried by the Florida Current.
131djTimes Cited:2Cited References Count:16

Tectonics and relative sea-level change - Nelson, A. R. (Encyclopedia of Quaternary Science, 2007)
id: 998

Terrestrial subsidies of aquatic metabolism and food webs: A turorial and review - Cole, J. J. (American Society of Limnology and Oceanography; Aquatic Science meeting, 2007)
69
id: 480

Is there a thorium-230 deficit in Arctic sediments? - Hoffmann, S. S.; McManus, J. F. (Earth and Planetary Science Letters, 2007)
id: 711

The timing and evolution of the post-glacial transgression across the Sea of Marmara shelf south of Istanbul - Eris, K. K.; Ryan, W. B. F.; Cagatay, M. N.; Sancar, U.; Lericolais, G.; Menot, G.; Bard, E. (Marine Geology, 2007)
High-resolution seismic reflection profiles and analyses of the sedimentary substrate at the Sea of Marmara (SoM) entrance to the Strait of Istanbul (Sol, Bosphorus) provide a detailed record of the transgression that took place after the SoM reconnected with the Mediterranean. The sediments progressively fill a paleo shelf valley that incised the margin from the Sol to the shelf break at the time of the pre-Holocene lowstand. We map seven seismic reflection units that can be confidently correlated to sediment cores by lithology and physical properties. Sediments in the cores are dated by radiocarbon methods. Early channel and levee deposits within the paleo valley belong to the Younger Dryas cold stage and record outflow from the Black Sea via the Sol. Small clinoform packages on the valley margin formed in proximity to climbing paleo shorelines. The elevations of these deposits conform to the sealevel history recorded in Barbados corals. The younger part of the succession includes a subaqueous prodelta sourced from the Kurbagalidere River. Its relatively young age when the Holocene sea had almost reached its modem level suggests that the thick progradational and aggradational clinoform development was primarily a response to sediment supply rather than the filling of expanding accommodation space. Our findings refute the hypothesis of Aksu et al. (Aksu, A.E., Hiscott, R.N., Mudie., P.J., Rochon, A., Kaminski, M.A., Abrojano, T., Yasar, D., 2002a. Persistent Holocene outflow fromn the Black Sea to the Eastern Mediterranean contradicts Noah's Flood hypothesis, GSA Today 10,(6), 3-7., Aksu, A.E., Hiscott, R.N., Kaminski, M.A., Mudie, P.J., Gillespie, H., Abrojano, T., Yasar, D., 2002b. Last glacial-Holocene paleoceanography of the Black Sea and Marmara Sea: stable isotopic, foraminiferal and coccolith evidence. Mar. Geol., 190, 119-149.) and Hiscott et al. (Hiscott, R.N., Aksu, A.E., Yasar, D., Kaminski, M.A., Mudie, P.J., Kostylev, V.E., MacDonald, J.C. Isler, F.I., Lord, A.R., 2002. Deltas south of the Bosphorus Strait record persistent Black Sea outflow to the Marmara Sea since similar to 10 ka, Mar. Geol., 190,95-118., Hiscott, R.N., Aksu, A.E., Mudie., P.J., Kaminski, M.A., Abrajano, T, Yasar, D., Rochon, A., 2007. The Marmara Sea gateway since similar to 16 ky BP: non-catastrophic causes of paleoceanographic events in the Black Sea at 8.4 and 7.15 ky BR In Yanko-Hombach,V, Gilbert, A.S., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question, Springer, The Netherlands, 89-117.) that this deposit was supplied from the Sol and that its presence requires a persistent Black Sea outflow since 10 C-14 ka bp (not corrected from the reservoir age or calibrated). (c) 2007 Elsevier B.V All rights reserved.
210tuTimes Cited:36Cited References Count:52

Tropical Pacific - mid-latitude teleconnections in medieval times - Graham, N. E.; Hughes, M. K.; Ammann, C. M.; Cobb, K. M.; Hoerling, M. P.; Kennett, D. J.; Kennett, J. P.; Rein, B.; Stott, L.; Wigand, P. E.; Xu, T. Y. (Climatic Change, 2007)
Terrestrial and marine late Holocene proxy records from the western and central US suggest that climate between approximately 500 and 1350 A.D. was marked by generally arid conditions with episodes of severe centennial-scale drought, elevated incidence of wild fire, cool sea surface temperatures (SSTs) along the California coast, and dune mobilization in the western plains. This Medieval Climate Anomaly (MCA) was followed by wetter conditions and warming coastal SSTs during the transition into the "Little Ice Age" (LIA). Proxy records from the tropical Pacific Ocean show contemporaneous changes indicating cool central and eastern tropical Pacific SSTs during the MCA, with warmer than modern temperatures in the western equatorial Pacific. This pattern of mid-latitude and tropical climate conditions is consistent with the hypothesis that the dry MCA in the western US resulted (at least in part) from tropically forced changes in winter NH circulation patterns like those associated with modern La Nina episodes. We examine this hypothesis, and present other analyses showing that the imprint of MCA climate change appears in proxy records from widely distributed regions around the planet, and in many cases is consistent with a cool medieval tropical Pacific. One example, explored with numerical model results, is the suggestion of increased westerlies and warmer winter temperatures over northern Europe during medieval times. An analog technique for the combined use of proxy records and model results, Proxy Surrogate Reconstruction (PSR), is introduced.
160ufTimes Cited:125Cited References Count:151

Ultra-microscale analysis of lipids by 14C-AMS: Assessment and correction for sample processing blanks - Shah, S. R.; Pearson, A. (Radiocarbon, 2007)
id: 501

A unique Yellow River-derived distal subaqueous delta in the Yellow Sea - Yang, Z. S.; Liu, J. P. (Marine Geology, 2007)
Newly acquired high-resolution Chirp sonar profiles reveal a unique Yellow River-derived, alongshore distributed, bidirectional (landward and seaward) across-shelf transported, omega-shaped (Omega") distal subaqueous deltaic lobe deposited around the eastern tip of the Shandong Peninsula in the Yellow Sea. This clinoform deposit directly overlies the postglacial transgressive surface, featured by convex-up seafloor morphology, up to 40 in thick locally. Radiocarbon-14 dates from the underlain pre-Holocene and transgressive sediments indicate this distal lobe has formed since the middle-Holocene highstand under a relatively stable sea level. This along-shelf distributed distal clinoform has been deposited mainly by the resuspended Yellow River sediments carried down by the coastal current, interacting with the local waves, tides and upwelling. Collectively, over the past 7000 years, nearly 30% of the Yellow River-derived sediment has been re-suspended and transported out of the Bohai Sea into the Yellow Sea. Overall, the Yellow River-derived sediment could reach the -80 m water depth in the central South Yellow Sea, about 700 kin from the river mouth; in contrast, a very small fraction of the modem riverine sediment could escape the outer shelf or reach the Okinawa Trough. (c) 2007 Elsevier B.V. All rights reserved.
178psTimes Cited:88Cited References Count:39

Validated age, growth, and mortality estimates of the ocean quahog (Arctica islandica) in the western Atlantic - Kilada, R. W.; Campana, S. E.; Roddick, D. (Ices Journal of Marine Science, 2007)
The age structure of offshore (Sable Bank) and inshore (St Mary's Bay) populations of eastern Canadian ocean quahogs (Arctica islandica), and of a northwestern Iceland population, is investigated. Age estimates for eastern Canadian ocean quahogs were validated through analysis of bomb-produced C-14 in quahog shell growth increments deposited before, during, and after the atmospheric atomic bomb testing periods of the 1950s and 1960s. Delta 14C from shells with presumed birthdates between the late 1950s and 1970s clearly reflects the sharp increase in oceanic radiocarbon attributable to nuclear testing. The results validate our age interpretations of Sable Bank quahogs to an age of 45 y, and support longevity estimates of more than 200 y for the same population. Longevity calculations for the other populations exceeded 60 y. Von Bertalanffy growth parameters were estimated for the three populations, the growth rate of all three was relatively rapid for the first 20 - 30 y of life, but thereafter was very slow. The instantaneous rate of natural mortality (M), calculated using the age-frequency distribution of the unexploited populations, was estimated to be 0.03 and 0.10 for the Sable Bank and St Mary's Bay populations, respectively.
id: 807; 173HY Times Cited:6 Cited References Count:51Y

Variability of major carbon pools in the Mississippi River: importance of tributary inputs and regional land use on carbon and organic matter biogeochemistry - Perkey, D. W.; Bauer, J. E.; Keesee, E. J. (ASLO Aquatic Sciences Meeting, 2007)
id: 484

Variability of the marine ITCZ over the eastern Pacific during the past 30,000 years: Regional perspective and global context - Koutavas, Athanasios; Lynch-Stieglitz, Jean (The Hadley Circulation: Present, Past and Future, 2007)
id: 642

14C methane and DIC in the deep terrestrial subsurface: implications for microbial methanogenesis - Slater, Greg F.; Lippmann-Pipke, Johanna; Moser, Duane P.; Reddy, Christopher M.; Onstott, T. C.; Lacrampe-Couloume, Georges; Lollar, Barbara Sherwood (Geomicrobiology Journal, 2006)
id: 1100

A 5,000-year record of coastal settlement on Anacapa Island, California - Rick, Torben C. (Journal of California and Great Basin Anthropology, 2006)
id: 1088

A 6,000 year old red abalone midden from Otter Point, San Miguel Island, California - Vellanoweth, Rene L.; Rick, Torben C.; Erlandson, Jon M.; Reynolds, Gnessa (North American Archaeologist, 2006)
id: 1090

Abrupt tropical climate change: past and present - Thompson, L. G.; Mosley-Thompson, E.; Brecher, H.; Davis, M.; Leon, B.; Les, D.; Lin, P. N.; Mashiotta, T.; Mountain, K. (Proc Natl Acad Sci U S A, 2006)
Three lines of evidence for abrupt tropical climate change, both past and present, are presented. First, annually and decadally averaged delta(18)O and net mass-balance histories for the last 400 and 2,000 yr, respectively, demonstrate that the current warming at high elevations in the mid- to low latitudes is unprecedented for at least the last 2 millennia. Second, the continuing retreat of most mid- to low-latitude glaciers, many having persisted for thousands of years, signals a recent and abrupt change in the Earth's climate system. Finally, rooted, soft-bodied wetland plants, now exposed along the margins as the Quelccaya ice cap (Peru) retreats, have been radiocarbon dated and, when coupled with other widespread proxy evidence, provide strong evidence for an abrupt mid-Holocene climate event that marked the transition from early Holocene (pre-5,000-yr-B.P.) conditions to cooler, late Holocene (post-5,000-yr-B.P.) conditions. This abrupt event, approximately 5,200 yr ago, was widespread and spatially coherent through much of the tropics and was coincident with structural changes in several civilizations. These three lines of evidence argue that the present warming and associated glacier retreat are unprecedented in some areas for at least 5,200 yr. The ongoing global-scale, rapid retreat of mountain glaciers is not only contributing to global sea-level rise but also threatening freshwater supplies in many of the world's most populous regions.
Thompson, Lonnie GMosley-Thompson, EllenBrecher, HenryDavis, MaryLeon, BlancaLes, DonLin, Ping-NanMashiotta, TracyMountain, KeithengResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.2006/07/04 09:00Proc Natl Acad Sci U S A. 2006 Jul 11;103(28):10536-43. Epub 2006 Jun 30.

Abrupt vegetation changes in tropical South America over the last 120,000 years - Hughen, K. A.; Drenzek, N.; Bice, M.; Eglinton, T. I. (EOS Abstracts, 2006 Ocean Sciences Meeting, 2006)
id: 1078

Absence of 14C in PM2.5 Emissions from Gasohol Combustion in Small Engines - Lewis, C. W.; Volkens, J.; Braddock, J. N.; Crews, W. S.; Lonneman, W. A.; McNichol, A. P. (Aerosol Science and Technology, 2006)
id: 1699

Age mixing among sympatrick bivalves and brachiopods from the Brazilian South Atlantic - Krause R.A, Jr.; Barbour-Wood, S.; Kowalewski, M.; Simoes, M. G.; Kaufman, D.; Romanek, C. S.; Wehmiller, J. R. (Geological Society of America Abstracts with Programs, 2006)
id: 1170

Ahead of the Game: Middle and upper palaeolithic hunting behaviors in the southern Caucasus - Adler, Daniel S.; Bar-Oz, Guy; Belfer-Cohen, Anna; Bar-Yosef, Ofer (Current Anthropology, 2006)
id: 1137

Alkenone-based reconstruction of late-Holocene surface temperature and salinity changes in Lake Qinghai, China - Liu, Z.; Henderson, A. C. G.; Huang, Y. (Geophysical Research Letters, 2006)
id: 1157

Anomalous radiocarbon ages for foraminifera shells - Broecker, W.; Barker, S.; Clark, E.; Hajdas, I.; Bonani, G. (Paleoceanography, 2006)
The causes for discordant radiocarbon results on multiple species of planktonic foraminifera from high-sedimentation-rate marine sediments are investigated. We have documented two causes for these anomalous results. One is the addition of secondary radiocarbon for which we have, to date, only one firm example. It involves an opal-rich sediment. The other is the incorporation of reworked material. Again, we have, to date, only one firm example. It involves a rapidly deposited ocean margin sediment. However, we have three other examples where reworking is the most likely explanation. On the basis of this study it is our conclusion that, where precise radiocarbon dating of high-deposition-rate marine sediment is required, a prerequisite is to demonstrate that concordant ages can be obtained on pairs of fragile and robust planktic shells. For sediment rich in opal, it is advisable to check for secondary calcite by comparing ages obtained on acid-leached samples with those on unleached samples.
id: 980; 041JB Times Cited:7 Cited References Count:7

Anthropogenic markers in the Holocene stratigraphic sequence of the Gulf of Trieste (northern Adriatic Sea) - Covelli, S.; Fontolan, G.; Faganeli, J.; Ogrinc, N. (Marine Geology, 2006)
The Gulf of Trieste is a shallow serni-enclosed marine basin in the northernmost part of the Adriatic Sea that has been affected by the relative rise in sea-level during the Holocene. The sedimentary sequences in three cores, ranging in length from 130 to 320 cm, were investigated through the variability in grain-size parameters, major (Al, Fe, S, N, Ca and Mg) and trace (Ti, Mn, Cr, Ni, Cu, Zn and Hg) elements, organic and inorganic C, delta C-13 and C-14 dating in order to obtain information on paleoenvironmental evolution and the historical development of heavy metal contamination. The potential sources of pollution are: urban sewage from nearly 400,000 inhabitants, industrial effluents, and 500 yr of Hg mining activity in the Idrija region (western Slovenia), located in the upper basin of the Isonzo river, the main freshwater input to the coastal zone. The conventional 14 C ages of bulk sedimentary OC in the basal part of the three cores were 9030 +/- 70 (GTI), 8270 +/- 50 (GT2) and 9160 +/- 120 (GT3) yr BP. An upward increase in highly negative delta C-13(org) values from the core bottoms indicates that lacustrine-swamp conditions in the study area were rapidly followed by a typical marine depositional environment. Cluster analysis performed on the geochemical data for all subsamples of the three cores identifies several groups with a clear stratigraphic meaning. Factor analysis of the data shows related element groups that can be interpreted as being related to, for instance, the natural contribution from alummosilicates and carbonates, from organic matter (peat) and the more recent anthropogenic "impact". Predicted natural linear relationships for metal-Al were obtained from the core subsamples and they can be used as a baseline to evaluate metal enrichments on a regional scale. Results show that more recent sediments in the central sector of the Gulf of Trieste are slightly enriched in Cu (max Enrichment Factor EF=2.1) and Zn (max EF=1.6), and noticeably contaminated by Hg (up to 23.32 mu g g(-1)) to a maximum depth of 90 cm and up to 60 times above the estimated regional background (0.13 mu g g(-1)). The Hg historical trend is well correlated with extraction activity at the Idrija mine, thus allowing indicative sedimentation rate estimation and tentative assessment of the rate of Hg accumulation in bottom sediments (from 1.77 to 31.49 mg m(-2) yr(-1) at the surface). The large inventory of Hg in the core GT2 appeared to be the result of proximity to the fluvial source, which is still active in supplying Hg to the coastal areas and makes the Gulf of Trieste one of the most Hg contaminated area in the whole Mediterranean basin. (c) 2006 Elsevier B.V. All rights reserved.
069seTimes Cited:37Cited References Count:61

The ARCADIA cruise: Assessing long-term changes in tropical reef coral distribution along the Atlantic Continental Margin, southeastern United States - Piniak, G. A. (Project report to NOAA Office of Ocean Exploration, 2006)
id: 1103

