TY - JOUR T1 - Unusual C35 to C38 alkenones in mid-Holocene sediments from a restricted estuary (Charlotte Harbor, Florida) JF - Organic Geochemistry Y1 - 2014 A1 - van Soelen, E. E. A1 - Lammers, J. M. A1 - Eglinton, T. I. A1 - Sinninghe Damsté, J. S. A1 - Reichart, G. J. AB - Unusual C35 to C38 alkenones were identified in mid-Holocene (8–3.5 kyr BP) sediments from a restricted estuary in southwest Florida (Charlotte Harbor). The distribution was dominated by a C36 diunsaturated (ω15,20) ethyl ketone, identical to the one present in Black Sea Unit 2 sediments. Other unusual alkenones were tentatively assigned as a C35:2 (ω15,20) methyl ketone, a C37:2 (ω17,22) methyl ketone and a C38:2 (ω17,22) ethyl ketone. In late Holocene sediments < 3.5 kyr BP, the common C37 to C39 alkenones were found. Compound-specific 14C, 13C, and D isotope measurements were used to constrain the possible origin of the alkenones. Conventional radiocarbon ages of alkenones and higher plant-derived long chain n-alcohols indicated no significant difference in age between mid-Holocene alkenones and higher plant n-alcohols. Both alcohols and alkenones were offset vs. calibrated ages of shell fragments in the same sediment core, which suggests they were pre-aged by 500–800 yr, implying resuspension and redistribution of the fine-grained sedimentary particles with which they are associated. The hydrogen isotopic (δD) composition (−190‰ to −200‰) of the C37 and C38 alkenones in the late Holocene sediments is in line with values for coastal haptophytes in brackish water. However, the unusual C36 and C38 alkenones from the mid Holocene sediments were enriched in D (by ca. 100‰) vs. the late Holocene alkenones. Also, δ13C values of mid-Holocene alkenones were consistently offset compared with late Holocene alkenones (−21‰ to −22‰ and −22‰ to −23‰, respectively). We suggest that the alkenones in Charlotte Harbor were produced by unknown alkenone-producing haptophyte. VL - 70 UR - http://www.sciencedirect.com/science/article/pii/S0146638014000345 JO - Unusual C35 to C38 alkenones in mid-Holocene sediments from a restricted estuary (Charlotte Harbor, Florida) ER - TY - JOUR T1 - Prominent bacterial heterotrophy and sources of C-13-depleted fatty acids to the interior Canada Basin JF - BIOGEOSCIENCES Y1 - 2013 A1 - Shah, S. R. A1 - Griffith, D. R. A1 - Galy, V. A1 - McNichol, A. P. A1 - Eglinton, T. I. AB - In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to deeper waters, particularly as our baseline understanding of organic carbon cycling in the deep basin is quite limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated and C-13-enriched under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have delta C-13 values that are similar to suspended POC at all depths and are more C-13-enriched than even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. Below surface waters, there is also the suggestion of a source of saturated even-numbered fatty acids which could represent contributions from laterally advected organic carbon and/or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C20-24), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon. At these deep depths, two individual fatty acids (C-12 and iso-C-17) are significantly depleted in C-13, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin. VL - 10 ER - TY - JOUR T1 - Carbon dynamics in the western Arctic Ocean: insights from full-depth carbon isotope profiles of DIC, DOC, and POC JF - Biogeosciences Y1 - 2012 A1 - Griffith, D. R. A1 - McNichol, A. P. A1 - Xu, L. A1 - McLaughlin, F. A. A1 - Macdonald, R. W. A1 - Brown, K. A. A1 - Eglinton, T. I. AB - Arctic warming is projected to continue throughout the coming century. Yet, our currently limited understanding of the Arctic Ocean carbon cycle hinders our ability to predict how changing conditions will affect local Arctic ecosystems, regional carbon budgets, and global climate. We present here the first set of concurrent, full-depth, dual-isotope profiles for dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and suspended particulate organic carbon (POCsusp) at two sites in the Canada Basin of the Arctic Ocean. The carbon isotope composition of sinking and suspended POC in the Arctic contrasts strongly with open ocean Atlantic and Pacific sites, pointing to a combination of inputs to Arctic POCsusp at depth, including surface-derived organic carbon (OC), sorbed/advected OC, and OC derived from in situ DIC fixation. The latter process appears to be particularly important at intermediate depths, where mass balance calculations suggest that OC derived from in situ DIC fixation contributes up to 22% of POCsusp. As in other oceans, surface-derived OC is still a dominant source to Arctic POCsusp. Yet, we suggest that significantly smaller vertical POC fluxes in the Canada Basin make it possible to see evidence of DIC fixation in the POCsusp pool even at the bulk isotope level. VL - 9 IS - 3 N1 - id: 2254; PT: J; TC: 4; UT: WOS:000302179500026 JO - Carbon dynamics in the western Arctic Ocean: insights from full-depth carbon isotope profiles of DIC, DOC, and POC ER - TY - JOUR T1 - Variations in the distribution and radiocarbon age of lignin phenols exported by large river systems JF - Geochimica Et Cosmochimica Acta Y1 - 2010 A1 - Feng, X. J. A1 - Montlucon, D. B. A1 - Eglinton, T. I. VL - 74 SN - 0016-7037 IS - 12, Supplement N1 - Suppl. 1676tl Times Cited:0 Cited References Count:0 JO - Geochim Cosmochim Ac ER - TY - JOUR T1 - DNA and lipid molecular stratigraphic records of haptophyte succession in the Black Sea during the Holocene JF - Earth and Planetary Science Letters Y1 - 2009 A1 - Coolen, M. J. L. A1 - Saenz, J. P. A1 - Giosan, L. A1 - Trowbridge, N. Y. A1 - Dimitrov, P. A1 - Dimitrov, D. A1 - Eglinton, T. I. AB - Previous studies suggest that the coccolithophorid haptophyte Emiliania huxleyi entered the Black Sea similar to 3400 yrs ago and since then a coccolith ooze defined as Unit I has developed. Unit I sediments contain long-chain alkenones derived from E huxleyi whereas the alkenone distribution of the deeper coccolith-free sapropel (Unit II) is rather unusual. Alkenone-derived past sea surface temperature (SST) estimates suggest a large difference between Unit II and Unit I, which is likely a result of unusual biological precursors of the alkenones in Unit II. Here, we report a high-resolution stratigraphic analysis of ancient haptophyte DNA to establish the Holocene succession of haptophytes as sources of the alkenones in the Black Sea. Haptophytes related to brackish Isochrysis spp. were the initial sources of alkenones, and appeared immediately after the onset of sapropel deposition (similar to 7550 yrs before present [a BP]). As salinity increased, Isochrysis-related haptophytes were slowly replaced by a complex suite of huxleyi strains as sources of alkenones. Our paleogenetic data showed that E. huxleyi colonized the Black Sea shortly after the onset of sapropel deposition, similar to 4000 yrs earlier than previously recognized based on their preserved coccoliths. E. huxleyi strains were the most likely source of the previously reported abundant and unusual C-36 di-unsaturated "Black Sea alkenone". Strong haptophyte species and strain-specific effects were observed on the level of unsaturation of alkenones which resulted in spurious alkenone-derived SST estimates before 5250 a BP. In contrast, from similar to 5250 a BP onwards a relatively stable haptophyte assemblage dominated by a different suite of E. huxleyi strains yielded robust alkenone-SST values and indicated a gradual cooling from 19 degrees C to similar to 15 degrees C at the top of the record (similar to 450 a BP). Published by Elsevier B.V. VL - 284 IS - 3-4 N1 - id: 1853; 487NY Times Cited:1 Cited References Count:78; YY JO - DNA and lipid molecular stratigraphic records of haptophyte succession in the Black Sea during the Holocene ER - TY - JOUR T1 - Dynamics of particle export on the Northwest Atlantic margin JF - Deep-Sea Research Part I-Oceanographic Research Papers Y1 - 2009 A1 - Hwang, J. A1 - Manganini, S. J. A1 - Montlucon, D. B. A1 - Eglinton, T. I. AB - The Northwest Atlantic margin is characterized by high biological productivity in shelf and slope surface waters. In addition to carbon supply to underlying sediments, the persistent, intermediate depth nepheloid layers emanating from the continental shelves, and bottom nepheloid layers maintained by strong bottom currents associated with the southward flowing Deep Western Boundary Current (DWBC), provide conduits for export of organic carbon over the margin and/or to the interior ocean. As a part of a project to understand dynamics of particulate organic carbon (POC) cycling in this region, we examined the bulk and molecular properties of time-series sediment trap samples obtained at 968 m, 1976 m, and 2938 m depths from a bottom-tethered mooring on the New England slope (water depth, 2988 m). Frequent occurrences of higher fluxes in deep relative to shallower sediment traps and low Delta C-14 values of sinking POC together provide strong evidence for significant lateral transport of aged organic matter over the margin. Comparison of biogeochemical properties such as aluminum concentration and flux, and iron concentration between samples intercepted at different depths shows that particles collected by the deepest trap had more complex sources than the shallower ones. These data also suggest that at least two modes of lateral transport exist over the New England margin. Based on radiocarbon mass balance, about 30% (+/- 10%) of sinking POC in all sediment traps is estimated to be derived from lateral transport of resuspended sediment. A strong correlation between Delta C-14 values and aluminum concentrations suggests that