Fluxes of Dissolved Organic Matter form Marine Sediments

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9302120 Burdige Previous work has begun to illustrate the important role that dissolved organic carbon (DOC) fluxes from marine sediments play in oceanic and sedimentary carbon cycling. At the same time, benthic fluxes of dissolved organic nitrogen (DON) represent a poorly quantified component of sedimentary nitrogen remineralization that may be similarly important in oceanic and sedimentary nitrogen cycling. The goals of this proposal are therefore to continue studies of benthic DOC fluxes, and to begin studies examining benthic DON fluxes. Pore water DOC an DON studies will also be carried out in conjunction with these flux studies. In part, this work will examine the characteristics of pore water DOC and DON as they relate to the controls on benthic fluxes of DOC and DON. Our proposed work will be carried out at sites in the Chesapeake Bay on the California continental margin. Studies in continental margin sediments are of particular interest since several lines of evidence suggest that carbon and nitrogen cycling in margin sediments (and benthic fluxes of DOC and DON from margin sediments) may play important roles in oceanic carbon and nitrogen cycling. Given the range of characteristics among the sites chosen, the data will provide further insights into the factors controlling benthic fluxes of DOC and DON. These results will be used to improve estimates of the global DOC flux from marine sediments and to initiate a similar examination of the role of benthic DON fluxes in oceanic and sedimentary nitrogen cycling. Finally, these new results will be used to critically examine a model which may describe the relationship between benthic DOC fluxes and overall rates of benthic carbon remineralization.