Archaeological geology of the central Penobscot River Valley, Maine, USA - Kelley, Alice R. (2006 Philadelphia Annual Meeting, 2006)
id: 1172

Aspartic acid racemization dating of Holocene brachiopods and bivalves from the southern Brazilian shelf, South Atlantic - Barbour-Wood, S. L.; Krause R.A, Jr.; Kowalewski, M.; Wehmiller, J. F.; Simoes, M. G. (Quaternary Research, 2006)
The extent of racemization of aspartic acid (Asp) has been used to estimate the ages of 9 shells of the epifaunal calcitic brachiopod Bouchardia rosea and 9 shells of the infaunal aragonitic bivalve Semele casali. Both taxa were collected concurrently from the same sites at depths of 10 m and 30 m off the coast of Brazil. Asp D/L values show an excellent correlation with radiocarbon age at both sites and for both taxa (r2Site 9 B. rosea = 0.97, r2Site 1 B. rosea = 0.997, r2Site 9 S. casali = 0.9998, r2Site 1 S. casali = 0.93). The Asp ratios plotted against reservoir-corrected AMS radiocarbon ages over the time span of multiple millennia can thus be used to develop reliable and precise geochronologies not only for aragonitic mollusks (widely used for dating previously), but also for calcitic brachiopods. At each collection site, Bouchardia specimens display consistently higher D/L values than specimens of Semele. Thermal differences between sites are also notable and in agreement with theoretical expectations, as extents of racemization for both taxa are greater at the warmer, shallower site than at the cooler, deeper one. In late Holocene marine settings, concurrent time series of aragonitic and calcitic shells can be assembled using Asp racemization dating, and parallel multi-centennial to multi-millennial records can be developed simultaneously for multiple biomineral systems.
id: 1168
Keywords: Amino acid racemization; Aspartic; Bouchardia; Brachiopods; Brazil; Holocene; Mollusks; Radiocarbon dating; Semele; Ubatuba Bay

Atmospheric fossil sources of river and estuarine organic carbon transported to the coastal ocean - Wozniak, A. S.; Bauer, J. E.; Dickhut, R. M.; Keesee, E. J. (Ocean Sciences Meeting, 2006)
id: 1028

Behavioral ecology and the transition from hunting and gathering to Agriculture - Winterhalder, B.; Kennett, D. J. (Behavioral Ecology and the Transition to Agriculture, 2006)
id: 467

Behavioral Ecology and the Transition to Agriculture - Kennett, D. J.; Winterhalder, B. (University of California Press, 2006)
id: 459

Bioreactivity of estuarine dissolved organic matter: A combined geochemical and microbiological approach - McCallister, S. L.; Bauer, J. E.; Canuel, E. A. (Limnology and Oceanography, 2006)
An integrated multidisciplinary study utilizing geochemical and microbial ecological approaches was conducted to characterize the origins, chemical nature, and quantities of dissolved and particulate organic matter (OM) utilized by heterotrophic bacteria in a temperate estuary. C: N, stable isotope (delta C-13), and lipid biomarker analyses revealed differences in the inferred reactivity of autochthonous versus allochthonous OM sources. Isotopic comparison of OM size fractions and bacterial nucleic acids suggests that high-molecular-weight dissolved OM (DOM) is consistently linked to bacterial biomass synthesis along the estuarine salinity gradient. Polyunsaturated fatty acids (as percent of total fatty acids, FA) were a reliable predictor of DOM decomposition in bioassays, thus providing an indicator directly linking DOM reactivity to its composition. Significant positive correlations between FA diagnostic of bacterial sources and lipid biomarker compounds diagnostic of planktonic origin indicate a systematic bacterial response to autochthonous DOM sources along the estuarine continuum. These findings further suggest that, although the geochemical signature of algal-derived OM in the dissolved phase may appear quantitatively insignificant, this fraction may nevertheless represent a principal source of bioreactive OM to heterotrophic bacteria in estuarine waters.
040scTimes Cited:39 Cited References Count:32
Keywords: acids; bacteria; bay; bioavailability; carbon-isotope analysis; extraction; food webs; sediments

Bomb dating and age validation using the spines of spiny dogfish (Squalus acanthias) - Campana, S. E.; Jones, C.; McFarlane, G. A.; Myklevoll, S. (Environmental Biology of Fishes, 2006)
Bomb radiocarbon has previously been used to validate the age of large pelagic sharks based on incorporation into vertebrae. However, not all sharks produce interpretable vertebral growth bands. Here we report the first application of bomb radiocarbon as an age validation method based on date-specific incorporation into spine enamel. Our results indicate that the dorsal spines of spiny dogfish, Squalus acanthias, recorded and preserved a bomb radiocarbon pulse in growth bands formed during the 1960s with a timing which was very similar to that of marine carbonates. Using radiocarbon assays of spine growth bands known to have formed in the 1960s and 1970s as a dated marker, we confirm the validity of spine enamel growth band counts as accurate annual age indicators to an age of at least 45 year. Radiocarbon incorporation into northeast Atlantic dogfish spines occurred in similar years as those in the northwest Atlantic and northeast Pacific, although the amount of radiocarbon differed in keeping with the radiocarbon content of the different water masses. Published reports suggesting that Pacific dogfish are longer lived and slower growing than their Atlantic counterparts appear to be correct, and are not due to errors in interpreting the spine growth bands. Radiocarbon assays of fin spine enamel appears to be well suited to the age validation of sharks with fin spines which inhabit the upper 200 m of the ocean.
107bsTimes Cited:38Cited References Count:25

Bomb radiocarbon dating calibrates beluga (Delphinapterus leucas) age estimates - Stewart, R. E. A.; Campana, S. E.; Jones, C. M.; Stewart, B. E. (Canadian Journal of Zoology-Revue Canadienne De Zoologie, 2006)
The ages of many mammals are estimated by counting growth layers in tooth sections, yet validation of age estimation techniques using free-ranging mammals has been problematic. Contrary to age estimates for most other animals in which it is assumed that one bipartite growth increment forms annually, beluga whale (Delphinapterus leucas (Pallas, 1776)) age estimates have been calculated assuming that two growth layer groups (GLGs) form each year. Here we report the age validation for belugas based on date-specific incorporation of atomic bomb radiocarbon into tooth GLGs. Radiocarbon assays of dentinal layers formed in belugas harvested between 1895 and 2001 indicated that radiocarbon from atmospheric testing of nuclear weapons was incorporated into growing teeth and retained for the remaining life of the animal. Comparison of age determined by bomb radiocarbon with age determined by GLG counts indicated that GLGs form annually, not semiannually, and provide an accurate indicator of age for belugas up to at least 60 years old. Radiocarbon signatures of belugas were temporally and metabolically stable and were apparently derived more from the radiocarbon content of their prey than from water. Our understanding of many facets of beluga population dynamics is altered by the finding that this species lives twice as long as previously thought.
140vdTimes Cited:51Cited References Count:73

Calibration and natural variability of skeletal stable carbon isotopes in the Pacific sclerosponge acanthocheatetes wellsi: implications for reconstructing CO2 uptake in coastal tropical environments - Grottoli, A. G. (Ocean Sciences Meeting, 2006)
id: 1133

Carbon flow in salt marsh sediments: Natural-level radiocarbon as a tracer for incorporation of petroleum-derived carbon into bacteria - Wakeham, S. G.; McNichol, A. P.; Kostka, J.; Pease, T. K. (Geochim. Cosmochim. Acta, 2006)
id: 762

Carbon flux in seagrass ecosystems - Mateo, M. A.; Cebrián, J.; Dunton, K.; Mutchler, T. (Seagrasses: Biology, Ecology and Conservation., 2006)
id: 2006

Carbon isotopic constraints on relict organic carbon contributions to Ross Sea sediments - Ohkouchi, N.; Eglinton, T. I. (G-cubed, 2006)
id: 759

Carbon remineralization in the Amazon-Guianas tropical mobile mudbelt: A sedimentary incinerator - Aller, R. C.; Blair, N. E. (Continental Shelf Research, 2006)
The Amazon River spawns a vast mobile mudbelt extending similar to 1600 km from the equator to the Orinoco delta. Deposits along the Amazon-Guianas coastline are characterized by some of the highest C-org remineralization rates reported for estuarine, deltaic, or shelf deposits, however, paradoxically, except where stabilized by mangroves or intertidal algal mats, they are usually suboxic and nonsulfidic. A combination of tides, wind-driven waves, and coastal currents forms massive fluid muds and mobile surface sediment layers similar to 0.5-2m, thick which are dynamically refluxed and frequently reoxidized. Overall, the seabed functions as a periodically mixed batch reactor, efficiently remineralizing organic matter in a gigantic sedimentary incinerator of global importance. Amazon River material entering the head of this dynamic dispersal system carries an initial terrestrial sedimentary Corg loading of similar to 0.7 mg Cm-2 particle surface area. Total C-org loading is lowered to similar to 0.2 mg Cm-2 in the proximal delta topset, similar to 60-70% of which remains of terrestrial origin. Loading decreases further to 0.12-0.14 mg Cm-2 (similar to 60% terrestrial) in mudbanks similar to 600 km downdrift along French Guiana, values comparable to those found in the oligotrophic deepsea. DOC/Sigma CO2 ratios in pore waters of French Guiana mudbanks indicate that > 90% of metabolized organic substrates are completely oxidized. Within the Amazon delta topset at the head of the dispersal system, both terrestrial and marine organic matter contribute substantially to early diagenetic remineralization, although reactive marine substrate dominates (similar to 60-70%). The conditional rate constant for terrestrial C-org in the delta topset is similar to 0.2 a(-1). As sedimentary C-org is depleted during transit, marine sources become virtually the exclusive substrate for remineralization except very near the mangrove shoreline. The delta C-13 and Delta C-14 values of pore water Sigma CO2 in mudbanks demonstrate that the primary source of remineralized organic matter within similar to 1 km of shore is a small quantity of bomb signature marine plankton (+ 80 parts per thousand). Thus, fresh marine organic material is constantly entrained into mobile deposits and increasingly drives early diagenetic reactions along the transit path. Relatively refractory terrestrial C-org is lost more slowly but steadily during sedimentary refluxing and suboxic diagenesis. Amazon Fan deposits formed during low sea level stand largely bypassed this suboxic sedimentary incinerator and stored material with up to similar to 3X the modern high stand inner shelf C-org load (Keil et al., 1997b. Proceedings of the Ocean Drilling Program, Scientific Results. Vol. 155. pp. 531-537). Sedimentary dynamics, including frequency and magnitude of remobilization, and the nature of dispersal systems are clearly key controls on diagenetic processes, biogeochemical cycling, and global C storage along the continental margins. (c) 2006 Elsevier Ltd. All rights reserved.
id: 979; 109UE Times Cited:28 Cited References Count:93

Carbon stable isotope composition of DNA isolated from an incipient paleosol - Jahren, A. H.; Kelm, K.; Wendland, B.; Petersen, G.; Seberg, O. (Geology, 2006)
We determined the carbon isotope (delta(13)C) value of double-stranded DNA (dsDNA) isolated from the organic horizons of a Delaware soil that is actively being covered by an encroaching sand dune. The soil belongs to a Nymphaea odorata Ait. (water lily) wetland, and we regard its active acquisition of a thick (similar to 24 cm) surface mantle to embody the process of palleopedogenesis; therefore, we have termed it an "incipient paleosol." In this study, we compared the delta(13)C value of paleosoll dsDNA to the bulk delta(13)C value of N. odorata, as well as to the delta(13)C value of plants that had colonized the surface mantle. The isotopic offset between palleosol delta(13)C(dsDNA) and N. odorata delta(13)Ca(tissue) was identical to the relationship between delta(13)C(dsDNA) and delta(13)C(tissue) for tracheophytes, which we had previously determined. In contrast, the isotopic offset between paleosol delta(13)C(dsDNA) and the delta(13)C(tissue) of plants colonizing the surface mantle differed from this relationship by as much as 41%. Similarly, the delta(13)C value of bulk palleosoll organic matter was extremely heterogeneous and varied across 6%. All palleosol DNA pollymerase chain reaction (PCR) products produced clear, sharp, 350 base-pair (bp) fragments of rbcL, a gene shared by all photosynthetic organisms. These results open the exciting possibility that stable isotope analysis of dsDNA isolated from palleosol organic matter can be used to infer the delta(13)C value of the plant that dominated the nucleic acid contribution.
039nnTimes Cited:4Cited References Count:19

Characterizing biodegration and microbial metabolic activity in situ using natural abundance, molecular-level 14C analysis - Slater, G. F.; Nelson, R. K.; Kile, B. M.; Reddy, C. M. (Organic Geochemistry, 2006)
id: 614

Chemical composition of the graphitic black carbon fraction in riverine and marine sediments at submicron scales using carbon X-ray spectromicroscopy - Haberstroh, P. R.; Brandes, J. A.; Gelinas, Y.; Dickens, A. F.; Wirick, S. (Geochimica et Cosmochimica Acta, 2006)
id: 1703

The Chilean Fjords - Lange, C. B.; Pantoja, S.; Sepulveda, J.; Rebolledo, L.; Smith-Wellner, J.; Anderson, J. B.; Hughen, K. A. (Abstracts, EGU General Assembly, 2006)
id: 561

Chronologie des variations climatiques repides pendant la derniere periode glaciaire - Bard, E.; Rostek, F.; G, Menot-Combes (Comptes Rendus de l'Academie des Sciences, 2006)
id: 398

A climatic driver for abrupt mid-Holocene vegetation dynamics and the hemlock decline in New England - Foster, D. R.; Oswald, W. W.; Faison, E. K.; Doughty, E. D.; Hansen, B. C. (Ecology, 2006)
The mid-Holocene decline of eastern hemlock is widely viewed as the sole prehistorical example of an insect- or pathogen-mediated collapse of a North American tree species and has been extensively studied for insights into pest-host dynamics and the consequences to terrestrial and aquatic ecosystems of dominant-species removal. We report paleoecological evidence implicating climate as a major driver of this episode. Data drawn from sites across a gradient in hemlock abundance from dominant to absent demonstrate: a synchronous, dramatic decline in a contrasting taxon (oak); changes in lake sediments and aquatic taxa indicating low water levels; and one or more intervals of intense drought at regional to continental scales. These results, which accord well with emerging climate reconstructions, challenge the interpretation of a biotically driven hemlock decline and highlight the potential for climate change to generate major, abrupt dynamics in forest ecosystems.
Foster, David ROswald, W Wyatt Faison, Edward K Doughty, Elaine D Hansen, Barbara C S eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2007/01/26 09:00 Ecology. 2006 Dec;87(12):2959-66.
Keywords: *Climate; *Ecosystem; Geologic Sediments; new england; Tsuga/*physiology

Coherence between solar activity and the East Asian winter monsoon variability in the past 8000 years from Yangtze River-derived mud in the East China Sea - Xiao, S. B.; Li, A. C.; Liu, J. P.; Chen, M. H.; Xie, Q.; Jiang, F. Q.; Li, T. G.; Xiang, R.; Chen, Z. (Palaeogeography Palaeoclimatology Palaeoecology, 2006)
AMS(14)C dating and grain-size analysis for Core PC-6, located in the middle of a mud area on the inner shelf of the East China Sea (ECS), were used to rebuild the Holocene history of the East Asian winter monsoon (EAWM). The 7.5-m core recorded the history of environmental changes during the postglacial transgression. The core's mud section (the upper 450 cm) has been formed mainly by suspended sediment delivered from the Yangtze River mouth by the ECS Winter Coastal Current (ECSWCC) since 7.6 kyr BP. Using a mathematical method called "grain size vs. standard deviatioW', we can divide the Core PC-6's grain-size distribution into two populations at about 28 mu m. The fine population (< 28 mu m) is considered to be transported by the ECSWCC as suspended loads. Content of the fine population changes little and represents a stable sedimentary environment in accord with the present situation. Thus, variation of mean grain-size from the fine population would reflect the strength of ECSWCC, which is mainly controlled by the East Asian winter monsoon.Abrupt increasing mean grain size in the mud section is inferred to be transported by sudden strengthened ECSWCC, which was caused by the strengthened EAWM. Thus, the high resolution mean grain-size variation might serve as a proxy for reconstruction of the EAWM. A good correlation between sunspot change and the mean grain-size of suspended fine population suggests that one of the primary controls on centennial- to decadal-scale changes of the EAWM in the past 8 ka is the variations of sun irradiance, i.e., the EAWM will increase in intensity when the number of sunspots decreases. Spectral analyses of the mean grain-size time series of Core PC-6 show statistically significant periodicities centering on 2463, 1368, 128, 106, 100, 88-91, 7678, and 70-72 years. The EAWM and the East Asian summer monsoon (EASM) agree with each other well on these cycles, and the East Asian Monsoon (EAM) and the Indian Monsoon also share in concurrent cycles in Holocene, which are in accord with the changes of the sun irradiance. (c) 2005 Elsevier B.V. All rights reserved.
072kpTimes Cited:52Cited References Count:61