the aged organic matter is associated with lithogenic particles. Our results suggest that lateral transport of organic matter, particularly that resulting from sediment resuspension, should be considered in addition to vertical supply of organic matter derived from primary production, in order to understand carbon cycling and export over continental margins. (C) 2009 Elsevier Ltd. All rights reserved. VL - 56 IS - 10 N1 - id: 1829; 490AT Times Cited:0 Cited References Count:61Y JO - Dynamics of particle export on the Northwest Atlantic margin ER - TY - JOUR T1 - Molecular and isotopic constraints on the sources of suspended particulate organic carbon on the northwestern Atlantic margin JF - Deep-Sea Research Part I-Oceanographic Research Papers Y1 - 2009 A1 - Hwang, J. A1 - Montlucon, D. A1 - Eglinton, T. I. AB - The abundance, carbon isotopic composition (Delta C-14 and delta C-13), and lipid biomarker (alkenones and saturated fatty acids) distributions of suspended particulate organic matter were investigated at three stations centered on the 2000, 3000, and 3500 m isobaths over the New England slope in order to assess particulate carbon sources and dynamics in this highly productive and energetic region. Transmissometry profiles reveal that particle abundances exhibit considerable fine structure, with several distinct layers of elevated suspended particulate matter concentration at intermediate water depths in addition to the presence of a thick bottom nepheloid layer at each station. Excluding surface water samples, the Delta C-14 values of particulate organic carbon (POC) indicated the presence of a pre-aged component in the suspended POC pool (Delta C-14 VL - 56 IS - 8 N1 - id: 774; 471WJ Times Cited:1 Cited References Count:73Y JO - Molecular and isotopic constraints on the sources of suspended particulate organic carbon on the northwestern Atlantic margin ER - TY - JOUR T1 - 3500 yr record of centennial-scale climate variability from the Western Pacific Warm Pool JF - Geology Y1 - 2008 A1 - Langton, S. J. A1 - Linsley, B. K. A1 - Robinson, R. S. A1 - Rosenthal, Y. A1 - Oppo, D. W. A1 - Eglinton, T. I. A1 - Howe, S. S. A1 - Djajadihardja, Y. S. A1 - Syamsudin, F. AB - We use geochemical data from a sediment core in the shallow-silled and intermittently dysoxic Kau Bay in Halmahera (Indonesia, lat 1 degrees N, long 127.5 degrees E) to reconstruct century-scale climate variability within the Western Pacific Warm Pool over the past similar to 3500 yr. Downcore variations in bulk sedimentary delta N-15 appear to reflect century-scale variability in basin ventilation, attributed to changes in oceanographic conditions related to century-scale fluctuations in El Nino Southern Oscillation (ENSO). We infer an increase in century-scale El Nino activity beginning ca. 1700 yr B.P. with peaks in El Nino activity ca. 1500 yr B.P., 1150 yr B.P., and ca. 700 yr B.P. The Kau Bay results suggest that there was diminished ENSO amplitude or frequency, or a departure from El Nino-like conditions during the Medieval Warm Period, and distinctive, but steadily decreasing, El Nino activity during and after the Little Ice Age. VL - 36 IS - 10 N1 - id: 1894; ISI Document Delivery No.: 357HB Times Cited: 1 Cited Reference Count: 36 Cited References: ALDRIAN E, 2003, INT J CLIMATOL, V23, P1435, DOI 10.1002/joc.950 ALTABET MA, 1994, GLOBAL BIOGEOCHEM CY, V8, P103 ALTABET MA, 2001, LIMNOL OCEANOGR, V46, P368 ARRUDA WZ, 2003, J PHYS OCEANOGR, V33, P2815 BRANDES JA, 1998, LIMNOL OCEANOGR, V43, P1680 BRANDES JA, 2002, GLOBAL BIOGEOCHEMICA, V16 CASCIOTTI KL, 2002, ANAL CHEM, V74, P4905, DOI 10.1021/ac020113w CHRISTIAN JR, 2004, DEEP-SEA RES PT II, V51, P209, DOI 10.1016/j.dsr2.2003.06.002 DEUTSCH C, 2007, NATURE, V445, P163, DOI 10.1038/nature05392 GANESHRAM RS, 2000, PALEOCEANOGRAPHY, V15, P361 GRANGER J, 2004, EOS T AM GEOPHYS U S, V85 GRANGER J, 2004, LIMNOL OCEANOGR, V49, P1763 HAUG GH, 1998, PALEOCEANOGRAPHY, V13, P427 HAUG GH, 2001, SCIENCE, V293, P1304 HODELL DA, 2005, QUATERNARY SCI REV, V24, P1413, DOI 10.1016/j.quascirev.2004.10.013 LIU KK, 1989, LIMNOL OCEANOGR, V34, P820 MAKOU MC, 2007, ORG GEOCHEM, V38, P1680, DOI 10.1016/j.orggeochem.2007.06.003 MARIOTTI A, 1981, PLANT SOIL, V62, P413 MASUMOTO Y, 2001, GEOPHYS RES LETT, V28, P1631 MIDDELBURG JJ, 1990, GEOL ULTRIECTIN, V71, P177 MOY CM, 2002, NATURE, V420, P162 NEWTON A, 2006, GEOPHYS RES LETT, V33, ARTN L19710 REIN B, 2004, GEOPHYS RES LETT, V31, ARTN L17211 REIN B, 2005, PALEOCEANOGRAPHY, V20, ARTN PA4003 REYNOLDS RW, 1994, J CLIMATE, V7, P929 RODBELL DT, 1999, SCIENCE, V283, P516 SIGMAN DM, 2003, GEOCHEM GEOPHY GEOSY, V4, ARTN 1040 SIGMAN DM, 2005, GLOBAL BIOGEOCHEM CY, V19, ARTN GB4022 STOTT L, 2004, NATURE, V431, P56, DOI 10.1038/nature02903 STREETPERROTT FA, 1997, SCIENCE, V278, P1422 THUNELL R, 2004, GLOBAL BIOGEOCHEMICA, V18, UNSP GB3001 UEKI I, 2003, J GEOPHYS RES-OCEANS, V108, ARTN 3243 VANAKEN HMV, 1988, NETHERLANDS J SEA RE, V22, P403, DOI 10.1016/0077-7579(88)90011-7 VANDERWEIJDEN CH, 1989, NETH J SEA RES, V24, P583 VANRIEL PM, 1943, OCEANOGRAPHIC RESU 5, V2 WYRTKI K, 1961, NAGA REPORT, V2 Langton, S. J. Linsley, B. K. Robinson, R. S. Rosenthal, Y. Oppo, D. W. Eglinton, T. I. Howe, S. S. Djajadihardja, Y. S. Syamsudin, F. U.S. National Science Foundation [OCE-0502550, OCE-0502504, OCE-052960] This work was supported by the U.S. National Science Foundation (grants OCE-0502550, OCE-0502504, and OCE-052960). We thank the captain, crew, technicians, and the scientific crew who helped with sample collection on the R/V Baruna Jaya VIII. Geological soc amer, inc Boulder; YY JO - 3500 yr record of centennial-scale climate variability from the Western Pacific Warm Pool ER - TY - JOUR T1 - Lateral organic carbon supply to the deep Canada Basin JF - Geophysical Research Letters Y1 - 2008 A1 - Hwang, J. A1 - Eglinton, T. I. A1 - Krishfield, R. A. A1 - Manganini, S. J. A1 - Honjo, S. AB - Understanding the processes driving the carbon cycle in the Arctic Ocean is important for assessing the impacts of the predicted rapid and amplified climate change in this region. We analyzed settling particle samples intercepted by a time-series sediment trap deployed in the abyssal Canada Basin ( at 3067 m) in order to examine carbon export to the deep Arctic Ocean. Strikingly old radiocarbon ages ( apparent mean 14 C age = similar to 1900 years) of the organic carbon, abundant lithogenic material (similar to 80%), and mass flux variations temporally decoupled from the cycle of primary productivity in overlying surface waters together suggest that, unlike other ocean basins, the majority of the particulate organic carbon entering the deep Canada Basin is supplied from the surrounding margins. VL - 35 IS - 11 N1 - id: 1830; 314KU Times Cited:7 Cited References Count:33Y JO - Lateral organic carbon supply to the deep Canada Basin ER - TY - JOUR T1 - A radiocarbon-based assessment of the preservation characteristics of crenarchaeol and alkenones from continental margin sediments JF - Organic Geochemistry Y1 - 2008 A1 - Mollenhauer, G. A1 - Eglinton, T. I. A1 - HopmanSd, E. C. A1 - Damste, J. S. S. AB - Crenarchaeotal glycerol dibiphytanyl glycerol tetraether (GDGT) lipids and alkenones are two types of biomarkers, derived from planktonic marine microorganisms, which are used for reconstruction of sea surface temperature. We determined the radiocarbon contents of the archaeal GDGT crenarchaeol and of alkenones isolated from continental margin sediments. Systematic differences were found between the two biomarkers, with higher radiocarbon content in crenarchaeol than in the phytoplankton-derived alkenones. These differences can be explained by variable contributions of pre-aged, laterally-advected material to the core sites. Crenarchaeol appears to be more efficiently degraded during transport in oxygen-replete environments than alkenones. Whether this reflects the influence of chemical structure or mode of protection (e.g., particle association) is not known. (C) 2008 Elsevier Ltd. All rights reserved. VL - 39 IS - 8 N1 - id: 883; 344AQ Times Cited:11 Cited References Count:33Y JO - A radiocarbon-based assessment of the preservation characteristics of crenarchaeol and alkenones from continental margin sediments ER - TY - JOUR T1 - Aging of marine organic matter during cross-shelf lateral transport in the Benguela upwelling system revealed by compound-specific radiocarbon dating JF - Geochemistry Geophysics Geosystems Y1 - 2007 A1 - Mollenhauer, G. A1 - Inthorn, M. A1 - Vogt, T. A1 - Zabel, M. A1 - Damste, J. S. S. A1 - Eglinton, T. I. KW - alkenones KW - atlantic-ocean KW - burial KW - carbon accumulation KW - coastal KW - compound-specific radiocarbon dating KW - continental-margin KW - ionization mass-spectrometry KW - membrane-lipids KW - namibia KW - sea sediments KW - Sediment transport AB - Organic matter accumulation and burial on the Namibian shelf and upper slope are spatially heterogeneous and strongly controlled by lateral transport in subsurface nepheloid layers. Much of the material deposited in depo-centers on the slope ultimately derives from the shelf. Supply of organic matter from the shelf involves selective transport of organic matter. We studied these selective transport processes by analyzing the radiocarbon content of co-occurring sediment fractions. Here we present radiocarbon data for total organic carbon as well as three tracers of surface ocean productivity (phytoplankton-derived alkenones, membrane lipids of pelagic crenarchaeota (crenarchaeol), and calcareous microfossils of planktic foraminifera) in core-top and near-surface sediment samples. The samples were collected on the Namibian margin along a shelf-slope transect (85 to 1040 m) at 24 degrees S and from the upper slope depo-center at 25.5 degrees S. In