Radiocarbon dating of diatom-bound organic compounds - Ingalls, A. E.; Anderson, R. F.; Pearson, A. (Marine Chemistry, 2004)
Here we present a new method for obtaining radiocarbon dates for the organic compounds intrinsic to diatom frustules. This method will improve age models for sediment cores that lack calcium carbonate and improve current interpretations of diatom-based paleoproxies. In preparation for radiocarbon dating by Accelerator Mass Spectrometry, compounds intrinsic to diatom frustules are released from their opal matrix by dissolution in HF and then purified using preparative liquid chromatography-mass spectrometry (LC-MS). The method was applied to one sample from each of three cores (NBP9802 Station 7 GC2; TN057-13 PC4; Ell-2) and a plankton tow (CRS 746, FOODBANCS) collected in the Southern Ocean. In each sample, radiocarbon ages of diatom-bound organic compounds differed from those obtained from foraminiferal CaCO3. Agreement between the foraminifera and compound-specific date was best in cores Ell-2 and TN057-13. In contrast, compound-specific C-14 ages obtained from NBP9802 differed substantially from those measured for foraminiferal CaCO3. The influence of background contamination was assessed throughout all stages of the method and cannot be responsible for the discrepancy observed. Possible reasons for the disagreement between the ages of foraminifera and diatom-bound compounds are discussed in the context of sediment dynamics. These preliminary results suggest that our diatom-based dating method represents a major step forward in our ability interpret sediment records in the Southern Ocean and therefore our understanding of the role of the Southern Ocean in past climate. (C) 2004 Elsevier B.V. All rights reserved.
882iaTimes Cited:34Cited References Count:33

Radiocarbon evidence for a naturally-produced, bioaccumulation halogenated organic compound - Reddy, C. M.; Xu, L.; O'Neil, G. W.; Nelson, R. K.; Eglinton, T. I.; Faulkner, D. J.; Norstrom, R.; Ross, P. S.; Tittlemier, S. A. (Environmental Science and Technology, 2004)
id: 1806

Radiocarbon studies of Long Island Sound sediments - Groner, M.; Thomas, E.; Varekamp, J. C. (EOS Trans. AGU, 2004)
id: 737

Reconsidering Melt-water Pulses 1A and 1B: Global impacts of rapid sea-level rise - Liu, J. P.; Milliman, J. D. (Journal of Ocean University of China, 2004)
id: 649

Red abalone bead production and exchange on California's northern channel islands - Rick, Torben C. (North American Archaeologist, 2004)
id: 574

Relations between environmental black carbon sorption and geochemical sorbent characteristics - Cornelissen, G.; Kukulska, Z.; Kalaitzidis, S.; Christanis, K.; Gustafsson, O. (Environmental Science & Technology, 2004)
Pyrogenic carbon particles in sediments (soot and charcoal, collectively termed "black carbon" or BC) appear to be efficient sorbents of many hydrophobic organic compounds, so they may play an important role in the fate and toxicity of these substances. To properly model toxicant sorption behavior, it is important to (i) quantify the magnitude of the role of BC in sorption and (ii) elucidate which geochemical BC characteristics determine the strength of environmental BC sorption. Sorption isotherms of d(10)-phenanthrene (d(10)-PHE) were determined over a wide concentration range (0.0003-20 mug/L), for five sediments with widely varying characteristics. From the sorption isotherms, we determined Freundlich coefficients of environmental BC sorption, K-F,BC(env). These varied from 10(4.7) to 10(5.5). From the data, it could be deduced that BC was responsible for 49-85% of the total d(10)-PHE sorption at a concentration of 1 ng/L. At higher concentrations, the importance of BC for the sorption process diminished to <20% at 1 mug/L and 0-1% at 1 mg/L. There were no significant relationships between BC sorption strength and the tested geochemical BC characteristics [the fraction of small (<38 mum) BC particles, the BC resistance to high-temperature oxidation, the fraction of biomass-derived BC, the native polycyclic aromatic hydrocarbon and total organic carbon contents]. Because of the limited variation in BC sorption strength with widely varying BC characteristics, the presented BC sorption coefficients may putatively be used as generic starting points for environmental modeling purposes.
834fgTimes Cited:90Cited References Count:48

The Remarkable Metrological History of Radiocarbon Dating [II] - Currie, L. A. (J Res Natl Inst Stand Technol, 2004)
This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought (14)C measurement from a crude, bulk [8 g carbon] dating tool, to a refined probe for dating tiny amounts of precious artifacts, and for "molecular dating" at the 10 microg to 100 microg level. The metrological advances led to opportunities and surprises, such as the non-monotonic dendrochronological calibration curve and the "bomb effect," that gave rise to new multidisciplinary areas of application, ranging from archaeology and anthropology to cosmic ray physics to oceanography to apportionment of anthropogenic pollutants to the reconstruction of environmental history. Beyond the specific topic of natural (14)C, it is hoped that this account may serve as a metaphor for young scientists, illustrating that just when a scientific discipline may appear to be approaching maturity, unanticipated metrological advances in their own chosen fields, and unanticipated anthropogenic or natural chemical events in the environment, can spawn new areas of research having exciting theoretical and practical implications.
Currie, Lloyd Aeng2004/01/01 00:00J Res Natl Inst Stand Technol. 2004 Apr 1;109(2):185-217. doi: 10.6028/jres.109.013. Print 2004 Mar-Apr.

Role of bottom water transport and diapycnic mixing in determing the radiocarbon distribution in the Pacific - Roussenov, V.; Williams, R. G.; Follows, M. J.; Key, R. M. (J. Geophys. Res., 2004)
id: 526

Sampling Mantle Heterogeneity through Oceanic Basalts: Isotopes and Trace Elements - Hofmann, A. W. (Treatise on Geochemistry, 2004)
id: 1525

Sensitivity of present and future surface temperatures to precipitation characteristics - Lynn, Barry H.; Druyan, Leonard; Hogrefe, Christian; Dudhia, Jimy; Rosenzweig, Cynthia; Goldberg, Richard; Rind, David; Healy, Richard; Rosenthal, Joyce; Kinney, Patrick (Climate Research, 2004)
A model simulation study shows that different diurnal cycles of precipitation are consistent with radically different present and future climate characteristics. In projected future climate scenarios, divergence in the time of day and type of precipitation had very divergent impacts on the radiation balance and consequently on surface temperatures. The relationship between the diurnal cycle of precipitation versus the present and future climate was examined using the GISS-MM5 (Goddard Institute for Space Studies Mesoscale Model 5) regional climate modeling system with 2 alternative moist convection schemes. June-August (JJA) mean surface temperatures of the 1990s, 2050s, and 2080s were simulated over the eastern US on a double nested 108/36 km domain, with the 36 km domain centered over the eastern US. In the 1990s, one model version simulated maxima in (convective) precipitation during the early morning, while the second model simulated the hour of precipitation maxima with considerable spatial variability (in better agreement with observations). In the futuristic climate scenarios, differences in the time of day of precipitation had very important impacts on the radiation balance at the surface. One version gave more precipitation at night and fewer clouds during the day, promoting higher surface temperatures. The alternative version created more precipitation during the day, consistent with diminished absorption of solar radiation at the surface and consequently lower surface temperatures. The results demonstrate the importance of improving cumulus parameterizations in regional mesoscale and global climate models and suggest that such improvements would lead to greater confidence in model projections of climate change.
id: 1696

Shoreline Changes on the Elizabeth Islands over the Past 5000 Years - Gaines, Sarah (Cuttyhunk Historical Society, 2004)
id: 715

Social and economic dynamics on Late Holocene San Miguel Island, California - Rick, Torben C. (Foundations of Chumash Complexity, 2004)
id: 575

Spatial variations in a condensed interval between estuarine and open-marine settings: Holocene Hudson River estuary and adjacent continental shelf - McHugh, C. M. G.; Pekar, S. F.; Christie-Blick, N.; Ryan, W. B. F.; Carbotte, S.; Bell, R. (Geology, 2004)
An interval of stratigraphic condensation extending for 300 km from the fluvially dominated Hudson River estuary to the adjacent continental shelf reveals stratal relationships within an unconformity-rellated depositional sequence that are commonly difficult to resolve in seismic reflection profiles and outcrop. High-resolution side-scan sonar and bathymetry, more than 100 sediment cores similar to2 m long, and radioisotope (C-14, Cs-137) age control show that much of the valley was filled by ca. 3 to 1 ka. The present rate of sediment accumulation averages 1 mm/yr, corresponding with a sea-level rise of similar to1.2 mm/yr relative to local bedrock. Condensation is manifested today by sedimentary bypass in most parts of the estuary and by the trapping of available sediment (1.2-5.6 x 10(5) t/yr [metric tons]) along narrow reaches and primarily in the vicinity of the estuarine turbidity maximum, a part of the estuary located upstream of the salinity intrusion similar to25 km from the mouth (3.0 x 10(5) t/yr). Shelf condensation is due to sediment starvation. The condensed interval merges updip with a nascent sequence boundary as the estuary reaches its final filling phase and downdip with the sequence boundary that developed at the Last Glacial Maximum. Delta progradation may take place as available shelf accommodation is filled, but such sediments are expected to be removed once sea level begins to fall. This sedimentation pattern, in which a condensed interval merges with different sequence boundaries, is consistent with the stratigraphic record of the Atlantic margin back to the Paleogene and may be typical of sediment-starved margins.
772lcTimes Cited:10Cited References Count:30

Stable carbon and nitrogen isotopic compositions of organic compound classes in high molecular weight dissolved organic matter from four U. S. estuaries - Wang, X. C.; Altabet, A. M.; Callahan, J.; Chen, R. F. (Geochimica et Cosmochimica Acta, 2004)
id: 515

Stable carbon and oxygen isotope records in a Palau sclerosponge - Grottoli, A. G.; Gibb, O. (Geochimica Et Cosmochimica Acta, 2004)
Suppl. S827th Times Cited:0 Cited References Count:0

Stable carbon isotope ratios in lake and swamp sediments as a proxy for prehistoric forest clearance and crop cultivation in the Neotropics - Lane, C. S.; Horn, S. P.; Mora, C. I. (Journal of Paleolimnology, 2004)
Close correspondence between stable carbon isotope ratios (delta(13)C), pollen, and charcoal profiles in sediment cores from Laguna Zoncho and Machita swamp, Costa Rica, shows that prehistoric forest clearance and crop cultivation can be detected in the stable carbon isotope ratios of total organic carbon (delta(13)C(TOC)). Analyses of delta(13)C(TOC) complement evidence from pollen, charcoal, and phytoliths and provide a proxy that is sensitive to the intensity and/or proximity to core sites of prehistoric forest clearance and agriculture in watersheds. Stable carbon isotope analyses are particularly useful in situations in which other evidence of forest clearance and agriculture is limited.
881ycTimes Cited:30Cited References Count:36

Style, context, and chronology of a wooden canoe model from Santa Rosa Island, California - Rick, Torben C.; Johnson, John R.; Erlandson, Jon M.; Gamble, Lynn H. (Journal of California and Great Basin Anthropology, 2004)
id: 1092

Temporal variability of Delta 14C, delta13C, and C/N in sinking particulate organic matter at a deep time series station in the northeast Pacific Ocean - Hwang, Jeomshik; Druffel, Ellen R. M.; Griffin, Sheila; L, Smith Kenneth, Jr.; Baldwin, Roberta J.; Bauer, James E. (Global Biogeochemical Cycles, 2004)
id: 531

Time averaging on a shallow subtropical shelf: the search for a taphomomic clock - Barbour-Wood, S. L.; Krause R.A, Jr.; Kowalewski, M.; Wehmiller, J. F.; Simoes, M. G. (Geological Society of America, Abstracts with Programs, 2004)
36(2):134
id: 719

The urban sea: anthropogenic influences on benthic foraminifera in Long Island Sound - Thomas, E.; Varekamp, J. C.; Thaler, B.; Groner, M. (IGC 32, 2004)
id: 738

The use of stable carbon isotopes in foraminiferal calcite to trace changes in biological oxygen demand in Long Island Sound - Lugolobi, F.; Varekamp, J. C.; Thomas, E.; Buchholtz ten Brink, M. R. (6th Biennual LIS Res. Conf. Proc., 2004)
id: 723

Variable ageing and storage of dissolved organic components in the open ocean - Loh, A. N.; Bauer, J. E.; Druffel, E. R. M. (Nature, 2004)
Seawater dissolved organic matter (DOM) is the largest reservoir of exchangeable organic carbon in the ocean, comparable in quantity to atmospheric carbon dioxide(1,2). The composition, turnover times and fate of all but a few planktonic constituents of this material are, however, largely unknown(3,4). Models of ocean carbon cycling are thus limited by the need for information on temporal scales of carbon storage in DOM subcomponents, produced via the 'biological pump', relative to their recycling by bacteria(3,4). Here we show that carbohydrate- and protein-like substances in the open Atlantic and Pacific oceans, though often significantly aged, comprise younger fractions of the DOM, whereas dissolved lipophilic material exhibits up to similar to90 per cent fossil character. In contrast to the millennial mean ages of DOM observed throughout the water column, weighted mean turnover times of DOM in the surface ocean are only decadal in magnitude. An observed size-age continuum further demonstrates that small dissolved molecules are the most highly aged forms of organic matter, cycling much more slowly than larger, younger dissolved and particulate precursors, and directly links oceanic organic matter age and size with reactivity(3,5).
847daTimes Cited:93Cited References Count:30

Vegetation and climate changes around the Lama Lake, Taymyr Peninsula, Russia during the Late Pleistocene and Holocene - Andreev, A.A.; Tarasov, P.E.; Klimanov, V.A.; Melles, M.; Lisitsyna, O.M.; Hubberten, H.-W. (HIgh resolution lake sediment records in climate and Environment variability studies:European lake drilling program, 2004)
A continuous lacustrine sequence from the western part of Lama Lake (69°32′N, 90°12′E), complemented by a peat sequence from the lake catchment provides the first detailed environmental reconstruction for the Late Glacial and Holocene on the Taymyr Peninsula. Scarce steppe-like communities with Artemisia, Poaceae, and Cyperaceae dominated during the Late Glacial. Tundra-like communities with Betula nana, Dryas, and Salix grew on more mesic sites. There are distinct climatic signals, which may be correlated with the Bølling and Allerød warming and Middle and Younger Dryas cooling. The Late Glacial/Preboreal transition, at about 10,000 14C yr BP, was characterized by changes from predominantly open herb communities to shrub tundra ones. Larch forest might have been established as early as 9700–9600 14C yr BP, whilst shrub alder came to the area ca 9500–9400 14C yr BP, and spruce did not reach area before ca 9200 14C yr BP. Spruce-larch forests with shrub alder and tree birch dominated the vegetation around the Lama Lake from ca 9000 14C yr BP. Dwarf birch communities were also broadly distributed. The role of spruce in the forest gradually decreased after 4500 14C yr BP. The vegetation cover in the Lama Lake area became similar to the modern larch-spruce forest ca 2500 14C yr BP. A pollen-based biome reconstruction supports a quantitative interpretation of the pollen spectra. Climate reconstructions obtained with information-statistical and plan-functional-type methods show very similar trends in reconstructed July temperature since ca 12,300 14C yr BP, while precipitation anomalies are less coherent, especially during the Late Glacial–Holocene transition.

Vegetation and sedimentation in the Lake Edward Basin, Uganda-Congo during the late Pleistocene and early Holocene - Beuning, K. R. M.; Russell, J. M. (Journal of Paleolimnology, 2004)
New palynological and sedimentological data obtained from the basal 3 m of core E96-2P from Lake Edward, Uganda-Congo record conditions wetter than present in the Edward basin from similar to11000 to 6700 yr BP, in phase with other climate and vegetation records of northern hemispheric East Africa. Dominant pollen taxa include Celtis spp., Alchornea spp., Olea spp., and Moraceae indicating a moist semi-deciduous tropical forest. More xeric indicators such as Amaranthaceae and Asteraceae together with Poaceae comprise less than 5% of the pollen sum throughout this interval as compared with between 44 and 50% during a lake lowstand at similar to2000 cal yr BP and at the core top ( near modern). The differences between these two assemblages suggest a similar to25 to 60% increase in annual precipitation during the early- to mid-Holocene as compared to modern (1500-2000 vs. 1200 mm/yr today). Early Holocene sediments in E96-2P are composed of laminated diatom oozes with moderately high total sulfur concentrations (2.8-4.7%) and no authigenic calcite, also indicative of conditions wetter than present. Between similar to9000 and 6700 yr BP, palynological and sedimentary proxies indicate sub-millennial-scale events related to changes in riverine discharge and runoff in the Edward basin. We attribute the variability in runoff, and hence precipitation, to Holocene variability in Indian or Atlantic Ocean SSTs or to shifts in the relative contribution of Indian and Atlantic moisture sources to the western Rift of equatorial Africa.
814suTimes Cited:11Cited References Count:77

Ventilation of the glacial deep Pacific Ocean - Broecker, W.; Barker, S.; Clark, E.; Hajdas, I.; Bonani, G.; Stott, L. (Science, 2004)
Measurements of the age difference between coexisting benthic and planktic foraminifera from western equatorial Pacific deep-sea cores suggest that during peak glacial time the radiocarbon age of water at 2-kilometers depth was no greater than that of today. These results make unlikely suggestions that a slowdown in deep-ocean ventilation was responsible for a sizable fraction of the increase of the ratio of carbon-14 (14C) to carbon in the atmosphere and surface ocean during glacial time. Comparison of 14C ages for coexisting wood and planktic foraminifera from the same site suggests that the atmosphere to surface ocean 14C to C ratio difference was not substantially different from today's.
Broecker, WallaceBarker, StephenClark, ElizabethHajdas, IrkaBonani, GeorgesStott, Lowelleng2004/11/13 09:00Science. 2004 Nov 12;306(5699):1169-72.