Continental slope sediment delivery and storage on an active margin: the Waipaoa Margin example - Alexander, C.; Walsh, J. P.; Sumner, B.; Orpin, A. R.; Kuehl, S. A. (2006 AGU meeting, 2006)
id: 1121

Corals and sclerosponges as geochemical recorders of past climate change - Grottoli, A. G. (AAPG/SEMP Course 19, 2006)
id: 1134

Cosmogenic isotope 14C: production and carbon cycle - Hughen, K. A. (PAGES Newsletter, 2006)
id: 1075

Cross-shelf lateral transport in the Benguela Upwelling System: Aging of marine organic matter in the benthic boundary layer - Mollenhauer, Gesine; Inthorn, Maik; Zabel, Matthias; Damste, Jaap Sinninghe; Eglinton, Timothy I. (Ocean Sciences Meeting, 2006)
id: 545

Deglaciation and Holocene climate change in the western Peruvian Andes - Weng, C. Y.; Bush, M. B.; Curtis, J. H.; Kolata, A. L.; Dillehay, T. D.; Binford, M. W. (Quaternary Research, 2006)
Pollen, charcoal, magnetic susceptibility, and bulk density data provide the first paleoecological record spanning the last 33,000 years from the western cordillera of the Peruvian Andes. Sparse super-puna vegetation existed before 30,000 cat yr B.P. around Lake Compuerta (3950 m elevation), prior to a sedimentary hiatus that lasted until c. 16,200 cat yr B.P. When sedimentation resumed, a glacial foreland or super-puna flora is represented in which Polylepis was a significant element. Glacial outwash, marked by high sedimentary magnetic susceptibility, increased from c. 16,200 cat yr B.P. and reached a peak at c. 13,200 cat yr B.P. Between c. 12,500 cat yr B.P. and 10,000 cat yr B.P., magnetic susceptibility was reduced. Vegetation shifts suggest a cool dry time, consistent with regional descriptions of the Younger Dryas event. Deglaciation resumes by 10,000 cat yr B.P. and the last ice is lost from the catchnient at similar to 7500 cat yr B.P. During the early Holocene warm and dry period between 10,000 and 5500 cat yr B.P., Alnus expanded in downslope forests. Alnus declined in abundance at 5500 cat yr B.P. when wetter and cooler conditions returned and human activity intensified. Maize (Zea mays) pollen first occurred in the core at similar to 2600 cat yr B.P., indicating a minimum age for local agriculture. An increase in Alnus pollen abundance at similar to 1000 cat yr B.P. could be due to human activity or perhaps due to a regional climate change associated with cultural turnover elsewhere in the Andes at this time. (c) 2006 University of Washington. All rights reserved.
058upTimes Cited:27Cited References Count:55

Depth limit for reef building corals in the Au'au Channel, S. E. Hawaii - Grigg, R. W. (Coral Reefs, 2006)
id: 1085

Determination of carbon dioxide, hydrographic and chemical parameters during the R/V Nathaniel B. Palmer cruise in the southern Indian Ocean (WOCE section S041) - Takahashi, R.; Millero, F. J.; Key, R. M.; Chipman, D.; Peltola, E.; Rubin, S.; Sweeney, C.; Sutherland, S. (2006)
id: 1053

Diageneitc and sedimentological controls on the composition of organic matter preserved in California Borderland Basin sediments - Mollenhauer, Gesine; Eglinton, Timothy I. (Limnology & Oceanography Paleoceanography, submitted, 2006)
id: 1705

Dissolved and particulate organic matter source-age characterization in the upper and lower Chesapeake Bay: A combined isotope and biochemical approach - Loh, A. N.; Bauer, J. E.; Canuel, E. A. (Limnology and Oceanography, 2006)
In order to characterize the sources and ages of organic matter contributing to river and estuarine outflow waters, the present study investigated Delta C-14 and delta C-13 signatures of the major operationally defined biochemical classes of ultrafiltered dissolved organic matter (UDOM) in conjunction with lipid biomarker and elemental compositions of UDOM and suspended particulate organic matter (POM) in the Chesapeake Bay. Freshwater (Susquehanna River) UDOM was dominated by a molecularly uncharacterized (MUC) fraction, followed by total carbohydrate (TCHO), total hydrolysable amino acid (THAA) and total lipid (TLE) components. In contrast, UDOM at the bay mouth (salinity similar to 22-24) was comprised mainly of TCHO, followed by MUC, THAA, and TLE. The Delta C-14 and delta C-13 signatures of both UDOM and its major biochemical classes indicate that Susquehanna DOM is derived in part from old allochthonous terrestrial sources, whereas young marine sources dominate at the bay mouth. In contrast to the other biochemical classes, lipophilic DOM at both sites was very old (similar to 5,000-7,000 years B.P.). In addition, factor analysis of lipid biomarker compounds revealed unique signatures for the UDOM and POM pools that imply disparate source and/or recycling properties as well as potential influences due to physical partitioning. Lipid biomarker compounds showed that although autochthonous riverine/estuarine sources dominated both the UDOM and POM pools, terrigenous lipids were elevated in the Susquehanna during high flow conditions. The presence of lipid biomarkers diagnostic of "fresh" algal material in UDOM further suggested its greater reactivity than POM. The observed biochemical and lipid biomarker compositions and isotopic signatures of UDOM and POM are consistent with previous findings suggesting that these two major organic matter pools have dissimilar reactivities and cycling times, and they derive from comparatively unique source-age materials in rivers and estuaries.
045nhTimes Cited:24 Cited References Count:37
Keywords: biomarkers; carbon; delta-c-13; lipid-composition; ocean; radiocarbon; river; san-francisco; sediments; variability

Do inland waters matter in the regional or global C balance: A review and turorial - Cole, J. J. (American Society of Limnology and Oceanography Summer Meeting, 2006)
id: 479

The early history of Long Island Sound - Varekamp, J. C.; Thomas, E. (The last deglaciation, 2006)
id: 1185

Early Holocene land use and subsistence on eastern Santa Rosa Island, California - Rick, T. C.; Kennett, D. J.; Erlandson, J. M. (Current Research in the Pleistocene, 2006)
id: 1021

Early holocene openlands in southern New England - Faison, E. K.; Foster, D. R.; Oswald, W. W.; Hansen, B. C.; Doughty, E. (Ecology, 2006)
The pre-historical vegetation structure in temperate forest regions is much debated among European and North American ecologists and conservationists. Frans Vera's recent hypothesis that large mammals created mosaics of forest and openland vegetation in both regions throughout the Holocene has been particularly controversial and has provoked new approaches to conservation management. Thirty years earlier, American paleoecologists Herb Wright and Margaret Davis debated whether abundant ragweed pollen at Rogers Lake, Connecticut at 9500 yr BP signified local forest openings or long-distance transport of pollen from Midwestern prairies. Using new pollen records from Harvard Forest and the North American Pollen Database, we address this question and offer insights to the openland discussion. Ragweed and other forbs exceed 3.5% at five sites in a restricted area of southern New England between 10,100 and 7700 yr BP. Strong evidence suggests this pollen originated from the landscapes surrounding these sites (supporting Davis), as ragweed pollen percentages do not increase with longitude from New England to the Midwest. Ragweed pollen percentages are also unrelated to basin size and therefore unrelated to the proportion of extraregional pollen in New England. High forbs values were associated with increases in oak, decreases in white pine, and relatively high charcoal values. Modern pollen records with similar forb and tree percentages occur along the Prairie Peninsula region of the Upper Midwest. However, the closest analogue to the southern New England early Holocene assemblages comes from Massachusetts' Walden Pond in the early 18th century. These results and the affiliation of ragweed for open, disturbed habitats suggest that oak-pine forests with large openings persisted for over 2000 years due to dry conditions and perhaps increased fire frequency. This conclusion is corroborated by independent lake level and climate reconstructions. Because these early Holocene openlands have no detectable analogue in New England for the past 7000 years before European settlement, we suggest that all important openlands today are almost exclusively a legacy of Colonial agriculture and should be managed accordingly. Nonetheless, our results may have implications for forest dynamics accompanying projected climate change to more arid conditions in New England over the next century.
Faison, E KFoster, D R Oswald, W W Hansen, B C S Doughty, E eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2006/11/09 09:00 Ecology. 2006 Oct;87(10):2537-47.
Keywords: *Ambrosia; *Pollen; Ecosystem; Geography; new england; Paleontology

Effects of differential degradation of marine organic compounds on preserved radiocarbon ages and biomarker-based SST reconstructions, Poster - Mollenhauer, Gesine; Sinninghe, Jaap S.; Eglinton, Timothy I. (EGU General Assembly, 2006)
id: 1072

Elemental and isotopic characterization of organic matter and carbon in the South Atlantic bight, a net heterotrophic ocean margin - De Alteris, J.; Bauer, J. E.; Perkey, D. W.; Keesee, E. J.; Cai, W. J. (Ocean Sciences Meeting, 2006)
id: 481

Environmental impact on LIS from the early colonial society - Thomas, E.; Varekamp, J. C. (Long Island Sound Research Conference, 2006)
id: 750

Evaluating the Holocene c=dynamics of oceanographic processes in the Southeast Brazilian Bight using accumulations of calcitic and aragonitic shells - Krause R.A, Jr.; Barbour-Wood, S.; Kowalewski, M.; Simoes, M. G.; Kaufman, D.; Romanek, C. S.; Wehmiller, J. F. (American Geophysical Union, Fall Meeting, 2006)
PP43A-01233
id: 716

Evaluation of ageing accuracy of bocaccio (Sebastes paucispinis) rockfish using bomb radiocarbon - Piner, K. R.; Wallace, J. R.; Hamel, O. S.; Mikus, R. (Fisheries Research, 2006)
The accuracy of bocaccio rockfish age assignments was evaluated using radiocarbon levels measured in otoliths collected from fish taken off the coast of Washington state (USA). Otoliths from 24 randomly selected fish with estimated birth years from 1950 to 1977, based on paired otolith age estimates, were used in this study. The level of radiocarbon measured in the core of each otolith was compared to a reference radiocarbon chronology based on radiocarbon levels in otoliths from known-age Pacific halibut. The degree of graphical phase correspondence between the two series was sufficient to support the hypothesis that the annuli were formed yearly in bocaccio otoliths but were somewhat difficult to identify. Statistical analysis of the ageing errors could not document a bias in production ageing of bocaccio. Pre-bomb radiocarbon levels measured in otolith cores confirm that bocaccio can live at least 37 years. Published by Elsevier B.V.
011qtTimes Cited:10Cited References Count:40

An evolutionary model for the origins of agriculture on the Pacific coast of southern Mexico - Kennett, D. J.; Voorhies, B.; Martorana, D. (Behavioral Ecology and the Transition to Agriculture, 2006)
id: 465

Flooding of Bering Strait and Holocene climate in the Chukchi Sea - Keigwin, L. D.; Donnelly, J. P.; Cook, M. S.; Driscoll, N. W.; Brigham-Grette, J. (Geology, 2006)
id: 678

Foraminiferal and sedimentary record of Late Holocene barrier island evolution, Pea Island, North Carolina: The role of storm overwash, inlet processes, and anthropogenic modification - Culver, S. J.; Ames, D. V.; Corbett, D. R.; Mallinson, D. J.; Riggs, S. R.; Smith, C. G.; Vance, D. J. (Journal of Coastal Research, 2006)
Foraminiferal and sedimentary data, supplemented with geochemical dating and ground-penetrating radar transects, show that the barrier island at Pea Island National Wildlife Refuge just north of Rodanthe, North Carolina, has been dominated by a combination of inlet and overwash processes for at least 1000 years. The stratigraphic record of several vibracores does not preserve every, or even many, overwash events but, instead, is characterized by three to four fining-upward sequences. The last three commence with overwash sand or gravel that is overlain by a variety of finer-grained estuarine, inlet, and marsh deposits. The dynamic nature of this segment of the Outer Banks was muted in the late 1930s by construction of artificial barrier dune ridges, extensive planting of grass and shrubs, and construction of Highway 12 in 1953. Subsequently, the road and barrier dune ridge were rebuilt and relocated several times following storm events.
070tkTimes Cited:19Cited References Count:33

The formation history of Long Island Sound - Varekamp, J. C.; Thomas, E.; Lewis, R.; Altabet, M. (Long Island Sound Research Conference, 2006)
id: 1187

Geomorphologic controls on the age of particulate organic carbon from small mountainous and upland rivers - Leithold, E. L.; Blair, N. E.; Perkey, D. W. (Global Biogeochemical Cycles, 2006)
To assess the role that erosion processes play in governing the character of particulate organic carbon (POC) discharged from small mountainous and upland rivers, a suite of watersheds from Oregon, California, and New Zealand was investigated. The rivers share similar geology, tectonic setting, and climate, but have sediment yields that range over 3 orders of magnitude. The (14)C age of the POC loads is highly correlated with sediment yield. Carbon isotope mass balances reveal that the rivers carry bimodal mixtures of modern-plant-and ancient-rock-derived OC. At lower yields, modern plant OC dominates the material delivered to the river by sheetwash and shallow landsliding. With increasing yield, a progressively larger part of the POC is contributed directly from bedrock erosion via deep gully incision. Our results support the inference that active margin watersheds are important sources of aged POC to the ocean.
082xbTimes Cited:78Cited References Count:77
Keywords: 14C; kerogen recycling; particulate organic carbon

A geostatistical approach to watershed sources of aged riverine organic matter to the Hudson-Mohawk River system - Longworth, B. E.; Petsch, S. T.; Raymond, P. A.; Bauer, J. E. (American Geophysical Union Fall Meeting, 2006)
id: 483

Great earthquakes of variable magnitude at the Cascadia subduction zone - Nelson, A. R.; Kelsey, H. M.; Witter, R. C. (Quaternary Research, 2006)
Comparison of histories of great earthquakes and accompanying tsunamis at eight coastal sites suggests plate-boundary ruptures of varying length, implying great earthquakes of variable magnitude at the Cascadia subduction zone. Inference of rupture length relies on degree of overlap on radiocarbon age ranges for earthquakes and tsunamis, and relative amounts of coseismic subsidence and heights of tsunamis. Written records of a tsunami in Japan provide the most conclusive evidence for rupture of much of the plate boundary during the earthquake of 26 January 1700. Cascadia stratigraphic evidence dating from about 1600 cal yr B.P., similar to that for the 1700 earthquake, implies a similarly long rupture with substantial subsidence and a high tsunami. Correlations are consistent with other long ruptures about 1350 cal yr B.P., 2500 cal yr B.P., 3400 cal yr B.P., 3800 cal yr B.P., 4400 cal yr B.P., and 4900 cal yr B.P. A rupture about 700-1100 cal yr B.P. was limited to the northern and central parts of the subduction zone, and a northern rupture about 2900 cal yr B.P. may have been similarly limited. Times of probable short ruptures in southern Cascadia include about I 100 cal yr B.P., 1700 cal yr B.P., 3200 cal yr B.P., 4200 cal yr B.P., 4600 cal yr B.P., and 4700 cal yr B.P. Rupture patterns suggest that the plate boundary in northern Cascadia usually breaks in long ruptures during the greatest earthquakes. Ruptures in southernmost Cascadia vary in length and recurrence intervals more than ruptures in northern Cascadia. Published by University of Washington.
046pgTimes Cited:70Cited References Count:66

Gulf Stream density structure and transport during the past millennium - Lund, D. C.; Lynch-Stieglitz, J.; Curry, W. B. (Nature, 2006)
The Gulf Stream transports approximately 31 Sv (1 Sv = 10(6) m(3) s(-1)) of water and 1.3 x 10(15) W of heat into the North Atlantic ocean. The possibility of abrupt changes in Gulf Stream heat transport is one of the key uncertainties in predictions of climate change for the coming centuries. Given the limited length of the instrumental record, our knowledge of Gulf Stream behaviour on long timescales must rely heavily on information from geologic archives. Here we use foraminifera from a suite of high-resolution sediment cores in the Florida Straits to show that the cross-current density gradient and vertical current shear of the Gulf Stream were systematically lower during the Little Ice Age (ad approximately 1200 to 1850). We also estimate that Little Ice Age volume transport was ten per cent weaker than today's. The timing of reduced flow is consistent with temperature minima in several palaeoclimate records, implying that diminished oceanic heat transport may have contributed to Little Ice Age cooling in the North Atlantic. The interval of low flow also coincides with anomalously high Gulf Stream surface salinity, suggesting a tight linkage between the Atlantic Ocean circulation and hydrologic cycle during the past millennium.
Lund, David CLynch-Stieglitz, JeanCurry, William BengResearch Support, U.S. Gov't, Non-P.H.S.England2006/12/01 09:00Nature. 2006 Nov 30;444(7119):601-4.