core-top sediments, alkenone ages gradually increased from modern to 3490 radiocarbon years with distance from shore and with water depth. Crenarchaeol, while younger than alkenones, also increased in age with distance offshore. It was concluded that the observed ages were a consequence of cross-shelf transport and associated aging of organic matter. Radiocarbon ages of preserved lipid biomarkers in sediments thus at least partially depend on the relative amount of laterally supplied, pre-aged material present in a sample, highlighting the importance of nepheloid transport for the sedimentation of organic matter over the Namibian margin. VL - 8 SN - 1525-2027 N1 - 213qvTimes Cited:3 Cited References Count:60 JO - Geochem Geophy Geosy ER - TY - JOUR T1 - Diagenetic and sedimentological controls on the composition of organic matter preserved in California Borderland Basin sediments JF - Limnology and Oceanography Y1 - 2007 A1 - Mollenhauer, G. A1 - Eglinton, T. I. KW - c-14 measurements KW - compound-specific radiocarbon KW - continental-margin KW - fatty-acids KW - marine-sediments KW - monica basin KW - oxic degradation KW - oxygen exposure time KW - santa-barbara basin KW - surface sediments AB - Compound-specific radiocarbon (C-14) contents, stable carbon isotopes, and abundances of phytoplankton and vascular plant derived lipid biomarkers (alkenones and fatty acids) were obtained from Santa Barbara Basin and Santa Monica Basin sediments, along with radiocarbon contents of planktic foraminifera and total organic carbon. We investigated core-top and prebomb sediment intervals at sites from the flanks and depocenters of the basins deposited under contrasting bottom water oxygen concentrations. Bulk organic matter generally has the lowest radiocarbon levels of all sediment constituents measured, whereas planktic foraminifera tend to be the most radiocarbon enriched. Alkenones are systematically depleted in radiocarbon with respect to foraminifera. Short-chain (C-14, C-16, C-18) fatty acids decrease rapidly in absolute abundance and relative to longer-chain (> C-24) homologues from core-top to prebomb samples. The loss of short-chain fatty acids with depth is associated with C-13 depletion of short-chain fatty acids, indicating preferential preservation of terrestrially derived fatty acids. Short-chain fatty acids tend to be more C-14-enriched relative to alkenones in core-top sediments, whereas longer-chain homologues are generally the most radiocarbon depleted of the lipids studied here. Less refractory compounds (e.g., short-chain fatty acids) are thus enriched in radiocarbon with respect to more recalcitrant biomarkers (alkenones, long-chain fatty acids). The lower C-14 content of more refractory compounds reflects a larger proportion of laterally supplied, preaged material. Greater preservation of labile organic compounds observed at the depocenters than in flank sediments results in the presence of "younger" biomarkers, underlining the important influence of selective degradation of labile compounds on their radiocarbon ages. VL - 52 SN - 0024-3590 IS - 2 N1 - 149kgTimes Cited:43 Cited References Count:67 JO - Limnol Oceanogr ER - TY - CONF T1 - Radiocarbon and Th-230 data reveal temperal changes in sediment focusing at ODP site 984, Poster T2 - EGU General Assembly Y1 - 2007 A1 - Mollenhauer, Gesine A1 - McManus, J. F. A1 - Wagner, T. A1 - McCave, I. N. A1 - Eglinton, T. I. JF - EGU General Assembly CY - Vienna, Austria N1 - id: 547 ER - TY - CONF T1 - Abrupt vegetation changes in tropical South America over the last 120,000 years T2 - EOS Abstracts, 2006 Ocean Sciences Meeting Y1 - 2006 A1 - Hughen, K. A. A1 - Drenzek, N. A1 - Bice, M. A1 - Eglinton, T. I. JF - EOS Abstracts, 2006 Ocean Sciences Meeting CY - Honolulu, HI N1 - id: 1078 ER - TY - JOUR T1 - Carbon isotopic constraints on relict organic carbon contributions to Ross Sea sediments JF - G-cubed Y1 - 2006 A1 - Ohkouchi, N. A1 - Eglinton, T. I. VL - 7 N1 - id: 759 ER - TY - CONF T1 - Investigating the temperoral relationship between the synthesis and sediment incorporation of vascular plant biomarkers using molecular level 14C analysis T2 - EOS Abstracts, 2006 AGU Ocean Sciences Meeting Y1 - 2006 A1 - Drenzek, N. A1 - Poussart, P. A1 - Lima, A. L. A1 - Hughens, K. A1 - Reddy, C. A1 - Eglinton, T. I. JF - EOS Abstracts, 2006 AGU Ocean Sciences Meeting CY - Honolulu, HI N1 - id: 562 ER - TY - JOUR T1 - Ongoing build-up of refractory organic carbon in boreal soils during the Holocene JF - Science Y1 - 2006 A1 - Smittenberg, R. H. A1 - Eglinton, T. I. A1 - Schouten, S. A1 - Sinninghe-Damste, J. S. VL - 314 N1 - id: 1146 ER - TY - CONF T1 - Western Atlantic intertropical convergence zone variability over the last full glacial cycle, Abstract T2 - Eos Trans. AGU 87, Fall Meeting Suppl. Y1 - 2006 A1 - Drenzek, N. A1 - Hughe, K. A1 - Sessions, A. A1 - Bice, M. A1 - Eglinton, T. I. JF - Eos Trans. AGU 87, Fall Meeting Suppl. CY - San Francisco, CA N1 - id: 558 ER - TY - JOUR T1 - Abundance, composition, and vertical transport of PAHs in marsh sediments JF - Environ Sci Technol Y1 - 2005 A1 - White, H. K. A1 - Xu, L. A1 - Lima, A. L. A1 - Eglinton, T. I. A1 - Reddy, C. M. AB - Petroleum-derived hydrocarbons continue to persist in Wild Harbor, West Falmouth, MA, following a spill of No. 2 fuel oil in 1969 from the barge Florida. Recent analysis of marsh sediments revealed that residues of degraded oil are present with concentrations of total petroleum hydrocarbons as high as approximately 9 mg g(-1). Polycyclic aromatic hydrocarbons (PAHs) constitute only a minor fraction of these residues with maximum concentrations of 134 mirog g(-1), but their fate is of interest because of their potential toxicity to organisms. As compared to typical unweathered No. 2 fuel oil, the current distribution of PAHs in the sediments reflects substantial weathering by abiotic and biotic processes, specifically a preferential loss of naphthalenes relative to phenanthrenes, as well as isomer-specific biodegradation of alkylated PAHs. Based on comparison to results from an earlier study, it appears that little or no change has occurred to the distribution of PAHs since 1989, indicating that weathering at this site has stalled or is now proceeding at a significantly slower rate. To assess whether sediment-water partitioning and molecular diffusion in the interstitial medium are now the dominant processes controlling the vertical distribution of PAHs, downcore profiles were compared to a numerical model. While in some cases the model accurately reproduced the measured data, there were instances where the distribution of PAHs was slightly under or overestimated. Reasons for these discrepancies are discussed and are likely due to bioturbation, colloid-facilitated transport, or both. Assessment of the influence of these processes on the spilled oil expands our understanding of the overall fate of these compounds and their potential long-term effects on the environment. VL - 39 IS - 21 N1 - White, Helen KXu, LiLima, Ana Lucia CEglinton, Timothy IReddy, Christopher MengResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.2005/11/22 09:00Environ Sci Technol. 2005 Nov 1;39(21):8273-80. JO - Abundance, composition, and vertical transport of PAHs in marsh sediments ER - TY - JOUR T1 - Are bacteria actively degrading petroleum residues from the West Falmouth oil spill? New insights from 14C analysis of bacterial lipids JF - Environmental Science and Technology Y1 - 2005 A1 - Slater, G. F. A1 - White, H. K. A1 - Eglinton, T. I. A1 - Reddy, C. M. VL - 39 N1 - id: 1189 ER - TY - JOUR T1 - Bacterial incorporation of relict carbon in the hydrothermal environment of Guaymas Basin JF - Geochimica Et Cosmochimica Acta Y1 - 2005 A1 - Pearson, A. A1 - Seewald, J. S. A1 - Eglinton, T. I. AB - Radiocarbon analyses of bulk carbon and individual organic compounds are presented for the hydrothermal environment of the Rebecca's Roost vent in the southern trough of the Guaymas Basin hydrothermal field. The Delta(14)C values of CO, and CH4 in the hottest hydrothermal fluids (317 degrees C) are nearly "radiocarbon dead" (-944 parts per thousand and -923 parts per thousand, respectively). In contrast, the Delta(14)C values of sediments and individual fatty acids (-418 parts per thousand to -227 parts per thousand) obtained from a bacterial mat located south of the vent site are similar to values previously reported for hydrothermal petroleum in this environment and are more depleted in C-14 than overlying waters. Hydrothermal fluids moving through the sediments appear to supply C-14 of intermediate age to the bacteria. This carbon may take the form of, or may be supplied by processes similar to, the generation of hydrothermal petroleum. Although the bacterial mat visibly was dominated by Beggiatoa spp., such mats are known to include numerous other species. Individual compound data show that preaged carbon is being consumed by the integrated bacterial assemblage. Values of delta(13)C and Delta(14)C indicate that petroleum-derived carbon is incorporated directly into fresh bacterial biomass. Subsequently, some of this newly synthesized material also is consumed by heterotrophs, as eukaryotic sterols from the same sample also have C-14-depleted values (Delta(14)C = -136 parts per thousand to -110 parts per thousand). Therefore, the entire system may operate as a complex consortium to transform relict carbon back into biomass. Bacterial consumption of relict carbon occurs despite the ample supply of fresh carbon delivered from the productive, overlying water column. Copyright (c) 2005 Elsevier Ltd. VL - 69 IS - 23 N1 - 999tpTimes Cited:36Cited References Count:69 JO - Bacterial incorporation of relict carbon in the hydrothermal environment of Guaymas Basin ER - TY - JOUR T1 - Determination of microbial carbon sources in petroleum contaminated sediments using molecular 14C analysis JF - Environmental Science and Technology Y1 - 2005 A1 - Slater, G. F. A1 - White, H. K. A1 - Eglinton, T. I. A1 - Reddy, C. M. VL - 39 N1 - id: 595 ER - TY - JOUR T1 - Determination of Microbial Carbon Sources in Petrolleum Contaminated Sediments Using Molecular 14C Analysis JF - Environ. Sci. Technol Y1 - 2005 A1 - Slater, G. F. A1 - White, H. K. A1 - Eglinton, T. I. A1 - Reddy, C. M. VL - 39 N1 - id: 1225 ER - TY - JOUR T1 - High-resolution historical records from Pettaquamscutt River basin sediments; 2. Chronology and record of 137Cs released by the Chernobyl accident JF - Geochimica et Cosmochimica Acta Y1 - 2005 A1 - Lima, A. L. A1 - Hubeny, J. B. A1 - Reddy, C. M. A1 - King, J. W. A1 - Hughen, K. A. A1 - Eglinton, T. I. VL - 69 N1 - id: 555 ER - TY - JOUR T1 - Isotopic constraints on the fate of petroleum residues sequestered in salt marsh sedimetns JF - Environmental Science and Technology Y1 - 2005 A1 - White, H. K. A1 - Reddy, C. M. A1 - Eglinton, T. I. VL - 39 N1 - id: 969 JO - Isotopic constraints on the fate of petroleum residues sequestered in salt marsh sedimetns ER - TY - CHAP T1 - Microbial transformations of organic matter in black shales and implications for global biogeochemical cycles T2 - Geobiology: Objectives, Concepts, Perspectives Y1 - 2005 A1 - Petsch, S. T. A1 - Edwards, K. J. A1 - Eglinton, T. I. ED - Noffke, N. JF - Geobiology: Objectives, Concepts, Perspectives PB - Elsevier N1 - id: 758 ER - TY - CONF T1 - Millennial scale variability in tropical South American vegetation during the last glaciation T2 - Eos Trans. AGU, 86(52), Fall Meeting Suppl. Y1 - 2005 A1 - Hughen, K. A. A1 - Drenzek, N. A1 - Bice, M. A1 - Eglinton, T. I. JF - Eos Trans. AGU, 86(52), Fall Meeting Suppl. CY - San Francisco, CA N1 - id: 563 ER - TY - JOUR T1 - Radiocarbon dating of alkenones from marine sediments: I. Isolation protocol JF - Radiocarbon Y1 - 2005 A1 - Ohkouchi, N. A1 - Xu, L. A1 - Reddy, C. M. A1 - Montlucon, D. A1 - Eglinton, T. I. KW - AMS KW - carbon KW - indicators KW - proxy KW - records KW - tool AB - The chemical and isotopic compositions of long-chain (C-36-C-39) unsaturated ketones (alkenones), a unique class of algal lipids, encode surface ocean properties useful for paleoceanographic reconstruction. Recently, we have sought to extend the utility of alkenones as oceanic tracers through measurement of their radiocarbon contents. Here. we describe a method for isolation of alkenones from sediments as a compound class based on a sequence of wet chemical techniques. The steps involved, which include silica gel column chromatography, urea adduction, and silver nitrate-silica gel column chromatography, exploit various structural attributes of the alkenones. Amounts of purified alkenones estimated by GC/FID measurements were highly correlated with CO2 yields after sample combustion, indicating purities of greater than 90% for samples containing >= 100 mu g C. The degree of alkenone unsaturation (U-37(K')) also varied minimally through the procedure. We also describe a high-performance liquid chromatography (HPLC) method to isolate individual alkenones for molecular-level structural and isotopic determination. VL - 47 SN - 0033-8222 IS - 3 N1 - 993nkTimes Cited:13 Cited References Count:22 JO - Radiocarbon ER - TY - JOUR T1 - Radiocarbon dating of alkenones from marine sediments: II. Assessment of carbon process blanks JF - Radiocarbon Y1 - 2005 A1 - Mollenhauer, G. A1 - Montlucon, D. A1 - Eglinton, T. I. KW - c-14 ams KW - organic-compounds KW - records KW - samples KW - system KW - tool AB - We evaluate potential process blanks associated with radiocarbon measurement of microgram to milligram quantities of alkenones at the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility. Two strategies to constrain the contribution of blanks to alkenone C-14 dates were followed: 1) dating of samples of known age and 2) multiple measurements of identical samples. We show that the potential contamination associated with the procedure does not lead to a systematic bias of the results of alkenone dating to either younger or older ages. Our results indicate that alkenones record Delta(14)C of ambient DIC with an accuracy of approximately 10 parts per thousand. A conservative estimate of measurement precision is 17 parts per thousand for modern samples. Alkenone C-14 ages are expected to be reliable within 500 yr for samples younger than 10,500 C-14 yr. VL - 47 SN - 0033-8222 IS - 3 N1 - 993nkTimes Cited:13 Cited References Count:20 JO - Radiocarbon ER - TY - JOUR T1 - Radiocarbon dating of alkenones from marine sediments-III. Influence of solvent extractions procedures on 14C measurements of foraminifera JF - Radiocarbon Y1 - 2005 A1 - Ohkouchi, N. A1 - Eglinton, T. I. A1 - Hughen, K. A. A1 - Roosen, E. A1 - Keigwin, L. VL - 47 N1 - id: 554 ER - TY - CONF T1 - Rapid lateral particle transport in the Argintine Basin: Th-230 and molecular C-14 Evidence, Poster T2 - EGU General Assembly Y1 - 2005 A1 - Mollenhauer, Gesine A1 - McManus, J. F. A1 - Benthien, A. A1 - Muller, P. J. A1 - Eglinton, T. I. JF - EGU General Assembly CY - Vienna, Austria N1 - id: 548 ER - TY - JOUR T1 - On the sedimentological origin of downcore variations of bulk sedimentary nitrogen isotope ratios JF - Paleoceanography Y1 - 2005 A1 - Kienast, M. A1 - Higginson, M. J. A1 - Mollenhauer, G. A1 - Eglinton, T. I. A1 - Chen, M. T. A1 - Calvert, S. E. AB - The bulk sedimentary nitrogen isotopic composition of two cores from nearby sites on the northern slope of the South China Sea (Site 17940 and Ocean Drilling Program (ODP) Site 1144) differs by up to >2‰ during the last glacial period. Given their close proximity, both core sites are located in the same biogeographic zone and nutrient regime, and it is thus unlikely that this offset is due to a true gradient in surface ocean conditions. In an attempt to resolve this offset, we have investigated the possible effects of two sedimentological parameters that can affect bulk sedimentary δ15N, namely, the variable contribution of inorganic N to bulk N in the sediment and the grain-size dependence of bulk δ15N. We find that neither effect, singly or in combination, is sufficient to explain the significant δ15N offset between the two down-core records. By elimination the most likely explanation for the observed discrepancy is a different origin of both the organic and inorganic nitrogen at each site. This study adds to the growing body of evidence highlighting the complex nature and origin of the sedimentary components in sediment drifts, such as ODP Site 1144. VL - 20 N1 - id: 1066 JO - On the sedimentological origin of downcore variations of bulk sedimentary nitrogen isotope ratios ER - TY - JOUR T1 - The supply and preservation of ancient and modern components of organic carbon on the Canadian Beaufort Shelf of the Arctic Ocean JF - Marine Chemistry Y1 - 2005 A1 - Goñi, M. A. A1 - Yunker, M. B. A1 - Macdonald, R. W. A1 - Eglinton, T. I. VL - 93 N1 - id: 757 ER - TY - JOUR T1 - Abrupt tropical vegetation response to rapid climate changes JF - Science Y1 - 2004 A1 - Hughen, K. A. A1 - Eglinton, T. I. A1 - Xu, L. A1 - Makou, M. AB - Identifying leads and lags between high- and low-latitude abrupt climate shifts is needed to understand where and how such events were triggered. Vascular plant biomarkers preserved in Cariaco basin sediments reveal rapid vegetation changes in northern South America during the last deglaciation, 15,000 to 10,000 years ago. Comparing the biomarker records to climate proxies from the same sediment core provides a precise measure of the relative timing of changes in different regions. Abrupt deglacial climate shifts in tropical and high-latitude North Atlantic regions were synchronous, whereas changes in tropical vegetation consistently lagged climate shifts by several decades. VL - 304 IS - 5679 N1 - Hughen, Konrad AEglinton, Timothy IXu, LiMakou, MatthewengResearch Support, Non-U.S. Gov't2004/05/25 05:00Science. 2004 Jun 25;304(5679):1955-9. Epub 2004 May 20. JO - Abrupt tropical vegetation response to rapid climate changes ER - TY - JOUR T1 - Compound-specific radiocarbon dating of the varved Holocene sedimentary record of Saanich Inlet, Canada JF - Paleoceanography Y1 - 2004 A1 - Smittenberg, R. H. A1 - Hopmans, E. C. A1 - Schouten, S. A1 - Hayes, J. M. A1 - Eglinton, T. I. A1 - Damste, J. S. S. KW - british-columbia KW - compound-specific radiocarbon dating KW - crenarchaeol KW - ionization mass-spectrometry KW - marine-sediments KW - mediterranean sea KW - membrane-lipids KW - ne pacific KW - odp leg 169s KW - organic-matter KW - pacific-ocean KW - rapid isolation KW - Reservoir age KW - reservoir ages KW - saanich inlet AB - [1] The radiocarbon contents of various biomarkers extracted from the varve-counted sediments of Saanich Inlet, Canada, were determined to assess their applicability for dating purposes. Calibrated ages obtained from the marine planktonic archaeal biomarker crenarchaeol compared favorably with varve-count ages. The same conclusion could be drawn for a more general archaeal biomarker (GDGT-0), although this biomarker proved to be less reliable due to its less-specific origin. The results also lend support to earlier indications that marine crenarchaeota use dissolved inorganic carbon (DIC) as their carbon source. The average reservoir age offset DeltaR of 430 years, determined using the crenarchaeol radiocarbon ages, varied by +/-110 years. This may be caused by natural variations in ocean-atmosphere mixing or upwelling at the NE Pacific coast but variability may also be due to an inconsistency in the marine calibration curve when used at sites with high reservoir