Western Long Island Sound: evidence from diatom studies of eutrophication and environmental change in the 19th centure - Cooper, S. R.; Thomas, E.; Varekamp, J. C.; Sangiorgio, F. (AERS fall meeting, 2004)
id: 736

14C activity and global carbon cycle changes over the past 50,000 years - Hughen, K. A.; Lehman, S. J.; Southon, J.; Overpeck, J. T.; Marchal, O.; Herring, C.; Turnbull, J. (Abstracts, 18th International Radiocarbon Conf., 2003)
id: 1079

A 1600-year history of the Labrador Current off Nova Scotia - Keigwin, L. D.; Sachs, J. P.; Rosenthal, Y. (Climate Dynamics, 2003)
A multicore from Emerald Basin, on the continental margin off Nova Scotia, has a modern C-14 age at the top, and other C-14 dates indicate a linear sedimentation rate of similar to30 cm/ka to 1600 calendar years BP. This rate is great enough to record century-to-millennial scale changes in the surface and deep (similar to250 m) waters in the basin that are influenced by the Labrador Current. We applied five proxies for seawater temperature changes to the sediments of Emerald Basin, including the percent abundance and the oxygen isotope ratio (delta(18)O) of the polar planktonic foraminifer N. pachyderma (s.), the unsaturation ratio of alkenones (U-37(k')) produced by prymnesiophyte phytoplankton, and the delta(18)O and Mg/Ca of benthic foraminifera. All five proxies indicate the ocean warmed suddenly sometime in the past 150 years or so. The exact timing of this event is uncertain because C-14 dating is inaccurate in recent centuries, but this abrupt warming probably correlates with widespread evidence for warming in the Arctic in the nineteenth century. Because the Canadian Archipelago is one of the two main sources for the Labrador Current, warming and melting of ice caps in that region may have affected Labrador Current properties. Before this recent warming, sea surface temperature was continually lower by 1-2 degreesC, and bottom water was colder by about 6 degreesC in Emerald Basin. These results suggest that there was no Medieval Warm Period in the coastal waters off Nova Scotia. Because there is also no evidence of medieval warming in the Canadian archipelago, it seems likely that coastal waters from Baffin Bay to at least as far south as Nova Scotia were continually cold for similar to1500 of the past 1600 years.
698thTimes Cited:25Cited References Count:31

1999 RV Melville Baja California cruise, on the preservation of laminated sediments along the western margin of North America - van Geen, A.; Zheng, Y.; Bernhard, J. M.; Cannariato, K. G.; Carriquiry, J.; Dean, E.; Eakins, B. W.; Ortiz, J. D.; Pike, J. (Paleoceanography, 2003)
id: 1102

A 725 yr cycle in the climate of central Africa during the late Holocene - Russell, J. M.; Johnson, T. C.; Talbot, M. R. (Geology, 2003)
High-resolution analyses of the chemical and stable isotope composition of endogenic calcite from Lake Edward, an equatorial rift take in central Africa, reveal large oscillations in African climate and moisture balance over the past 5400 yr. These oscillations indicate a series of droughts from 4900 to 400 yr B.P. that define a drought period of similar to725 yr. This period may be correlated to variations in the Indian Ocean monsoons, as documented by similar periods in sea-surface salinity records from the northern Indian Ocean. The similarities in periodicity of the Lake Edward and Indian Ocean records may indicate that low-frequency variability within the Indian and Pacific Oceans dominates millennial-scale African moisture balance and the Holocene climate of the tropical Indian Ocean.
710ajTimes Cited:27Cited References Count:34

Abrupt changes in the Asian southwest monsoon during the Holocene and their links to the North Atlantic Ocean - Gupta, A. K.; Anderson, D. M.; Overpeck, J. T. (Nature, 2003)
During the last ice age, the Indian Ocean southwest monsoon exhibited abrupt changes that were closely correlated with millennial-scale climate events in the North Atlantic region(1-3), suggesting a mechanistic link. In the Holocene epoch, which had a more stable climate, the amplitude of abrupt changes in North Atlantic climate was much smaller, and it has been unclear whether these changes are related to monsoon variability. Here we present a continuous record of centennial-scale monsoon variability throughout the Holocene from rapidly accumulating and minimally bioturbated sediments in the anoxic Arabian Sea. Our monsoon proxy record reveals several intervals of weak summer monsoon that coincide with cold periods documented in the North Atlantic region(4)-including the most recent climate changes from the Medieval Warm Period to the Little Ice Age and then to the present. We therefore suggest that the link between North Atlantic climate and the Asian monsoon is a persistent aspect of global climate.
637uwTimes Cited:483Cited References Count:30

Acceptance of the 2002 V. M. Goldschmidt Award - Hayes, J. M. (Geochimica Et Cosmochimica Acta, 2003)
693mfTimes Cited:0Cited References Count:0

Accumulation of biogenic and lithogenic material in the Pacific sector of the Southern Ocean during the past 40,000 years - Chase, Z.; Anderson, R. F.; Fleisher, M. Q.; Kubik, P. W. (Deep-Sea Research Part Ii-Topical Studies in Oceanography, 2003)
The (230)Th-normalization technique was applied to surface sediments and down-core records from the Pacific sector of the Southern Ocean between 120degreesW and 170degreesW in order to reconstruct vertical rain rates, corrected for lateral redistribution of sediment. Preserved rain rates of opal, organic carbon and biogenic Ba all indicate that biological productivity south of the Antarctic Polar Front (APF) was much lower than today during the Last Glacial Maximum (LGM), probably in response to increased ice cover. However, by analogy with modern opal fluxes south of the ACC, we show that year-round ice cover is not a prerequisite for very low rates of opal accumulation. Available records from north of the APF indicate little to no change in opal export, in contrast to records from the Indian and Atlantic sectors, which show enhanced opal export north of the APF during the LGM. Glacial records from north of 66degreesS in the Pacific all show lithogenic fluxes that were greater than today, but significantly lower than lithogenic fluxes in the glacial Atlantic and Indian sectors. Together, these new records from the Pacific sector show that during the LGM the three basins of the Southern Ocean were significantly more differentiated than today. The observed inter-basin distribution of lithogenic fluxes and opal burial, and the presumed geographical distribution of increased dust input to the Southern Ocean during the LGM, are consistent with an Atlantic-Indian-Pacific gradient in the degree of iron-stimulated diatom productivity within the zone lying between the APF and the Subantarctic Front. Previous studies, which focused primarily on the Atlantic sector, may have overestimated the glacial increase in the strength of the biological pump in the Southern Ocean. (C) 2002 Elsevier Science Ltd. All rights reserved.
662agTimes Cited:82 Cited References Count:86
Keywords: antarctic circumpolar current; atmospheric co2; biological productivity; Deep-sea; interglacial changes; Last glacial maximum; marine-sediments; organic-carbon; pa-231/th-230 ratio; terrigenous sediment

Age determination, validation and growth of Grand Bank yellowtail flounder (Limanda ferruginea) - Dwyer, K. S.; Walsh, S. J.; Campana, S. E. (Ices Journal of Marine Science, 2003)
Yellowtail flounder (Limanda ferruginea) (Storer, 1839) on the Grand Bank off Newfoundland were traditionally aged using surface-read whole otoliths. Age determination of otoliths from recaptures of fish tagged in the early 1990s indicated that the traditional ageing technique was underestimating the ages of yellowtail flounder when compared with the time at liberty. Age comparisons between whole and thin-sectioned otoliths showed agreement in age readings up to 7 years; thereafter whole otoliths tended to give much lower ages than those estimated by thin sections. Length-frequency analysis of pelagic and demersal juveniles, captive rearing of juveniles and marginal increment analysis all corroborated age determination based on thin sections. Tag-recaptures and bomb radiocarbon assays validated age interpretations based on thin sections in young and old yellowtail flounder, respectively. Ages were validated up to 25 years for females and 21 years for males. However, because of increased narrowing of annuli in thin-sectioned otoliths from old fish, even thin sections may underestimate the true age of the fish. von Bertalanfly growth curve parameters (combined sexes) were L-infinity = 55.6 cm total length, K = 0.16 and t(0) = -0.003. These results challenge the conventional view that yellowtail flounder on the Grand Banks are a relatively fast growing, short-lived species. Crown Copyright (C) 2003 Published by Elsevier Ltd on behalf of International Council for the Exploration of the Sea. All rights reserved.
723jaTimes Cited:43Cited References Count:57

Alkenone radiocarbon stratigraphy at high resolution continental margin sites - Mollenhauer, Gesine; Eglinton, Timothy I.; Freudenthal, Tim; Lamy, Frank (EGS-AGU-EUG Joint Assembly, 2003)
id: 1071

The amplitude and phasing of climate change during the last deglaciation in the Sulu Sea, western equatorial Pacific - Rosenthal, Y.; Oppo, D. W.; Linsley, B. K. (Geophysical Research Letters, 2003)
[1] Variations in tropical sea surface temperature patterns and the phasing relative to climate change in higher-latitudes provide insight into the mechanisms of climate change on both orbital and shorter time-scales. Here, we present well-dated, high-resolution records of planktonic foraminiferal delta(18)O and Mg/Ca-based SST spanning the last deglaciation from the Sulu Sea, located in the western equatorial Pacific. The results indicate that the last glacial maximum was 2.3 +/- 0.5degreesC cooler than present in the Sulu Sea with a concomitant decrease in sea surface salinity. The similarity between variations in surface salinity in the Sulu Sea, the western and eastern equatorial Pacific, and the Greenland ice-core record suggests that the observed changes in salinity reflect large-scale rearrangement of atmospheric patterns, which were coherent and synchronous throughout the Northern Hemisphere. The results suggest that the glacial equatorial Pacific climate was strongly influenced by both tropical, and extra-tropical forcing, although it is not clear whether interannual (ENSO) variability is a good analogue of glacial-interglacial climate change.
677zxTimes Cited:122 Cited References Count:18
Keywords: china; enso; level; monsoon; record; surface temperature

Analog for Holocene and future Climate? - McManus, J. F.; Oppo, D. W.; Cullen, J. L.; Healey, S. L. (Geophysical Monograph 137, Earth's Climate and Orbital Eccentricity: The Marine Isotope State 11 Questions, 2003)
id: 1166

Ancient organic matter sources to the Hudson-Mohawk River system: implications of riverine transport of ancient organic matter for the global biogeochemical - Longworth, B. E.; Raymond, P. A.; Petsch, S. T. (American Geophysical Union (AGU), 2003)
id: 1027

Anthropogenically induced changes in sediment and biogenic silica fluxes in Chesapeake Bay - Colman, S. M.; Bratton, J. F. (Geology, 2003)
Sediment cores as long as 20 m, dated by C-14, Pb-210, and Cs-137 methods and pollen stratigraphy, provide a history of diatom productivity and sediment-accumulation rates in Chesapeake Bay. We calculated the flux of biogenic silica and total sediment for the past 1500 yr for two high-sedimentation-rate sites in the mesohaline section of the bay. The data show that biogenic silica flux to sediments, an index of diatom productivity in the bay, as well as its variability, were relatively low before European settlement of the Chesapeake Bay watershed. In the succeeding 300400 yr, the flux of biogenic silica has increased by a factor of 4 to 5. Biogenic silica fluxes still appear to be increasing, despite recent nutrient-reduction efforts. The increase in diatom-produced biogenic silica has been partly masked (in concentration terms) by a similar increase in total sediment flux. This history suggests the magnitude of anthropogenic disturbance of the estuary and indicates that significant changes had occurred long before the twentieth century.
632uhTimes Cited:47Cited References Count:35

An assessment of the Late Holocene record of severe storm impacts from Lake Shelby, Alabama - Lambert, W. Joe; Aharon, Paul; Rodriguez, Antonio B. (Gulf Coast Association of Geological Societies Transactions, 2003)
The historical record of severe storms on the Gulf Coast extends back only about 100 years. To better predict how the Gulf Coast will be impacted by future climate change and associated changes in storm frequency it is necessary to extend the severe storm record back to the time when global climate was different than today. A 3200-year record of severe storm impacts was reported from Lake Shelby, AL, using sand layers as proxies of storm intensity and frequency (Liu and Fearn, 1993). To enhance the understanding of the Lake Shelby environment and changes that may occur during severe storms seismic data, water chemistry profiles, sediment cores, radiocarbon dates, and geochemical measurements were obtained. The results indicate that Lake Shelby is a stratified lake in terms of salinity and dissolved oxygen. The lake floor is composed of two general lithologies, gyttja located below about 2 m water depth, and sand located along the entire perimeter of the lake. Radiocarbon dates and stable isotope data indicate that the lake was a brackish water lagoon prior to 80014C yrs BP when it became isolated and transformed into a lacustrine environment. Interpretation of sand layers recognized in sediment cores from Lake Shelby as indicators of severe storms may be ambiguous. New data suggest that severe-storm records based on geochemical stratigraphy may provide higher resolution and confidence than conventional overwash techniques.
id: 1111

Asynchronous alkenone and foraminifera records from the Benguela Upwelling System - Mollenhauer, Gesine; Eglinton, Timothy I.; Ohkouchi, Naohiko; Schneider, Ralph R.; Muller, Peter J.; Grootes, Pieter M.; Rullkotter, Jurgen (Geochimica et Cosmochimica Acta, 2003)
id: 1067

Atlantic Ocean circulation during the Younger Dryas: Insights from a new Cd/Ca record from the western subtropical South Atlantic - Came, R. E.; Oppo, D. W.; Curry, W. B. (Paleoceanography, 2003)
[Benthic foraminiferal Cd/ Ca from an intermediate depth, western South Atlantic core documents the history of southward penetration of North Atlantic Intermediate Water ( NAIW). Cd seawater estimates ( Cd-W) for the last glacial are consistent with the production of NAIW and its export into the South Atlantic. At similar to 14.5 ka concurrently with the onset of the Bolling- Allerod to Younger Dryas cooling, the NAIW contribution to the South Atlantic began to decrease, marking the transition from a glacial circulation pattern to a Younger Dryas circulation. High Cd-W in both the deep North Atlantic and the intermediate South Atlantic imply reduced export of deep and intermediate water during the Younger Dryas and a significant decrease in northward oceanic heat transport. A modern circulation was achieved at similar to 9 ka, concurrently with the establishment of Holocene warmth in the North Atlantic region, further supporting a close linkage between deepwater variability and North Atlantic climate.
749rtTimes Cited:30Cited References Count:39

Biomass burning and oceanic primary production estimates in the Sulu Sea area over the last 380 kyr and the East Asian monsoon dynamics - Beaufort, L.; de Garidel-Thoron, T.; Linsley, B.; Oppo, D.; Buchet, N. (Marine Geology, 2003)
Coccolithophorid assemblages and micro-charcoal content were analysed in giant piston core MD97-2141 recovered in the Sulu Sea (Philippines). These proxies help to reconstruct respectively the dynamics of the oceanic primary production (PP) and biomass burning in that area. PP in the Sulu Sea intensifies during the East Asian winter monsoon (EAWM) and therefore PP constitutes a proxy for EAWM dynamics. Most of the precipitation in the Sulu Sea region occurs during the East Asian summer monsoon (EASM). Because the intensity of biomass burning is related to dryness of the surrounding area, the sedimentary micro-charcoal content can be used as an inverse proxy for EASM intensity. Our results show that the EAWM intensifies during glacial times in agreement with previous studies. Precessional forcing appears to act directly on EAWN because of the early response of PP in that frequency band. The micro-charcoal record exhibits complex dynamics, which we attribute to the competing influence of the long-term El Nino Southern Oscillation (ENSO)-like forcing and the glacial/interglacial cycle on EASM. These influences create an unusual frequency spectrum with power around 30 kyr and 19 kyr attributed to the non-linear response to the 100-kyr cycle (glacial) and the 23-kyr (ENSO) cycle. A factor of two increase in the amplitude of the micro-charcoal variability between 51 and 10 ka BP could correspond to Homo sapiens biomass burning in the style of the fire-stick farming of the Australian Aborigines. We also find, on precession cycles, an opposite phase between EASM and EAWM records and an advance of -delta(18)O and delta(18)O respectively by 2000 yr. (C) 2003 Elsevier B.V. All rights reserved.
Symposium on Asian Monsoons and Global Linkages on Milankovitch and Sub-Milankovitch Time ScalesMAY 09-11, 2001 BEIJING, PEOPLES R CHINA 70
Keywords: arabian sea; atlantic; climatic-change; EARLY HOLOCENE; EQUATORIAL; fire; GLACIAL MAXIMUM; indian-ocean; late pleistocene; Late Quaternary; monsoon; nannoplankton; Pleistocene; SOUTH CHINA; Sulu Sea; WEST-JAVA

Calcium carbonate budget in the Atlantic Ocean based on water column inorganic carbon chemistry - Chung, S. N.; Lee, K.; Feely, R. A.; Sabine, C. L.; Millero, F. J.; Wanninkhof, R.; Bullister, J. L.; Key, R. M.; Peng, T. H. (Global Biogeochemical Cycles, 2003)
[1] Recent independent lines of evidence suggest that the dissolution of calcium carbonate (CaCO3) particles is substantial in the upper ocean above the calcite 100% saturation horizon. This shallow-water dissolution of carbonate particles is in contrast with the current paradigm of the conservative nature of pelagic CaCO3 at shallow water depths. Here we use more than 20,000 sets of carbon measurements in conjunction with CFC and C-14 data from the WOCE/JGOFS/OACES global CO2 survey to estimate in situ dissolution rates of CaCO3 in the Atlantic Ocean. A dissolution rate is estimated from changes in alkalinity as a parcel of water ages along an isopycnal surface. The in situ CaCO3 dissolution increases rapidly at the aragonite 100% saturation horizon. Estimated dissolution rates north of 40degreesN are generally higher than the rates to the south, which is partly attributable to the production of exported CaCO3 being higher in the North Atlantic than in the South Atlantic. As more CaCO3 particles move down the water column, more particles are available for in situ dissolution. The total water column CaCO3 dissolution rate in the Atlantic Ocean is determined on an annual basis by integrating estimated dissolution rates throughout the entire water column and correcting for alkalinity input of approximately 5.6 x 10(12) mol C yr(-1) from CaCO3-rich sediments. The resulting water column dissolution rate of CaCO3 for the Atlantic Ocean is approximately 11.1 x 10(12) mol C yr(-1). This corresponds to about 31% of a recent estimate (35.8 x 10(12) mol C yr(-1)) of net CaCO3 production by Lee [2001] for the same area. Our calculation using a large amount of high-quality water column alkalinity data provides the first basin-scale estimate of the CaCO3 budget for the Atlantic Ocean.
732egTimes Cited:44 Cited References Count:73
Keywords: alkalinity; anthropogenic co2; caco3 dissolution; calcium carbonate budget; chemical lysocline; Deep-sea; dioxide system; dissociation-constants; dissolution kinetics; dissolution of calcium carbonate; eastern north-atlantic; ocean carbon cycle; organic-carbon; pacific-ocean; saturation state of seawater

Carbon cycling in Long Island Sound over the last 1000 years - Lugolobi, F.; Varekamp, J. C.; Thomas, E.; Buchholtz ten Brink, M. L.; Mecray, E. (AGU, Fall meeting, 2003)
id: 1179

Carbon isotopic compositions of prokaryotic lipids as tracers of carbon cycling in diverse settings - Pancost, R. D.; Damste, J. S. S. (Chemical Geology, 2003)
Recent work has highlighted the ubiquity of bacteria and archaea and continues to affirm their significance in diverse biogeochemical processes. The delta(13)C values and distributions of diagnostic lipids derived from such microorganisms can provide insights into prokaryotic processes in modem settings and are one of the few means by which past prokaryotic processes in depositional settings can be elucidated. Here we present a brief review of prokaryotic lipids commonly observed in sediments and the controls on their carbon isotopic compositions. We then present two case studies-one of Mediterranean cold seeps at which anaerobic oxidation of methane occurs and one of a Holocene peat deposit in which a variety of aerobic and anaerobic microorganisms govern the degradation of organic matter. These two studies illustrate the potential utility of compound-specific carbon isotope analyses to deconvolute pathways of carbon flow in microbial communities. (C) 2002 Elsevier Science B.V. All rights reserved.
id: 1331; 666LX Times Cited:59 Cited References Count:144

