Quantitative Appraisal of Organic Carbon Sources in Marine Sediments

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Kerogen is the major repository of carbon in the marine environment. Two techniques used separately in the past, namely flash pyrolysis and &13C analysis, have proven useful in understanding the sources and structures of kerogen and other complex cross-linked macromolecules. This work will investigate combining these techniques in newly developed on- line systems to quantitatively determine the kinds of structural subunits present in kerogen (via pyrolysis) while at the same time determining the marine and terrestrial sources of organic carbon in these subunits (via &13C analys is). Ancillary techniques such as conventional Py-GC-MS and selective chemical degradation will also be used to characterize the kerogens. This work is anticipated to provide the analytical basis in the future to address two research topics, (1) whether the large pool of aliphatic carbon in surface sediments has a marine rather than terrestrial origin, as new research seems to suggest, and (2) whether it is marine or terrestrial carbon that is more susceptible to reaction with sulfides in sediments, forming bioresistant "vulcanized" kerogen.