The historical fur trade and climate change - Varekamp, J. C. (EOS, 2006)
id: 725

Holocene elephant seal distribution implies warmer-than-present climate in the Ross Sea - Hall, B. L.; Hoelzel, A. R.; Baroni, C.; Denton, G. H.; Le Boeuf, B. J.; Overturf, B.; Topf, A. L. (Proceedings of the National Academy of Sciences of the United States of America, 2006)
We show that southern elephant seal (Mirounga leonina) colonies existed proximate to the Ross Ice Shelf during the Holocene, well south of their core sub-Antarctic breeding and molting grounds. We propose that this was due to warming (including a previously unrecognized period from approximate to 1,100 to 2,300 C-14 yr B.P.) that decreased coastal sea ice and allowed penetration of warmer-than-present climate conditions into the Ross Embayment. If, as proposed in the literature, the ice shelf survived this period, it would have been exposed to environments substantially warmer than present.
id: 1918; PT: J; NR: 25; TC: 14; J9: P NATL ACAD SCI USA; PG: 5; GA: 064DM; UT: WOS:000239069400013

Hudson River Paleoecology from Marshes - Peteet, D.; Pederson, D.; Kurdyla, D.; Guilderson, T. (Hudson River Fishes and their Environment., 2006)
id: 1165

Human Impacts on Rapa, French Polynesia - Kennett, D. J.; Anderson, A.; Prebble, M.; Conte, E.; Southon, J. (Antiquity, 2006)
id: 1020

The ideal free distribution, food production, and the colonization of Oceania - Kennett, D. J.; Anderson, A.; Winterhalder, B. (Behavioral Ecology and the Transition to Agriculture, 2006)
id: 466

Incorporation of aged dissolved organic carbon (DOC) onto oceanic particulate organic carbon (POC): an experimental approach using carbon isotopes - Hwang, J.; Druffel, E. R. M.; Bauer, J. E. (Marine Chemistry, 2006)
id: 682

The influence of seasonal precipitation and temperature regimes on lake levels in the northeastern United States during the Holocene - Shuman, B.; Donnelly, J. P. (Quaternary Research, 2006)
AMS-dated sediment cores combined with ground-penetrating radar profiles from two lakes in southeastern Massachusetts demonstrate that regional water levels rose and fell multiple times during the Holocene when the known climatic controls (i.e., ice extent and insolation) underwent unidirectional changes. The lakes were lowest between 10,000 and 9000 and between 5500 and 3000 cat yr B.P. Using a heuristic moisture-budget model, we explore the hypothesis that changes in seasonal precipitation regimes, driven by monotonic trends in ice extent and insolation, plausibly explain the multiple lake-level changes. Simulated lake levels resulting from low summer precipitation rates match observed low lake levels of 10,000-9000 cat yr B.P., whereas a model experiment that simply shifts the seasonality of the modem Massachusetts precipitation regime (i.e., moving the peak monthly precipitation from winter to summer) produces levels that are similar to 2 in lower than today as observed for 5500-3000 cat yr BY, The influence of the Laurentide ice sheet could explain dry summers before ca. 8000 cat yr B.P. A later shift from a summer-wet to a winter-wet moisture-balance regime could have resulted from insolation-driven changes in the influence of the Bermuda subtropical high. Temperature changes probably further modified lake levels by affecting snowmelt and transpiration. (c) 2005 Published by University of Washington.
003pfTimes Cited:40Cited References Count:48

IntCal04 Update: The future of radiocarbon calibration - Reimer, P.; Hughen, K. A. (PAGES Newsletter, 2006)
id: 557

Intra-shell radiocarbon variability in marine mollusks - Culleton, B. J.; Kennett, D. J.; Ingram, B. L.; Erlandson, J. M.; Southon, J. (Radiocarbon, 2006)
id: 1019

Intrinsic bacterial biodegradation of petroleum contamination demonstrated in situ using natural abundance, molecular-level 14C analysis - Slater, Gregory F.; Nelson, Robert K.; Kile, Brian M.; Reddy, Christopher M. (Organic Geochemistry, 2006)
id: 594

Investigating the temperoral relationship between the synthesis and sediment incorporation of vascular plant biomarkers using molecular level 14C analysis - Drenzek, N.; Poussart, P.; Lima, A. L.; Hughens, K.; Reddy, C.; Eglinton, T. I. (EOS Abstracts, 2006 AGU Ocean Sciences Meeting, 2006)
id: 562

Las morenas de Punta Banderas, Lago Argentino - Strelin, J.; Denton, G. H. (Proceedings of the XVI Congreso Geologico Argentino, 2006)
id: 707

Late Holocene climate variability of South America reconstructed by a multi-proxy analysis of Chilean fjord sediments - Bertrand, S.; Hughen, K. A.; Giosan, L.; Tierney, J.; Sepfulveda, J.; Pantoja, S. (Abstracts, EGU General Assembly, 2006)
id: 560

The late Pleistocene-Holocene history of Long Island Sound - Varekamp, J. C.; Thomas, E.; Groner, M. (LISRC proceedings, 2006)
id: 1175

Late Quaternary sea-level lowstand environments and chronology of outer Saco Bay, Maine - Lee, K. (University of Maine, 2006)

Late-Quaternary paleoenvironmental evolution of Lesina lagoon (sosuthern Italy) from subsurface data - Lucchi, Marianna Ricci; Fiorini, Flavia; Colalongo, Maria Luisa; Curzi, Pietro Vittorio (Sedimentary Geology, 2006)
Integrated sedimentological and micropaleontological (foraminifers and ostracods) analyses of two 55 m long borehole cores (S3 and S4) drilled in the subsurface of Lesina lagoon (Gargano promontory—Italy) has yielded a facies distribution characteristic of alluvial, coastal and shallow-marine sediments. Stratigraphic correlation between the two cores, based on strong similarity in facies distribution and AMS radiocarbon dates, indicates a Late Pleistocene to Holocene age of the sedimentary succession. Two main depositional sequences were deposited during the last 60-ky. These sequences display poor preservation of lowstand deposits and record two major transgressive pulses and subsequent sea-level highstands. The older sequence, unconformably overlying a pedogenized alluvial unit, consists of paralic and marine units (dated by AMS radiocarbon at about 45–50,000 years BP) that represent the landward migration of a barrier-lagoon system. These units are separated by a ravinement surface (RS1). Above these tansgressive deposits, highstand deposition is characterised by progradation of the coastal sediments. The younger sequence, overlying an unconformity of tectonic origin, is a 10 m-thick sedimentary body, consisting of fluvial channel sediments overlain by transgressive–regressive deposits of Holocene age. A ravinement surface (RS2), truncating the transgressive (lagoonal and back-barrier) deposits in core S4, indicates shoreface retreat and landward migration of the barrier/lagoon system. The overlying beach, lagoon and alluvial deposits are the result of mid-Holocene highstand sedimentation and coastal progradation.
id: 1060
Keywords: Foraminifers; Late Quaternary; Lesina lagoon (Italy); Ostracods; Sea-level changes

Long Island Sound - a human dominated estuary - Varekamp, J. C.; Thomas, E. (AGU spring meeting, 2006, 2006)
id: 1186

MAGic: A Phanerozoic model for the geochemical cycling of major rock-forming components - Arvidson, R. S.; Mackenzie, F. T.; Guidry, M. (American Journal of Science, 2006)
A dynamical model (MAGic) is presented that describes the elemental cycling of sedimentary materials involving sodium, potassium, calcium, magnesium, chloride, carbon, oxygen, iron, sulfur and phosphorous through much of the Phanerozoic. The model incorporates the basic reactions controlling atmospheric carbon dioxide and oxygen concentrations, continental and seafloor weathering of silicate and carbonate rocks, net ecosystem productivity, basalt-seawater exchange reactions, precipitation and diagenesis of chemical sediments and authigenic silicates, oxidation-reduction reactions involving carbon, sulfur, and iron, and subduction-decarbonation reactions. Although MAGic contains feedback and forcing functions adapted from the GEOCARB models (Berner, 1991, 1994; Berner and Kothavala, 2001), these functions are incorporated in a reservoir-reaction scheme that is considerably more detailed. Coupled reservoirs include shallow and deep cratonic silicate and carbonate rocks and sediments, seawater, atmosphere, oceanic sediments and basalts, and the shallow mantle. Model results are reasonably consistent with recently published constraints provided by fluid inclusion, isotopic, floral, and mineralogical records. We have used these results to evaluate sensitivity to uncertainties in the history of the earth-ocean-atmosphere system over the past 500 Ma: the advent of pelagic carbonate sedimentation, the importance of burial versus early diagenetic dolomite formation, the importance of reverse weathering, and the relationship of these processes to seafloor spreading rates. Results include a general pattern of dolomite abundance during periods of elevated seafloor spreading and alkalinity production, elevated atmospheric CO2 concentrations for most of the Phanerozoic similar to those predicted by GEOCARB, and covariance of seawater sulfate to calcium ratios with magnesium to calcium ratios. These trends are broadly consistent with proxies for seawater composition and the mass-age data of the rock record itself.
53
Keywords: ATMOSPHERIC CARBON-DIOXIDE; CENOZOIC EVOLUTION; Clay minerals; CO2; DOLOMITE PROBLEM; marine-sediments; REVISED MODEL; SEAWATER CHEMISTRY; SECULAR VARIATION; time

Marine 14C calibration and activity record for the past 50,000 years from the Cariaco Basin, Abstract - Hughen, K. A.; Southon, J.; Lehman, S. J.; Jenkins, W. (Eos Trans AGU 87, Fall Meeting Supple., 2006)
id: 1076

Marine 14C data sets: contributions to calibration and Earth Systems research, Abstract - Hughen, K. A. (19th International Radiocarbon Conference, 2006)
id: 1077

Marine-derived 14C calibration and activity record for the past 50,000 years updated from the Cariaco Basin - Hughen, K. A.; Southon, J. A.; Lehman, S. J.; Bertrand, C. J. H.; Turnbull, J. (Quaternary Science Reviews, 2006)
id: 553

Mechanism of 15N enrichment in eutrophication-impacted estuaries - Varekamp, J. C.; Altabet, M. A.; Thomas, C. R. (ASLO Ocean Sciences meeting, 2006)
id: 745

Mercury contamination in Connecticut and Long Island Sound from historic hat-making sources - Goldoff, B.; Varekamp, J. C.; Neupane, A. (GSA Annual Meeting, 2006)
id: 747

Mercury contamination in Long Island Sounds, USA, from the historic hat-making industry - Varekamp, J. C. (ISEG7 meeting, 2006)
id: 746

Meridional overturning circulation in the South Atlantic at the last glacial maximum - Lynch-Stieglitz, J.; Curry, W. B.; Oppo, D. W.; Ninneman, U. S.; Charles, C. D.; Munson, J. (Geochemistry Geophysics Geosystems, 2006)
The geostrophic shear associated with the meridional overturning circulation is reflected in the difference in density between the eastern and western margins of the ocean basin. Here we examine how the density difference across 30 degrees S in the upper 2 km of the Atlantic Ocean ( and thus the magnitude of the shear associated with the overturning circulation) has changed between the last glacial maximum and the present. We use oxygen isotope measurements on benthic foraminifera to reconstruct density. Today, the density in upper and intermediate waters along the eastern margin in the South Atlantic is greater than along the western margin, reflecting the vertical shear associated with the northward flow of surface and intermediate waters and the southward flowing North Atlantic Deep Waters below. The greater density along the eastern margin is reflected in the higher delta(18)O values for surface sediment benthic foraminifera than those found on the western margin for the upper 2 km. For the last glacial maximum the available data indicate that the eastern margin foraminifera had similar delta(18)O to those on the western margin between 1 and 2 km and that the gradient was reversed relative to today with the higher delta(18)O values in the western margin benthic foraminifera above 1 km. If this reversal in benthic foraminifera delta(18)O gradient reflects a reversal in seawater density gradient, these data are not consistent with a vigorous but shallower overturning cell in which surface waters entering the Atlantic basin are balanced by the southward export of Glacial North Atlantic Intermediate Water.
092siTimes Cited:17Cited References Count:46

Mid-Holocene El Nino-Southern Oscillation (ENSO) attenuation revealed by individual foraminifera in eastern tropical Pacific sediments - Koutavas, A.; deMenocal, P. B.; Olive, G. C.; Lynch-Stieglitz, J. (Geology, 2006)
Holocene reconstructions of the Ell Nino-Southern Oscillation (ENSO) provide valuable perspective on its recent evolution and can be important for assessing its future. Optimal assessment of past ENSO variability requires observations from its center of action in the eastern equatorial Pacific, but these are limited due to paucity of high-resolution paleoceanographic archives (e.g., corals). Here we use a new approach to quantify past ENSO variance based on the oxygen isotopic composition (delta O-18) of individual foraminifera (Globigerinoides ruber) from deep-sea sediments in the ENSO source region.. Individual G. ruber foraminifera behave as monthly recorders of sea-surface conditions, including ENSO extremes, circumventing the lack of annual resolution in the sediments. Intrapopulation delta O-18 distributions derived with this method from a core near the Galapagos Islands reveal mid-Holocene reductions in variance or 50%, requiring drastic attenuation of the ENSO amplitude. Furthermore, Mg/Ca thermometry indicates that mid-Holocene background conditions were accompanied by a stronger zonal temperature gradient that coincided with a northward-displaced Intertropical Convergence Zone (ITCZ). The results suggest that the position of the ITCZ is an important factor in the low-frequency modulation of ENSO and could influence its future evolution.
113wzTimes Cited:128Cited References Count:26

Modern saltmarsh diatom distributions of the Outer Banks, North Carolina, and the development of a transfer function for high resolution reconstructions of sea level - Horton, B. P.; Corbett, R.; Culver, S. J.; Edwards, R. J.; Hillier, C. (Estuarine Coastal and Shelf Science, 2006)
We collected modern diatom samples from Currituck Barrier Island, Oregon inlet and Pea Island marshes, Outer Banks, North Carolina, USA, which have different salinity regimes due to their varying distances from a major barrier island inlet. Multivariate analyses separate the saltmarsh diatom assemblages into distinct elevational zones, dominated by differing abundances of polyhalobous, mesohalobous and oliohalobous taxa. suggesting that the distribution of saltmarsh diatoms is a direct function of elevation, with the most important controlling factors being the duration and frequency of subaerial exposure.We developed the first diatom-based transfer function for the east coast of North America to reconstruct former sea levels based upon the relationship between diatom assemblage and elevation. Results imply that this is possible to a precision of +/- 0.08 m, superior to most similar studies from temperate, mid-latitude environments. The transfer function is used to construct a relative sea-level curve from fossil assemblages from Salvo. North Carolina. These results suggest a sea-level rise of 0.7 m over the last c. 150 years, at an average of c. 3.7 mm year(-1). This is consistent with existing sea-level data, and illustrates the utility of the transfer function approach. (c) 2006 Elsevier Ltd. All rights reserved.
090jmTimes Cited:37Cited References Count:74

The Montana Creek Sites: Archaeological Investigations at Lovewell Reservoir, Jewell County, Kansas-2004 - Ritterbush, Lauren W.; Logan, Brad (Nebraska-Kansas Area Office, Bureau of Reclamation. Dept. of Sociology, Anthropology and Social Work, Kansas State University, 2006)
id: 619

Monthly resolved stable oxygen isotope record in a Palauan sclerosponge Acanthocheatetes wellsi for the period of 1977-2001 - Grottoli, Andrea G. (10th International Coral Reef Symposium, 2006)
id: 1131