The Catfish Lake scarp: preliminary field data and implications for earthquake hazards posed by the Tacoma fault - Sherrod, B. L.; Nelson, A. R.; Kelsey, H. M.; Brocher, T. M.; Blakely, R. J.; Weaver, C. S.; Rountree, N. K.; Rhea, S.; Jackson, B. S. (U. S. Geological Survey Open-File Report, 2003)
id: 430

Changes in the 13C/12C of dissolved inorganic carbon in the ocean as a tracer of anthropogenic CO2 uptake - Quay, P.; Sonnerup, R.; Westby, T.; Stutsman, J.; McNichol, A. (Global Biogeochemical Cycles, 2003)
id: 1546

Changes of the 13C/12C of dissolved inorganic carbon in the ocean as a tracer of anthropogenic C)2 uptake - Quay, P. D.; Sonnerup, T.; Westby, J.; Stutsman, J.; McNichol, A. P. (Global Biogeochemical Cycles, 2003)
id: 1689

Climate and the collapse of Mayan civilization - Haug, G. H.; Gunther, D.; Peterson, L. C.; Sigman, D. M.; Hughen, K. A. (Science, 2003)
id: 556

COMPARE04-Comparison/calibration of 14C records 26-50 ka - van der Plicht, J.; Hughen, K. A.; Guilderson, T. P.; Reimer, P. (Abstracts, 18th International Radiocarbon Conf., 2003)
id: 564

A comparison of rates of time averaging between the bivalve Macoma cleryana and brachiopod Bouchardia rosea on a shallow subtropical shelf - Barbour-Wood, S. L.; Krause R.A, Jr.; Kowalewski, M.; Wehmiller, J. F.; Simoes, M. G.; Goodfriend, G. A. (Geological Society of America, Abstracts with Programs, 2003)
35(6):273
id: 720

Composition and syngeneity of molecular fossils from the 2.78 to 2.45 billion-year-old Mount Bruce Supergroup, Pilbara Craton, Western Australia - Brocks, J. J.; Buick, R.; Logan, G. A.; Summons, R. E. (Geochimica Et Cosmochimica Acta, 2003)
Shales of very low metamorphic grade from the 2.78 to 2.45 billion-year-old (Ga) Mount Bruce Supergroup, Pilbara Craton, Western Australia, were analyzed for solvent extractable hydrocarbons. Samples were collected from ten drill cores and two mines in a sampling area centered in the Hamersley Basin near Wittenoom and ranging 200 km to the southeast, 100 km to the southwest and 70 km to the northwest. Almost all analyzed kerogenous sedimentary rocks yielded solvent extractable organic matter. Concentrations of total saturated hydrocarbons were commonly in the range of 1 to 20 ppm ( mug/g rock) but reached maximum values of 1000 ppm. The abundance of aromatic hydrocarbons was similar to1 to 30 ppm. Analysis of the extracts by gas chromatography-mass spectrometry (GC-MS) and GC-MS metastable reaction monitoring (MRM) revealed the presence of n-alkanes, mid- and end-branched monomethylalkanes, omega-cyclohexylalkanes, acyclic isoprenoids, diamondoids, tri- to pentacyclic terpanes, steranes, aromatic steroids and polyaromatic hydrocarbons. Neither plant biomarkers nor hydrocarbon distributions indicative of Phanerozoic contamination were detected. The host kerogens of the hydrocarbons were depleted in C-13 by 2 to 21parts per thousand relative to n-alkanes, a pattern typical of, although more extreme than, other Precambrian samples. Acyclic isoprenoids showed carbon isotopic depletion relative to n-alkanes and concentrations of 2alpha-methylhopanes were relatively high, features rarely observed in the Phanerozoic but characteristic of many other Precambrian bitumens. Molecular parameters, including sterane and hopane ratios at their apparent thermal maxima, condensate-like alkane profiles, high mono- and triaromatic steroid maturity parameters, high methyladamantane and methyldiamantane indices and high methylphenanthrene maturity ratios, indicate thermal maturities in the wet-gas generation zone. Additionally, extracts from shales associated with iron ore deposits at Tom Price and Newman have unusual polyaromatic hydrocarbon patterns indicative of pyrolytic dealkylation.The saturated hydrocarbons and biomarkers in bitumens from the Fortescue and Hamersley Groups are characterized as 'probably syngenetic with their Archean host rock' based on their typical Precambrian molecular and isotopic composition, extreme maturities that appear consistent with the thermal history of the host sediments, the absence of biomarkers diagnostic of Phanerozoic age, the absence of younger petroleum source rocks in the basin and the wide geographic distribution of the samples. Aromatic hydrocarbons detected in shales associated with iron ore deposits at Mt Tom Price and Mt Whaleback are characterized as 'clearly Archean' based on their hypermature composition and covalent bonding to kerogen. Copyright (C) 2003 Elsevier Ltd.
741dvTimes Cited:124Cited References Count:102

Compound specific radiocarbon dating of alkenones: methodological considerations and applications in paleoceanography - Mollenhauer, Gesine; Eglinton, Timothy I.; Schneider, Ralph R.; Meggers, Helge; Lamy, Frank; Ohkouchi, Nao; Hayes, John M. (18th International Radiocarbon Conference, 2003)
id: 1070

Continuous-Flow Accelerator Mass Spectrometry - Roberts, M. L.; Benthien, A.; Schneider, R. J.; von Reden, K. F.; Hayes, J. M. (International Symposium on Radiation Physics, 2003)
id: 1683

Contrasting He-C relationships in Nicaragua and Costa Rica: insights into C cycling through subduction zones - Shaw, A. M.; Hilton, D. R.; Fischer, T. P.; Walker, J. A.; Alvarado, G. E. (Earth and Planetary Science Letters, 2003)
We report He-3/He-4 ratios, relative He, Ne, and CO2 abundances as well as delta(13)C values for volatiles from the volcanic output along the Costa Rica and Nicaragua segments of the Central American arc utilising fumaroles, geothermal wells, water springs and bubbling hot springs. CO2/He-3 ratios are relatively constant throughout Costa Rica (av. 2.1 X 10(10)) and Nicaragua (av. 2.5 X 10(10)) and similar to arcs worldwide (similar to1.5 X 10(10)). delta(13)C values range from -6.8parts per thousand (MORB-like) to -0.1parts per thousand (similar to marine carbonate (0parts per thousand)). He-3/He-4 ratios are essentially MORB-like (8 +/- R-A) with some samples showing evidence of crustal He additions - water spring samples are particularly susceptible to modification. The He-CO2 relationships are consistent with an enhanced input of slab-derived C to magma sources in Nicaragua ((L+S)/M = 16; where L, M and S represent the fraction of CO2 derived from limestone and/or marine carbonate (L), the mantle (M) and sedimentary organic C (S) sources) relative to Costa Rica ((L+S)/M = 10). This is consistent with prior studies showing a higher sedimentary flux to the arc volcanics in Nicaragua (as traced by Ba/La, Be-10 and La/Yb). Possible explanations include: (1) offscraping of the uppermost sediments in the Costa Rica forearc, and (2) a cooler thermal regime in the Nicaragua subduction zone, preserving a higher proportion of melt-inducing fluids to subarc depths, leading to a higher degree of sediment transfer to the subarc mantle. The absolute flux Of CO2 from the Central American arc as determined by correlation spectrometry methods (5.8 X 10(10) mol/yr) and CO2/He-3 ratios (7.1 X 10(10) mol/yr) represents approximately 14-18% of the amount of CO2 input at the trench from the various slab contributors (carbonate sediments, organic C, and altered oceanic crust). Although the absolute flux is comparable to other arcs, the efficiency Of CO2 recycling through the Central American are is surprisingly low (14-18% vs. a global average of similar to50%). This may be attributed to either significant C loss in the forearc region, or incomplete decarbonation of carbonate sediments at subarc depths. The implication of the latter case is that a large fraction of C (up to 86%) may be transferred to the deep mantle (depths beyond the source of arc magmas). (C) 2003 Elsevier B.V. All rights reserved.
725paTimes Cited:98Cited References Count:50

Cosmochemical Estimates of Mantle Composition - Palme, H.; O'Neill, H. St C. (Treatise on Geochemistry, 2003)
id: 1583

Dates, demography, and disease: Cultural contacts and possible evidence for old world epidemics among the island Chumash - Erlandson, J. M.; Rick, T. C.; Kennett, D. J.; Walker, P. L. (Pacific Coast Archaeological Society Quarterly, 2003)
id: 1022

Decadal timescale shift in the 14C record of a central equatorial Pacific coral - Grottoli, A. G.; Gille, S. T.; Druffel, E. R. M.; Dunbar, R. B. (Radiocarbon, 2003)
id: 1130

Deep sea records from the southeast Labrador Ocean circulation changes and ice-rafting events during hte last 160,000 years - Rasmussen, T. L.; Oppo, D. W.; Thompson, E.; Lehman, S. J. (Paleoceanography, 2003)
id: 989

Early cave occupations on San Miguel Island, California - Rick, Torben C.; Erlandson, Jon M.; Vellanoweth, Rene L. (Current Research in the Pleistocene, 2003)
id: 1093

East Asian monsoon forcing of suborbital variability in the Sulu Sea during Marine Isotope Stage 3: Link to Northern Hemisphere climate - Dannenmann, S.; Linsley, B. K.; Oppo, D. W.; Rosenthal, Y.; Beaufort, L. (Geochemistry Geophysics Geosystems, 2003)
[1] We have generated a new high-resolution record of variations in planktonic foraminiferal oxygen isotopes (delta(18)O) and Mg/Ca from a sediment core (IMAGES 97-2141) in the Sulu Sea located in the Philippine archipelago of western tropical Pacific. This record reveals distinct, suborbital-scale delta(18)O changes, most notably during Marine Isotope Stage 3 (MIS3) (similar to30,000 to 60,000 years B.P.). The amplitudes of these delta(18)O fluctuations (0.4 to 0.7parts per thousand) exceed that which can be attributed to sea level changes and must be due to changes in sea surface conditions. In the same interval, variations in planktonic foraminifera Mg/Ca suggest that suborbital surface ocean temperature variations of 1 to 1.5degreesC in the Sulu Sea were not in phase with delta(18)O. Combined, this evidence indicates that the MIS3 millennial delta(18)O events in the Sulu Sea were primarily the result of changes in surface water salinity, which today is directly related to the East Asian Monsoon (EAM) and its influence on the balance between surface water contributions from the South China Sea and Western Pacific Warm Pool (WPWP). Within dating uncertainties the MIS3 Sulu Sea delta(18)O suborbital variability indicates that times of fresher surface conditions in the Sulu Sea coincide with similar conditions in the WPWP [Stott et al., 2002] and also with intensifications of the summer EAM as recorded in the U-Th dated Chinese (Hulu Cave) speleothem delta(18)O record [Wang et al., 2001] and thus by inference with interstadials in the Greenland Ice core records. Combined, these results indicate that pronounced suborbital variability in the summer EAM and Intertropical Convergence Zone (ITCZ) during MIS3 was tightly coupled with climate conditions in the northern high latitudes.
631mwTimes Cited:41 Cited References Count:53
Keywords: 1620 global change : climate dynamics (3309); 4267 oceanography : general : paleoceanography; dissolution; equatorial pacific; eurasian snow cover; isotope stage 3; last glacial period; late pleistocene; Mg/Ca; millennial-scale climate change; oxygen isotopes; paleoceanography; planktonic-foraminifera; records; se asian monsoon; south china sea; summer monsoon; surface temperature-variations

Ecosystem modulation of dissolved carbon age in a temperate marsh-dominated estuary - Raymond, P. A.; Hopkinson, C. S. (Ecosystems, 2003)
We measured the concentrations and isotopic values (Delta(14)C and delta(13)C) of dissolved inorganic, dissolved organic, and particulate organic carbon (DIC, DOC, and POC, respectively) in the Parker River watershed and estuary in Massachusetts, USA, to determine the age of carbon (C) entering the estuary and how estuarine processing affects the quantity and apparent age of C transported to the Gulf of Maine. The watershed measurements indicated the transport of Delta(14)C-enriched modern DIC and DOC and variably aged POC from the watershed to the estuary. The transport of organic matter from the watershed was dominated by DOC transport, with POC making up less than 10% of the total. Surveys within the watershed aimed at determining which land-use type dominated the DOC export indicated that wetlands, although they made up only around 20% of the land use, could be responsible for approximately 75% of the DOC export. We therefore conclude that the wetland land uses of the Parker River watershed are exporting mainly Delta(14)C-enriched modem DOC. DIC isotopes indicate that the source of DIC in the Parker River watershed is dominated by the weathering of noncarbonate parent material by Delta(14)C-enriched carbon dioxide (CO2) originating from the respiration of young organic matter in soils. Transects in the estuary displayed net additions of all C species. For DOC and DIC, the export of this internally added DOC and DIC was approximately equal to the amount being exported from the watershed, showing the importance of focusing on estuaries when estimating the export of C to the coastal ocean. With respect to DIC, the total input is even larger when the atmospheric exchange of excess PCO2 is calculated. The Delta(14)C -DOC and Delta(14)C-DIC transects indicate that the internally added DOC and DIC is Delta(14)C-enriched modern material. The source of this material is the fringing marshes and estuarine phytoplankton, with the relative importance of these two sources changing over time. Taken together, the bulk C and Delta(14)C measurements show that the estuary is adding significant quantities of young DOC despite the presence of vast quantities of old marsh peat flanking the entire estuary. Furthermore, the DIC data indicate that Delta(14)C-enriched modern material is what is fueling the majority of heterotrophic respiration within the system.
746zrTimes Cited:42Cited References Count:73

Emergence of Late Holocene sociopolitical complexity on Santa Rosa and San Miquel Islands - Kennett, D. J.; Conlee, C. A. (Catalist to Complexity: The Late Holocene Archaeology of the California Coast: Perspectives in California Archaeology, 2003)
id: 472

Eutrophication and carbon sources in Chesapeake Bay over the last 2700 yr: human impacts in context - Bratton, John F.; Colman, Steven M.; Seal, Robert R. (Geochimica et Cosmochimica Acta, 2003)
To compare natural variability and trends in a developed estuary with human-influenced patterns, stable isotope ratios (δ13C and δ15N) were measured in sediments from five piston cores collected in Chesapeake Bay. Mixing of terrestrial and algal carbon sources primarily controls patterns of δ13Corg profiles, so this proxy shows changes in estuary productivity and in delivery of terrestrial carbon to the bay. Analyses of δ15N show periods when oxygen depletion allowed intense denitrification and nutrient recycling to develop in the seasonally stratified water column, in addition to recycling taking place in surficial sediments. These conditions produced 15N-enriched (heavy) nitrogen in algal biomass, and ultimately in sediment. A pronounced increasing trend in δ15N of +4‰ started in about A.D. 1750 to 1800 at all core sites, indicating greater eutrophication in the bay and summer oxygen depletion since that time. The timing of the change correlates with the advent of widespread land clearing and tillage in the watershed, and associated increases in erosion and sedimentation. Isotope data show that the region has experienced up to 13 wet-dry cycles in the last 2700 yr. Relative sea-level rise and basin infilling have produced a net freshening trend overprinted with cyclic climatic variability. Isotope data also constrain the relative position of the spring productivity maximum in Chesapeake Bay and distinguish local anomalies from sustained changes impacting large regions of the bay. This approach to reconstructing environmental history should be generally applicable to studies of other estuaries and coastal embayments impacted by watershed development.
id: 541

Evaluating system-specific variability in riverine organic matter ages: implications for determining terrestrial contributions to oceanic DOC - Raymond, P. A. (Symposium on New Approaches in Marine Organic Biogeochemistry, 2003)
id: 486

Evolution of a habitable planet - Kasting, J. F.; Catling, D. (Annual Review of Astronomy and Astrophysics, 2003)
Giant planets have now been discovered around other stars, and it is only a matter of time until Earth-sized planets are detected. Whether any of these planets are suitable for life depends on their volatile abundances, especially water, and on their climates. Only planets within the liquid-water habitable zone (HZ) can support life on their surfaces and, thus, can be analyzed remotely to determine whether they are inhabited. Fortunately, current models predict that HZs are relatively wide around main-sequence stars not too different from our sun. This conclusion is based on studies of how our own planet has evolved over time. Earth's climate has remained conducive to life for the past 3.5 billion years or more, despite a large increase in solar luminosity, probably because of previous higher concentrations Of CO2 and/or CH4. Both these gases are involved in negative feedback loops that help to stabilize the climate. In addition to these topics, we also briefly discuss the rise of atmospheric O-2 and O-3, along with their possible significance as indicators of life on other planets.
742axTimes Cited:217Cited References Count:146

Evolution of Sedimentary Rocks - Veizer, J.; Mackenzie, F. T. (Treatise on Geochemistry, 2003)
id: 1604

Extensive deposits on the Pacific plate from Late Pleistocene North American glacial lake outbursts - Normark, W. R.; Reid, J. A. (Journal of Geology, 2003)
One of the major unresolved issues of the Late Pleistocene catastrophic-flood events in the northwestern United States (e.g., from glacial Lake Missoula) has been what happened when the flood discharge reached the ocean. This study compiles available 3.5-kHz high-resolution and airgun seismic reflection data, long-range sidescan sonar images, and sediment core data to define the distribution of flood sediment in deepwater areas of the Pacific Ocean. Upon reaching the ocean at the mouth of the Columbia River near the present-day upper continental slope, sediment from the catastrophic floods continued flowing downslope as hyperpycnally generated turbidity currents. The turbidity currents resulting from the Lake Missoula and other latest Pleistocene floods followed the Cascadia Channel into and through the Blanco Fracture Zone and then flowed west to the Tufts Abyssal Plain. A small part of the flood sediment, which was stripped off the main flow at a bend in the Cascadia Channel at its exit point from the Blanco Fracture Zone, continued flowing more than 400 km to the south and reached the Escanaba Trough, a rift valley of the southern Gorda Ridge. Understanding the development of the pathway for the Late Pleistocene flood sediment reaching Escanaba Trough provides insight for understanding the extent of catastrophic flood deposits on the Pacific plate.
758frTimes Cited:37Cited References Count:53

Field and laboratory data from an earthquake history study of the Waterman Point fault, Kitsap County, Washington - Nelson, A. R.; Johnson, S. Y.; Kelsey, S. K.; Wells, R. E.; Sherrod, B. L.; Bradley, L. A.; Okumura, K.; Bogar, R. (U. S. Geological Survey Miscellaneous Field Studies, 2003)
id: 429

Fossil Sources of Ambient Aerosol Carbon Based on 14C Measurements - Tanner, R. L.; Parker, W. J.; McNichol, A. P. (Aerosol Science and Technology, 2003)
id: 1690