ages. VL - 19 SN - 0883-8305 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Alerting&SrcApp=Alerting&DestApp=WOS&DestLinkType=FullRecord;UT=WOS:000221326700001 IS - 2 N1 - 819piTimes Cited:18 Cited References Count:69 JO - Paleoceanography ER - TY - JOUR T1 - Radiocarbon evidence for a naturally-produced, bioaccumulation halogenated organic compound JF - Environmental Science and Technology Y1 - 2004 A1 - Reddy, C. M. A1 - Xu, L. A1 - O'Neil, G. W. A1 - Nelson, R. K. A1 - Eglinton, T. I. A1 - Faulkner, D. J. A1 - Norstrom, R. A1 - Ross, P. S. A1 - Tittlemier, S. A. VL - 38 IS - 7 N1 - id: 1806 ER - TY - JOUR T1 - Radiocarbon dating of individual fatty acids as a tool for refining Antarctic margin sediment chronologies JF - Radiocarbon Y1 - 2003 A1 - Ohkouchi, N. A1 - Eglinton, T. I. A1 - Hayes, J. M. KW - carbon KW - ice-sheet KW - marine-sediments KW - north-atlantic KW - organic-matter KW - ross-sea KW - southern-ocean AB - 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. VL - 45 SN - 0033-8222 IS - 1 N1 - 735tqTimes Cited:25 Cited References Count:29 JO - Radiocarbon ER - TY - JOUR T1 - Composition, age, provenance of organic matter in N. W. African dust over the Atlantic Ocean JF - Geochemistry, Geophysics, Geosystems G3 Y1 - 2002 A1 - Eglinton, T. I. A1 - Eglinton, G. A1 - Dupont, L. A1 - Montlucon, D. A1 - Sholkovitz, E. A1 - Reddy, C. M. VL - 3 IS - 8 N1 - id: 611 ER - TY - JOUR T1 - A Critical Evaluation of Interlaboratory Data on Total, Elemental, and Isotopic Carbon in the Carbonaceous Particle Reference Material, NIST SRM 1649a JF - J Res Natl Inst Stand Technol Y1 - 2002 A1 - Currie, L. A. A1 - Benner, B. A., Jr. A1 - Kessler, J. D. A1 - Klinedinst, D. B. A1 - Klouda, G. A. A1 - Marolf, J. V. A1 - Slater, J. F. A1 - Wise, S. A. A1 - Cachier, H. A1 - Cary, R. A1 - Chow, J. C. A1 - Watson, J. A1 - Druffel, E. R. A1 - Masiello, C. A. A1 - Eglinton, T. I. A1 - Pearson, A. A1 - Reddy, C. M. A1 - Gustafsson, O. A1 - Quinn, J. G. A1 - Hartmann, P. C. A1 - Hedges, J. I. A1 - Prentice, K. M. A1 - Kirchstetter, T. W. A1 - Novakow, T. A1 - Puxbaum, H. A1 - Schmid, H. AB - 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. VL - 107 IS - 3 N1 - 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. U2 - PMC4861351 JO - A Critical Evaluation of Interlaboratory Data on Total, Elemental, and Isotopic Carbon in the Carbonaceous Particle Reference Material, NIST SRM 1649a ER - TY - JOUR T1 - Radiocarbon as a tool to apportion the sources of polycyclic aromatic hydrocarbons and black carbon in environmental samples JF - Environmental Science & Technology Y1 - 2002 A1 - Reddy, C. M. A1 - Pearson, A. A1 - Xu, L. A1 - McNichol, A. P. A1 - Benner, B. A. A1 - Wise, S. A. A1 - Klouda, G. A. A1 - Currie, L. A. A1 - Eglinton, T. I. AB - To determine the relative inputs of polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) in environmental samples from the combustion of fossil fuels and biomass we have developed two independent analytical methods for determining the C-14 abundance of PAHs and BC. The 5730 yr half-life of C-14 makes it an ideal tracer for identifying combustion products derived from fossil fuels (C-14-free) versus those stemming from modern biomass (contemporary C-14). The C-14 abundance of PAHs in several environmental Standard Reference Materials was measured by accelerator mass spectrometry after extraction and then purification by high-performance liquid chromatography and preparative capillary gas chromatography. This method yields pure compounds that allow for a high degree of confidence in the C-14 results. The PAHs data were then used to compare and evaluate results from an operationally defined thermal oxidation method used to isolate a BC fraction. The C-14 compositions of PAHs and BC were very similar and suggest that the thermal oxidation method employed for isolating BC is robust and free from interferences by non-BC components. In addition, these data indicate that both the PAHs and the BC species derive mostly from fossil fuels and/or their combustion products. VL - 36 IS - 8 N1 - 541gfTimes Cited:133Cited References Count:59 JO - Radiocarbon as a tool to apportion the sources of polycyclic aromatic hydrocarbons and black carbon in environmental samples ER - TY - JOUR T1 - Radiocarbon content of synthetic and natural semi-volatile halogenated organic compounds JF - Environ Pollut Y1 - 2002 A1 - Reddy, C. M. A1 - Xu, L. A1 - Eglinton, T. I. A1 - Boon, J. P. A1 - Faulkner, D. J. KW - Animals KW - Carbon Radioisotopes/*analysis KW - Environmental Pollutants/*analysis KW - Hydrocarbons, Halogenated/chemical synthesis/*chemistry KW - Insecticides/chemistry KW - Polychlorinated Biphenyls/chemistry KW - Porifera/*chemistry KW - Toxaphene/chemistry AB - Some halogenated organic compounds, such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polybrominated diphenyl ethers (PBDEs), have been suggested to have natural sources but separating these compounds from their commercially synthesized counterparts is difficult. Molecular-level 14C analysis may be beneficial since most synthetic compounds are manufactured from petrochemicals (14C-free) and natural compounds should have "modern" or "contemporary" 14C levels. As a baseline study, we measured, for the first time, the 14C abundance in commercial PCB and PBDE mixtures, a number of organochlorine pesticides, as well as one natural product 2-(3',5'-dibromo-2'-methoxyphenoxy)-3,5-dibromoanisole. The latter compound was isolated from a marine sponge and is similar in structure to a PBDE. All of the synthetic compounds were 14C-free except for the pesticide toxaphene. which had a modern 14C abundance, as did the brominated natural compound. The result for toxaphene was not surprising since it was commercially synthesized by the chlorination of camphene derived from pine trees. These results suggest that measuring the 14C content of halogenated organic compounds may be quite useful in establishing whether organic compounds encountered in the environment have natural or synthetic origins (or both) provided that any synthetic counterparts derive from petrochemical feedstock. VL - 120 SN - 0269-7491 (Print)0269-7491 (Linking) UR - https://www.ncbi.nlm.nih.gov/pubmed/12395826 IS - 2 N1 - Reddy, Christopher MXu, Li Eglinton, Timothy I Boon, Jan P Faulkner, D John eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. England 2002/10/25 04:00 Environ Pollut. 2002;120(2):163-8. ER - TY - JOUR T1 - Spatial and temporal offsets between proxy records in a sediment drift JF - Science Y1 - 2002 A1 - Ohkouchi, N. A1 - Eglinton, T. I. A1 - Keigwin, L. D. A1 - Hayes, J. M. AB - Chronologies for Late Quaternary marine sediment records are usually based on radiocarbon ages of planktonic foraminifera. Signals carried by other sedimentary components measured in parallel can provide complementary paleoclimate information. A key premise is that microfossils and other indicators within a given sediment horizon are of equal age. We show here that haptophyte-derived alkenones isolated from Bermuda Rise drift sediments are up to 7000 years older than coexisting planktonic foraminifera. This temporal offset, which is apparently due to lateral transport of alkenones on fine-grained particles from the Nova Scotian margin, markedly influences molecular estimates of sea surface temperatures. More broadly, the observation raises questions about both the temporal and the geographic delity of paleoenvironmental records encoded by readily transported components of sediments. VL - 298 IS - 5596 N1 - 612mqTimes Cited:147Cited References Count:38 JO - Spatial and temporal offsets between proxy records in a sediment drift ER - TY - JOUR T1 - Stable chlorine and carbon isotopic compositions of selected semi-volatile organochlorine compounds JF - Organic Geochemistry Y1 - 2002 A1 - Drenzek, N. J. A1 - Tarr, C. H. A1 - Eglinton, T. I. A1 - Heraty, L. J. A1 - Sturchio, N. C. A1 - Shiner, V. J. A1 - Reddy, C. M. KW - aroclors KW - fractionation KW - hydrocarbons KW - intrinsic bioremediation KW - samples KW - solvents KW - trichloroethene AB - To assess whether the isotopic composition of semi-volatile organochlorine compounds (SVOCs) may be a useful tool, we measured the bulk delta(37)Cl and delta(13)C values of several pesticides and Aroclor mixtures from different suppliers. Overall, the delta(37)Cl and delta(13)C values ranged from -5.10 to + 1.22% and -31.63 to -22.39%, respectively. These values are narrower than the ranges observed previously for volatile organic contaminants (VOCs). In particular, the isotopic compositions of the Aroclor mixtures were very tightly constrained for both chlorine and carbon, We also observed that SVOCs synthesized from hexachlorocyclopentadiene had the most enriched delta(37)Cl values. These data provide a baseline for future work employing isotope ratios to study the environmental fate of SVOCs. (C) 2002 Elsevier Science Ltd. All rights reserved. VL - 33 SN - 0146-6380 IS - 4 N1 - 545bnTimes Cited:41 Cited References Count:25 JO - Org Geochem ER - TY - JOUR T1 - The West Falmouth oil spill after thirty years: the persistence of petroleum hydrocarbons in marsh sediments JF - Environ Sci Technol Y1 - 2002 A1 - Reddy, C. M. A1 - Eglinton, T. I. A1 - Hounshell, A. A1 - White, H. K. A1 - Xu, L. A1 - Gaines, R. B. A1 - Frysinger, G. S. KW - *Accidents KW - Chromatography, Gas KW - Environmental Monitoring KW - Geologic Sediments/*chemistry KW - Hydrocarbons/*analysis KW - Massachusetts KW - Petroleum/*analysis KW - Ships KW - Time Factors KW - Water Pollutants, Chemical/*analysis AB - The long-term fate of petroleum hydrocarbons in marsh sediments (West Falmouth, MA) contaminated in 1969 by the spill of the barge Florida was investigated. A 36-cm-long sediment core was collected in August 2000, and sediment extracts were analyzed by gas chromatography (GC) and comprehensive two-dimensional gas chromatography (GC x GC). The latter technique is capable of separating 1 order of magnitude more compounds than the former and was used to observe whether any compositional changes in the unresolved complex mixture (UCM) occurred. No evidence of petroleum residues was detected in the top 6 cm (0-6 cm) and the lower 8 cm (28-36 cm) of the core. However, the central sections 16-28 cm) were dominated by a UCM in the boiling range of n-C13-n-C25 alkanes, consistent with a No. 2 fuel oil source. The 12-14- and 14-16-cm sections had the highest concentrations of UCM approximately 8 mg g(-1)). These values are similar to concentrations observed shortly after the spill. Initial GC x GC analysis revealed that only the n-alkanes were completely degraded, and contrary to previous studies, pristane and phytane as well as numerous other branched alkanes are still present in the sediments. These results suggestthatatthis site hydrocarbon contamination will persist indefinitely in the sedimentary record. VL - 36 SN - 0013-936X (Print)0013-936X (Linking) UR - https://www.ncbi.nlm.nih.gov/pubmed/12487296 IS - 22 N1 - Reddy, Christopher MEglinton, Timothy I Hounshell, Aubrey White, Helen K Xu, Li Gaines, Richard B Frysinger, Glenn S eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2002/12/19 04:00 Environ Sci Technol. 