A multiproxy palaeoecological record of Holocene lake sediments from the Rio Tapajos, eastern Amazonia - Irion, G.; Bush, M. B.; de Mello, J. A. N.; Stuben, D.; Neumann, T.; Muller, G.; De, J. O.; Junk, J. W. (Palaeogeography Palaeoclimatology Palaeoecology, 2006)
Two sediment cores up to 42 m in length were raised from the wide, deep, section of the lower Tapajos River, Amazonia, referred to as Lago Tapajos. These cores reveal a history of subtle environmental change that began with the formation of Lago Tapajos as sea level rose about 11,000 years ago. The sediments of the lake were deposited fairly quickly-at a rate of ca. 4 m per millennium and are uniformly fine grained, with low organic content. The fossil pollen record derived from these sediments reveals that forest surrounded this site throughout the Holocene. The largest change in the core took place between ca. 5500 and 4200 cal. years BP and reflects a transition from coarser to finer sediments. Coincident with the change in sediment is a slight transition in the pollen spectra with an increase in Poaceae abundance at the expense of the pioneer tree Cecropia cecropia. A tentative explanation is offered in which increased human activity, possibly spurred by climatic change, resulted in the formation of some local grasslands. However, despite the apparent actions of humans, there is no indication of basin-wide transformation of landscapes in this record. The Holocene persistence of forest as the dominant landscape matrix around Lago Tapajos is supported by low delta C-13 values and by the constant geochemistry and mineralogy of the lake sediments. (c) 2006 Elsevier B.V. All rights reserved.
097fbTimes Cited:40Cited References Count:78

Multiproxy records of eutrophication in Long Island Sound - Varekamp, Thomas E.; Avener, J. C. (GSA Annual Meeting, 2006)
id: 748

The mystery interval 1.5 to 14.5 kyrs ago - Denton, G. H.; Broecker, W. S.; Alley, R. B. (Pages News, 2006)
id: 701

National register evaluation and geoarchaeological analysis of the sites and shovel testing at Fort Riley, Kansas - Sherman, Stephen A.; Johnson, William C. (Center for Environmental Management of Military Lands, Colorado State Univ., 2006)
id: 696

Natural 14C in Saccoglossus Bromophenolosus compared to its surrounding sediments - Teuten, E. L.; King, G. M.; Reddy, C. M. (Marine Ecology Progress Series, 2006)
id: 613

Natural abundance radiocarbon as a tracer of assimilation of petrolleum carbon by bacteria in salt marsh sediments - Wakeham, S. G.; McNichol, A. P.; Kostka, J.; Pease, T. K. (Geochim. Cosmochim. Acta, 2006)
id: 520

Natural-abundance radiocarbon as a tracer of assimilation of petroleum carbon by bacteria in salt marsh sediments - Wakeham, S. G.; McNichol, A. P.; Kostka, J. E.; Pease, T. K. (Geochimica Et Cosmochimica Acta, 2006)
The natural abundance of radiocarbon ((14)C) provides unique insight into the source and cycling of sedimentary organic matter. Radiocarbon analysis of bacterial phospholipid lipid fatty acids (PLFAs) in salt-marsh sediments of southeast Georgia (USA)-one heavily contaminated by petroleum residues-was used to assess the fate of petroleum-derived carbon in sediments and incorporation of fossil carbon into microbial biomass. PLFAs that are common components of eubacterial cell membranes (e.g., branched C(15) and C(17), 10-methyl-C(16)) were depleted in (14)C in the contaminated sediment (mean Delta(14)C value of +25 +/- 19 parts per thousand for bacterial PLFAs) relative to PLFAs in uncontaminated "control" sediment (Delta(14)C = +101 +/- 12 parts per thousand). We suggest that the (14)C-depletion in bacterial PLFAs at the contaminated site results from microbial metabolism of petroleum and subsequent incorporation of petroleum-derived carbon into bacterial membrane lipids. A mass balance calculation indicates that 6-10% of the carbon in bacterial PLFAs at the oiled site could derive from petroleum residues. These results demonstrate that even weathered petroleum may contain components of sufficient lability to be a carbon source for biomass production by marsh sediment microorganisms. Furthermore, a small but significant fraction of fossil carbon is assimilated even in the presence of a much larger pool of presumably more-labile and faster-cycling carbon substrates. (c) 2006 Elsevier Inc. All rights reserved.
030olTimes Cited:27Cited References Count:65

New evidence for remnant deposits recorded by columnar sediments in the shelf of the northern South China Sea - Xiao, S. B.; Chen, M. H.; Lu, J. (Marine Geology & Quaternary Geology, 2006)
id: 568

New middle and late Holocene radiocarbon dates for alluvial deposits containing the Sand Creek pit hearths of northwestern Nebraska, U.S.A - LaGarry, L. A.; LaGarry, H. E.; Wandsnider, L.; Richardson, E. L. (14th Annual Island in the Planes Archeological and Historical Symposium Program and Abstracts, 2006)
id: 517

Non-pollen palynomorphs from organic deposits of Posidonia oceanica: a new tool for palaeoenvironmental studies in marine peat-like deposits - López-Sáez, J. A.; López-García, P.; Pozuelo, R.; Mateo, M. A.; Renom, P.; Garrido, D. (Palyno-Bulletin, 2006)
The in situ accumulation of large quantities of biogenic materials over millennia is very relevant and occurs only in a limited number of ecosystems. Peat bogs are probably the bestknown example among terrestrial ecosystems (e.g. Aaby & Berglund, 1986) and coral reefs among marine ecosystems (e.g. Clausen & Roth, 1975). In situ organic accumulations in the marine environment are rare, having been described for mangroves and seagrass species. The Mediterranean seagrass Posidonia oceanica accumulates large quantities of organic debris. Roots, rhizomes and leaf sheaths are progressively buried fonning a bioconstruction called 'matte'. The organic material remains with little morphological alteration for millennia (Mateo et aI. , 1997), constitnting a marine peat-like deposit with a great interest from a palaeoenvironmental point of view. The present paper evaluates the palaeoecological potential of the organic deposits generated by the marine phanerogame Posidonia oceanica in the Bay of Port Lligat, Girona, NE Spain. This stndy discusses the detailed evolution of the vegetation in the landscape of the area.
id: 2005

The North Anatolian fault in the Gulf of Izmit (Turkey): Rapid vertical motion in response to minor bends of a non-vertical continental transform - Cormier, M. H.; Seeber, L.; McHugh, C. M. G.; Polonia, A.; Cagatay, M. N.; Emre, O.; Gasperini, L.; Gorur, N.; Bortoluzzi, G.; Bonatti, E.; Ryan, W. B. F.; Newman, K. R. (Journal of Geophysical Research, 2006)
id: 532

Ongoing build-up of refractory organic carbon in boreal soils during the Holocene - Smittenberg, R. H.; Eglinton, T. I.; Schouten, S.; Sinninghe-Damste, J. S. (Science, 2006)
id: 1146

Organic Carbon in Rivers (Plenary Lecture) - Raymond, P. A. (Geochemical Earth Reference Model (GERM) Workshop, 2006)
id: 488

Origin of PCDD in ball clay assessed with compound-specifric chlorine isotope analysis and radiocarbon dating - Holmstrand, H. D.; Gadomski, D.; Mandalakis, M.; Tysklind, M.; Irvine, R.; Andersson, P.; Gustafsson, O. (Environmental Science and Technology, 2006)
id: 1040

Paleotsunami deposits in coastal lagoons, Sri Lanka: Are tsunamis always sedimentologically important events? - Jackson, K. L.; Rankey, E. C.; Eberli, G. P.; Amelung, F.; Andres, M. S.; Peterson, L. C.; Swart, P. K.; Jayasena, H. A. H.; Kehelpannala, K. V. W. (EOS Trans. AGU Fall Meeting Suppl. Abstracts, 2006)
id: 664

Pedological properties of the eroding coastline along the Beaufort Sea, Alaska - Ping, C. L.; Dou, F.; Jorgenson, G.; Michaelson, J.; Lynn, L. A.; Shur, Y.; Kanevsky, M. (Eos Trans. AGU Fall Meeting Supplement, 2006)
id: 1002

Postglacial climate reconstruction based on compound-specific D/H ratios of fatty acids from Blood Pond, New England - Hou, J. Z.; Huang, Y. S.; Wang, Y.; Shuman, B.; Oswald, W. W.; Faison, E.; Foster, D. R. (Geochemistry Geophysics Geosystems, 2006)
We determined hydrogen isotope ratios of individual fatty acids in a sediment core from Blood Pond, Massachusetts, USA, in order to reconstruct climate changes during the past 15 kyr. In addition to palmitic acid (C-16 n-acid), which has been shown to record lake water D/H ratios, our surface sediments and down core data indicate that behenic acid (C-22 n-acid), produced mainly by aquatic macrophytes, is also effective for capturing past environmental change. Calibration using surface sediments from two transects across eastern North America indicates that behenic acid records delta D variation of lake water. Down core variations in delta D values of behenic acid and pollen taxa are consistent with the known climate change history of New England. By evaluating the hypothesis that D/H fractionations of long chain even numbered fatty acids (C-24-C-32 n-acids) relative to lake water provide independent estimates of relative humidity during the growing season, we find that differences between lake-level records and isotopically inferred humidity estimates may provide useful insight into seasonal aspects of the hydrologic cycle. Combined analyses of D/H of short and long chain fatty acids from lake sediment cores thus allow reconstructions of both past temperature and growing season relative humidity. Comparison of delta D records from two lakes in New England provides critical information on regional climate variation and abrupt climate change, such as the 8.2 ka event.
031uaTimes Cited:32 Cited References Count:43
Keywords: atmospheric processes : paleoclimatology; eastern north-america; fatty acids; geochemistry : organic and biogenic geochemistry; geochemistry : stable isotope geochemistry; Holocene; hydrogen isotope; hydrogen isotope ratios; lacustrine organic-matter; lake-sediments; Paleoclimate; record; Stable isotopes; united-states; vegetation history; younger-dryas

Pre-Columbian maize agriculture in Costa Rice: Pollen and other evidence from lake and swamp sediments - Horn, S. P. (Histories of Maize: Multidisciplinary Approaches to the Prehistory, Biogeography, Domestication, and Evolution of Maize, 2006)
id: 1113

Quantifying archaeal community autotrophy in the mesopelogic ocean using natural radiocarbon - Ingalls, A. E.; Shah, S. R.; Hansman, R. L.; Aluwihare, L. I.; Santos, G. M.; Druffel, E. R. M.; Pearson, A. (Proc. Natl. Acad. Sci. USA, 2006)
id: 502

Rapid lateral particle transport in the Argentine Basin: Molecular 14C and 230Th evidence - Mollenhauer, Gesine; McManus, Jerry F.; Benthien, Albert; Muller, Peter J.; Eglinton, Timothy I. (Deep-Sea Research I, 2006)
id: 543

Rapid sea-level rise and Holocene climate in the Chukchi Sea - Keigwin, L. D.; Donnelly, J. P.; Cook, M. S.; Driscoll, N. W.; Brigham-Grette, J. (Geology, 2006)
Three new sediment cores from the Chukchi Sea preserve a record of local paleoenvironment, sedimentation, and flooding of the Chukchi Shelf (similar to-50 m) by glacial-eustatic sea-level rise. Radiocarbon dates on foraminifera provide the first marine evidence that the sea invaded Hope Valley (southern Chukchi Sea, -53 m) as early as 12 ka. The lack of significant sediment accumulation since ca. 7 ka in Hope Valley, southeastern Chukchi Shelf, is consistent with decreased sediment supply and fluvial discharge to the shelf as deglaciation of Alaska concluded. Abundant benthic foraminifera from a site west of Barrow Canyon indicate that surface waters were more productive 4-6 ka, and this productivity varied on centennial time scales. An offshore companion to this core contains a 20 m record of the Holocene. These results show that carefully selected core sites from the western Arctic Ocean can have a temporal resolution equal to the best cores from other regions, and that these sites can be exploited for high-resolution studies of the paleoenvironment.
089zkTimes Cited:67Cited References Count:18

Rapid subsidence and sedimentation from oblique slip near a bend on the North Anatolian transform fault in the Marmara Sea, Turkey - Seer, L.; Cormier, M. H.; McHugh, C.; Emre, O.; Polonia, A.; Sorlien, C. (Geology, 2006)
id: 533

Recent investigations of maritime archaic structures at White Point, Northern Labrador - Wolff, Christopher B. (Provincial Archaeology Office of Newfoundland and Labrador Archaeological Review, 2006)
id: 410

Reduced agulhas leakage at the LGM inferred from an integrated provenance and flux dtudy - Franzese, A. M.; Hemming, S. R.; Goldstein, S. L.; Anderson, R. F. (Earth & Planatary Science Letters, 2006)
id: 632

Refining the radiocarbon dating of Antarctic marine sediments via stepped combustion - Schrum, H.; Hayes, J.; Domack, E. (Eps Trans AGU, 2006)
id: 702

A revised late Holocene sea-level record for northern Massachusetts, USA - Connelly, J. P. (Journal of Coastal Research, 2006)
id: 497

The rise and fall of the refugial hypothesis - Bush, M. B.; De Oliveira, P. E. (Biota Neotropica, 2006)
id: 457

Rotasonic vibracores from northeastern North Carolina, cores OBX-10 through OBX-18 - Hoffman, C. W.; Farrell, K. M.; Pierson, J. A.; Ward, A. N.; Nickerson, J. G.; Brooks, R. W.; Ganey, J. G. (NCGS Open-file Report, 2006)
id: 704

Sea surface temperatures of southern middle-latitudes 0-160 by BP - Pahnke, K.; Sachs, J. P. (Paleoceanography, 2006)
id: 591

Sea-level and tectonic control of middle to late Pleistocene turbidite systems in Santa Monica Basin, offshore California - Normark, W. R.; Piper, D. J. W.; Sliter, R. (Sedimentology, 2006)
Small turbidite systems offshore from southern California provide an opportunity to track sediment from river source through the turbidity-current initiation process to ultimate deposition, and to evaluate the impact of changing sea level and tectonics. The Santa Monica Basin is almost a closed system for terrigenous sediment input, and is supplied principally from the Santa Clara River. The Hueneme fan is supplied directly by the river, whereas the smaller Mugu and Dume fans are nourished by southward longshore drift. This study of the Late Quaternary turbidite fill of the Santa Monica Basin uses a dense grid of high-resolution seismic-reflection profiles tied to new radiocarbon ages for Ocean Drilling Program (ODP) Site 1015 back to 32 ka. Over the last glacial cycle, sedimentation rates in the distal part of Santa Monica Basin averaged 2-3 mm yr(-1), with increases at times of extreme relative sea-level lowstand. Coarser-grained mid-fan lobes prograded into the basin from the Hueneme, Mugu and Dume fans at times of rapid sea-level fall. These pulses of coarse-grained sediment resulted from river channel incision and delta cannibalization. During the extreme lowstand of the last glacial maximum, sediment delivery was concentrated on the Hueneme Fan, with mean depositional rates of up to 13 mm yr(-1) on the mid- and upper fan. During the marine isotope stage (MIS) 2 transgression, enhanced rates of sedimentation of > 4 mm yr(-1) occurred on the Mugu and Dume fans, as a result of distributary switching and southward littoral drift providing nourishment to these fan systems. Longer-term sediment delivery to Santa Monica Basin was controlled by tectonics. Prior to MIS 10, the Anacapa ridge blocked the southward discharge of the Santa Clara River into the Santa Monica Basin. The pattern and distribution of turbidite sedimentation was strongly controlled by sea level through the rate of supply of coarse sediment and the style of initiation of turbidity currents. These two factors appear to have been more important than the absolute position of sea level.
063ieTimes Cited:24Cited References Count:38

Sea-level variation during the holocene deduced from the morphologic and stratigraphic evolution of Morgan Peninsula, Alabama, USA - Rodriguez, A. B.; Meyer, C. T. (Journal of Sedimentary Research, 2006)
Recent Gulf of Mexico shoreline studies interpret middle to late Holocene sea level as failing from a level above present elevation or stable at present elevation; however, the architecture of Morgan Peninsula, Alabama, does not support this. Morgan Peninsula is a beach-ridge strandplain composed of two obliquely aligned Holocene beach-ridge sets. Ground-penetrating radar profiles discriminate between parallel, even to wavy reflectors of the eolian dune environment and the underlying seaward-dipping, complex sigmoidal-oblique reflectors of the foreshore and upper-shoreface environment. The contact between foreshore and eolian facies in beach ridges can be used as a sea-level indicator. The average elevation of this contact in Morgan Peninsula rises throughout shoreline accretion, which occurred throughout the last 5.4 ka, suggesting that there was continual sea-level rise during this time. Morgan Peninsula is a useful modern analog to ancient shoreface-shelf parasequences and demonstrates the significant internal complexities that can exist in these deposits. Erosional discontinuities imaged in the Holocene foreshore-upper shoreface environment are laterally continuous, extend to elevations above mean sea level, and correlate to beach ridges and the transition between beach-ridge sets. An increase in the wave regime or fluctuations in sediment supply appear to be likely mechanisms for forming erosional discontinuities below beach ridges. The erosional surface separating beach-ridge sets may have formed by increased storm activity and associated barrier breaching, or a reconfiguration of the Mobile Bay tidal-delta complex superimposed on a gradual rate of sea-level rise. This boundary is recognized by a change in beach-ridge orientation at the surface and an increase in the aggradational component of shoreline accretion.
id: 2040; PT: J; UT: WOS:000235746800018