Geochemistry of hydrothermally altered oceanic crust: DSDP/ODP Hole 504B - Implications for seawater-crust exchange budgets and Sr- and Pb-isotopic evolution of the mantle - Bach, Wolfgang; Peucker-Ehrenbrink, Bernhard; Hart, STanly R.; Blusztajn, Jerzy S. (Geochemistry, Geophysics, Geosystems G3, 2003)
id: 1536

Glacial-interglacial dynamics of the eastern equatorial Pacific cold tongue Intertropical Convergence Zone system reconstructed from oxygen isotope records - Koutavas, A.; Lynch-Stieglitz, J. (Paleoceanography, 2003)
We use planktonic oxygen isotope (delta(18)O) records spanning the last 30,000 years (kyr) to constrain the magnitude and spatial pattern of glacial cooling in the upwelling environment of the eastern equatorial Pacific (EEP). Fourteen new downcore delta(18)O records were obtained from surface-dwelling planktonic foraminifera Globigerinoides sacculifer and Globigerinoides ruber in eight cores from the upwelling tongue of the EEP. All sites have sedimentation rates exceeding 5 cm/kyr and, with one exception, lie above the modern depth of the foraminiferal lysocline. Sites directly underlying the cool band of upwelling immediately south of the equator record mean late Holocene (LH)-Last Glacial Maximum (LGM) delta(18)O amplitudes ranging between 1.0 and 1.3parts per thousand. We estimate that mean sea surface temperatures (SST) in this region during the LGM were on average 1.5 +/- 0.5degreesC lower than the LH. Larger delta(18)O amplitudes are observed in sites north of the equator, indicating a spatial pattern of reduced meridional SST gradient across the equator during the LGM. This result is supported by comparison of Mg/Ca SST reconstructions from two sites straddling the equator. We interpret the reduction of this gradient during the LGM as evidence for a less intense cold tongue-Intertropical Convergence Zone (ITCZ) frontal system, a more southerly position of the ITCZ, and weaker southeast equatorial trades in the EEP.
756nfTimes Cited:56Cited References Count:100

Global MORB chemistry compilation at the segment scale - Su, Y.; Langmuir, C. H. (Database available at http://www.petdb.org., 2003)
id: 1600

Heterogeneity in the radiocarbon content of Polycyclic aromatic hydrocarbons in household soot - Reddy, C. M.; Xu, L.; O'Connor, R. (Environmental Forensics, 2003)
id: 507

High-temperature seafloor hydrothermal circulation over geologic time and archean banded iron formations - Lowell, R. P.; Keller, S. M. (Geophysical Research Letters, 2003)
Under the assumption of simple plate tectonics with a range of continental growth scenarios, we construct models of global lithospheric heat loss, hydrothermal heat loss and hydrothermal iron flux to the ocean as functions of geologic time from 4.0 Ga to present. The models show that lithospheric heat loss scales with the square root of the plate creation rate, whereas hydrothermal heat loss scales linearly with that rate. Thus during the Archean lithospheric and hydrothermal heat losses were approximate to3 and approximate to10 times greater than present, respectively. Straightforward extrapolation of hydrothermal Fe flux from the present to the Archean using these models indicates that hydrothermal Fe may not have been sufficient to supply the large Superior-type Banded Iron Formations deposited between 2.7 and 1.8 Ga.
669jkTimes Cited:5Cited References Count:31

Hydrothermal alteration of upper oceanic crust formed at a fast-spreading ridge: mineral, chemical, and isotopic evidence from ODP Site 801 - Alt, J. C.; Teagle, D. A. H. (Chemical Geology, 2003)
ODP Hole 801C penetrates >400 m into 170-Ma oceanic basement formed at a fast-spreading ridge. Most basalts are slightly (10-20%) recrystallized to saponite, calcite, minor celadonite and iron oxyhydroxides, and trace pyrite. Temperatures estimated from oxygen isotope data for secondary minerals are 5-100 degreesC, increasing downward. At the earliest stage, dark celadonitic alteration halos formed along fractures and celadonite, and quartz and chalcedony formed in veins from low-temperature (
id: 1537; 748HG Times Cited:42 Cited References Count:56

Isotopic and geochemical assessment of in situ biodegradation of chlorinated hydrocarbons - Kirtland, B. C.; Aelion, C. M.; Stone, P. A.; Hunkeler, D. (Environ Sci Technol, 2003)
Currently there is no in situ method to detect and quantify complete mineralization of chlorinated hydrocarbons (CHCs) to CO2. Combined isotopic measurements in conjunction with traditional chemical techniques were used to assess in situ biodegradation of trichloroethylene (TCE) and carbon tetrachloride (CT). Vadose zone CHC, ethene, ethane, methane, O2, and CO2 concentrations were analyzed using gas chromatography over 114 days at the Savannah River Site. delta13C of CHC and delta13C and 14C of vadose zone CO2, sediment organic matter, and groundwater dissolved inorganic carbon (DIC)were measured. Intermediate metabolites of TCE and CT accounted for < or = 10% of total CHCs. Delta13C of cis-1,2-dichloroethylene (DCE) was always heavier than TCE indicating substantial DCE biodegradation. 14C-CO2 values ranged from 84 to 128 percent modern carbon (pMC), suggesting that plant root-respired CO2 was dominant. 14C-CO2 values decreased over time (up to 12 pMC), and contaminated groundwater 14C-DIC (76 pMC) was substantially depleted relative to the control (121 pMC). 14C provided a direct measure of complete CHC mineralization in vadose zone and groundwater in situ and may improve remediation strategies.
Kirtland, Brian CAelion, C MarjorieStone, Peter AHunkeler, DanielengResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.2003/10/04 05:00Environ Sci Technol. 2003 Sep 15;37(18):4205-12.

KN167-KN168A/B: AHC-800 coring on the New Jersey Shelf for ONR's Geoclutter Initiative, R/V KNORR - Alexander, C. R.; Austin J.A, Jr. (Cruise Report, 2003)
id: 635

La colonisation et les fortifications de Rapa - Kennett, D. J.; Anderson, A. J.; Prebble, M.; Conte, E. (Bilan de la recherche archeologique en Polynesie francaise, 2003)
id: 471

Late Holocene earthquakes on the Toe Jam Hill fault, Seattle fault zone, Bainbridge Island, Washington - Nelson, A. R.; Johnson, S. Y.; Kelsey, H. M.; Wells, R. E.; Sherrod, B. L.; Pezzopane, S. K.; Bradley, L. A.; Koehler, R. D.; Bucknam, R. C. (Geological Society of America Bulletin, 2003)
Five trenches across a Holocene fault scarp yield the first radiocarbon-measured earthquake recurrence intervals for a crustal fault in western Washington. The scarp, the first to be revealed by laser imagery, marks the Toe Jam Hill fault, a north-dipping backthrust to the Seattle fault. Folded and faulted strata, liquefaction features, and forest soil A horizons buried by hanging-wall-collapse colluvium record three, or possibly four, earthquakes between 2500 and 1000 yr ago. The most recent earthquake is probably the 1050-1020 cal. (calibrated) yr B.P. (A.D. 900930) earthquake that raised marine terraces and triggered a tsunami in Puget Sound. Vertical deformation estimated from strati-graphic and surface offsets at trench sites suggests late Holocene earthquake magnitudes near M7, corresponding to surface ruptures >36 km long. Deformation features recording poorly understood latest Pleistocene earthquakes suggest that they were smaller than late Holocene earthquakes. Postglacial earthquake recurrence intervals based on 97 radiocarbon ages, most on detrital charcoal, range from similar to12,000 yr to as little as a century or less; corresponding fault-slip rates are 0.2 mm/ yr for the past 16,000 yr and 2 mm/yr for the past 2500 yr. Because the Toe Jam Hill fault is a backthrust to the Seattle fault, it may not have ruptured during every earthquake on the Seattle fault. But the earthquake history of the Toe Jam Hill fault is at least a partial proxy for the history of the rest of the Seattle fault zone.
740qwTimes Cited:41Cited References Count:53

Late-Holocene climate and ecosystem history from Chesapeake Bay sediment cores, USA - Willard, D. A.; Cronin, T. M.; Verardo, S. (Holocene, 2003)
Palaeoclimate records from late-Holocene sediments in Chesapeake Bay, the largest estuary in the USA, provide evidence that both decadal to centennial climate variability and European colonization had severe impacts on the watershed and estuary. Using pollen and dinoflagellate cysts as proxies for mid-Atlantic regional precipitation, estuarine salinity and dissolved oxygen (DO) during the last 2300 years, we identified four dry intervals, centred on AD 50 (P1/D1), AD 1000 (P2/D2), AD 1400 (P3) and AD 1600 (P4). Two centennial-scale events, P1/D1 and P2/D2, altered forest composition and led to increased salinity and DO levels in the estuary. Intervals P3 and P4 lasted several decades, leading to decreased production of pine pollen. Periods of dry mid-Atlantic climate correspond to 'megadroughts' identified from tree-ring records in the southeastern and central USA. The observed mid-Atlantic climate variability may be explained by changes in atmospheric circulation resulting in longer-term, perhaps amplified, intervals of meridional flow. After European colonization in the early seventeenth century, forest clearance for agriculture, timber and urbanization altered estuarine water quality, with dinoflagellate assemblages indicating reduced DO and increased turbidity.
650thTimes Cited:56Cited References Count:101

Late-Quaternary cold events recorded in the Southern Ocean sediments, Pacific Sector - Langone, L.; Capotondi, L.; Giglio, F.; Focaccia, P.; C, Morigi; Ravaioli, M. (Terra Antartica, 2003)
id: 1000

Lipid-Like material as the source of the uncharacterized organic carbon in the ocean? - Hwang, Jeomshik; Druffel, Ellen R. M. (Science, 2003)
id: 530

Magnitude and variability of Holocene sediment accumulation in Santa Monica Bay, California - Sommerfield, C. K.; Lee, H. J. (Mar Environ Res, 2003)
The spatial variability of Holocene (past 10,000 years) sediment accumulation in Santa Monica Bay (California) was examined to identify controls sediment trapping in a bathymetrically complex coastal embayment and to provide geologic context for the post-industrial sedimentary record and associated pollution gradients. Sediment chronologies based on downcore AMS 14C dates were used to quantify long-term (millennia) accumulation rates in an effort to elucidate particle-transport pathways and sinks. Sediment accumulation rates for the full range of bayfloor environments (50-630 m water depths) range from 22 to 102 mg/cm(2)/year (15-88 mm/100 year), have an overall mean of 51+/-21 mg/cm(2)/year (1 sigma, n=11), and are comparable to rates reported for adjacent borderland basins. Maximal accumulation rates on the Malibu shelf and within a reentrant to Redondo canyon are interpreted to reflect (1) proximity to sediment sources and (2) localized oceanographic and topographic conditions conducive to sediment trapping and deposition. The 14C-derived accumulation rates are 2-10 times lower than rates determined through (210)Pb geochronology for the same sites in a related study, revealing that Holocene sediment accumulation has been non-steady-state. Santa Monica Bay is an important sink for suspended matter; averaged over the past several millennia a mass of sediment equivalent to 10-80% of the modern annual river supply is sequestered yearly. Net influx of suspended matter derived from the adjacent Palos Verdes shelf is evinced by a concentration gradient of p,p'-DDE in bayfloor sediments, whereas the distribution of anthropogenic silver suggests transport from Santa Monica shelf to the southeastern boundary of the bay. The results of this study provide new insight to the long-term fates of particulate matter in Los Angeles coastal waters.
Sommerfield, Christopher KLee, Homa JengResearch Support, U.S. Gov't, Non-P.H.S.England2003/03/22 04:00Mar Environ Res. 2003 Jul-Aug;56(1-2):151-76.

Mantle Volatiles--Distribution and Consequences - Luth, R. W. (Treatise on Geochemistry, 2003)
id: 1597

Map and data for Quaternary faults and folds in Washington State - Lidke, D. J.; Johnson, S. Y.; McCory, P. A.; Personius, S. F.; Nelson, A. R.; Dart, R. L.; Bradley, L. A.; Haller, K. M.; Machette, M. N. (Geological Survey Open-File Report, 2003)
id: 997

Maps and data from a trench investigation of the Utsalady Point fault, Whidbey Island, Washington - Johnson, S. Y.; Nelson, A. R.; Personius, S. F.; Wells, R. E.; Kelsey, H. M.; Sherrod, B. L.; Okumura, K.; Koehler, R., III; Witter, R. C.; Bradley, L. A.; Harding, D. J. (U. S. Geological Survey Miscellaneous Field Studies, 2003)
id: 996

Mercury contamination chronologies from Connecticut wetlands and Long Island Sound sediments - Varekamp, J. C.; Kreulen, B.; ten Brink, M. R. B.; Mecray, E. L. (Environmental Geology, 2003)
Sediment cores were used to investigate the mercury deposition histories of Connecticut and Long Island Sound. Most cores show background (pre-1800s) concentrations (50-100 ppb Hg) below 30-50 cm depth, strong enrichments up to 500 ppb Hg in the core tops, with lower Hg concentrations in the surface sediments (200-300 ppb Hg). A sediment core from the Housatonic River has peak levels of 1,500 ppb Hg, indicating the presence of a Hg point source in this watershed. The Hg records were translated into Hg contamination chronologies through Pb-210 dating. The onset of Hg contamination occurred in similar to1840-1850 in eastern Connecticut, whereas in the Housatonic River the onset is dated at around 1820. The mercury accumulation profiles show periods of peak contamination at around 1900 and at 1950-1970. Peak Hg* (Hg* = Hg measured minus Hg background) accumulation rates in the salt marshes vary; dependent on the sediment character, between 8 and 44 ng Hg/cm(2) per year, whereas modern Hg* accumulation rates range from 4-17 ng Hg/cm(2) per year; time-averaged Hg* accumulation rates are 15 ng Hg/cm(2) per year. These Hg* accumulation rates in sediments are higher than the observed Hg atmospheric deposition rates (about 1-2 ng Hg/cm(2) per year), indicating that contaminant Hg from the watershed is focused into the coastal zone. The Long Island Sound cores show similar Hg profiles as the marsh cores, but time-averaged Hg* accumulation rates are higher than in the marshes (26 ng Hg/cm(2) a year) because of-the different sediment characteristics. In-situ atmospheric deposition of Hg in the marshes and in Long Island Sound is only a minor component of the total Hg budget. The 1900 peak of Hg contamination is most likely related to climatic factors (the wet period of the early 1900s) and the 1950-1970 peak was caused by strong anthropogenic Hg emissions at that time. Spatial trends in total Hg burdens in cores are largely related to sedimentary parameters (amount of clay) except for the high inventories of the Housatonic River, which are related to Hg releases from hat-making in the town of Danbury. Much of the contaminated sediment transport in the Housatonic River Basin occurs during floods; creating distinct layers of Hg-contaminated sediment in western Long Island Sound. The drop of about 40% in Hg accumulation rates between the 1960s and 1990s seems largely the result of reduced Hg emissions and to a much lesser extent of climatic factors.
643lmTimes Cited:22Cited References Count:45

Microbial dolomite crusts from the carbonate platform off western India - Rao, V. P.; Kessarkar, P. M.; Krumbein, W. E.; Krajewski, K. P.; Schneider, R. J. (Sedimentology, 2003)
The occurrence of Late Pleistocene dolomite crusts that occur at 64 m depth on the carbonate platform off western India is documented. Dolomite is the most predominant mineral in the crusts. In thin section, the crust consists of dolomitized microlaminae interspersed with detrital particles. Under scanning electron microscopy, these laminae are made up of tubular filaments or cellular structures of probable cyanobacterial origin. Dolomite crystals encrust or overgrow the surfaces of the microbial filaments and/or cells; progressive mineralization obliterates their morphology. Well-preserved microbial mats, sulphide minerals (pyrrhotite and marcasite) and the stable isotope composition of dolomite in the crusts indicate hypersaline and anoxic conditions during dolomite formation. The crusts are similar to dolomite stromatolites, and biogeochemical processes related to decaying microbial mats under anoxic conditions probably played an important role in dolomite precipitation. The dolomite is therefore primary and/or very early diagenetic in origin. The dolomite crusts are interpreted to be a composite of microbial dolomite overprinted by early burial organic dolomite. The results of this study suggest that a microbial model for dolomite formation may be relevant for the origin of ancient massive dolomites in marine successions characterized by cryptalgal laminites. The age of the crusts further suggests that the platform was situated at shallow subtidal depths during the Last Glacial Maximum.
724ejTimes Cited:19Cited References Count:69

Mid-depth circulation in the northwest Pacific during the last deglaciation: Evidence from foraminiferal radiocarbon ages - Ahagon, N.; Ohkushi, K.; Uchida, M.; Mishima, T. (Geophysical Research Letters, 2003)
Sediment cores (MR01-K03 PC4/PC5, 1366 m water depth) collected from off northern Japan were studied using coexisting planktonic and benthic foraminiferal radiocarbon measurements to reconstruct the history of mid-depth circulation in the northwest Pacific. Reconstructed ventilation ages indicate that, consistent with data from a previous radiocarbon study at a shallower site, there was significant variation in mid-depth circulation during the last deglaciation, especially in the Bolling-Allerod (13-15 ka) and Younger Dryas (11.5-13 ka) intervals. Our record indicates that the ventilation changes in the North Pacific were antiphase to those of the North Atlantic, suggesting that atmospheric moisture transport associated with the Asian Monsoon might have played a great role in millennium-scale ventilation changes in the North Pacific during the last deglaciation.
id: 405; 742FU Times Cited:19 Cited References Count:23

Mid-holocene climate change in Lake Bosumtwi, Ghana - Russell, J.; Talbot, M. R.; Haskell, B. J. (Quaternary Research, 2003)
Lake Bosumtwi is one of the most widely studied palaeoclimate archives in West Africa. Results from numerous AMS C-14 dates of samples from four piston cores from Lake Bosumtwi show that an abrupt sedimentary transition from a mid-Holocene sapropel to calcareous laminated muds occurred at about 3200 cal yr B.P. High-resolution analyses of the nitrogen isotopic composition of organic matter across this transition confirm its abrupt nature, and suggest that the change may signal a step toward increased aridity and intensified surface winds that affected western equatorial Africa from Ghana to the Congo basin. Northern and Eastern Africa experienced a similar abrupt shift toward aridity during the late Holocene, but at about 5000 cal yr B.P., a difference in timing that illustrates the regional nature of climate changes during the Holocene and the importance of feedback mechanisms in regulating Holocene climate variability. Furthermore, an abrupt change at about 3000 cal yr B.P. occurs at several sites adjacent to the tropical and subtropical Atlantic, which may hint at major changes in the surface temperatures of the tropical Atlantic and/or Pacific at this time. (C) 2003 University of Washington. Published by Elsevier Inc. All rights reserved.
716arTimes Cited:43Cited References Count:39

Modeling the d180 in precipitation over the Americas: 1. Simulation of the stable isotope in Andean ice cores - Vuille, M.; Bradley, R. S.; Healy, R.; Werner, M.; Handy, D. R.; Thompson, L. G.; Keimig, F. (JGR, 2003)
id: 1771

Modeling the d18O in precipitation over the Americas: 1. Simulation of the stable isotope in Andean ice cores - Vuille, M.; Bradley, R. S.; Healy, R.; Werner, M.; Hardy, D. R.; Thompson, L. G.; Keimig, F. (JGR, 2003)
id: 1691

Modeling the d18O in precipitation over the Americas: 2. Interannual variability and climatic controls - Vuille, M.; Bradley, R. S.; Werner, M.; Healy, R.; Keimig, F. (JGR, 2003)
id: 1692

Muckrakers discover history in Long Island Sound - Varekamp, J. C. (New York Times, 2003)

Multiple sulfur isotopes and the evolution of the atmosphere - Farquhar, J.; Wing, B. A. (Earth and Planetary Science Letters, 2003)
Interest in multiple sulfur isotope analyses has been fueled by recent reports of mass-independent sulfur isotope signatures in the geologic record. A non-zero multiple isotopic signature of sulfur (Delta(33)S and Delta(36)S) is produced primarily through photochemical reactions, and it is an almost perfect tracer of the source of sulfur. Once the signature is passed on to a given sulfur reservoir, it will be preserved unless there is addition of sulfur with a different Delta(33)S or Delta(36)S. In the geological record, this signature has been used to study the evolution of the Earth's atmosphere and to trace movement of sulfur through geological systems early in Earth's history. Recently, small but significant mass-independent sigriatures have been reported for some younger samples, raising the possibility of additional applications of multiple isotope studies. The purpose of this review is to introduce and discuss the implications of multiple isotope studies and to focus attention on these anomalous, but not uncommon isotopic signatures. (C) 2003 Elsevier Science B.V. All rights reserved.
708vdTimes Cited:280Cited References Count:56

Niaqla revisited: Archaeology and ethnohistory of a Chumash Village on Santa Rosa Island, California - Rick, Torben C. (Society for California Archaeology 16, 2003)
id: 576

Palaeo-oceanography: Deepwater variability in the Holocene epoch - Oppo, D. W.; McManus, J. F.; Cullen, J. L. (Nature, 2003)
Oppo, Delia WMcManus, Jerry FCullen, James LengEngland2003/03/21 04:00Nature. 2003 Mar 20;422(6929):277.