2002 Nov 15;36(22):4754-60. ER - TY - JOUR T1 - Compound-specific D/H ratios of lipid biomarkers from sediments as a proxy for environmental and climatic conditions JF - Geochimica Et Cosmochimica Acta Y1 - 2001 A1 - Sauer, P. E. A1 - Eglinton, T. I. A1 - Hayes, J. M. A1 - Schimmelmann, A. A1 - Sessions, A. L. AB - Hydrogen isotope ratios (D/H) of lipid biomarkers extracted from aquatic sediments were measured to determine whether they can be used as a proxy for D/H of environmental water. Values of deltaD were determined by using a recently developed isotope-ratio-monitoring gas chromatograph-mass spectrometer system (irmGCMS) and were confirmed by conventional hydrogen isotopic measurements (i.e., combustion followed by reduction) on individual compounds isolated by preparative capillary gas chromatography. Diverse lipids (alkanes, n-alkanols, sterols, and pentacyclic triterpenols) were analyzed to examine hydrogen-isotopic controls on lipids of varying origin and biosynthetic pathway. For algal sterols (24-methylcholest-3 beta -ol, 24-ethylcholest-5,22-dien-3 beta -ol, and 4,23,24-trimethylcholesterol, or dinosterol), the fractionation between sedimentary lipids and environmental water was -201 +/- 10 parts per thousand and was similar in both marine and freshwater sites. In a sediment from a small lake in a forested catchment, triterpenols from terrestrial sources were enriched in D by 30 parts per thousand relative to algal sterols. Apparent fractionation factors for n-alkyl lipids were smaller than those of triterpenols and were more variable, probably reflecting multiple sources for these compounds. We conclude that hydrogen-isotopic analyses of algal sterols provide a viable means of reconstructing D/H of environmental waters. Results are less ambiguous than reconstructions based on analyses of kerogen or other operationally defined organic matter fractions. Copyright (C) 2001 Elsevier Science Ltd. VL - 65 IS - 2 N1 - 395npTimes Cited:209Cited References Count:64 JO - Compound-specific D/H ratios of lipid biomarkers from sediments as a proxy for environmental and climatic conditions ER - TY - JOUR T1 - Evaluation of a protocol for the quantification of black carbon in sediments, soils, and aquatic sediments JF - Global Biogeochem. Cycles Y1 - 2001 A1 - Gustafsson, O. A1 - Bucheli, T. D. A1 - Kululska, M. A1 - Andersson, C. A1 - Largeau, C. A1 - Rouzard, J. N. A1 - Reddy, C. M. A1 - Eglinton, T. I. VL - 15 N1 - id: 1439 ER - TY - JOUR T1 - Identification of a novel alkenone in Black Sea sediments JF - Organic Geochemistry Y1 - 2001 A1 - Xu, L. A1 - Reddy, C. M. A1 - Farrington, J. W. A1 - Frysinger, G. S. A1 - Gaines, R. B. A1 - Johnson, C. G. A1 - Nelson, R. K. A1 - Eglinton, T. I. AB - We report the identification of a novel long-chain ketone in Holocene Black Sea sediments. Based on chemical properties, and chromatographic and mass spectrometric characteristics, this compound has been identified as a diunsaturated C-36 ethyl ketone. Further analyses indicated the position and configuration of the double bonds, and the novel alkenone was determined to be hexatriaconta-(16E,21E)-dien-3-one. While this compound is present in only trace quantities in Unit I sediments, it is the most abundant alkenone in portions of Unit II. Its presence thus apparently pre-dates the invasion of Emiliania huxleyi in the Black Sea. The down-core profiles and isotopic compositions suggest that the precursor for the C-36:2 alkenone may be distinct from that of the C37-39 alkenones, however the biological origin of this novel compound is presently unknown. (C) 2001 Elsevier Science Ltd. All rights reserved. VL - 32 IS - 5 N1 - id: 1946; PT: J; UT: WOS:000168692100002 JO - Identification of a novel alkenone in Black Sea sediments ER - TY - JOUR T1 - New techniques define combustion product signatures in sediments JF - Woods Hole Oceanographic Institution 2000 annual report Y1 - 2001 A1 - Eglinton, T. I. N1 - id: 1487 ER - TY - CHAP T1 - Ocean Process Tracers: Single compound radiocarbon measurements T2 - Encyclopedia of Ocean Sciences Y1 - 2001 A1 - Eglinton, T. I. A1 - Pearson, A. JF - Encyclopedia of Ocean Sciences PB - Academic Press CY - London N1 - id: 1420 ER - TY - JOUR T1 - Origins of lipid biomarkers in Santa Monica Basin surface sediment: A case study using compound-specific D14C analysis JF - Geochimica et Cosmochimica Acta Y1 - 2001 A1 - Pearson, A. A1 - McNichol, A. P. A1 - Benitez-Nelson, B. C. A1 - Hayes, J. M. A1 - Eglinton, T. I. VL - 65 IS - 18 N1 - id: 1419 ER - TY - JOUR T1 - Proceedings of a Workshop on Alkenone-Based Paleoceanographic Indicators (Introduction to special issue of journal) JF - Geochem. Geophys. Geosyst. Y1 - 2001 A1 - Eglinton, T. I. A1 - Conte, M. H. A1 - Eglinton, G. A1 - Hayes, John M. VL - 2 IS - 2000GC000122 N1 - id: 1739 ER - TY - JOUR T1 - A solid state 13C NMR study of kerogen degradation during black shale weathering JF - Geochim. Cosmochim. Acta Y1 - 2001 A1 - Petsch, S. T. A1 - Smernik, R. J. A1 - Eglinton, T. I. A1 - Oades, J. M. VL - 65 N1 - id: 277 ER - TY - CONF T1 - Validation of compound-specific 14C dating using the varved sedimentary record of Saanich Inlet, Canada T2 - Proceedings of the 20th international meeting on organic geochemistry Y1 - 2001 A1 - Smittenberg, R. H. A1 - Hopmans, E. C. A1 - Eglinton, T. I. A1 - Hayes, J. M. A1 - Whiticar, M. J. A1 - Schouten, S. A1 - Sinninghe Damsté, J. S. JF - Proceedings of the 20th international meeting on organic geochemistry CY - Nancy, France N1 - id: 270 ER - TY - JOUR T1 - Identification of a novel alkenone in Black Sea sediments JF - Organic Geochemistry Y1 - 2000 A1 - Xu, L. A1 - Reddy, C. M. A1 - Farrington, J. W. A1 - Frysinger, G. S. A1 - Gaines, R. B. A1 - Johnson, C. G. A1 - Nelson, R. K. A1 - Eglinton, T. I. KW - Alkenone KW - Black Sea KW - Haptophytes KW - Holocene KW - Sediment KW - Structure characterization AB - We report the identification of a novel long-chain ketone in Holocene Black Sea sediments. Based on chemical properties, and chromatographic and mass spectrometric characteristics, this compound has been identified as a di-unsaturated C36 ethyl ketone. Further analyses indicated the position and configuration of the double bonds, and the novel alkenone was determined to be hexatriaconta-(16E,21E)-dien-3-one. While this compound is present in only trace quantities in Unit I sediments, it is the most abundant alkenone in portions of Unit II. Its presence thus apparently pre-dates the invasion of Emiliania huxleyi in the Black Sea. The down-core profiles and isotopic compositions suggest that the precursor for the C36:2 alkenone may be distinct from that of the C37-39 alkenones, however the biological origin of this novel compound is presently unknown. VL - 32 N1 - id: 1719 JO - Identification of a novel alkenone in Black Sea sediments ER - TY - JOUR T1 - An organic tracer for surface ocean radiocarbon JF - Paleoceanography Y1 - 2000 A1 - Pearson, A. A1 - Eglinton, T. I. A1 - McNichol, A. P. AB - The Delta(14)C of surface water dissolved inorganic carbon (DIC) in the Southern California Eight was compared to Delta(14)C as recorded by the sterols in Santa Monica and Santa Barbara Basin sediments. All of the C-26, C-27, C-28, and C-29 sterols as well as dinosterol had C-14 concentrations equal to surface water DIG, indicating that all of the major sterols were derived from phytoplanktonic production. There is no detectable terrestrial component. Their tracer capability was confirmed by comparing the "bomb C-14"-derived change in surface water Delta(14)C(DIC) With the change in Delta(14)C(sterol). The "prebomb" Delta(14)C(DIC) was similar to 82 parts per thousand, and prebomb sterols averaged -75 +/- 19 parts per thousand. The Delta(14)C value in 1996 was +71 parts per thousand, Eighteen measurements representing eight different sterols from the sediment-water interface of both Santa Monica and Santa Barbara Basins averaged +62 +/- 23 parts per thousand. When three of these values were eliminated because of suspected contamination, the remaining data averaged +71 +/- 12 parts per thousand. The entire compound class could serve as an excellent proxy for the C-14 concentration of ocean surface waters. VL - 15 IS - 5 N1 - 358wyTimes Cited:37Cited References Count:58 JO - An organic tracer for surface ocean radiocarbon ER - TY - JOUR T1 - The origin of