On sediment accumulation rates and stratigraphic completeness: Lessons from Holocene ocean margins - Sommerfield, C. K. (Continental Shelf Research, 2006)
Stratigraphic completeness is a fundamental consideration when deciphering the mass accumulation history of sediments and the geologic record of earth and ocean processes. In this study, stratigraphic completeness was examined in the context of late Holocene sedimentary successions using published sediment accumulation rates for five ocean margin systems (Amazon shelf, Hudson estuary, northern California shelf, Mid-Atlantic slope, Santa Monica Bay). Plots of mass accumulation rate versus time span of averaging were used to determine how rates scale with measurement period, and to estimate levels of stratigraphic completeness for comparison within and among margin systems. Statistically significant inverse correlations between accumulation rate and time span of averaging are indicated for all but one of these systems-most of the sedimentary records examined are stratigraphically incomplete. At the 10(3)-yr level of resolution, completeness is 20-48% for strongly tidal estuarine (Hudson estuary) and deltaic shelf (Amazon shelf) sites, 51-91% for accretionary shelves (northern California shelf) and slopes (Mid-Atlantic slope), and 85-100% for a sediment-starved slope (Santa Monica bay). Mass accumulation rates converge to a relatively narrow range (0.01-0.1 g cm(-2) yr(-1)) at the 10(4)-yr level of resolution, consistent with the notion that there are universal controls on sediment accumulation rate, i.e., rate of sea-level rise and sediment supply. Among sites on the Amazon and northern California shelves, within-system completeness varies by similar to 10-20% on account of site-specific sedimentary processes that preferentially trap or disperse suspended sediment. Overall, stratigraphic completeness increases with water depth shelf-to-slope, yet depth is not a robust predictor of completeness in general owing to differences in strata-forming processes among shallow-marine environments. Significantly, completeness varies inversely with instantaneous deposition rate as the most sediment-rich systems tend to exhibit the most incomplete sedimentary records. The findings of this study emphasize the importance of considering time span and fidelity when interpreting the accumulation history of modern and Holocene sedimentary strata. (c) 2006 Elsevier Ltd. All rights reserved.
109ueTimes Cited:24Cited References Count:61

Sediment Cd and Mo accumulation in the oxygen-minimum zone off western Baja California linked to global climate over the past 52 kyr - Dean, W. E.; Zheng, Y.; Ortiz, J. D.; van Geen, A. (Paleoceanography, 2006)
[ 1] Concentrations of organic carbon (orgC), cadmium (Cd), and molybdenum (Mo) were measured in two sediment cores raised from depths of 430 and 700 m within the oxygen-minimum zone (OMZ) off southern Baja California at a temporal resolution of similar to 0.5 kyr over the past 52 kyr. These records are supplemented with diffuse spectral reflectance (DSR) measurements obtained on board ship soon after collection at a resolution of similar to 0.05 kyr. In the core from 700 m depth, a component extracted from the DSR data and the three geochemical proxies generally vary in concert with each other and over a wide range ( 4 - 22% orgC; 1 - 40 mg/kg Cd; 5 120 mg/kg Mo). Intervals of increased orgC, Cd, and Mo accumulation generally correspond to warm periods recorded in the oxygen-isotopic composition of Greenland ice, with the exception of the Bolling/Allerod which is only weakly expressed off Baja California. Concentrations of the biogenic proxies are higher in the core from 430 m depth, but erratic sediment accumulation before 15 ka precludes dating of the older intervals that are laminated and contain elevated orgC, Cd, and Mo concentrations. The new data provide further evidence of an intimate teleconnection between global climate and the intensity of the OMZ and/or productivity along the western margin of North America. On the basis of a comparison with Cd and Mo records collected elsewhere in the region, we conclude that productivity may actually have varied off southern Baja California by no more than a factor of 2 over the past 52 kyr.
110idTimes Cited:34 Cited References Count:68
Keywords: continental-margin; enhanced preservation; late pleistocene; marine-sediments; nitrogen isotope; northeast pacific waters; organic-carbon preservation; productivity variations; santa-barbara basin; suboxic sediments

Sedimentary facies and climate control on formation of vivianite and siderite microconcretions in sediments of Lake Baikal, Siberia - Sapota, T.; Aldahan, A.; Al-Aasm, I. S. (Journal of Paleolimnology, 2006)
Authigenic vivianite and siderite microconcretions were found, respectively, in hemipelagic and deltaic facies of 600-m-long BDP-98 sediment section from Lake Baikal. Textural investigations of these microconcretions show that they are typically < 1 mm in size, irregular in shape and composed of aggregated crystallites. Dissimilar orientation of vivianite and siderite crystallites suggests formation at different depths in the sediment; up to tens of centimeters for vivianite and tens of meters for siderite. Chemical analyses of both the vivianite and the siderite indicate cation composition characterized by minor amounts of Mn, Ca and Mn apart from the dominating Fe. Rather limited and distinctive carbon isotopic composition of the siderite, with delta C-13(VPDB) values between about +13 and +16 degrees, implies formation of the mineral in the methanogenic zone of diagenesis. Isotopic composition of oxygen in the siderite (delta O-18(VPDB) values between about -10 and -11 degrees) is consistent with crystallization temperature at about 10-30 degrees C and water delta O-18(SMOW) values between about -10 and -16 degrees. The distribution of the authigenic minerals in the section suggests changes in both sedimentary facies and climate, where vivianite formation was controlled by hemipelagic depositional conditions during the Pliocene and Quaternary, whereas siderite reflects impact of deltaic conditions during the Miocene.
092qrTimes Cited:32Cited References Count:37

Sedimentary features of the Yangtze River-derived along-shelf clinoform deposit in the East China Sea - Liu, J. P.; Li, A. C.; Xu, K. H.; Veiozzi, D. M.; Yang, Z. S.; Milliman, J. D.; DeMaster, D. (Continental Shelf Research, 2006)
A predominant sigmoidal clinoform deposit extends from the Yangtze River mouth southwards 800 kin along the Chinese coast. This clinoform is thickest (similar to 40m) between the 20 and 30 m isobaths and progressively thins offshore, reaching water depths of 60 and 90 m and distances up to 100 km offshore. Clay mineral, heavy metal, geochemical and grain-size analyses indicate that the Yangtze River is the primary source for this longshore-transported clinoform deposit. (210)Pb chronologies show the highest accumulation rates (> 3 cm/yr) occur immediately adjacent to the Yangtze subaqueous delta (north of 30 degrees N), decreasing southward alongshore and eastward offshore. The interaction of strong tides, waves, the China Coastal Current, winter storms, and offshore upwelling appear to have played important roles in trapping most Yangtze-derived sediment on the inner shelf and transporting it to the south. (c) 2006 Elsevier Ltd. All rights reserved.
109ueTimes Cited:158Cited References Count:62

Sedimentology, physical properties and age of mass transport deposits associated with the Marques de Pombal Fault, Southwest Portuguese Margin - Vizcaino, Alexis; Gracia, Eulalia; Pallas, Raimon; Garcia-Orellana, Jordi; Escutia, Carlota; Casas, David; Willmott, Veronica; Diez, Susana; Asioli, Alessandra; Danobeitia, Juanjo (Norwegian Journal of Geology, 2006)
id: 623

Shell fragmentation as an indicator of benthic conditions - Best, Mairi M. R.; Bibeau, Karine; Spitzberg, Daniel; Thomas, Ellen; Varekamp, Johan C.; Bernatis, Jennifer (GSA Annual Meeting, 2006)
id: 749

Solid-state 13C NMR analysis of size and density fractions of marine sediments: Insight into organic carbon sources and preservation mechanisms - Dickens, A. F.; Baldock, J. A.; Smernik, R. J.; Wakeham, S. G.; Arnarson, T. S.; Gelinas, Y.; Hedges, J. I. (Geochimica et Cosmochimica Acta, 2006)
id: 1702

Source and transport of terrigenous organic matter of the upper Yukon River: evidence from isotope (13C, 14C and 15N) composition of dissolved, colloidal and particulate phases - Guo, L.; Macdonald, R. W. (Global Biogeochemical Cycles, 2006)
id: 1129

Sources age and composition of dissolved and particulate organic matter delivered to a passive margin river system - Petsch, S. T.; Gordon, E. S.; Longworth, B. E.; Schillawki, S. E.; Raymond, P. A. (ASLO/AGU Ocean Science Meeting, 2006)
id: 485

Sources and potential transformation of estuarine dissolved and particulate organic matter: a multi-tracer approach - McCallister, S. L.; Bauer, J. E.; Ducklow, H. W.; Canuel, E. A. (Organic Geochemistry, 2006)
id: 597

Sources, fate and turnover of terrestrial organic carbon in rivers (Lecture) - Raymond, P. A.; Oh, N. H. (Organic Geochemistry Gordon Conference, 2006)
id: 491

Sources, fate and turnover of terrestrial organic carbon in rivers - Raymond, P. A. (Goldschmidt Conference, 2006)
id: 489

Spacial and temporal variation in cores from Lake Titicaca, Bolivia/Peru during the last 13,000 yrs - Fritz, S. C.; Baker, P. A.; Tapia, P.; Garland, J. (Quaternary International, 2006)
id: 588

Stable carbon isotopes in coastal Puerto Rico corals and adjacent natural waters: implications for land-ocean connectivity and land-use history - Moyer, R. P.; Grottoli, A. G. (Ocean Sciences Meeting, 2006)
id: 655

Stable isotopes from marine shells, ancient environments, and human subsistence on Middle Holocene Santa Rosa Island, California, U.S.A - Rick, Torben C.; Robbins, John A.; Ferguson, Kurth M. (Journal of Island and Coastal Archaeology, 2006)
id: 578

Submarine earthquake geology along the North Anatolia Fault in the Marmara Sea, Turkey: A model for transform basin sedimentation - McHugh, C. M. G.; Seeber, L.; Cormier, M. H.; Dutton, J.; Cagatay, N.; Polonia, A.; Ryan, W. B. F.; Gorur, N. (Earth and Planetary Science Letters, 2006)
The submerged portions of the North Anatolia Fault system beneath the Marmara Sea were studied with high-resolution multibeam bathymetry, subbottom profiling and sediment cores. The major objectives were to learn about the seismic and tectonic history of the fault from the stratigraphic record at a scale similar to paleoseismic studies on land and to develop tools for submarine earthquake geology that can be applied to fault-controlled basins in general. We focused on Holocene sediment in several Marmara Sea basins of different sizes. The approach was to test whether: (1) the depocenters of the larger basins contain a record of all historic Ms > 7 earthquakes within the Marmara Sea region; (2) the small transform basins record earthquakes that rupture through them; (3) vertical and strike-slip Holocene deformation can be quantified; and (4) the effects of an earthquake generally includes both primary structural features due to rupture of the sea floor, such as strata offset, scarps and tilting, as well as secondary effects due to shaking, such as mass-wasting and gravitational flows. We found evidence of earthquakes that we correlate with historic events in 181 AD, 740 AD, 1063 AD, 1343 AD, 1509 AD, 1766 AD, 1894 AD and 1912 AD. The geologic evidence is primarily from those basins adjacent to the rupture as inferred from historic data. This suggests that coseismic deformation of the sea floor along the rupture is a critical factor in the sedimentary record. We propose a qualitative sedimentation model that relates this coseismic deformation to mass-wasting of the slope, scour of the basin floor, seiche motions and homogenite deposition. Frequent earthquake activity sheds sediments from the flanks, contributes to the much thicker sediment on the basin floor and decreases the likelihood of sediment failures in response to normal marine gravity-driven processes. The surveying techniques and approaches used have therefore the potential of documenting earthquake ruptures of fault segments and to extend the earthquake record far before the known history, thus improving hazard evaluations and the fundamental understanding of earthquake process. (c) 2006 Elsevier B.V. All rights reserved.
085kgTimes Cited:55Cited References Count:98

Temporal and spatial complexity in post-glacial shelf sedimentation on the tectonically active, Poverty Bay continental margin of New Zealand - Orpin, A. R.; Alexander, C.; Carter, L.; Kuehl, S.; Walsh, J. P. (Continental Shelf Research, 2006)
id: 634

Tracking the weathering of an oil spill with comprehensive two-dimensional gas chromatography - Nelson, R. K.; Kile, B. M.; Plata, D. L.; Sylva, S. P.; Xu, L.; Reddy, C. M.; Gaines, R. B.; Frysinger, G. S.; Reichenbach, S. E. (Environmental Forensics, 2006)
Comprehensive two-dimensional gas chromatography (GC x GC) was used to investigate the Bouchard 120 oil spill. The latter occurred on April 25, 2003, when the barge Bouchard 120 spilled similar to 375,000 liters of No. 6 fuel oil into Buzzards Bay, Massachusetts. In order to gain a better understanding of the natural processes affecting the fate of the spilled product, we collected and analyzed oil-covered rocks from Nyes Neck beach in North Falmouth, Massachusetts. Here we discuss the data from samples collected on May 9, 2003, and six months later, on November 23, 2003. Along with standard two-dimensional gas chromatographic analysis, we employed unique data-visualization techniques such as difference, ratio, and addition chromatograms to highlight how evaporation, water washing, and biodegradation weathered the spilled oil. These approaches provide a new perspective to studying oil spills and aid attempts to remediate them.
032ldTimes Cited:62Cited References Count:21

Tsunami sediemnts in coastal lagoons, Sri Lanka: implications for paleotsunamis - Jackson, K. L.; Amelung, F.; Andres, M. S.; Eberli, G. P.; Jayasena, H. A. H.; Kehelpannala, K. V. W. (American Association of Petroleum Geologists Abstracts with Programs, 2006)
id: 665; Annual Meeting

Two ecological shifts in Long Island Sound during the industrial period - Thomas, E.; Varekamp, J. C.; Mecray, E. L.; Buchholtzten-Brink, M. R. L.; Cooper, S.; Brinkhuis, H.; Sangioirgio, F. (Long Island Sound Research Center, 2006)
id: 751

An updated 14C calibration and activity record for the past 50,000 years from marine Cariaco Basin, Abstract - Hughen, K. A.; Southon, J. A.; Lehman, S. J.; Bertrand, C. J. H.; Turnbull, J. (19th International Radiocarbon Conference, 2006)
id: 559

Using packrat middens to assess how grazing influences vegetation change in Glen Canyon National Recreation Area, Utah - Fisher, J.; Cole, K. L.; Anderson, R. S. (USGS open-file report 2006-1183, 2006)
id: 1105

Variability in radiocarbon ages of biochemical compound classes of high molecular weight dissolved organic matter in estuaries - Wang, X. C.; Callahan, J.; Chen, R. F. (Estuarine Coastal and Shelf Science, 2006)
High molecular weight dissolved organic matter (HMW-DOM, > 1000 Da) represents a major fraction (> 30%) of dissolved organic carbon (DOC) in the ocean and thus plays an important role in the global biogeochemical cycling of carbon and many other elements. Its organic sources and formation mechanisms, however, are still not well understood especially in estuarine and coastal regions where multiple natural and anthropogenic sources contribute to total HMW-DOM. In this paper we report our measurements of natural radiocarbon (C-14) abundances and stable carbon isotope (C-13) compositions of the major biochemical compound classes: amino acids, carbohydrates and lipids separated from eight HMW-DOM samples collected from five US estuaries as part of our on-going study of sources, distribution and transport of chromophoric dissolved organic matter (CDOM) in estuarine and coastal waters. Distinct differences in both C-14 and C-13 values were found among the bulk HMW-DOM samples as well as the individual compound classes. Radiocarbon ages of the major compound classes varied by as much as 27,000 years in a single sample. The calculated average radiocarbon ages of the compound fractions of HMW-DOM indicate that the total lipid fraction is very "old", while the acid-insoluble fraction is slightly younger. Total amino acid and carbohydrate fractions, however, have relatively modern apparent C-14 ages. The significant variability in C-14 ages among the compound classes indicates not only multiple organic carbon sources but also different formation and turnover pathways controlling the cycling of different biochemical components of HMW-DOM in estuarine and coastal waters. (c) 2006 Elsevier Ltd. All rights reserved.
057ogTimes Cited:6Cited References Count:41

Variability in the character, age and reactivity of organic matter exported from rivers and estuaries to ocean margins - Bauer, J. E.; Cole, J. J.; Caraco, N. F.; Raymond, P. A.; Keesee, E. J.; Fernald, S.; Mull, K. (Ocean Sciences Meeting, 2006)
id: 476