The paleo environmental history of Long Island Sound, Abstract - Varekamp, J. C.; Thomas, E.; Buchholtz ten Brink, M. F.; Altabet, M.; Cooper, S. (Long Island Sound Lobster Research meeting, 2003)
id: 1178

Paleoenvironmental inferences from core Anta95-1 (Granite Harobr, Sw Ross Sea-Antarctica) - Orsini, G.; Giglio, F.; Langone, L.; Ravaioli, M. (Terra Antarctica reports, 2003)
id: 1001

Penetration of anthropogenic carbon into organic particles of the deep ocean - Druffel, E. R. M.; Bauer, J. E.; Griffin, S.; Hwang, J. (Geophysical Research Letters, 2003)
[1] In the late 1980s, bomb C-14 was present in suspended particulate organic carbon (POC) from the North Central Pacific (NCP) and Sargasso Sea ( SS) throughout most of the water column, demonstrating that deep POC had exchanged with atmospheric CO2 in the past 30 years. Upon reoccupation of these sites in 1999 and 2000, respectively, we observed that the delta(13)C values of suspended POC were lower than those measured a decade earlier. This demonstrates that anthropogenic CO2 from fossil fuel and biomass burning has penetrated a major organic matter pool in the deep ocean. Delta(14)C measured in the suspended POC showed similar or higher values in the deep Sargasso Sea and decreased values in the deep NCP compared to those measured previously. We use a box model to show that the differences in the radiocarbon results are likely due to the presence of resuspended sediment that is laterally advected from the continental margin to the deep Sargasso Sea.
709dpTimes Cited:12 Cited References Count:29
Keywords: bomb radiocarbon; C-14; CO2; delta-c-13; MATTER; NORTH PACIFIC-OCEAN; SARGASSO SEA; Sediment; variability; water

Persistence of Gulf Stream separation during the Last Glacial Period: Implications for current separation theories - Matsumoto, K.; Lynch-Stieglitz, J. (Journal of Geophysical Research-Oceans, 2003)
[1] We present stable oxygen isotope ratio (delta(18)O) measurements on deep-dwelling planktonic foraminifera from the western margin of the North Atlantic in order to reconstruct the latitude at which the Gulf Stream separated from the western boundary of the Atlantic Ocean in the past. The modern separation latitude can be reconstructed within one degree from delta(18)O measured on the fossil shells of deep-dwelling planktonic foraminifera Globorotalia truncatulinoides from the Holocene sediments representing the past 10,000 years of mild climate conditions similar to today. The separation latitude is captured in a sharp delta(18)O gradient, which reflects the prominent hydrographic change across the boundary between the warm waters south and east of the Gulf Stream and the cold Slope Water to the north. The latitudinal delta(18)O profile from approximately the Last Glacial Maximum shows that the Gulf Stream separated from the coast near Cape Hatteras at almost the same latitude as it does today. We assess our finding in light of existing Gulf Stream separation theories and conclude that one of the theories, the wind-induced separation mechanism, is not consistent with our paleoceanographic reconstruction.
690nvTimes Cited:14 Cited References Count:56
Keywords: cape-hatteras; deep-ocean; gulf stream separation; Last glacial maximum; marine sediment cores; north-atlantic; Ocean circulation; oxygen isotope composition; oxygen isotopic composition; past 21,000 years; planktonic foraminifera; planktonic-foraminifera; SARGASSO SEA; western boundary current; western boundary undercurrent; wind-driven

The persistence of memory: The fate of ancient sedimentary organic carbon in a modern sedimentary system - Blair, N. E.; Leithold, E. L.; Ford, S. T.; Peeler, K. A.; Holmes, J. C.; Perkey, D. W. (Geochimica Et Cosmochimica Acta, 2003)
The cycle of organic carbon burial and exhumation moderates atmospheric chemistry and global climate over geologic timescales. The burial of organic carbon occurs predominantly at sea in association with clay-sized particles derived from the erosion of uplifted continental rocks. It follows that the history of the fine-grained particles on land may bear on the nature of the organic carbon buried. In this study, the evolution of clay-associated organic matter was followed from bedrock source to the seabed in the Eel River sedimentary system of northern California using natural abundance C-13 and C-14 tracers. Approximately half of the fine-grained organic carbon delivered to the shelf is derived from ancient sedimentary organic carbon found in the uplifted Mesozoic-Tertiary Franciscan Complex of the watershed. The short residence time of friable soils on steep hill slopes, coupled with rapid sediment accumulation rates on the shelf-slope, act to preserve the ancient organic carbon. A comparable quantity of modem organic carbon is added to particles in the watershed and on the shelf and slope. The bimodal mixture of ancient and modem C in soils and sediments may be characteristic of many short, mountainous rivers. If the Eel River chemistry is typical of such rivers, more than 40 Tg of ancient organic C may be delivered to the world's oceans each year. A flux of that magnitude would have a significant influence on marine and global C-cycles. Copyright (C) 2003 Elsevier Science Ltd.
634jvTimes Cited:143Cited References Count:63

A possible record of the Younger Dryas event in deep-sea sediments of the Southern Ocean (Pacific sector) - Morigi, C.; Capotondi, L.; Giglio, F.; Langone, L.; Brilli, M.; Turi, B.; Ravaioli, M. (Palaeogeography Palaeoclimatology Palaeoecology, 2003)
The oxygen isotope record combined with radiocarbon dating from two deep-sea cores collected along a transect between New Zealand and the Ross Sea are used to establish a reliable chronostratigraphy for the last 14 kyr. After an integrated geochemical and micropaleontological analysis in this timeframe we detected a cooling interval dated between 12.5 cal kyr BP and 11.4 cal kyr BP. The age control suggests that this event started 1.5 kyr after the onset of the Antarctic Cold Reversal previously observed in several Antarctic ice cores. We infer that the observed cool event corresponds to the Younger Dryas event defined in Northern Europe. This suggests that climate change recorded in this sector of the Southern Hemisphere still shows some synchronicity with Northern Hemisphere variations and that the decoupling of climate change between the two hemispheres likely occurred south of the Polar Front. (C) 2003 Elsevier B.V. All rights reserved.
723feTimes Cited:15Cited References Count:55

Post little ice age uplift at Juneau, Alaska reconstructed from dendrochronology and geomorphology - Motyka, R. J. (Quaternary Research, 2003)
id: 698

On the preservation of laminated sediments along the western margin of North America - van Geen, A.; Zheng, Y.; Bernhard, J. M.; Cannariato, K. G.; Carriquiry, J.; Dean, W. E.; Eakins, B. W.; Ortiz, J. D.; Pike, J. (Paleoceanography, 2003)
id: 1128

Quantitative estimates of time-averaging in terebratulidbrachiopod shell accumulations from a modern tropical shelf - Carroll, M.; Kowalewski, M.; Simoes, M. G.; Goodfriend, G. A. (Paleobiology, 2003)
Quantitative estimates of time-averaging in marine shellaccumulations available to date are limited primarily toaragonitic mollusk shells. We assessed time-averaging in Holoceneassemblages of calcitic brachiopod shells by direct dating ofindividual specimens of the terebratulid brachiopod Bouchardiarosea. The data were collected from exceptional (brachiopod-rich)shell assemblages, occurring surficially on a tropical mixedcarbonate-siliciclastic shelf (the Southeast Brazilian Bight, SWAtlantic), a setting that provides a good climatic andenvironmental analog for many Paleozoic brachiopod shell beds ofNorth America and Europe. A total of 82 individual brachiopodshells, collected from four shallow (5-25 m) nearshore (
id: 2231; Source type: scholarlyjournals; Object type: Article; Object type: Feature; CSAUnique: BONE5712965; AccNum: 5712965; DOI: 10.1043/0094-8373(2003)029(0381:QEOTIT)2.0.CO;2; ISSN: 0094-8373; Peer Reviewed: true

Radiocarbon ages of marine biomarkers and co-occurring foraminifera: evidence for differential particle transport on continental margins - Mollenhauer, Gesine; Eglinton, Timothy I.; Hayes, John M.; Keinast, Markus; Lamy, Frank; Meggers, Helge; Schneider, Ralph R. (AGU Fall Meeting 2003, 2003)
id: 1069

Radiocarbon dating of individual fatty acids as a tool for refining Antarctic margin sediment chronologies - Ohkouchi, N.; Eglinton, T. I.; Hayes, J. M. (Radiocarbon, 2003)
We have measured the radiocarbon contents of individual, solvent-extractable, short-chain (C-14, C-16, and C-18) fatty acids isolated from Ross Sea surface sediments. The corresponding C-14 ages are equivalent to that of the post-bomb dissolved inorganic carbon (DIC) reservoir. Moreover, molecular C-14 variations in surficial (upper 15 cm) sediments indicate that these compounds may prove useful for reconstructing chronologies of Antarctic margin sediments containing uncertain (and potentially variable) quantities of relict organic carbon. A preliminary molecular C-14 chronology suggests that the accumulation rate of relict organic matter has not changed during the last 500 C-14 yr. The focus of this study is to determine the validity of compound-specific C-14 analysis as a technique for reconstructing chronologies of Antarctic margin sediments.
735tqTimes Cited:25 Cited References Count:29
Keywords: carbon; ice-sheet; marine-sediments; north-atlantic; organic-matter; ross-sea; southern-ocean

A radiocarbon method and multi-tracer approach to quantifying groundwater discharge to coastal waters - Gramling, Carolyn (MIT/WHOI, 2003)

Sea-level changes and depositional environments in the Izmit Gulf, eastern Marmara Sea, during the late glacial-Holocene period - Cagatay, M. N.; Gorur, N.; Polonia, A.; Demirbag, E.; Sakinc, M.; Cormier, M. H.; Capotondi, L.; McHugh, C.; Emre, O.; Eris, K. (Marine Geology, 2003)
Offshore and onshore stratigraphic studies, together with high-resolution shallow seismic reflection profiling and multibeam bathymetric mapping, were carried out in the western and central part of the Izmit Gulf. These studies indicate that the Izmit Gulf was a lacustrine environment as part of the Marmara 'Lake' during the late glaciation and early deglaciation until similar to12 kyr BP, when the Marmara Basin was inundated by the Mediterranean waters. Correlation of C-14-dated onshore and offshore stratigraphic units in the Western Izmit Gulf indicates that generally coarse late glacial sediments overlie a marked erosional surface formed during the low water level of the Marmara 'Lake'. These coarse sediments are succeeded by 10.4-7 kyr BP old transgressive, and by late Holocene post-transgression mud units. The bathymetry and sub-bottom Chirp profiles clearly show that the paleoshoreline of the Gulf was located at -85 m, having been controlled by the bedrock sill depth of the Canakkale Strait. Another paleoshoreline observed at -65 m on the northern margin of the Western Izmit and Karamursel basins was probably formed during the Younger Dryas sea-level stillstand. The shelf areas during this time were colonized by bioherms, which were subsequently drowned and disappeared after a further rise of the sea level. The presence of a -65 in marine paleoshoreline in the Karamursel Basin indicates that the sill restricting this basin to the west was much deeper than its present -55 in level and was located further south. The Golcuk Basin, restricted by a -38 in sill to its west, was probably not flooded by marine waters until similar to9 kyr BP. (C) 2003 Published by Elsevier B.V.
749gpTimes Cited:52Cited References Count:30

Sediment characteristics at selected sites of the Ross Sea continental shelf: does the sedimentary record reflect water column fluxes? - Frignani, M.; Giglio, F.; Accornero, A.; Langone, L.; Ravaioli, M. (Antarctic Science, 2003)
id: 440

Sedimentology and age control of late Quaternary New Jersey shelf deposits - Alexander, C.; Sommerfield, C.; Austin J.A, Jr.; Christensen, B.; Fulthorpe, C.; Goff, J.; Gulick, S.; Nordfjord, S.; Nielson, D.; Schock, S. (AGU Fall 2003 Meeting, 2003)
id: 636

Soil-productivity relationships and organic matter turnover in dry tropical forests of the Florida Keys - Ross, M. S.; Coultas, C. L.; Hsieh, Y. P. (Plant and Soil, 2003)
Soils and aboveground production in five types of upland forest in the Florida Keys were examined. Throughout the habitat gradient represented by these forest types, the soils were predominantly shallow and organic, forming in place directly on the limestone bedrock. However, the well-drained soils in the most productive broadleaved forests were deep enough to qualify as Histosols (Folists). Soils decreased in electrical conductivity and increased in nutrient content with increasing aboveground production. At 3-12 Mg ha(-1) yr(-1), production was within the range reported for dry tropical forests. Measured rates of decomposition were moderate or fast, and estimates of the organic C turnover of several soils based on their bomb radiocarbon signature were 100 years or less. In the face of these rapid turnover rates, we attribute the development of organic soils to the absence of mineral residues from weathering of the underlying limestone bedrock. Fast turnover of organic matter, and rapid and efficient cycling of nutrients are necessary to sustain the high production rates obtained on these shallow organic soils.
702ymTimes Cited:12Cited References Count:46

Stratigraphic evolution of the late Holocene Ganges-Brahmaputra lower delta plain - Allison, M. A.; Khan, S. R.; Goodbred, S. L.; Kuehl, S. A. (Sedimentary Geology, 2003)
Sediment cores from the Ganges-Brahmaputra delta in Bangladesh were examined for sedimentological character, clay mineralogy, elemental trends (C, N, S), and C-14 geochronology to develop a model for the sedimentary sequence resulting from lower delta plain progradation in the late Holocene. A widespread facies succession from Muddy Sand to Interbedded Mud records progradation of shoal-island complexes and the transition from subtidal to intertidal conditions. Mangrove-vegetated islands and peninsulas represent the final phase of progradation; a Mottled Mud that is deposited by penetration of turbid coastal water into the mangroves during high water events. Organic matter preservation is generally low ( < 1% TOC) in most of these well-drained deposits that are characterized by a permeable, silt-dominated granulometry. Clay mineralogy in the cores records the relative influence of smectite and kaolinite-rich Ganges sediments and illite and chlorite-rich Brahmaputra material. The lower delta plain west of the modem river mouths was deposited as a Ganges-dominated delta in three phases since 5000 cal years BP, with Brahmaputra influence confined to the Meghna estuary area and to the supratidal section of western delta deposits. Evolution of the lower delta plain in the late Holocene was influenced by regional subsidence patterns in the tectonically active Bengal Basin, which controlled distributary channel avulsion and migration, and the creation of accommodation space. (C) 2002 Elsevier Science B.V. All rights reserved.
642qaTimes Cited:92Cited References Count:84
Keywords: Ganges–Brahmaputra; Late Holocene; Stratigraphic evolution

Suitability of glycerin-preserved otoliths for age validation using bomb radiocarbon - Campana, S. E.; Stanley, R. D.; Wischniowski, S. (Journal of Fish Biology, 2003)
The effect of glycerin storage on the bomb radiocarbon content of otoliths was determined experimentally. Storage in either pre- or post-bomb glycerin had no detectable effect on the bomb radiocarbon content of either pre- or post-bomb otoliths. Therefore bomb-dated age validation studies need not be restricted to freshly-collected samples or dry otoliths, implying that the large numbers of glycerin-archived otoliths around the world are suitable for age validation studies using bomb radiocarbon. (C) 2003 The Fisheries Society of the British Isles.
734gqTimes Cited:5Cited References Count:9

Tufts submarine fan: Turbidity-current gateway to Escanaba Trough - Reid, J. A.; Normark, W. R. (U. S. Geological Survey Bulletin 2216, 2003)
id: 418

Using radiocarbon to apportion sources of polycyclic aromatic hydrocarbons in household soot - Reddy, C. M.; Xu, L.; O'Connor, R. (Environmental Forensics, 2003)
To determine whether polycyclic aromatic hydrocarbons (FAHs) in household soot were derived from the combustion of scrap wood or creosote that was impregnated in the wood (or some combination of both), the molecular composition and radiocarbon (C-14) content of the total carbon and several PAHs in the soot was investigated. The 5730-year half-life of C-14 makes it an ideal marker for identifying creosote-derived PAHs (C-14-free) versus those derived from the combustion of wood (contemporary C-14). The C-14 abundance of phenanthrene, fluoranthene, pyrene, and retene was determined by accelerator mass spectrometry after solvent extraction and purification by preparative capillary gas chromatography. The molecular analysis (presence of retene and 1,7-dimethylphenanthrene) and bulk C-14 content (contemporary) of the soot indicated that wood combustion was a strong source of carbon to the soot. The C-14 of retene in two soot samples was also contemporary, indicating that it was derived from the combustion of the scrap wood. These results are consistent with previous work that has suggested that retene is an excellent marker of wood combustion. However, the C-14 content of phenanthrene, fluoranthene, and pyrene in one soot sample was much lower and revealed that these compounds had a mixed creosote and wood source. Using an isotopic mass balance approach, we estimate that 40 to 70% of phenanthrene, fluoranthene, and pyrene were derived from the combustion of the scrap wood. The results of this study show that molecular marker and bulk C-14 analysis can be potentially misleading in apportioning sources of every PAH, and that molecular-level C-14 analysis of PAHs can be a powerful tool for environmental forensics.
731ytTimes Cited:16Cited References Count:42

