ORCID Profile
0000-0002-7139-1075
Current Organisations
University of California, San Diego
,
University of California, Irvine
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Publisher: Geological Society of America
Date: 03-2009
DOI: 10.1130/G25351A.1
Publisher: American Chemical Society (ACS)
Date: 10-2010
DOI: 10.1021/AC1016584
Abstract: The ability to measure the radiocarbon content of compounds isolated from complex mixtures has begun to revolutionize our understanding of carbon transformations on earth. Because s les are often small, each new compound isolation method must be tested for background carbon contamination (C(ex)). Here, we present a new method for compound-specific radiocarbon analysis (CSRA) of higher plant-derived lignin phenols. To test for C(ex), we compared the Δ(14)C values of unprocessed lignin phenol containing standard materials (woods, leaves, natural vanillin, and synthetic vanillin) with those of lignin phenols liberated by CuO oxidation and purified by two-dimensional high-pressure liquid chromatography (HPLC) coupled to mass spectrometry (MS) and UV detection. We assessed C(ex) associated with (1) microwave assisted CuO oxidation of bulk s les to lignin phenol monomers, (2) HPLC purification, and (3) accelerator mass spectrometry (AMS) s le preparation. The Δ(14)C of purified compounds (corrected for C(ex)) agreed, within error, with those of bulk materials for s les that were >10 μg C. This method will allow routine analysis of the Δ(14)C of lignin phenols isolated from terrestrial, aquatic, and marine settings, revealing the time scale for the processing of one of the single largest components of active organic carbon reservoirs on earth.
Publisher: Cambridge University Press (CUP)
Date: 25-01-2022
DOI: 10.1017/RDC.2021.105
Abstract: We discuss present and developing techniques for studying radiocarbon in marine organic carbon (C). Bulk DOC (dissolved organic C) Δ 14 C measurements reveal information about the cycling time and sources of DOC in the ocean, yet they are time consuming and need to be streamlined. To further elucidate the cycling of DOC, various fractions have been separated from bulk DOC, through solid phase extraction of DOC, and ultrafiltration of high and low molecular weight DOC. Research using 14 C of DOC and particulate organic C separated into organic fractions revealed that the acid insoluble fraction is similar in 14 C signature to that of the lipid fraction. Plans for utilizing this methodology are described. Studies using compound specific radiocarbon analyses to study the origin of biomarkers in the marine environment are reviewed and plans for the future are outlined. Development of r ed pyrolysis oxidation methods are discussed and scientific questions addressed. A modified elemental analysis (EA) combustion reactor is described that allows high particulate organic C s le throughput by direct coupling with the MIniCArbonDAtingSystem.
Publisher: Elsevier BV
Date: 2019
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-1998
DOI: 10.1126/SCIENCE.280.5364.725
Abstract: Coupled radiocarbon and thorium-230 dates from benthic coral species reveal that the ventilation rate of the North Atlantic upper deep water varied greatly during the last deglaciation. Radiocarbon ages in several corals of the same age, 15.41 ± 0.17 thousand years, and nearly the same depth, 1800 meters, in the western North Atlantic Ocean increased by as much as 670 years during the 30- to 160-year life spans of the s les. Cadmium/calcium ratios in one coral imply that the nutrient content of these deep waters also increased. Our data show that the deep ocean changed on decadal-centennial time scales during rapid changes in the surface ocean and the atmosphere.
Publisher: Cambridge University Press (CUP)
Date: 2002
DOI: 10.1017/S0033822200031921
Abstract: Deep-sea corals are a promising new archive of paleoclimate. Coupled radiocarbon and U-series dates allow 14 C to be used as a tracer of ocean circulation rate in the same manner as it is used in the modern ocean. Diagenetic alteration of coral skeletons on the seafloor requires a thorough cleaning of contaminating phases of carbon. In addition, 10% of the coral must be chemically leached prior to dissolution to remove adsorbed modern CO 2 . A survey of modern s les from the full δ 14 C gradient in the deep ocean demonstrates that the coralline CaCO 3 records the radiocarbon value of the dissolved inorganic carbon.
Publisher: Proceedings of the National Academy of Sciences
Date: 25-04-2006
Abstract: An ammonia-oxidizing, carbon-fixing archaeon, Candidatus “ Nitrosopumilus maritimus ,” recently was isolated from a salt-water aquarium, definitively confirming that chemoautotrophy exists among the marine archaea. However, in other incubation studies, pelagic archaea also were capable of using organic carbon. It has remained unknown what fraction of the total marine archaeal community is autotrophic in situ . If archaea live primarily as autotrophs in the natural environment, a large ammonia-oxidizing population would play a significant role in marine nitrification. Here we use the natural distribution of radiocarbon in archaeal membrane lipids to quantify the bulk carbon metabolism of archaea at two depths in the subtropical North Pacific gyre. Our compound-specific radiocarbon data show that the archaea in surface waters incorporate modern carbon into their membrane lipids, and archaea at 670 m incorporate carbon that is slightly more isotopically enriched than inorganic carbon at the same depth. An isotopic mass balance model shows that the dominant metabolism at depth indeed is autotrophy (83%), whereas heterotrophic consumption of modern organic carbon accounts for the remainder of archaeal biomass. These results reflect the in situ production of the total community that produces tetraether lipids and are not subject to biases associated with incubation and/or culture experiments. The data suggest either that the marine archaeal community includes both autotrophs and heterotrophs or is a single population with a uniformly mixotrophic metabolism. The metabolic and phylogenetic ersity of the marine archaea warrants further exploration these organisms may play a major role in the marine cycles of nitrogen and carbon.
Location: United States of America
No related grants have been discovered for Ellen Druffel.