Constraints on Organic Carbon Inputs to Continental Margin Sediments: A Coupled Molecular Isotopic Approach

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ABSTRACTOCE-9907129The role of marine sediments, particularly those on the ocean margins, as long-term repositories of terrigenous organic carbon is one of the most complex issues of low-temperature geochemistry and biogeochemistry. Several decades of research have produced conflicting estimates of the abundance and distribution of terrestrially-derived carbon in these sediments. In this project, this classic problem will be tackled again with recently developed, state-of-the-art analytical tools. Using techniques to determine the 14C composition of individual sedimentary organic compounds developed with previous NSF funding, the investigator and his colleagues at the Woods Hole Oceanographic Institution will investigate the relative importance of various sources of terrigenous organic matter to the sedimentary organic pool stored on continental margins. There are three major objectives: (1) to determine the contributions to the sedimentary pool of organic carbon derived from vascular plants and relict sedimentary rocks; (2) to determine the relationship between drainage basin characteristics and the quantity, composition, and age distributions of continentally-derived organic carbon; and (3) to determine the relationship between organic carbon contributions and particle characteristics for river-influenced margin sediments. In addition to further informing the current understanding of carbon storage in the sediments of the ocean margins, it is expected that the new information should assist in ongoing efforts to constrain global organic carbon budgets.