Variations in the hydrological regime of Kara-Bogaz-Gol Gulf Lake Issyk-Kul, and the Aral Sea assessed based on data of bottom sediment studies - Ferronskii, V. I.; Polyakov, V. A.; Brezgunov, V. S.; Vlasova, L. S.; Karpychev, Yu A.; Bobkov, A. F.; Romaniovskii, V. V.; Johnson, T. C.; Ricketts, R. D.; Rasmussen, K. A. (Water Resources, 2003)
id: 493

An 11,000 year lithostratigraphic and paleohydrologic record from equatorial Africa: Lake Edward, Uganda-Congo - Russell, J. M.; Johnson, T. C.; Kelts, K. R.; Laerdal, T.; Talbot, M. R. (Paleogeography, Paleoclimatology, Palaeoecology, 2002)
id: 1010

The 14C AMS system at the University of Georgia - Roberts, M. L.; Culp, R. A.; Dvoracek, D. K.; Hodgins, G. W. L.; Neary, M. P.; Noakes, J. E. (International Conference on Accelerator Mass Spectrometry, 2002)
id: 1684

A 20,000-yr sedimentological record from Lake Malawi, East Africa: the Late-Pleistocene/Holocene transition in the southern tropics - Barry, S. L.; Filippi, M. L.; Talbot, M.; Johnson, T. C. (The East African Great Lakes: Limnology, Palaeoclimatology and Biodiversity, 2002)
id: 1478

A 24,600 year diatom record from the northern basin of Lake Malawi - Gasse, F.; Barker, P.; Johnson, T. C. (The East African Great Lakes, Limnology, Palaeoclimatology and Biodiversity, 2002)
id: 1479

A 4000-Year Lacustrine Record of Environmental Change in the Southern Maya Lowlands, Petén, Guatemala - Rosenmeier, Michael F.; Hodell, David A.; Brenner, Mark; Curtis, Jason H.; Guilderson, Thomas P. (Quaternary Research, 2002)
A 4000-yr sediment core record from Lake Salpetén, Guatemala, provides evidence for Maya-induced forest clearance and consequent soil erosion between ∼1700 cal yr B.C. and 850 cal yr A.D. Radiocarbon ages of wood, seeds, and charcoal support an age-depth model with average errors of ±110 cal yr. Relatively low carbonate δ18O values between 1300 and 400 cal yr B.C. coincide with pollen evidence for forest loss, consistent with increased surface and groundwater flow to the lake. Minimum δ18O values between 400 cal yr B.C. and 150 cal yr A.D. suggest a high lake level, as do 14C-dated aquatic gastropods as much as 7.5 m above the present lake stage. High lake levels resulted from reduced evaporation-to-precipitation ratios, increased hydrologic input caused by anthropogenic deforestation, or both. The Preclassic abandonment (150 A.D.) and Early Classic/Late Classic boundary (550 A.D.) are marked by relatively high δ18O values indicating reduced lake levels. Oxygen isotope composition increased further coincident with the Terminal Classic Maya demographic decline between 800 and 900 A.D. This period of high δ18O may have been caused by the greater aridity that has been documented in northern Yucatán lakes or by decreased hydrologic input to the lake as a consequence of forest recovery. Reduced soil erosion after 850 cal yr A.D. coincided with the Terminal Classic Maya demographic decline and permitted forest recovery and resumption of organic sedimentation.
id: 2106

A 6100 14C year record of El Nino activity from the Galapagos Islands - Riedinger, M. A.; Steinitz-Kannan, M.; Last, W. M.; Brenner, M. (Journal of Paleolimnology, 2002)
id: 1485

Abundant brachiopods on a tropical, upwelling-influenced shelf (Southeast Brazilian Bight, South Atlantic - Kowalewski, M.; Simeos, M. G.; Carroll, M.; Rodland, D. L. (Palaios, 2002)
Rhynchonelliform brachiopods were diverse and often dominant benthos of tropical seas in the Paleozoic. In contrast, they are believed to be rare in open habitats of modern oceans, especially at low latitudes. This study documents numerous occurrences of rhynchonelliform brachiopods on a modern tropical shelf, particularly in areas influenced by upwelling. Extensive sampling of the outer shelf and coastal bays of the Southeast Brazilian Bight revealed dense populations of terebratulid brachiopods (>103 individuals / m2 of seafloor) between 24° and 26°S. On the outer shelf, brachiopods are more abundant than bivalves and gastropods combined. However, brachiopod diversity is low: only four species belonging to the genera Bouchardia, Terebratulina, Argyrotheca, and Platidia were identified among over 16000 examined specimens. Brachiopods occur preferentially on carbonate bottoms and include two substrate-related associations: Bouchardia (40–70% CaCO3 weight content) and Terebratulina-Argyrotheca (70–95% CaCO3). All four species display a broad bathymetric range that contrasts with a narrow depth tolerance postulated for many Paleozoic rhynchonelliforms. The most abundant populations occur in the depth range between 100 and 200 m, and coincide with zones of shelf-break upwelling, where relatively colder and nutrient-rich water masses of the South Atlantic Central Water are brought upward by cyclonic meanders of the South Brazil Current (a western boundary current that flows poleward along the coast of Brazil). This is consistent with previous biological and paleontological studies that suggest upwelling may play a role in sustaining brachiopod-dominated benthic associations. The presence of abundant brachiopods in the open habitats of the tropical shelf of the western South Atlantic contrasts with current understanding of their latitudinal distribution and points to major gaps in our knowledge of their present-day biogeography. The ecological importance of rhynchonelliform brachiopods in modern oceans and their role as producers of biogenic sedimentary particles may be underestimated.
id: 1416

Akata Site (32SN121) 1996 Archeological Excavations. Anthropology Research, Department of Anthropology, University of North Dakota, Grand Forks (Report) - Toom, Dennis L. (Dakotas Area Office, U. S. Bureau of Reclamation, 2002)
id: 1362

The andesite aqueduct: prespectives on the evolution of intermediate magmatism in west-central (105-99 degrees W) Mexico - Carmichael, I. S. E. (Contributions to Mineralogy and Petrology, 2002)
id: 1588

The Antarctic ice sheet during the last glacial maximum and its subsequent retreat histroy: a review - Anderson, J. B.; Shipp, S. S.; Lowe, A. L.; Wellner, J. S.; Mosola, A. (Quaternary Science Reviews, 2002)
An emerging body of evidence from studies of the last glacial/interglacial cycle suggests that the East and West Antarctic ice sheets have not advanced and retreated in concert. The West Antarctic ice sheet advanced to the outer shelf in most regions during the Last Glacial Maximum (LGM). The retreat from the shelf commenced shortly after the LGM and continued into the late Holocene. The West Antarctic Ice Sheet in Ross and Amundsen seas slid across a deforming bed, at least during the final phases of extended glaciation. This implies that at this time the ice sheet had a low profile. Differences in the number and locations of grounding-zone wedges and smaller grounding zone features from trough to trough imply that individual West Antarctic Ice Sheet ice streams retreated episodically. Details concerning the expansion, retreat, and behavior of the East Antarctic Ice Sheet (EAIS) are more sparse. The picture emerging is that the EAIS did not expand to the continental shelf edge during the LGM; rather, it achieved a maximum extent of a mid-shelf position in some locations, while in other areas the ice terminus was situated near its present location. The timing of retreat along sectors within the EAIS appears diachronous, and in places occurred prior to the LGM. The Antarctic Peninsula shelf contained considerably more ice during the LGM than previously proposed. The results presented in this paper support more recent published ice-sheet models that call for greater contributions of melting ice from West Antarctica, including the Antarctic Peninsula, to the post-glacial rise in sea level.
id: 1126

On the antiquity of the single-piece shell fishhook: AMS radiocarbon evidence from the southern California coast - Rick, T. C.; Vellanoweth, R. L.; Erlandson, J. M.; Kennett, D. J. (Journal of Archaeological Sciences, 2002)
id: 1024

Assessing the linkages among climate variability, land-use change, and the sedimentary regime of the Upper Chesapeak Bay - Barros, A. P.; Gordon, S. J. (Proceedings Coastal Environment 2002, 2002)
id: 1218

Benthic foraminifera in Long Island Sound as indicators of eutrophication - Abramson, I.; Thomas, E.; Varekamp, J. C.; Buchholtz ten Brink, M. R. (GSA Annual meeting, 2002)
id: 731

Biogenic silica profiles in the sediments of large tropical lakes: examples from East Africa - Johnson, T. C. (Sedimentation in Continental Rifts, 2002)
id: 343

Birth of the modern Chesapeake Bay estuary between 7.4 and 8.2 ka and implications for global sea-level rise - Bratton, John F.; Colman, Steven M.; Thieler, E. Robert; Seal, Robert R. (Geo-Marine Letters, 2002)
Two major pulses of sea-level rise are thought to have taken place since the last glacial maximum — meltwater pulses (mwp) 1A (12 cal ka) and 1B (9.5 cal ka). Between mwp 1B and about 6 cal ka, many of the complex coastal ecosystems which ring the world’s oceans began to form. Here we report data for rhenium, carbon isotopes, total organic carbon, and fossil oysters from Chesapeake Bay which span the transition from fresh to brackish water conditions in the bay in the mid-Holocene. These data constrain sea-level change and resulting environmental change in the bay. They indicate that the transition was rapid, and that it was produced by (1) a third pulse of rapid eustatic sea-level rise, or (2) a geometry of the prehistoric Chesapeake Bay basin which predisposed it to a nonlinear response to a steadily rising sea level. Similar nonlinear changes in vulnerable coastal environments are likely to take place in the future due to polar warming, regardless of the timing or rate of sea-level rise.
id: 540

Blackwood Creek Stream restoration project design draft report - Beck, Nicole; Hydrology, Swanson (U.S. Forest Service Lake Tahoe Basin Management Unit, South Lake Tahoe, CA, 2002)
id: 350

Blackwood Creek Strem restoration project design draft report - Beck, N.; Hydrology, S. (2002)
id: 1140

Bomb dating and age determination of large pelagic sharks - Campana, S. E.; Natanson, L. J.; Myklevoll, S. (Canadian Journal of Fisheries and Aquatic Sciences, 2002)
Despite their notoriety and role as apex predators, the longevity of large pelagic sharks such as the porbeagle (Lamna nasus) and shortfin mako (Isurus oxyrinchus) is unknown. Vertebral growth bands provide an accurate indicator of age in young porbeagle, but age validation has never been reported for any large shark species past the age of sexual maturity. Here, we report the first application of bomb radiocarbon as an age validation method for long-lived sharks based on date-specific incorporation of radiocarbon into vertebral growth bands. Our results indicate that porbeagle vertebrae recorded and preserved a bomb radiocarbon pulse in growth bands formed during the 1960s. Through comparison of radiocarbon assays in young, known-age porbeagle collected in the 1960s with the corresponding growth bands in old porbeagle collected later, we confirm the validity of porbeagle vertebral growth band counts as accurate annual age indicators to an age of at least 26 years. The radiocarbon signatures of porbeagle vertebral growth bands appear to be temporally and metabolically stable and derived mainly from the radiocarbon content of their prey. Preliminary radiocarbon assays of shortfin mako vertebrae suggest that current methods for determining shortfin mako age are incorrect.
548ceTimes Cited:98Cited References Count:16

Bomb radiocarbon and anthropogenic CO2 in ocean biogeochemical models - Matsumoto, K.; Sarmiento, J.; Key, R.; Slater, C.; Sabine, C. (AGU/ASLO Conference, 2002)
id: 320

A Budget of Carbonate and Terrigenous Sediments, Hanalei Bay, Kauai, Hawaiian Islands - Calhoun, R. S.; Fletcher, C. H.; Harney, J. N. (Marine Geology, 2002)
The sediment budget of Hanalei Bay on the north shore of Kauai was calculated using sedimentological and geophysical methods. The calculations of the budget subsequently allowed an interpretation of the Holocene history of the bay. The bay sediments are easily separated into marine (carbonate) and terrigenous (siliciclastic) grains. Surficial sediments are dominated by carbonate grains (∼70%) of coralline algae, coral, and mollusc fragments as well as foraminifera, Halimeda, bryozoa, and echinoderm tests. However, siliciclastic grains (e.g. olivine, plagioclase, volcanic lithics) from the Hanalei River watershed draining shield volcanic highlands are the most common individual grain type (∼27%) and form a zone of high concentration from the mouth of the Hanalei River into the center of the bay. Flooding in the bay by the post-glacial sea-level rise began soon after 11.7 kyears. The resulting marine environment caused the net deposition of 45.5±1.5×106 m3 of sediment in the bay and approximately 33.7±11.2×106 m3 of sediment on the Hanalei coastal plain. The total volume of carbonate sediment stored in the bay and coastal plain is greater than the volume likely to have been produced exclusively within the bay during the same time. Calculations indicate that approximately 2490 m3 year−1 have been imported into the bay or coastal plain and deposited since 11,700 years ago. The majority of this sediment influx is likely delivered from the east by the strong tradewind-driven littoral currents that characterize Kauai's north shore. Net carbonate sediment deposition in Hanalei Bay peaked at a rate of 15,500 m3 year−1 between 5000 and 3000 years ago (when sea level may have been 2 m above present) diminishing to 3890 m3 year−1 from 1000 years ago to the present. This influx is likely to have played a significant role in the mid to late Holocene progradation of the Hanalei shoreline.
id: 105

Carbon isotopic composition of DOM - Bauer, J. E. (Biogeochemistry of Marine Dissolved Organic Matter, 2002)
id: 687

Challenges in radiocarbon dating organic carbon in opal-rich marine sediments - Zheng, Y.; Anderson, R. F.; Froelich, P. N.; Beck, W.; McNichol, A. P.; Guilderson, T. (Radiocarbon, 2002)
We explored the reliability of radiocarbon ages obtained on organic carbon phases in opal-rich Southern Ocean sediments. Paired biogenic carbonate and total organic carbon (TOC) C-14 analyses for three Southern Ocean cores showed that the TOC ages were systematically younger than the carbonate ages. Carbonate ages were consistent with oxygen isotopic and bio-stratigraphy, indicating error in TOC ages that could be explained by 5-24% of modern carbon contamination of TOC samples. Two possible sources of contamination are: 1) adsorption of atmospheric CO2 or volatile organic compounds to reactive opal surface sites, and 2) fixation of atmospheric CO2 by chemosynthetic bacteria during core storage. In an effort to reduce the modem carbon contamination, diatoms were separated from sediments, purified, and pre-oxidized by concentrated nitric and perchloric acids to permit dating of opal-intrinsic organic carbon (similar to0.1-0.3% by weight). C-14 ages of chemically pre-oxidized opal showed a significant amount of modem carbon contamination, from 11 to 32%, indicating adsorption from the atmosphere of modem carbon onto opal surfaces that were previously cleaned by acid oxidation. Several experiments designed to eliminate the modern C contamination were attempted, but so far we have not been able to obtain a radiocarbon age on C-14-dead Southern Ocean opal-rich sediments, either bulk TOC or purified diatom opal samples, as old as our procedural blank.
591keTimes Cited:13Cited References Count:28

Changes in the 13C/12C of dissolved inorganic carbon in the ocean as a tracer of anthropogenic CO2 uptake - Quay, P. D.; Sonnerup, R.; Westby, T.; Stutsman, J.; McNichol, A. P. (Global Biogeochemical Cycles, 2002)
id: 1715

Chemical and carbon isotopic evidence for the source and fate of dissolved organic matter in the northern Everglades - Wang, Y.; Hsieh, Y. P.; Landing, W. M.; Choi, Y. H.; Salters, V.; Campbell, D. (Biogeochemistry, 2002)
id: 616

Chemical composition and cycling of dissolved organic matter in the Mid-Atlantic Bight - Aluwihare, L. I.; Repeta, D. J.; Chen, R. F. (Deep-Sea Research Part Ii-Topical Studies in Oceanography, 2002)
This study focuses on the chemical characterization of high molecular-weight dissolved organic matter (HMW DOM) isolated from the Middle Atlantic Bight in April 1994 and March 1996. Using proton nuclear magnetic resonance spectroscopy ((HNMR)-H-1) and monosaccharide analysis we compared both spatial and temporal variations in the chemical structure of HMW DOM across this region. Our analyses support the presence of at least two compositionally distinct components to HMW DOM. The major component is acyl polysaccharide (APS), a biopolymer rich in carbohydrates, acetate and lipid, accounting for between 50% and 80% of the total high molecular-weight dissolved organic carbon (HMW DOC) in surface samples. APS is most abundant in fully marine, surface-water samples, and is a product of autochthonous production. Organic matter with spectral properties characteristic of humic substances is the second major component of HMW DOM. Humic substances are most abundant (up to 49% of the total carbon) in samples collected from estuaries, near the coast, and in deep water, suggesting both marine and perhaps terrestrial sources. Radiocarbon analyses of neutral monosaccharides released by the hydrolysis of APS have similar and modern (average 71parts per thousand) Delta(14)C values. Radiocarbon data support our suggestion that these sugars occur as part of a common macromolecule, with an origin via recent biosynthesis. Preliminary radiocarbon data for total neutral monosaccharides isolated from APS at 300 and 750m show this fraction to be substantially enriched relative to total HMW DOC and DOC. The relatively enriched radiocarbon values of APS at depth suggest APS is rapidly transported into the deep ocean. (C) 2002 Elsevier Science Ltd. All rights reserved.
607kxTimes Cited:74Cited References Count:44