Western Atlantic intertropical convergence zone variability over the last full glacial cycle, Abstract - Drenzek, N.; Hughe, K.; Sessions, A.; Bice, M.; Eglinton, T. I. (Eos Trans. AGU 87, Fall Meeting Suppl., 2006)
id: 558

Young Danube delta documents stable Black Sea level since the middle Holocene: Morphodynamic, paleogeographic, and archaeological implications - Giosan, L.; Donnelly, J. P.; Constantinescu, S.; Filip, F.; Ovejanu, I.; Vespremeanu-Stroe, A.; Vespremeanu, E.; Duller, G. A. T. (Geology, 2006)
New radiocarbon and optical dates show that the Holocene Danube delta started to build out of a Black Sea embayment similar to 5200 yr ago. Delta lobe development phases differ by as much as 5 k.y. from previously proposed ages. The new chronology allows for a better understanding of the Danube delta paleogeography, including the demise of Istria, the main ancient Greek-Roman city in the region. Prior reconstructions of sea level in the Black Sea inferred fluctuations to 15 m in range; however, stratigraphy of beach ridges in the delta shows that the relative Black Sea level for the past 5 k.y. was stable in the Danube delta region within -2 m and +1.5 of the current level. Hydroisostatic effects related to a proposed catastrophic reconnection of the Black Sea to the World Ocean in the early Holocene may have been responsible for the sea level reaching the highstand earlier than estimated by models. The new sea-level data suggest that submergence at several ancient settlements around the Black Sea may be better explained by local factors such as subsidence rather than by basin-wide sea-level fluctuations.
084aqTimes Cited:63Cited References Count:35

A 17,000 year history of Andean climatic and vegetation change from Laguna de Chochos, Peru - Bush, M. B.; Hansen, B. C. S.; Rodbell, D. T.; Seltzer, G. O.; Young, K. R.; Leon, B.; Abbott, M. B.; Silman, M. R.; Gosling, W. D. (Journal of Quaternary Science, 2005)
The manifestation of major climatic events such as the timing of deglaciation and whether, or not, the Younger Dryas affected Andean systems has garnered considerable recent attention. Even the Holocene is rapidly emerging as a time of considerable interest in Neotropical palaeoclimatology and palaeoecology. The Holocene of the Neotropics is now revealed as a time of some temperature change with precipitation:evaporation ratios fluctuating markedly. Major changes in lake level, ice-accumulation, and vegetation are indicative of changes both in precipitation and temperature regimes. Although global-scale forcing mechanisms may underlie some of these changes, e.g. the precessional rhythm, other variability appears to be localised. In a record from near the upper forest limit of the eastern Peruvian Andes, pollen, charcoal, and sedimentary data suggest that the deglaciational period from ca. 17 000 to ca. 11 500 cal. yr BP was a period of rapid climatic oscillations, set against an overall trend of warming. A warm-dry event is evident between ca. 9500 and ca. 7300 cal. yr BP, and comparisons with other regional archives suggest that it was regional in scale. A ca. 1500-yr periodicity in the magnetic susceptibility data is evident between 12 000 and 6000 cal. yr BP, reaching a peak intensity during the dry event. A weaker oscillation with a 500–600-yr periodicity is present throughout much of the Holocene. The uppermost sample of the pollen analysis reveals deforestation as modern human land use simplified the landscape.
id: 1015

A 2000-year reconstruction of forest disturbance from southern Pacific Costa Rica - Anchukaitis, K. J.; Horn, S. P. (Palaeogeography Palaeoclimatology Palaeoecology, 2005)
We reconstruct prehistoric and historic human forest disturbance and vegetation change in southern Pacific Costa Rica, in the vicinity of the Las Cruces Biological Station and the La Amistad International Park and Biosphere Reserve. Pollen and charcoal in sediments from Laguna Santa Elena reveal a nearly continuous record of human alteration of these tropical forests over the past two millennia. The basal portion of the core shows nearly intact premontane forests approximately 1800 cal. year B.P., although there is evidence of human presence on the landscape in the form of maize pollen and charcoal. Clearing for agriculture resulted in the dominance of disturbance taxa in the watershed beginning at least 1400 cal. year B.P. The pollen record reveals a possible, brief hiatus in human occupation of the watershed at approximately 540 cal. year B.P., although secondary succession began to occur in the Laguna Santa Elena watershed prior to that time, beginning about 700 cal. year B.P. Three eruptions of nearby Volcan Baru which we date to approximately 610, 1080, and 1440 cal. year B.P., apparently had little direct effect on the prehistoric populations in the immediate vicinity of the lake. Historic and modern land clearance has perpetuated a modem vegetation assemblage of disturbance and successional taxa, (c) 2005 Elsevier B.V. All rights reserved.
id: 1112; 931QJ Times Cited:14 Cited References Count:114

A 2.45 GHz Ion Source for use in Accelerator Mass Spectrometry - von Reden, K. F.; Schneider, R. J.; Roberts, M. L.; Han, B. X.; Wills, J. (11th International Conference on Ion Ssources, 2005)
id: 1707

3-D Electromagnetic Field Modeling and Ion Optics Calculations for a Continuous-Flow AMS System - Han, B. X.; von Reden, K. F.; Roberts, M. L.; Schneider, R. J.; Hayes, J. M. (10th International Conference on Accelerator Mass Spectrometry, 2005)
id: 1708

The 8200 year B. P. event in the slop water system, western sublpolar North Atlantic - Keigwin, L. D.; Sachs, J. P.; Rosenthal, Y.; Boyle, E. A. (Paleoceanography, 2005)
id: 1097

Abundance, composition, and vertical transport of PAHs in marsh sediments - White, H. K.; Xu, L.; Lima, A. L.; Eglinton, T. I.; Reddy, C. M. (Environ Sci Technol, 2005)
Petroleum-derived hydrocarbons continue to persist in Wild Harbor, West Falmouth, MA, following a spill of No. 2 fuel oil in 1969 from the barge Florida. Recent analysis of marsh sediments revealed that residues of degraded oil are present with concentrations of total petroleum hydrocarbons as high as approximately 9 mg g(-1). Polycyclic aromatic hydrocarbons (PAHs) constitute only a minor fraction of these residues with maximum concentrations of 134 mirog g(-1), but their fate is of interest because of their potential toxicity to organisms. As compared to typical unweathered No. 2 fuel oil, the current distribution of PAHs in the sediments reflects substantial weathering by abiotic and biotic processes, specifically a preferential loss of naphthalenes relative to phenanthrenes, as well as isomer-specific biodegradation of alkylated PAHs. Based on comparison to results from an earlier study, it appears that little or no change has occurred to the distribution of PAHs since 1989, indicating that weathering at this site has stalled or is now proceeding at a significantly slower rate. To assess whether sediment-water partitioning and molecular diffusion in the interstitial medium are now the dominant processes controlling the vertical distribution of PAHs, downcore profiles were compared to a numerical model. While in some cases the model accurately reproduced the measured data, there were instances where the distribution of PAHs was slightly under or overestimated. Reasons for these discrepancies are discussed and are likely due to bioturbation, colloid-facilitated transport, or both. Assessment of the influence of these processes on the spilled oil expands our understanding of the overall fate of these compounds and their potential long-term effects on the environment.
White, Helen KXu, LiLima, Ana Lucia CEglinton, Timothy IReddy, Christopher MengResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.2005/11/22 09:00Environ Sci Technol. 2005 Nov 1;39(21):8273-80.

Age and origin of Late Quaternary eolianite, Kaiehu Point (Moomomi), Molokai, Hawaii - Fletcher, C. H.; Murray-Wallace, C. V.; Glenn, C. R.; Sherman, C. E.; Popp, B.; Hessler, A. (Journal of Coastal Research, 2005)
A well-preserved, vertically stacked succession of two genetically distinct eolianites and associated caliche paleosol units, capped by modern and Holocene coastal dunes, occurs at Kaiehu Point, west Molokai, Hawaii. The Pleistocene eolianite facies comprise well-cemented, medium grained skeletal carbonate sand and their morphostratigraphic context implies formation at times of lower than present sea level. Amino acid racernization (AAR) evidence suggests eolianite formation late in marine Oxygen Isotope Stage (OIS) 5, but lacks the precision to uniquely define in which isotopic substage the deposits formed. Coupled with the AAR results, the morphostratigraphic evidence, would suggest that the Lower Eolianite formed in OIS 5c and the Middle Eolianite during 5a with their superposed caliche paleosols having formed in subsequent stadial stages. The unconsolidated coastal sand dunes of Holocene age contain reworked Late Pleistocene skeletal carbonate sand based on AAR evidence. The most likely source of the reworked carbonate is from the erosion of the eolianites at Kaiehu Point. The Pleistocene eolianite-caliche paleosol sediments reveal variable Mg-content, stable isotope ratios and petrological characteristics consistent with changing degrees of weathering intensity and meteoric diagenesis. These changes are attributed to orographic effects resulting from relative sea-level changes. Accordingly, a two-phase model is favored for the formation of the eolianite-paleosol successions at Kaiehu Point, west Molokai. Eolianite sedimentation is initiated at times of marginally lower sea levels promoting the landward migration of bioclastic sand to form extensive eolian sandsheets. This is followed by a more pronounced phase of pedogenesis associated with a further fall in sea level and concomitant increased rainfall due to enhanced orographic effects.
Sp. Iss. 42947fu Times Cited:3 Cited References Count:50
Keywords: Amino acid racemization; aminostratigraphy; bermuda; carbonate lithofacies; cementation; cliche paleosols; eolianite; hawaii; island; Late Quaternary; limestone petrology; Marine; molokai; oahu; precipitation; sea level; sea-level; south-australia; Stable isotopes; stratigraphy

Age validation of canary rockfish (Sebastes pinniger) from off the Oregon coast (USA) using the bomb radiocarbon method - Piner, K. R.; Hamel, O. S.; Menkel, J. L.; Wallace, J. R.; Hutchinson, C. E. (Canadian Journal of Fisheries and Aquatic Sciences, 2005)
The alternating translucent and opaque banding pattern in canary rockfish (Sebastes pinniger) otoliths, aged using a break-and-burn methodology, are annual markings. To validate age assignment, we compared measured radiocarbon levels in canary rockfish otolith cores with a reference chronology developed from known age Pacific halibut (Hippoglossus stenolepis). An average 2- to 3-year phase shift was detected between the canary rockfish and a Pacific halibut reference chronology that was likely the result of differences in the regional oceanography or underageing bias. The assumption of ageing bias consistency was tested with two sampling designs. The first design controled for age-related ageing error, and the second design related birth year to estimated age. No change in the magnitude of ageing bias as a function of age was detected.
932zxTimes Cited:27Cited References Count:27

The American Mediterranean: the influence of human populations on the ecosystem of Long Island Sound - Thomas, E.; Varekamp, J. C.; Thaler, B.; Sangiorgio, F. (Living on the Edge, 2005)
id: 1184

Amplitude and timing of sea-surface temperature change in the northern South China Sea: Dynamic link to the East Asian monsoon - Oppo, D. W.; Sun, Y. B. (Geology, 2005)
Magnesium/calcium (Mg/Ca) ratios of foraminiferal shells from a sediment core from the northern South China Sea, a semi-enclosed basin in the western tropical Pacific, document variations in sea-surface temperature (SST) during the past 145 k.y. Glacial SSTs were 4 degrees C colder than interglacial SSTs. During the last deglaciation, most of the warming was accomplished in a single abrupt step after continental ice-sheet decay had already begun, but warming and ice-sheet demise were nearly synchronous during the penultimate deglaciation. Abrupt SST changes of the past 15 k.y. were apparently synchronous with events in East Asian monsoon rainfall, suggesting that variations in monsoon winds and their influence on surface circulation of the western Pacific exerted a strong control on northern South China Sea SSTs. We suggest that this link persisted for the previous 130 k.y., during which time orbital-scale 2-3 degrees C SST changes and several small (<= 2 degrees C) abrupt SST events occurred in the northern South China Sea. The similar timing of northern South China Sea SST, on a benthic delta O-18 time scale, to a well-dated speleothem record from eastern China suggests that the demise of ice sheets associated with the penultimate deglaciation did not precede Northern Hemisphere summer insolation increase. Our results suggest that surface waters had higher delta O-18 values during times of strong summer monsoon than during times of weak monsoon, likely reflecting a redistribution of O-18 depleted rainfall from land during times of strong summer monsoons, to the western Pacific during times of weaker summer monsoons.
969rmTimes Cited:66Cited References Count:38

Are bacteria actively degrading petroleum residues from the West Falmouth oil spill? New insights from 14C analysis of bacterial lipids - Slater, G. F.; White, H. K.; Eglinton, T. I.; Reddy, C. M. (Environmental Science and Technology, 2005)
id: 1189

Assessing in situ mineralization of recalcitrant organic compounds in vadose zone sediments using delta(13)C and (14)C measurements - Kirtland, B. C.; Aelion, C. M.; Stone, P. A. (Journal of Contaminant Hydrology, 2005)
Few techniques exist to measure the biodegradation of recalcitrant organic compounds such as chlorinated hydrocarbons (CHC) in situ, yet predictions of biodegradation rates are needed for assessing monitored natural attenuation. Traditional techniques measuring O(2), CO(2), or chemical concentrations (in situ respiration, metabolite and soil air monitoring) may not be sufficiently sensitive to estimate biodegradation rates for these compounds. This study combined isotopic measurements ((14)C and delta(13)C Of CO(2) and delta(13)C of CHCs) in conjunction with traditional methods to assess in situ biodegradation of perchloroethylene (PCE) and its metabolites in PCE-contaminated vadose zone sediments. CHC, ethene, ethane, methane, O(2), and CO(2) concentrations were measured over 56 days using gas chromatography (GC). 613C of PCE, trichloroethylene (TCE) and cis- 1,2-dichloroethylene (DCE), delta(13)C and (14)C of vadose zone CO(2) and sediment organic matter, and delta(13)C, (14)C, and deltaD of methane were measured using a GC-isotope ratio mass spectrometer or accelerator mass spectrometer. PCE metabolites accounted for 0.2% to 18% of CHC concentration suggesting limited reductive dechlorination. Metabolites TCE and DCE were significantly enriched in (13)C with respect to PCE indicating metabolite biodegradation. Average delta(13)C-CO(2) in source area wells (-23.5parts per thousand) was significantly lower compared to background wells (- 18.4%o) indicating CHC mineralization. Calculated CHC mineralization rates were 0.003 to 0.01 mg DCE/kg soil/day based on lower (14)C values Of CO(2) in the contaminated wells (63% to 107% modem carbon (pMC) relative to the control well (117 pMC). Approximately 74% of the methane was calculated to be derived from in situ CHC biodegradation based on the (14)C measurement of methane (29 pMC). (14)C-CO(2) analyses was a sensitive measurement for quantifying in situ recalcitrant organic compound mineralization in vadose zone sediments for which limited methodological tools exist. (C) 2004 Elsevier B.V All rights reserved.
883lpTimes Cited:11Cited References Count:52

Assessing variability in the character and reactivity of DOM and POM delivered to the oceans by rivers and estuaries - Bauer, J. E. (Gordon Research Conference on Chemical Oceanography, 2005)
id: 1025

Bacterial incorporation of relict carbon in the hydrothermal environment of Guaymas Basin - Pearson, A.; Seewald, J. S.; Eglinton, T. I. (Geochimica Et Cosmochimica Acta, 2005)
Radiocarbon analyses of bulk carbon and individual organic compounds are presented for the hydrothermal environment of the Rebecca's Roost vent in the southern trough of the Guaymas Basin hydrothermal field. The Delta(14)C values of CO, and CH4 in the hottest hydrothermal fluids (317 degrees C) are nearly "radiocarbon dead" (-944 parts per thousand and -923 parts per thousand, respectively). In contrast, the Delta(14)C values of sediments and individual fatty acids (-418 parts per thousand to -227 parts per thousand) obtained from a bacterial mat located south of the vent site are similar to values previously reported for hydrothermal petroleum in this environment and are more depleted in C-14 than overlying waters. Hydrothermal fluids moving through the sediments appear to supply C-14 of intermediate age to the bacteria. This carbon may take the form of, or may be supplied by processes similar to, the generation of hydrothermal petroleum. Although the bacterial mat visibly was dominated by Beggiatoa spp., such mats are known to include numerous other species. Individual compound data show that preaged carbon is being consumed by the integrated bacterial assemblage. Values of delta(13)C and Delta(14)C indicate that petroleum-derived carbon is incorporated directly into fresh bacterial biomass. Subsequently, some of this newly synthesized material also is consumed by heterotrophs, as eukaryotic sterols from the same sample also have C-14-depleted values (Delta(14)C = -136 parts per thousand to -110 parts per thousand). Therefore, the entire system may operate as a complex consortium to transform relict carbon back into biomass. Bacterial consumption of relict carbon occurs despite the ample supply of fresh carbon delivered from the productive, overlying water column. Copyright (c) 2005 Elsevier Ltd.
999tpTimes Cited:36Cited References Count:69