n-alkanes in Santa Monica Basin surface sediment: A model based on compount-specific Delta14C and delta13C data JF - Org. Geochem Y1 - 2000 A1 - Pearson, A. A1 - Eglinton, T. I. VL - 31 N1 - id: 364 ER - TY - JOUR T1 - The radiocarbon content of individual lignin-derived phenols: Technique and initial results JF - Radiocarbon Y1 - 2000 A1 - McNichol, A. P. A1 - Ertel, J. R. A1 - Eglinton, T. I. KW - AMS KW - isotope-ratio KW - NOSAMS KW - oxidation-products AB - We present a method for the isolation of phenolic compounds derived from lignin for radiocarbon analysis. These phenols are generated by chemical oxidation of polymeric materials and derivatized for separation and recovery by preparative capillary gas chromatography (PCGC). This technique yields tens of micrograms of pure, stable compounds that can he converted to graphite and analyzed by accelerator mass spectrometry (AMS). Analysis of model flavor compounds and dated woods indicates that, in most cases, the radiocarbon (C-14) contents of the individual compounds, corrected for the contribution of the derivative, agree with that of the bulk material to within 20 parts per thousand. VL - 42 SN - 0033-8222 IS - 2 N1 - 365vkTimes Cited:19 Cited References Count:17 JO - Radiocarbon ER - TY - JOUR T1 - Stable chlorine isotopic compositions of aroclors and aroclor-contaminated sediments JF - Environmental Science & Technology Y1 - 2000 A1 - Reddy, C. M. A1 - Heraty, L. J. A1 - Holt, B. D. A1 - Sturchio, N. C. A1 - Eglinton, T. I. A1 - Drenzek, N. J. A1 - Xu, L. A1 - Lake, J. L. A1 - Maruya, K. A. AB - An exploratory investigation was conducted to evaluate if stable chlorine isotopic ratios of polychlorinated biphenyls (PCBs) could be useful in studying the processes that determine their transport and fate in the environment First, we determined the variability of delta(37)Cl in the source materials for PCBs. Second, we determined if the delta(37)Cl values of contaminated environmental samples fell outside the range in source variability. The isotopic variability among the source materials (Aroclors) was rather small; delta(37)- Cl values ranged from -3.37 to -2.11% (mean and standard deviation, -2.78 +/- 0.39%, n = 12). There was no correlation between the delta(37)Cl values and percentages of chlorine in the mixtures. We also found very similar values in several Clophen mixtures and one Phenoclor. The delta(37)Cl values in the total PCBs isolated from Aroclor-contaminated sediments from the Hudson River, New Bedford Harbor, and Turtle River Estuary ranged from -4.54 to -2.25% (n = 19). While most of the delta(37)Cl values were within 2 standard deviations of the mean Aroclor value (our assumed estimate for overall source variability), two of the PCB contaminated sediment samples from New Bedford Harbor did appear to be isotopically distinct. The PCBs in these sediments had lower amounts of less chlorinated congeners (when compared to the source material) and were likely isotopically affected by alteration processes that preferentially removed these congeners. Compound specific measurements of two congeners in Aroclor 1268 suggest that there are no large congener-specific differences in the stable chlorine isotope ratios in Aroclors. This study shows that the delta(37)Cl Values of PCBs may be a potentially useful diagnostic tool in studying the transport and fate of PCBs and indicates that additional research is warranted. VL - 34 IS - 13 N1 - 330rcTimes Cited:39Cited References Count:16 JO - Stable chlorine isotopic compositions of aroclors and aroclor-contaminated sediments ER - TY - JOUR T1 - Isotopic and molecular fractionation in combustion; three routes to molecular marker validation, including direct molecular 'dating' (GC/AMS) JF - Atmospheric Environment Y1 - 1999 A1 - Currie, L. A. A1 - Klouda, G. A. A1 - Benner, B. A. A1 - Garrity, K. A1 - Eglinton, T. I. AB - The identification of unique isotopic, elemental, and molecular markers for sources of combustion aerosol has growing practical importance because of the potential effects of fine particle aerosol on health, visibility and global climate. It is urgent, therefore, that substantial efforts be directed toward the validation of assumptions involving the use of such tracers for source apportionment. We describe here three independent routes toward carbonaceous aerosol molecular marker identification and validation: (1) tracer regression and multivariate statistical techniques applied to field measurements of mixed source, carbonaceous aerosols; (2) a new development in aerosol (14)C metrology: direct, pure compound accelerator mass spectrometry (AMS) by off-line GC/AMS ('molecular dating'); and (3) direct observation of isotopic and molecular source emissions during controlled laboratory combustion of specific fuels. Findings from the combined studies include. independent support for benzo(ghi)perylene as a motor vehicle tracer from the first (statistical) and second (direct 'dating') studies; a new indication, from the third (controlled combustion) study, of a relation between (13)C isotopic fractionation and PAH molecular fractionation, also linked with fuel and stage of combustion; and quantitative data showing the influence of both fuel type and combustion conditions on the yields of such species as elemental carbon and PAH, reinforcing the importance of exercising caution when applying presumed conservative elemental or organic tracers to fossil or biomass burning field data as in the first study. Published by Elsevier Science Ltd. VL - 33 IS - 17 N1 - 208duTimes Cited:38Cited References Count:31 JO - Isotopic and molecular fractionation in combustion; three routes to molecular marker validation, including direct molecular 'dating' (GC/AMS) ER - TY - CHAP T1 - New Developments at the NOSAMS Facility T2 - Proceeding of the International Workshop on Frontiers in Accelerator Mass Spectrometry Y1 - 1999 A1 - von Reden, K. F. A1 - Schneider, R. J. A1 - McNichol, A. P. A1 - Hayes, J. M. A1 - Pearson, A. A1 - Eglinton, T. I. ED - Science, Japan International ED - Technology Exchange, Center JF - Proceeding of the International Workshop on Frontiers in Accelerator Mass Spectrometry PB - National Institute for Environmental Studies, Tsukuba, National Museum of Japanese History CY - Tsukuba, Japan N1 - id: 1723(JISTEC) ER - TY - CONF T1 - New Developments at the NOSAMS Facility T2 - International Workshop on Frontiers in Accelerator Mass Spectrometry Y1 - 1999 A1 - von Reden, K. F. A1 - Schneider, R. J. A1 - McNichol, A. P. A1 - Hayes, J. M. A1 - Pearson, A. A1 - Eglinton, T. I. ED - Shibata, Y. JF - International Workshop on Frontiers in Accelerator Mass Spectrometry PB - National Institute for Environmental Studies Reprot CY - Tsukuba, Japan N1 - id: 1679 ER - TY - JOUR T1 - A reassessment of the sources and importance of land-derived organic matter in surface sediments from the Gulf of Mexico JF - Geochimica Et Cosmochimica Acta Y1 - 1998 A1 - Goñi, M. A. A1 - Ruttenberg, K. C. A1 - Eglinton, T. I. AB - Organic matter in surface sediments from two onshore-offshore transects in the northwestern Gulf of Mexico was characterized by a variety of techniques, including elemental, stable carbon, radiocarbon, and molecular-level analyses. In spite of the importance of the Mississippi River as a sediment source, there is little evidence for a significant terrigenous input based on the low carbon:nitrogen ratios (8-5) and the enriched delta(13)C values of bulk sedimentary organic carbon (-19.7 parts per thousand to -21.7 parts per thousand). Radiocarbon analyses, on the other hand, yield depleted Delta(14)C values (-277 parts per thousand to -572 parts per thousand) which indicate that a significant fraction of the sedimentary organic carbon (OC) in all these surface sediments must be relatively old and most likely of allochthonous origin. CuO oxidations yield relatively low quantities of lignin products (0.4-1.4 mg/100 mg OC) along with compounds derived from proteins, polysaccharides, and lipids. Syringyl:vanillyl and cinnamyl:vanillyl ratios (averaging 1.6 and 0.5, respectively) and acid:aldehyde ratios for both vanillyl and syringyl phenols (averaging 0.8 and 1.2, respectively) indicate that the lignin present in sediments originates from nonwoody angiosperm sources and is highly degraded. The delta(13)C values of lignin phenols in shelf sediments are relatively depleted in (13)C (averaging -26.3 parts per thousand) but are increasingly enriched in (13)C at the slope sites (averaging -17.5 parts per thousand for the two deepest stations). We interpret these molecular and isotopic compositions to indicate that a significant fraction (greater than or equal to 50%) of the lignin and, by inference, the land-derived organic carbon in northwestern Gulf of Mexico sediments ultimately originated from C(4) plants. The source of this material is likely to be soil organic matter eroded from the extensive grasslands of the Mississippi River drainage basin. Notably, the mixed C(4) and C(3) source and the highly degraded state of this material hampers its recognition and quantification in shelf and slope sediments. Our data are consistent with higher than previously estimated inputs of land-derived organic carbon to regions of the ocean, such as the Gulf of Mexico, with significant sources of terrigenous C(4)-derived organic matter. Copyright (C) 1998 Elsevier Science Ltd. VL - 62 IS - 18 N1 - 156xvTimes Cited:251Cited References Count:133 JO - A reassessment of the sources and importance of land-derived organic matter in surface sediments from the Gulf of Mexico ER - TY - JOUR T1 - Target preparation for continuous flow accelerator mass spectrometry JF - Radiocarbon Y1 - 1998 A1 - Schneider, R. J. A1 - Hayes, J. M. A1 - von Reden, K. F. A1 - McNichol, A. P. A1 - Eglinton, T. I. A1 - Wills, J. S. C. KW - gas KW - ion-source AB - For very small samples, it is difficult to prepare graphitic targets that will yield a useful and steady sputtered ion beam. Working with materials separated by preparative capillary gas chromatography, we have succeeded with amounts as small as 20 mu g C. This seems to be a practical limit, as it involves 1) multiple chromatographic runs with trapping of effluent fractions, 2) recovery and combustion of the fractions, 3) graphitization and 4) compression of the resultant graphite/cobalt matrix into a good sputter target. Through such slow and intricate work, radiocarbon ages of lignin derivatives and hydrocarbons from coastal sediments have been determined. If this could be accomplished as an "online" measurement by flowing the analytes directly into a microwave gas ion source, with a carrier gas, then the number of processing steps could be minimized. Such a system would be useful not just for chromatographic effluents, but for any gaseous material, such as CO2 produced from carbonates. We describe tests using such an ion source. VL - 40 SN - 0033-8222 IS - 1 N1 - 1 Sp. Iss. SI113kt Times Cited:11 Cited References Count:10 JO - Radiocarbon ER - TY - CONF T1 - Determination of the radiocarbon ages of individual PAH extracted from urban aerosol and marine sediment T2 - 16th International Radiocarbon Conference Y1 - 1997 A1 - Pearson, A. A1 - Eglinton, T. I. A1 - McNichol, A. P. A1 - Currie, L. A. A1 - Schneider, R. J. A1 - von Reden, K. F. A1 - Benner, B. A. A1 - Wise, S. A. JF - 16th International Radiocarbon Conference CY - Groningen VL - Book of Abstracts N1 - id: 951 ER - TY - JOUR T1 - Molecular radiocarbon dating of archeological artifacts and marine muds JF - Woods Hole Oceanographic Institution 1996 Annual Report Y1 - 1997 A1 - Eglinton, T. I. N1 - id: 368 ER - TY - JOUR T1 - Source and contribution of terrigenous organic carbon to surface sediments in the Gulf of Mexico JF - Nature Y1 - 1997 A1 - Goñi, M. A. A1 - Ruttenberg, K. C. A1 - Eglinton, T. I. AB - The sources and burial professes of organic matter in marine sediments are not well understood, yet they are important if we are to have a better understanding of the global carbon cycle(1). In particular, the nature and fraction of the terrestrial organic carbon preserved in marine sediments is poorly constrained. Here we use the chemical and stable carbon isotope signatures of oxidation products from a macromolecular component (lignin)(2) of the terrigenous organic matter preserved in offshore surface sediments in the Gulf of Mexico to complement similar data from an existing onshore transect(3) in this region. The complete onshore-offshore data set, along with radiocarbon dates of the bulk organic material at the same sites, allows the differentiation of material originating from plants that photosynthesize using the C-4 mechanism from those that undergo C-3 photosynthesis. We conclude that the offshore lignins derive from erosion of the extensive grassland (C-4) soils Of the Mississippi River drainage basin, and that the nearshore lignins originate largely from C-3 plant detritus from coastal forests and swamps, This distribution is probably due to the hydrodynamic sorting of the different source materials(4) during their seaward transport, These results suggest that previous studies(3,5) have significantly underestimated the terrigenous fraction of organic matter in offshore sediments by not recognizing the contribution of C-4 vegetation to the carbon-isotope composition. Such an underestimate may force revisions in the assessment of past marine primary productivity and associated organic carbon fluxes(6), and of organic matter preservation/remineralization(7) and nutrient cycling(8) in marine sediments. VL - 389 IS - 6648 N1 - Xw772Times Cited:194Cited References Count:30 JO - Source and contribution of terrigenous organic carbon to surface sediments in the Gulf of Mexico ER - TY - CONF T1 - Target preparation for continuous flow accelerator mass spectrometry T2 - 16th International Radiocarbon Conference Y1 - 1997 A1 - Schneider, R. J. A1 - Hayes, J. M. A1 - Eglinton, T. I. A1 - McNichol, A. P. A1 - von Reden, K. F. JF - 16th International Radiocarbon Conference CY - Groningen VL - Book of Abstracts N1 - id: 953 ER - TY - JOUR T1 - Target preparation for continuous flow accelerator mass spectrometry JF - Radiocarbon Y1 - 1997 A1 - Schneider, R. J. A1 - Hayes, J. M. A1 - von Reden, K. F. A1 - McNichol, A. P. A1 - Eglinton, T. I. VL - 40 N1 - id: 1661 ER - TY - JOUR T1 - Variability in radiocarbon ages of individual organic compounds from marine sediments JF - Science Y1 - 1997 A1 - Eglinton, T. I. A1 - BenitezNelson, B. C. A1 - Pearson, A. A1 - McNichol, A. P. A1 - Bauer, J. E. A1 - Druffel, E. R. M. AB - Organic carbon (OC) from multiple sources can be delivered contemporaneously to aquatic sediments. The influence of different OC inputs on carbon-14-based sediment chronologies is illustrated in the carbon-14 ages of purified, source-specific (biomarker) organic compounds from near-surface sediments underlying two contrasting marine systems, the Black Sea and the Arabian Sea, In the Black Sea, isotopic heterogeneity of n-alkanes indicated that OC was contributed from both fossil and contemporary sources. Compounds reflecting different source inputs to the Arabian Sea exhibit a 10,000-year range in conventional carbon-14 ages. Radiocarbon measurements of biomarkers of marine photoautotrophy enable sediment chronologies to be constructed independent of detrital OC influences. VL - 277 IS - 5327 N1 - Xq247Times Cited:175Cited References Count:37 JO - Variability in radiocarbon ages of individual organic compounds from marine sediments ER - TY - JOUR T1 - Compound specific radiocarbon analysis as a tool to quantitatively apportion modern and fossil sources of polycyclic aromatic hydrocarbons in environmental matrices. JF - Abstracts of Papers of the American Chemical Society Y1 - 1996 A1 - Eglinton, T. I. A1 - Pearson, A. A1 - McNichol, A. P. A1 - Currie, L. A. A1 - Benner, B. A. A1 - Wise, S. A. VL - 212 SN - 0065-7727 IS - 2 N1 - 1Va915 Times Cited:0 Cited References Count:0 JO - Abstr Pap Am Chem S ER - TY - JOUR T1 - Gas chromatographic isolation of individual compounds from complex matrices for radiocarbon dating JF - Anal Chem Y1 - 1996 A1 - Eglinton, T. I. A1 - Aluwihare, L. I. A1 - Bauer, J. E. A1 - Druffel, E. R. A1 - McNichol, A. P. AB - This paper describes the application of a novel, practical approach for isolation of individual compounds from complex organic matrices for natural abundance radiocarbon measurement. This is achieved through the use of automated preparative capillary gas chromatography (PCGC) to separate and recover sufficient quantities of individual target compounds for (14)C analysis by accelerator mass spectrometry (AMS). We developed and tested this approach using a suite of samples (plant lipids, petroleums) whose ages spanned the (14)C time scale and which contained a variety of compound types (fatty acids, sterols, hydrocarbons). Comparison of individual compound and bulk radiocarbon signatures for the isotopically homogeneous samples studied revealed that Delta(14)C values generally agreed well (+/-10%). Background contamination was assessed at each stage of the isolation procedure, and incomplete solvent removal prior to combustion was the only significant source of additional carbon. Isotope fractionation was addressed through compound-specific stable carbon isotopic analyses. Fractionation of isotopes during isolation of individual compounds was minimal (<5 per thousand for delta(13)C), provided the entire peak was collected during PCGC. Trapping of partially coeluting peaks did cause errors, and these results highlight the importance of conducting stable carbon isotopic measurements of each trapped compound in concert with AMS for reliable radiocarbon measurements. The addition of carbon accompanying derivatization of functionalized compounds (e.g., fatty acids and sterols) prior to chromatographic separation represents a further source of potential error. This contribution can be removed using a simple isotopic mass balance approach. Based on these preliminary results, the PCGC-based approach holds promise for accurately determining (14)C ages on compounds specific to a given source within complex, heterogeneous samples. VL - 68 IS - 5 N1 - Eglinton, T IAluwihare, L IBauer, J EDruffel, E RMcNichol, A Peng1996/03/01 00:00Anal Chem. 1996 Mar 1;68(5):904-12. doi: 10.1021/ac9508513. JO - Gas chromatographic isolation of individual compounds from complex matrices for radiocarbon dating ER - TY - JOUR T1 - Isolation of Individual Organic Compounds for AMS Radiocarbon Analysis--A Novel Approach JF - Radiocarbon Y1 - 1996 A1 - Eglinton, T. I. A1 - McNichol, A. P. A1 - Benitez-Nelson, B. C. A1 - Pearson, A. A1 - von Reden, K. F. A1 - Schneider, R. J. A1 - Bauer, J. E. A1 - Druffel, E. R. M. VL - 38 IS - 1 N1 - id: 1650 ER - TY - CONF T1 - Isolation of Individual Organic Compounds for AMS Radiocarbon Analysis -- A Novel Approach T2 - 7th International Conference on Accelerator Mass Spectrometry Y1 - 1996 A1 - Eglinton, T. I. A1 - McNichol, A. P. A1 - Benitez-Nelson, B. C. A1 - Pearson, A. A1 - von Reden, K. F. A1 - Schneider, R. J. A1 - Bauer, J. E. A1 - Druffel, E. R. M. JF - 7th International Conference on Accelerator Mass Spectrometry PB - Radiocarbon CY - Tucson, AZ VL - 38 N1 - id: 1800; 1 ER - TY - JOUR T1 - Preparative capillary gas chromatographic isolation of individual compounds from complex matrices for radiocarbon dating JF - Analytical Chemistry Y1 - 1996 A1 - Eglinton, T. I. A1 - Aluwihare, L. I. A1 - Bauer, J. E. A1 - Druffel, E. R. M. A1 - McNichol, A. P. VL - 68 N1 - id: 1340 ER -