Chemostratigraphy of Paleoproterozoic carbonate successions of the Wyoming Craton: tectonic forcing of biogeochemical change? - Bekker, A.; Karhu, J. A.; Eriksson, A.; Kaufman, A. J. (Precambrian Research, 2002)
The Archean Wyoming Craton is flanked on the south and east by belts of Paleoproterozoic supracrustal successions whose correlation is complicated by lack of geochronologic constraints and continuous outcrop. However, carbonate units in these successions may be correlated by integrating carbon isotope stratigraphy with lithostratigraphy. The ∼10 km thick Paleoproterozoic Snowy Pass Supergroup in the Medicine Bow Mountains was deposited on the present-day southern flank of the Wyoming Craton; it contains three discrete levels of glacial diamictite correlative with those in the Huronian Supergroup, on the southern margin of the Superior Craton. The Nash Fork Formation of the upper Snowy Pass Supergroup is significantly younger than the uppermost diamictite and was deposited after the end of the Paleoproterozoic glacial epoch. Carbonates at the base of the Nash Fork Formation record remarkable 13C-enrichment, up to +28‰ (V-PDB), whereas those from overlying members of the lower Nash Fork Formation have δ13C values between +6 and +8‰. Carbonates from the upper Nash Fork Formation above the carbonaceous shale have carbon isotope values ranging between 0 and +2.5‰. The transition from high carbon isotope values to those near 0‰ in the Nash Fork Formation is similar to that at the end of the ca. 2.2–2.1 Ga carbon isotope excursion in Fennoscandia. This chemostratigraphic trend and deposition of BIFs, Mn-rich lithologies, carbonaceous shales and phosphorites at the end of the global ca. 2.2–2.1 Ga carbon isotope excursion are likely related to ocean overturn associated with the final breakup of the Kenorland supercontinent. Correlative carbonates from the Slaughterhouse Formation in the Sierra Madre, WY, and from the Whalen Group in the Rawhide Creek area in the Hartville Uplift, WY, have highly positive carbon isotope values. In contrast, carbonates from other exposures of the Whalen Group in the Hartville Uplift and all carbonate units in the Black Hills, SD, have carbon isotope values close to 0‰. Combined with existing geochronologic and stratigraphic constraints, these data suggest that the Slaughterhouse Formation and the succession exposed in the Rawhide Creek area of the Hartville Uplift are correlative with the lower and middle Nash Fork Formation and were deposited during the ca. 2.2–2.1 Ga carbon isotope excursion. The Estes and Roberts Draw formations in the Black Hills and carbonates from other exposures in the Hartville Uplift postdate the ca. 2.2–2.1 Ga positive carbon isotope excursion and are most likely correlative with the upper Nash Fork Formation. The passive margin, on which the carbonates with highly positive carbon isotope values were deposited, extended around the southern flank of the Wyoming Craton through the Sierra Madre, Medicine Bow Mountains and Hartville Uplift. The presence of carbonates with carbon isotope values close to 0‰ in the upper Nash Fork Formation and the Whalen Group indicates that the passive margin persisted on the southern flank of the Wyoming Craton after the carbon isotope excursion. Rifting in the Black Hills, likely related to the final breakup of the Kenorland, succeeded the carbon isotope excursion, since the Estes and Roberts Draw formations, deposited during rifting and ocean opening on the eastern flank of the Wyoming Craton, postdate the carbon isotope excursion.
id: 1586
Keywords: Biogeochemistry; Chemostratigraphy; Kenorland; Paleoproterozoic; Wyoming

Composition, age, provenance of organic matter in N. W. African dust over the Atlantic Ocean - Eglinton, T. I.; Eglinton, G.; Dupont, L.; Montlucon, D.; Sholkovitz, E.; Reddy, C. M. (Geochemistry, Geophysics, Geosystems G3, 2002)
id: 611

Compositional characterization of prehistoric ceramics: A new approach - Kennett, D. J.; Sakai, S.; Neff, H.; Gossett, R.; Larson, D. O. (Journal of Archaeological Sciences, 2002)
id: 474

Converting AMS data to radiocarbon values: considerations and conventions - McNichol, A. P.; Jull, A. J. T.; Burr, G. S. (Radiocarbon, 2002)
id: 1818

A Critical Evaluation of Interlaboratory Data on Total, Elemental, and Isotopic Carbon in the Carbonaceous Particle Reference Material, NIST SRM 1649a - Currie, L. A.; Benner, B. A., Jr.; Kessler, J. D.; Klinedinst, D. B.; Klouda, G. A.; Marolf, J. V.; Slater, J. F.; Wise, S. A.; Cachier, H.; Cary, R.; Chow, J. C.; Watson, J.; et al. (J Res Natl Inst Stand Technol, 2002)
Because of increased interest in the marine and atmospheric sciences in elemental carbon (EC), or black carbon (BC) or soot carbon (SC), and because of the difficulties in analyzing or even defining this pervasive component of particulate carbon, it has become quite important to have appropriate reference materials for intercomparison and quality control. The NIST "urban dust" Standard Reference Material((R)) SRM 1649a is useful in this respect, in part because it comprises a considerable array of inorganic and organic species, and because it exhibits a large degree of ((14)C) isotopic heterogeneity, with biomass carbon source contributions ranging from about 2 % (essentially fossil aliphatic fraction) to about 32 % (polar fraction). A primary purpose of this report is to provide documentation for the new isotopic and chemical particulate carbon data for the most recent (31 Jan. 2001) SRM 1649a Certificate of Analysis. Supporting this is a critical review of underlying international intercomparison data and methodologies, provided by 18 teams of analytical experts from 11 institutions. Key results of the intercomparison are: (1) a new, Certified Value for total carbon (TC) in SRM 1649a; (2) (14)C Reference Values for total carbon and a number of organic species, including for the first time 8 individual PAHs; and (3) elemental carbon (EC) Information Values derived from 13 analytical methods applied to this component. Results for elemental carbon, which comprised a special focus of the intercomparison, were quite diverse, reflecting the confounding of methodological-matrix artifacts, and methods that tended to probe more or less refractory regions of this universal, but ill-defined product of incomplete combustion. Availability of both chemical and (14)C speciation data for SRM 1649a holds great promise for improved analytical insight through comparative analysis (e.g., fossil/biomass partition in EC compared to PAH), and through application of the principle of isotopic mass balance.
Currie, L ABenner, B A JrKessler, J DKlinedinst, D BKlouda, G AMarolf, J VSlater, J FWise, S ACachier, HCary, RChow, J CWatson, JDruffel, E R MMasiello, C AEglinton, T IPearson, AReddy, C MGustafsson, OQuinn, J GHartmann, P CHedges, J IPrentice, K MKirchstetter, T WNovakow, TPuxbaum, HSchmid, Heng2002/01/01 00:00J Res Natl Inst Stand Technol. 2002 Jun 1;107(3):279-98. doi: 10.6028/jres.107.022. Print 2002 May-Jun.

Data report: Australian Bight - Hine, A. C.; Brooks, G. R.; Mallinson, D.; Brunner, C. A.; James, N. P.; Feary, D. A.; Holbourn, A. E.; Drexler, T. M.; Howd, P. (Proc. ODP, Sci. Results, 2002)
id: 271

Differences in 14C age between stratigraphically associated charcoal and marine shell from the archaic period site of kilometer 4, southern Peru: old wood or old water? - Kennett, D. J.; Ingram, B. L.; Southon, J. R.; Wise, K. (Radiocarbon, 2002)
id: 1023

The distribution and inventory of bomb produced radiocarbon in the Pacific Ocean - Key, R. M. (AGU/ASLO Conference, 2002)
id: 1448

Drowned reefs and antecedent karst topography, Au'au Channel, S. E. Hawaiian Island - Grigg, R. W.; Grossman, E. E.; al, et (EOS, 2002)
id: 662

The dynamics of pore water dissolved organic carbon and the fate of organic matter in anoxic marine sediments: As assessment using carbon isotopes and ultrafiltration. PhD thesis - Seagle, Carol A. (University of North Carolina at Chapel Hill, 2002)

El Nino-like pattern in Ice Age Tropical Pacific Sea surace temperature - Koutavas, Athanasios; Lynch-Stieglitz, Jean; Marchitto, Thomas M.; Sachs, Julian P. (Science, 2002)
Sea surface temperatures (SSTs) in the cold tongue of the eastern equatorial Pacific exert powerful controls on global atmospheric circulation patterns. We examined climate variability in this region from the Last Glacial Maximum (LGM) to the present, using a SST record reconstructed from magnesium/calcium ratios in foraminifera from sea-floor sediments near the Galápagos Islands. Cold-tongue SST varied coherently with precession-induced changes in seasonality during the past 30,000 years. Observed LGM cooling of just 1.2°C implies a relaxation of tropical temperature gradients, weakened Hadley and Walker circulation, southward shift of the Intertropical Convergence Zone, and a persistent El Niño–like pattern in the tropical Pacific. This is contrasted with mid-Holocene cooling suggestive of a La Niña–like pattern with enhanced SST gradients and strengthened trade winds. Our results support a potent role for altered tropical Pacific SST gradients in global climate variations.
id: 644

ENSO mid-Holocene onset: constraints from an open ocean record in the eastern equatorial Pacific - Richaud, M.; Loubere, P. (AGU, 2002)
id: 352

Eolian processes, ground cover, and the archaeology of coastal dunes: a taphonomic case study from San Miguel Island, California, U.S.A - Rick, Torben C. (Geoarchaeology, 2002)
id: 1089

Eutrophication of Long Island Sound as traced by benthic foraminifera - Thomas, E.; Abramson, I.; Varekamp, J. C.; Buchholtz ten Brink, M. R. (Long Island Sound/NEERS Research Conference, 2002)
id: 727

Field and laboratory data from an earthquake history study of the Toe Jam Hill fault, Bainbridge Island, Washington - Nelson, A. R.; Johnson, S. Y.; Wells, R. E.; Kelsey, H. M.; Pezzopane, S. K.; Sherrod, B. L.; Bradley, L. A.; Iii, Koehler R. D.; Bucknam, R. C.; Haugerud, R. A.; LaPrade, W. T. (U.S. Geological Survey Open-File Report, 2002)
id: 428

Field and Laboratory data from an earthquake history study of the Toe Jam Hill fault, Bainbridge Island, Washington - Nelson, A. R.; Johnson, S. Y.; Wells, R. E.; Pezzopane, S. K.; Kelsey, H. M.; Sherrod, B. L.; Bradley, L. A.; Koehler, R. D., III; Bucknam, R. C.; Haugerud, R. A.; LaPrade, W. T. (U.S. Geological Survey Open-File Report 02-60, 2002)
id: 259

Foragers of the Congo: the early settlement of the Ituri forest - Mercader, J. (Under the Canopy: The Archaeology of Tropical Rain Forests, 2002)
id: 1197

Fossil sources of PM2.5 aerosol carbon based on 14C measurements - Tanner, R. L.; Parkhurst, W. J.; McNichol, A. P. (PM2.5 and electric power generation: recent findings and implications, 2002)
id: 353

A high-resolution paleoclimate record spanning the past 25,000 years in southern East Africa - Johnson, T. C.; Brown, E. T.; McManus, J.; Barry, S.; Barker, P.; Gasse, F. (Science, 2002)
High-resolution profiles of the mass accumulation rate of biogenic silica and other geochemical proxies in two piston cores from northern Lake Malawi provide a climate signal for this part of tropical Africa spanning the past 25,000 years. The biogenic silica mass accumulation rate was low during the relatively dry late Pleistocene, when the river flux of silica to the lake was suppressed. Millennial-scale fluctuations, due to upwelling intensity, in the late Pleistocene climate of the Lake Malawi basin appear to have been closely linked to the Northern Hemisphere climate until 11 thousand years ago. Relatively cold conditions in the Northern Hemisphere coincided with more frequent north winds over the Malawi basin, perhaps resulting from a more southward migration of the Intertropical Convergence Zone.
Johnson, Thomas CBrown, Erik TMcManus, JamesBarry, SylviaBarker, PhilipGasse, FrancoisengResearch Support, U.S. Gov't, Non-P.H.S.2002/04/06 10:00Science. 2002 Apr 5;296(5565):113-32.

The historical record of water quality in Long Island Sound - Varekamp, J. C.; Thomas, E.; Mecray, E. L.; Buchholtz ten Brink, M. F. (Long Island Sound workshop, 2002)
id: 726

Holocene chronology of a continental shelf mudbelt off southwestern Africa - Meadows, M. E.; Rogers, J.; Lee-Throp, J. A.; Bateman, M. D.; Dingle, R. V. (The Holocene, 2002)
The Holocene lithostratigraphy and geochronology of sediments on an inner continental-shelf mudbelt off the west coast of southern Africa is presented. Based on a study of seven large gravity cores, numerous grab samples and two vibracores, two distinctive sections of the mudbelt have been identi” ed. The northern section is associated with the Orange River prodelta, and is dominated by laminated clay-rich sediments, while the southern section off Namaqualand is associated with more homogeneous muds. AMS radiocarbon ages of 31 samples from these cores are problematic due to the absence of expected modern material at the sedimentocean interface and numerous age reversals and inconsistencies in some of the cores. Possible mechanisms to explain the apparently anomalously old surface and near-surface samples are suggested. Most likely expla nations appear to lie in a combination of sediment-retrieval problems, the periodic loss of ” ne particulate organic carbon from within the water column, the sampling of possible relic sediments and, most likely of all, the incorporation into the sediments of 14C-depleted terrigenous organic matter. The age reversals are especially evident in the laminated sediments, and the entrainment of ‘old’ carbon from the terrestrial source of these sediments is offered as the most parsimonious explanation. Stable carbon isotope analyses and a single lumi nescence age support the contention that radiocarbon date inconsistencies are a consequence of terrestrial inputs of carbon which is non-contemporaneous with the actual time of sedimentation. In studies of offshore accumulations of terrigenous material, the marine-derived organic fraction may therefore prove a more reliable measure of radiocarbon chronology.
id: 220

Holocene moisture changes and fire frequency at Rio Rubens Bog, Southern Patagonia - Huber, U. M.; Markgraf, V. (Fire History, 2002)
id: 233

Implications of environmental change for energy flow through natural systems: Freshwater wetlands and coastal zones - Chasar, L. (Florida State University, 2002)

In situ calcium carbonate dissolution in the Pacific Ocean - Feely, R. A.; Sabine, C. L.; Lee, K.; Millero, F. J.; Lamb, M. F.; Greeley, D.; Bullister, J. L.; Key, R. M.; Peng, T. H.; Kozyr, A.; Ono, T.; Wong, C. S. (Global Biogeochemical Cycles, 2002)
Over the past several years researchers have been working to synthesize the WOCE/JGOFS global CO(2) survey data to better understand carbon cycling processes in the oceans. The Pacific Ocean data set has over 35,000 sample locations with at least two carbon parameters, oxygen, nutrients, CFC tracers, and hydrographic parameters. In this paper we estimate the in situ CaCO(3) dissolution rates in the Pacific Ocean water column. Calcium carbonate dissolution rates ranging from 0.01-1.1 mumol kg(-1) yr(-1) are observed in intermediate and deepwater beginning near the aragonite saturation horizon. In the North Pacific Intermediate Water between 400 and 800 m, CaCO(3) dissolution rates are more than 7 times faster than observed in middle and deep water depths (average=0.051 m mol kg(-1) yr(-1)). The total amount of CaCO(3) that is dissolved within the Pacific is determined by integrating excess alkalinity throughout the water column. The total inventory of CaCO(3) added by particle dissolution in the Pacific Ocean, north of 40degreesS, is 157 Pg C. This amounts to an average dissolution rate of approximately 0.31 Pg C yr(-1). This estimate is approximately 74% of the export production of CaCO(3) estimated for the Pacific Ocean. These estimates should be considered to be upper limits for in situ carbonate dissolution in the Pacific Ocean, since a portion of the alkalinity increase results from inputs from sediments.
649rqTimes Cited:86 Cited References Count:60
Keywords: anthropogenic co(2); anthropogenic co2; aragonite saturation; atmospheric carbon; caco(3) dissolution; calcite saturation; carbonate lysocline; chemical lysocline; coccolithophore emiliania-huxleyi; indian-ocean; north pacific; organic-matter; Pacific Ocean; panama basin; particulate matter

Increase in the Asian southwest monsoon during the past four centuries - Anderson, D. M.; Overpeck, J. T.; Gupta, A. K. (Science, 2002)
Climate reconstructions reveal unprecedented warming in the past century; however, little is known about trends in aspects such as the monsoon. We reconstructed the monsoon winds for the past 1000 years using fossil Globigerina bulloides abundance in box cores from the Arabian Sea and found that monsoon wind strength increased during the past four centuries as the Northern Hemisphere warmed. We infer that the observed link between Eurasian snow cover and the southwest monsoon persists on a centennial scale. Alternatively, the forcing implicated in the warming trend (volcanic aerosols, solar output, and greenhouse gases) may directly affect the monsoon. Either interpretation is consistent with the hypothesis that the southwest monsoon strength will increase during the coming century as greenhouse gas concentrations continue to rise and northern latitudes continue to warm.
id: 536; Anderson, David M Overpeck, Jonathan T Gupta, Anil K New York, N.Y. Science. 2002 Jul 26;297(5581):596-9.

Influence of Vegetation Change on Watershed Hydrology: Implications for Paleoclimatic Interpretation of Lacustrine d180 Records - Rosenmeier, M. F.; Hodell, D. A.; Brenner, M.; Curtis, J. H.; Martin, J. B.; Anselmetti, F. S.; Ariztegui, D.; Guilderson, T. P. (Journal of Paleolimnology, 2002)
id: 1386

Inorganic carbon in the Indian Ocean: Distribution and dissolution processes - Sabine, C. L.; Key, R. M.; Feely, R. A.; Greeley, D. (Global Biogeochemical Cycles, 2002)
This study uses nearly 25,000 carbon measurements from the WOCE/JGOFS global CO2 survey to examine the distribution of dissolved inorganic carbon (DIC) and total alkalinity (TA) in the Indian Ocean. Shallow and intermediate distributions of inorganic carbon do not strictly follow temperature and salinity because of differing surface gradients and vertical biological processes that work to modify the circulation derived features. Anthropogenic CO2 has increased the shallow DIC by as much as 3%, decreasing the vertical DIC gradient. Deep ocean DIC and TA increase toward the north because of the decomposition and dissolution of organic and inorganic particles. Calcite saturation depths range from 2900-3900 m with the deepest saturation depth in the central Indian Ocean. Variations of aragonite saturation depth (200-1400 m) are similar to calcite, but the deepest saturations are in the southwestern Indian Ocean. The shallowest aragonite saturation depths are found in the Bay of Bengal. In the northern Arabian Sea and Bay of Bengal, the current aragonite saturations are 100 and 200 m shallower, respectively, than in preindustrial times. Estimates of carbonate dissolution rates on isopycnal surfaces range from 0.017 to 0.083 mumol kg(-1) yr(-1) in deep waters. Upper water column dissolution rates range from 0 to 0.73 mumol kg(-1) yr(-1), with a local maximum occurring in intermediate waters just below the aragonite saturation horizon. Dissolution is also generally higher north of the Chemical Front at 10-20degreesS. There is some evidence for significant sedimentary sources in the northern Indian Ocean.
643rkTimes Cited:50 Cited References Count:72
Keywords: alkalinity; anthropogenic co2; arabian sea; calcium carbonate; Carbon cycle; dioxide system; dissociation; indian ocean; pressure; saturation state; SEAWATER; Temperature; thermodynamics; total alkalinity; total co2; water

Ituhu Site (32SN110) 1995 Archeological Excavations. Anthropology Research, Department of Anthropology, University of North Dakota, Grand Forks (Report) - Toom, Dennis L. (Dakotas Area Office, U. S. Bureau of Reclamation, 2002)
id: 202

James River Archeological Project 1994-2000, Background and General Research Design - Stutsman County, North Dakota - Toom, Dennis L. (U.S. Bureau of Reclamation, Dakota Area Office, 2002)
id: 1221

Keyhole Reservoir 2001 Archeological Site Evaluations, Crook County, Wyoming - Jackson, Michael L.; Toom, Dennis L. (Anthropology Research, Department of Anthropology, University of North Dakota, Grand Forks, 2002)
id: 1432

Kilimanjaro ice core records: evidence of holocene climate change in tropical Africa - Thompson, L. G.; Mosley-Thompson, E.; Davis, M. E.; Henderson, K. A.; Brecher, H. H.; Zagorodnov, V. S.; Mashiotta, T. A.; Lin, P. N.; Mikhalenko, V. N.; Hardy, D. R.; Beer, J. (Science, 2002)
Six ice cores from Kilimanjaro provide an approximately 11.7-thousand-year record of Holocene climate and environmental variability for eastern equatorial Africa, including three periods of abrupt climate change: approximately 8.3, approximately 5.2, and approximately 4 thousand years ago (ka). The latter is coincident with the "First Dark Age," the period of the greatest historically recorded drought in tropical Africa. Variable deposition of F- and Na+ during the African Humid Period suggests rapidly fluctuating lake levels between approximately 11.7 and 4 ka. Over the 20th century, the areal extent of Kilimanjaro's ice fields has decreased approximately 80%, and if current climatological conditions persist, the remaining ice fields are likely to disappear between 2015 and 2020.
Thompson, Lonnie GMosley-Thompson, EllenDavis, Mary EHenderson, Keith ABrecher, Henry HZagorodnov, Victor SMashiotta, Tracy ALin, Ping-NanMikhalenko, Vladimir NHardy, Douglas RBeer, Jurgeng2002/10/19 04:00Science. 2002 Oct 18;298(5593):589-93.