Basal inflection-control led shelf-edge wedges off New Jersey track sea-level fall - Gulick, S. P. S.; Goff, J. A.; Austin, J. A.; Alexander, C. R.; Nordfjord, S.; Fulthorpe, C. S. (Geology, 2005)
A key marker for examining the latest Pleistocene history of the New Jersey margin is the high-amplitude, long-recognized R-horizon reflector. This time-transgressive surface was formed 4733 ka and represents the integrated topographic and bathymetric surface developed during the complicated sea-level oscillation associated with the regression that preceded the Last Glacial Maximum (LGM). From landward to seaward across the outer shelf, the R reflector changes from subhorizontal, in most locations < 9 m beneath the modern seafloor, to seaward dipping, forming the base of two of flapping sediment wedges: the previously described outer-shelf wedge and a deep-shelf wedge seaward of it. This transition occurs across two inflection zones, where the dip of the R reflector steepens seaward, that can be traced for tens of kilometers along strike and mark the landward limits of these wedges. These inflection zones are possibly former wave-dominated shorefaces; these represent the primary topographic elements present during the last regression. We speculate that these inflections dictated both the locations for deposition of the two prograding, of flapping wedges that developed during the complex sea-level fall prior to the LGM and their successive erosion before and after the LGM. We suggest that such inflection zones and their associated wedges are important markers of regression in clastic-dominated outer-shelf settings along passive margins.
922awTimes Cited:19Cited References Count:24

Basin-wide sedimentation changes and deglacial lake-level rise in the Hovsgol basin, NW Mongolia - Prokopenko, A. A.; Kuzmin, M. I.; Wlliams, D. F.; Gelety, V. F.; Kalmychkov, G. V.; Gvozdkov, A. N.; Solotchin, P. A. (Quaternary International, 2005)
A study of 15 gravity cores reveals consistent patterns of lithologic change throughout the Lake Hovsgol basin. Sediments of the last glacial are composed of calcareous clayey silt with an admixture of coarse material from sand to gravel. During the last deglaciation, a basin-wide deposition of finely laminated carbonate mud took place and was ultimately succeeded by the deposition of diatomaccous clayey ooze during the entire Holocene interval. Diatom productivity in Lake Hovsgol during the early Holocene was higher than today, but declined by ca. 6.6 cal ka BP. Sedimentation rate estimates for post-glacial section range from 1.5 to over 6.7 cm/ka for different parts of Lake Hovsgol. Rates appear to have decreased in the late Holocene.The last glacial maximum (LGM) corresponded to a dramatic low stand of Lake Hovsgol on the order of 100 m below today's level, as reflected by littoral facies retrieved in cores from intermediate depths. Age dating of plant fragments in these sediments suggests that lake level started rising no later than 15.4 cal ka BP. By the beginning of the Holocene, Lake Hovsgol evolved from a low-level closed basin lake to an overflowing freshwater lake. The observed dramatic lithologic change and evidence for lake-level change suggest that Lake Hovsgol may in fact serve as a sensitive 'water gauge' in continental interior Asia and that the Hovsgol sedimentary record preserves reliable proxies for past changes in effective moisture balance in the Lake Baikal catchment area. (c) 2004 Elsevier Ltd and INQUA. All rights reserved.
926rlTimes Cited:51Cited References Count:16

Beads, bifaces, and boats: an early maritime adaptation on the south coast of San Miguel Island, California - Erlandson, Jon M.; Braje, Todd J.; Rick, Torben C.; Peterson, Jenna (American Anthropologist, 2005)
id: 442

Beam Profile Measurements for a MC-SNICS Source with Spherical Ionizer - von Reden, K. F.; Griffin, V. S.; Roberts, M. L. (10th International Conference on Accelerator Mass Spectrometry, 2005)
id: 1706

Biogeochemical investigations of marine methane seeps, Hydrate Ridge, Oregon - Valentine, D. L.; Kastner, M.; Wardlaw, G. D.; Wang, X. C.; Purdy, A.; Bartlett, D. H. (Journal of Geophysical Research-Biogeosciences, 2005)
[1] A series of biogeochemical studies were conducted at the southern summit of Hydrate Ridge, offshore Oregon. Using the submersible DSV Alvin, sediment push cores were collected from two distinct seep environments characterized by the presence of clam fields (CF) or microbial mats (MM) at the sediment-water interface; samples were also collected from a nearby reference site characterized by a barren surface at the sediment-water interface. Sediment samples from each setting were analyzed for the depth distributions of total organic carbon (concentrations, delta C-13 and Delta C-14), total sedimentary nitrogen, and microbial abundance. Pore fluids were extracted and analyzed for sulfate, alkalinity, sulfide, organic carbon, and volatile organic acids. These depth distributions clearly indicate the presence of three distinctive biogeochemical settings in the surface sediments of Hydrate Ridge, and provide the basis for a comparative biogeochemical analysis. Both CF and MM sites display properties indicating enhanced microbial activity in the subsurface, compared with the reference site. MM sites display evidence of net biomass production in the subsurface; however, a loss of sediment nitrogen relative to the reference site indicates that mineralization is also enhanced. Calculations based on the removal of nitrogen indicate that greater than 30% of autochthonous organic material is lost to enhanced mineralization in the top 23 cm of one MM site. An isotope mass balance of sediment-bound organic carbon indicates a mixed source, including methane and allochthonous organic carbon dissolved in the seep fluids. The concentrations of organic carbon dissolved in seep fluids reach values of 22 mM and provide a first indication that advective transport of dissolved organic carbon from great depth may supply an important source of energy and carbon to "methane seep'' communities.
090wnTimes Cited:19 Cited References Count:72
Keywords: anaerobic oxidation; authigenic carbonates; cascadia convergent margin; community structure; dissolved organic-carbon; fluid-flow; ne pacific; odp site 892b; phylogenetic analysis; sulfate-reducing bacteria

Blank correction for Delta 14C measurements in organic compound classes of oceanic particulate matter - Hwang, Jeomshik; Druffel, Ellen R. M. (Radiocarbon, 2005)
id: 1054

Calculation of hydrogen isotopic fractionations in biogeochemical systems - Sessions, A. L.; Hayes, J. M. (Geochimica Et Cosmochimica Acta, 2005)
Hydrogen-isotopic data are often interpreted using mathematical approximations originally intended for other isotopes. One of the most common. apparent in literature over the last several decade's. assumes that delta values of reactants and products are separated by a constant fractionation factor delta(p) = delta(r) + epsilon(p/r). Because of the large fractionations that affect hydrogen isotopes, such approximations can lead to substantial errors. Here we review and develop general equations for isotopic mass balances that include the differential fractionation of each component in a mixture and discuss their use in three geochemical applications. For the fractionation of a single component. the reactant and product are related by delta(p) = a(p/r)delta(r) + epsilon(p/r), where alpha and epsilon refer to the same fractionation. Regression of delta(p) on delta(r) should give equivalent fractionations based on the intercept and slope, but this has not generally been recognized in studies of D/H fractionation. In a mixture of two components, each of which is fractionated during mixing, there is no unique solution for the three unknown variables (two fractionation factors and the elemental mixing ratio of the two hydrogen sources). The flow of H from CH4 and H2O to bacterial lipids in the metabolism of Methylococcus capsulatus provides an example of such a case. Data and conclusions from an earlier study of that system (Sessions et al., 2002) are reexamined here. Several constraints on the variables are available based on plausible ranges for fractionation factors. A possible refinement to current experimental procedures is the measurement of three different isotopes, which would allow unique determination of all variables. Copyright (C) 2005 Elsevier Ltd.
892wiTimes Cited:55Cited References Count:21

Carbon and nitrogen isotope compositions of organic matter in coastal marine sediments (the Gulf of Trieste, N Adriatic Sea): indicators of sources and preservation - Ogrinc, N.; Fontolan, G.; Faganeli, J.; Covelli, S. (Marine Chemistry, 2005)
Terrestrial organic carbon (OC) preserved in marine sediments is an important reservoir in the global carbon cycle, but remains poorly constrained. We determined the elemental and C- and N-isotopic compositions of organic material (OM) in surface sediments and sediment cores from the Gulf of Trieste (N Adriatic), an area characterized by relatively high riverine input. This multiple tracer approach permits evaluation of how sensitive each tracer is for constraining the terrestrial component of OM. Using the relevant terrestrial and marine OM end-members, we estimate that the terrestrial contribution ranges from about 90% at the mouth of the Isonzo River and decreases to <= 10% in the center of the Gulf. In the southern part of the Gulf, 32-44% of terrestrial OC is contributed from smaller rivers, while the delta(15)N values of OM reflect more effective nutrient utilization. Analyses of different size fractions show that smaller particles are consistently more organic-rich and tend to be transported further from the river mouth, depending on river discharge. In the size fraction 2-16 mu m, elemental ratios and delta(13)C(org) and delta(15)N isotopic signatures are consistent with a sedimentary OM pool dominated by bacterially derived biomass. Radiocarbon analyses of sedimentary OC yield depleted Delta(14)C values (-338.7 parts per thousand to -429.4 parts per thousand), indicating a significant fraction of relatively old OC. The natural abundance of C-13 and C-14 tracers suggests a two-component mixture of ancient and modem C in the sediments down to approximately 60 cm sub-bottom, with an estimated similar to 45% of sedimentary OC probably being derived from ancient sedimentary OC (kerogen). In addition, there is a significant change in the source of organic material downcore in these sediments which, along with geological evidence, indicate contributions from freshwater swamps typical of coastal lakes with intermittent connections to the sea (brackish) prior to similar to 9000 BP. Depth variations in a core from a salt marsh further indicate temporal variability of OM deposition and transformations in a changing brackish-marine environment in the past. (C) 2004 Elsevier B.V. All rights reserved.
934goTimes Cited:76Cited References Count:77

Carbon isotopes from fossil packrat pellets and elevational movements of Utah agave plants reveal the Younger Dryas cold period in Grand Canyon, Arizona - Cole, K. L.; Arundel, S. T. (Geology, 2005)
Carbon isotopes in rodent fecal pellets were measured on packrat (Neotoma spp.) middens from the Grand Canyon, Arizona. The pellet samples reflect the abundance of cold-intolerant C4 and Crassulacean acid metabolism (CAM) plant species relative to the predominant C3 vegetation in the packrat diet. The temporal sequence of isotopic results suggests a temperature decline followed by a sharp increase corresponding to the Boiling/ Allerod-Younger Dryas-early Holocene sequence. This pattern was then tested using the past distribution of Utah agave (Agave utahensis). Spatial analyses of the range of this temperature-sensitive CAM species demonstrate that its upper elevational limit is controlled by winter minimum temperature. Applying this paleotemperature proxy to the past ellevational limits of Utah agave suggests that minimum winter temperatures were similar to 8 degrees C below modern values during the Last Glacial Maximum, 4.5-6.5 degrees C below modern during the Bolling/Allerod, and 7.5-8.7 degrees C below modern during the early Younger Dryas. As the Younger Dryas terminated, temperatures warmed similar to 4 degrees C between ca. 11.8 ka and 11.5 ka. These extreme fluctuations in winter minimum temperature have not been generally accepted for terrestrial paleoecological records from the and southwestern United States, likely because of large statistical uncertainties of older radiocarbon results and reliance on proxies for summer temperatures, which were less affected.
960jfTimes Cited:22Cited References Count:26

Carbon Isotopes in Riverine Systems - Raymond, P. A. (Lindeman Speaker, Department of Ecology, Evolution and Behavior, 2005)
id: 487

Catastrophic meltwater discharge down the Hudson River Valley: A potential trigger for the Intra-Allerod cold period - Donnelly, J. P.; Driscoll, N.; Uchupi, E.; Keigwin, L.; Schwab, W.; Thieler, E. R.; Swift, S. (Geology, 2005)
id: 1033

Coastal foraging at Otter Cave: a 6600 year old shell midden on San Miquel Island, California - Erlandson, Jon M.; Vellanoweth, Rene L.; Rick, Torben C.; Batterson, Melissa R. (Journal of California and Great Basin Anthropology, 2005)
id: 580

The composition and transport of organic carbon in rainfall: insights from the natural (13C and 14C) isotopes of carbon - Raymond, P. A. (Geophysical Research Letters, 2005)
id: 599

Computer Control - Roberts, M. L. (Electrostatic accelerators: fundamentals and applications, 2005)
id: 1686

Continuous-Flow Accelerator Mass Spectrometry - Roberts, M. L.; von Reden, K. F.; Han, B. X.; Schneider, R. J.; Benthien, A.; Hayes, J. M. (the International Symposium on Utilization of Accelerators, 2005)
id: 767

Contribution of biomass burning to polycyclic aromatic hydrocarbons in European background aerosols - Mandalakis, M.; Gustafsson, O.; Alsberg, T.; Reddy, C.; Xu, L.; Klanova, J.; Holoubek, I.; Stephanou, E. (Environmental Science and Technology, 2005)
id: 510

Cross-formational flow and salinity sources inferred from a combined study of helium concentrations, isotopic ratios, and major elements in the Marshall aquifer, southern Michigan - Ma, L.; Castro, M. C.; Hall, C. M.; Walter, L. M. (Geochemistry Geophysics Geosystems, 2005)
Helium data and major ion chemistry are presented for the shallow Marshall aquifer in southern Michigan. This data set is subsequently analyzed in conjunction with major element data sets from deeper and shallower water levels previously collected in this area. He excesses and isotopic ratios suggest the presence of tritiogenic He-3 in young waters in the Marshall aquifer. He excesses in old groundwater samples are mostly of crustal origin although the presence of a significant mantle He component in some samples cannot be ruled out. He excesses in the Marshall aquifer are unusually high for such shallow depths ( <= 300 m) and reach over two and three orders of magnitude above those of air- saturated water ( ASW) for He-3 and He-4, respectively. He isotopes require a source external to the aquifer, partly supplied by underlying formations within the sedimentary sequence, partly from the crystalline basement. Calibration of He concentrations observed in the Marshall aquifer requires He fluxes of 1 x 10(-13) and 1.6 x 10(-6) cm(3) STP cm(-2) yr(-1) for He-3 and He-4, respectively. These He fluxes are far greater than those reported in other sedimentary basins around the world ( e. g., Paris Basin, Gulf Coast Basin) at similar and far greater depths. Such high He fluxes present at such shallow depths within the Michigan Basin strongly suggest the presence of a dominant vertical water flow component and further indicate that impact of recharge water at depth is minor. Upward cross- formational flow is also likely responsible for the extremely high salinities present in the shallow subsurface of the Michigan Basin. The observed positive correlation between helium and bromide strongly suggests that these two very distinct conservative tracers both originate at greater depths and further suggests that advection is the dominant transport mechanism within the basin. The occurrence of large- scale cross- formational flow is also consistent with the evolution displayed by the major ion chemistry throughout most of the sedimentary sequence, indicating that solutes from shallow levels carry the signature of deep formation brines.
973vwTimes Cited:18Cited References Count:63

A decrease in discharge-normalized DOC export by the Yukon River during summer through autumn - Striegl, R. G.; Aiken, G. R.; Dornblaser, M. M.; Raymond, P. A.; Wickland, K. P. (Geophysical Research Letters, 2005)
Climate warming is having a dramatic effect on the vegetation distribution and carbon cycling of terrestrial subarctic and arctic ecosystems. Here, we present hydrologic evidence that warming is also affecting the export of dissolved organic carbon and bicarbonate (DOC and HCO3-) at the large basin scale. In the 831,400 km(2) Yukon River basin, water discharge (Q) corrected DOC export significantly decreased during the growing season from 1978 - 80 to 2001 - 03, indicating a major shift in terrestrial to aquatic C transfer. We conclude that decreased DOC export, relative to total summer through autumn Q, results from increased flow path, residence time, and microbial mineralization of DOC in the soil active layer and groundwater. Counter to current predictions, we argue that continued warming could result in decreased DOC export to the Bering Sea and Arctic Ocean by major subarctic and arctic rivers, due to increased respiration of organic C on land.
985cuTimes Cited:163 Cited References Count:28
Keywords: alaska; arctic-ocean; climate-change; CO2; discontinuous permafrost; dissolved organic-carbon; flux; MATTER; tundra