Multitracers to Predict Paleoproductivity in the California Current System from Sediment and Sediment Trap Materials

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Long-term sediment trap deployment provide an opportunity to examine the fidelity of deep-sea sediments as recorders of near- surface oceanic processes. Such studies are important because a fundamental assumption of paleoceanographic research is that the micropaleontologic and sediment chemistry record can be used to examine changes in sea surface conditions over long geologic time scales. The present recommended award will support a multitracer study of the relation of "imput" and "preservation" in marine sediments. The use of stable isotope, geochemical, and micropaleontologic criteria should allow an accurate assessment of differences between deposited sediments and the initial surface water input. The field phase of the project will deploy an array of sediment traps in the California Current system which has strong seasonal gradients in net productivity and surface oceanography. Analyses on the sediment trap material and surface sediments will be used to develop a set of independent proxies for net productivity. Components most likely to provide this information include: biogenous, calcareous, and siliceous microfossils; barite and bio-limiting trace elements such as copper and zinc; and organic matter and certain of its nitrogenous compounds including iodine, bromine, and phosphorous. Such analyses should allow an accurate definition of those signal carriers most highly correlated to net biologic productivity. The principal investigators are highly qualified to undertake the field and analysis portion of the project and have successfully completed previous sediment trap projects. Funding is strongly recommended at the following levels: FY87 = $224,750; FY88 = $229,615; FY89 = $201,299.