Kirschenman III Site (32SN247) 1994 Archeological Excavation. Anthropology Research, Department of Anthropology, University of North Dakota, Grand Forks (Report) - Toom, Dennis L. (Dakotas Area Office, U. S. Bureau of Reclamation, 2002)
id: 201

A late glacial-Holocene tephrochronology for glacial lakes in southern Ecuador - Rodbell, D. T.; Bagnato, S.; Nebolini, J. C.; Seltzer, G. O.; Abbott, M. B. (Quaternary Research, 2002)
Despite the presence of numerous active volcanoes in the northern half of Ecuador, few, if any, distal tephras have been previously recognized in the southern one third of the country. In this article, we document the presence of thin (0.1-1.0-cm-thick) distal tephras comprising glass and/or phenocrysts of hornblende and feldspar in sediment cores from five glacial lakes and one bog in Las Cajas National Park (2degrees40'-3degrees00'S, 79degrees00'-79degrees25'W). The lake cores contain from 5 to 7 tephras, and each has a diagnostic major element geochemistry as determined from electron microprobe analysis of similar to710 glass shards and similar to440 phenocrysts of feldspar and hornblende. The loss of sodium with exposure to the electron microbeam causes a 10 +/- 7 wt.% (+/-1sigma) reduction in Na content, which we empirically determined and corrected for before correlating tephras among the sediment cores. We use a similarity coefficient to correlate among the sediment cores; pair-wise comparison of all tephras generally yields an unambiguous correlation among the cores. Six tephras can be traced among all or most of the cores, and several tephras are present in only one or two of the cores. Twenty-six accelerator mass spectrometry (14)C dates on macrofossils preserved in the sediment cores provide the basis for establishing a regional tephrochronology. The widespread tephras were deposited similar to9900, 8800,7300,5300,2500, and 2200 cal yr B.P. The oldest tephras were deposited similar to15,500 and 15,100 cal yr B.P., but these are not found in all cores. Two of the tephras appear correlative with volcaniclastic strata on the flanks of Volcan Cotopaxi and one tephra may correlate with strata on the flanks of Volcan Ninahuilca; both volcanoes are in central Ecuador. The absence of tephras in sediment cores correlative with the numerous eruptions of active volcanoes of the past two millennia implies that the earlier eruptions, which did deposit tephras in the lakes, must have been either especially voluminous, or southerly winds must have prevailed at the time of the eruption, or both. (C) 2002 University of Washington.
555kpTimes Cited:25Cited References Count:23

Late Pleistocene-Holocene paleoceanography and ventilation of the Gulf of California - Keigwin, L. D. (Journal of Oceanography, 2002)
Sediment cores collected in 1990 from the Gulf of California have been studied using stable isotope and radiocarbon techniques to reconstruct the climate and ventilation histories since the last glacial maximum. Benthic foraminiferal delta(18)O from core tops in a water depth range of 145 to 1442 m increases by about 2parts per thousand with increasing depth. This is consistent with a composite temperature profile constructed from several hydrocasts in the various gulf basins. However, the delta18O water/salinity relationship is not sufficiently linear in gulf locations or in nearby open Pacific Geochemical Ocean Sections Study (GEOSECS) stations to be useful in solving paleotemperature equations. Of the most common benthic foraminifera, only Planulina ariminensis has delta(13)C that is consistent with the measured delta(13)C of SigmaCO(2). Several cores in the depth range 500 to 900 m have the laminated Holocene and Bolling/Allerod sediments, and the nonlaminated glacial age and Younger Dryas sediments that are typical of the gulf and other locations such as Santa Barbara Basin. The best of those, Jumbo Piston Core (JPC) 56 from 818 m water depth on the western margin of Guaymas Basin, was sampled for intensive study. Oxygen isotope ratios in benthic and planktonic foraminifera show little evidence for deglacial temperature oscillations. Carbon isotope ratios are generally lower during warm epochs, but the most striking result is strongly lowered benthic and planktonic delta(13)C about 9500 years ago. This may reflect water column oxidation of locally released methane. Neither benthic delta(13)C in depth section nor paired benthic and planktonic (14)C data in JPC56 are consistent with increased intermediate water ventilation during the glacial maximum and Younger Dryas. Likewise, (14)C data from 5 pairs of foraminifera from the Okhotsk Sea fail to support better ventilation in that basin during the last glacial maximum.
554heTimes Cited:53Cited References Count:48

Late Quaternary sedimentation and climate in the Lake Edward and George area, Uganda-Congo - Laerdal, T.; Talbot, M. R.; Russell, J. M. (The East African Great Lakes: Limnology, Palaeolimnology, and Biodiversity, 2002)
id: 1012

Late-Quaternary lowstands of Lake Titicaca: evidence from high-resolution seismic data - D'Agostino, K.; Seltzer, G.; Baker, P.; Fritz, S.; Dunbar, R. (Palaeogeography Palaeoclimatology Palaeoecology, 2002)
Approximately 600 km of high-resolution seismic reflection data were collected to investigate the late-Quaternary stratigraphic development of Lake Titicaca. The focus of this report is on two seismic sequence boundaries, which are interpreted as erosional surfaces formed at times of low lake level. The younger erosional surface occurs as much as 90 in below the present lake level and up to 8 in below the present sediment-water interface. This erosional surface is interpreted to be coeval with a well-documented early- to mid-Holocene lowstand, dated between similar to 8000 and 3600 cal yr BP. An earlier and previously unknown erosional surface occurs at a sub-bottom depth of approximately 30 m, and as much as 240 in below the present lake level, which implies a major late-Pleistocene lowstand of Lake Titicaca. By extrapolation of sedimentation rates from the upper similar to 14 in of sediment, we estimate the age of this older lowstand at > 90 000 cal yr BP. Both lowstands of Lake Titicaca indicated by the seismic data are likely to have been a response to climatic change in the region. (C) 2002 Elsevier Science B.V. All rights reserved.
560qxTimes Cited:31 Cited References Count:33
Keywords: Andes; bolivian altiplano; central andes; climatic-change; Holocene; lacustrine; lake level change; lake titicaca; level; malawi; Peru; record; seismic reflection data; tropical paleoclimate; tropical south-america

The limits of paleontological resolution - Kowalewski, M.; Bambach, R. K. (High Resolution Approachews in Paleontology: Kluwer Academic/Plenum, 2002)
id: 1415

Linking vertical advection and diet to juvenile salmon condition and parasite load: A study using 14C, 13C, and 15N - Casillas, E.; Rau, G. H.; al, et (Transactions, American Geophysical Union, 2002)
id: 1142

Los Cerritos: an early fishing-farming community on the Pacific Coast of Mexico - Kennett, D. J.; Voorhies, B.; McClure, S. B. (Antiquity, 2002)
id: 473

Major Prehistoric Ceramic Series in the Middle Missouri Subarea of the Plains - Toom, Dennis L. (2002 Conference on the ceramics of the Northeastern Plains and adjacent areas, 2002)
id: 1434

A marine record of Holocene climate events in tropical South America, abstract - Haug, G. H.; Gunther, D.; Hughen, K. A.; Peterson, L. C.; Rohl, U. (Eos Trans. AGU 83, Fall Meeting Suppl, 2002)
id: 1080

Mercury from hatting industry in Connecticut - Varekamp, J. C. (2002)

Mercury in Connecticut and Long Island Sound sediment - Varekamp, J. C.; Buchholtz ten Brink, M. R. (Long Island Sound/NEERS Research Conference, 2002)
id: 729

Mercury issues from old industries - Varekamp, J. C. (2002)

Mercury legacy from hatmaking in Danbury, CT - Varekamp, J. C. (Hartford Courant, 2002)

A middle archaic archaeological site on the Est Coast of Mexico - Voorhies, B.; Kennett, D. J.; Jones, J. G.; Wake, T. A. (Latin American Antiquity, 2002)
id: 475

The Middle Stone Age occupation of Atlantic central Africa: new evidence from Equatorial Guinea and Cameroon - Mercader, J.; Marti, R. (Under the Canopy: The Archaeology of Tropical Rain Forests, 2002)
id: 1196

The nature of 'stone-lines' in the African Quaternary record: archaeological resolution at the rainforest site of Mosumu, Equatorial Guinea - Mercader, J.; Marti, R.; Martinez, J. L.; Brooks, A. (Quaternary International, 2002)
'Stone-lines' are widespread Quaternary features that appear in tropical and subtropical regions. They have a diverse nature and genesis, and are frequently associated with archaeological assemblages. However, archaeological deposition and 'stone-line' configuration may be unrelated geological events separated by thousands of years. The energetics involved in 'stone-line' formation, coarse and fine material translocation across space and in depth, and overall assemblage integrity vary from one site to another. This paper presents quantitative and spatial geoarchaeological data from the site of Mosumu, in the tropical rain forest of continental Equatorial Guinea. Mosumu yielded Middle and Later Stone Age assemblages dated to at least the last 30,000 years in a 'stone-line' context. Special attention to the study of vertical and horizontal variations of artifacts, sedimentary features, and taphonomic indicators allows analysis of the nature, meaning, and archeological resolution at this site. The results are placed in the wider debate over the meaning of 'stone-lines' in the African Quaternary record. (C) 2002 Elsevier Science Ltd and INQUA. All rights reserved.
536zcTimes Cited:15 Cited References Count:89
Keywords: Age; behavior; cameroon; congo; ituri; layers; origin; tools; vegetation

Nelson Site (32SN113) 2000 Archeological Excavations. Anthropology Research, Department of Anthropology, University of North Dakota, Grand Forks (Report) - Toom, Dennis L. (Dakotas Area Office, U. S. Bureau of Reclamation, 2002)
id: 203

Noble gases and volatile recycling at subduction zones - Hilton, D. R.; Fischer, T. P.; Marty, B. (Noble Gases in Geochemistry and Cosmochemistry, 2002)
Bw12hTimes Cited:243Cited References Count:219Reviews in Mineralogy & Geochemistry

Numerical models, geochemistry and the zero-paradox noble-gas mantle - Ballentine, C. J.; Van Keken, P. E.; Porcelli, D.; Hauri, E. H. (Philos Transact A Math Phys Eng Sci, 2002)
Numerical models of whole-mantle convection demonstrate that degassing of the mantle is an inefficient process, resulting in ca. 50% of the (40)Ar being degassed from the mantle system. In this sense the numerical simulations are consistent with the (40)Ar mass balance between the atmosphere and mantle reservoir. These models, however, are unable to preserve the large-scale heterogeneity predicted by models invoking geochemical layering of the mantle system. We show that the three most important noble-gas constraints on the geochemically layered mantle are entirely dependent on the (3)He concentration of the convecting mantle derived from the (3)He flux into the oceans and the average ocean-crust generation rate. A factor of 3.5 increase in the convecting-mantle noble-gas concentration removes all requirements for: a (3)He flux into the upper mantle from a deeper high (3)He source; a boundary in the mantle capable of separating heat from helium; and a substantial deep-mantle reservoir to contain a hidden (40)Ar rich reservoir. We call this model concentration for the convecting mantle the 'zero-paradox' concentration. The time-integrated flux of (3)He into the oceans is a robust observation, but only representative of the ocean-floor activity over the last 1000 years. In contrast, ocean-floor generation occurs over tens of millions of years. We argue that combining these two observations to obtain the (3)He concentration of the mantle beneath mid-ocean ridges is unsound. Other indicators of mantle (3)He concentration suggest that the real value may be at least a factor of two higher. As the zero-paradox concentration is approached, the noble-gas requirement for mantle layering is removed. We further consider the role that recycled material plays in ocean-island-basalt generation and show that a source with high (3)He and (3)He/(4)He must exist within the mantle. Nevertheless, only a small amount of this material is required to generate both the observed ocean-island (3)He/(4)He ratios and the concentrations inferred from basalt samples for this mantle source.
id: 1579; Ballentine, Chris J Van Keken, Peter E Porcelli, Don Hauri, Erik H England Philos Transact A Math Phys Eng Sci. 2002 Nov 15;360(1800):2611-31.

Oak, chestnut and fire: climatic and cultural controls of long-term forest dynamics in New England, USA - Foster, D. R.; Clayden, S.; Orwig, D. A.; Hall, B. (Journal of Biogeography, 2002)
Aim Despite decades of study we have limited insights into the nature of the pre-European landscape of the north-eastern USA and the forces and changes that shaped modern forest patterns. Information on such long-term forest dynamics would provide critical insights into the relationships among environmental change, land-use history and biotic responses and is greatly needed for conservation planning. To address these issues we used modern, historical, and palaeoecological approaches to reconstruct the 3500-year history of a New England upland region dominated by oak and (formerly) chestnut forests and to interpret the interactions among climate change, natural and human disturbance, and site factors in controlling vegetation patterns and dynamics at different spatial scales.Location The study focused on a broad upland ridge dominated by oak forests in the north-central Massachusetts town of New Salem. Detailed palaeoecological analyses were undertaken of wetland (Chamberlain Swamp) and lake (Lily Pond) basins in order to reconstruct local to regional scale vegetation dynamics, which were interpreted within the context of regional vegetation data from central Massachusetts.Methods Palaeoecological methods were used to reconstruct the vegetation, fire and land-use history of the local and subregional vegetation from the two basins and to place these in the context of regional information on vegetation and climate change based on other published data. Historical information including maps, archaeological and census data, and vegetation information were gathered for the landscape and areas surrounding the coring sites. Vegetation sampling in transects adjacent to the swamp coring area included tree cores for dendrochronological reconstructions.Results Stand, landscape and regional forest dynamics were most strongly driven by climate, notably an apparent cooling and increase in moisture availability c. 1500 yr BP, and European land-use activities commencing 260 yr BP. However, the abundance of oak and chestnut (fire-tolerant, sprouting species) and the distribution of hemlock (fire-intolerant) at a stand to landscape scale were also influenced by fire, which, in turn, varied with climate and human activity. Despite, or perhaps as a consequence of ongoing disturbance by fire and presumably windstorms in this hurricane-prone region, the pre-European period was marked by two 1000+ year periods of remarkably stable forest composition, separated by an abrupt compositional shift. In contrast, over the past 260 years the vegetation has changed rather continuously in response to human activity, producing stand, landscape and regional patterns that are novel as well as recent in origin.The results indicate that chestnut was a major component of some pre-European landscapes in New England, in part because of occasional fire, and that cultural and physical factors have interacted over millennia to control vegetation patterns and dynamics. Our analyses also suggest that the composition of low diversity forests can be remarkably stable over millennia. The range of ecological, cultural and management insights afforded by this study underscores the fundamental utility of very long-term research in science and policy development.
618gtTimes Cited:53Cited References Count:126

Ocean circulation: thermohaline circulation - Toggweiler, J. R.; Key, R. M. (Encyclopedia of Ocean Sciences, 2002)
id: 521

The Ocean Margins Program: an interdisciplinary study of carbon sources, transformations, and sinks in a temperate continental margin system - Verity, P. G.; Bauer, J. E.; Flagg, C. N.; DeMaster, D. J.; Repeta, D. J. (Deep-Sea Research Part Ii-Topical Studies in Oceanography, 2002)
The cycling of carbon on the US east coast shelf and upper slope has been studied for 20 years in a variety of interdisciplinary programs focused on the, Mid and South Atlantic Bights. The culmination of this research was a comprehensive field study conducted in 1996 to ascertain whether the Cape Hatteras shelf was a net source or sink for atmospheric CO(2), and the associated transformations and pathways of inorganic and organic carbon. The rationale, objectives, design, and overview of the Ocean Margins Program are given here as a framework to interpret the results of the papers presented in this special issue. (C) 2002 Elsevier Science Ltd. All rights reserved.
607kxTimes Cited:26 Cited References Count:96
Keywords: cape-hatteras; chesapeake bay; co2 fluxes; coastal zone; dissolved organic-carbon; gulf-stream; middle atlantic bight; north-carolina; slope sediments; united-states

Ocean ventilation and sedimentation since the glacial maximum at 3 km in the western North Atlantic - Keigwin, L. D.; Schlegel, M. A. (Geochemistry Geophysics Geosystems, 2002)
[1] Stable isotope, sedimentological, and radiocarbon data from cores at similar to 3 km water depth on the Blake Ridge, western subtropical North Atlantic, reveal the history of deep water ventilation since the last glacial maximum (LGM). Bulk sediment accumulation rates varied locally by a factor of 2 under the influence of bottom currents in this sediment drift environment, but the sand flux, mostly foraminifera, was nearly identical at a given time. This suggests that the rain rate of foraminifera (mostly planktonic) was constant, that transport of foraminifera was negligible, and that current-controlled differences in clay and silt transport drive bulk accumulation. In two of the cores, flux peaks in the benthic foraminifera Cibicidoides and Uvigerina peregrina occurred during the Younger Dryas (YD) cold event, and at 18.2, 19.6, 21.1, 25.0, and 28.1 ka. Radiocarbon measurements on those benthic foraminifera show the ventilation age of bottom waters was similar to 1000 years during the YD, and for older events it was as great as 2000 years. These results contrast with Holocene ventilation, which was similar to 500 years and 700 years at 1500 years and similar to 7100 years before present, respectively.
565rlTimes Cited:26 Cited References Count:43
Keywords: abyssal circulation; benthic foraminifera; c-14 ages; Calibration; climate-change; deep-water; Holocene; Last glacial maximum; ocean ventilation; radiocarbon; radiocarbon age; sea; sediment drifts; Younger Dryas