Elemental Tracers of Carbon Export and Recycling in the RossSea

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9418786 Dymond This project will analyze an existing suite of both sediment trap and ocean bottom samples from the Ross Sea for barium and other refractory elements (aluminum, sodium, vanadium, iron, thorium, and tin), and evaluate barium as a proxy for biological productivity and carbon export to the seafloor of the Ross Sea. These analyses bear directly on the question of how much and how quickly anthropogenic carbon dioxide is distributed among the various global carbon reservoirs. If the "new" atmospheric carbon is sequestered in non-atmospheric reservoirs within a relatively brief period, then the expected global warming will be reduced; however it is also possible that any global warming enhances the flux of carbon (and other greenhouse gases) from non-atmospheric reservoirs to the atmosphere, enhancing the expected global warming. While little is currently known about the planetary response, it is thought that oceanic processes, particularly changes in ocean fertility and interactions between ocean fertility and circulation, are defining factors in these questions. Time changes in the oceanic carbon reservoir are related to ocean productivity, and must be inferred from proxy observations. The disadvantage of the most widely used proxies -- organic carbon, calcium carbonate, and opal (silicon dioxide) -- is that they cannot distinguish between variable preservation rates and variable productivity rates. This project will link these proxies with the flux of barium through the water column and in the sediment, and constrain the extent of barium recycling with the refractory element data. This analysis will additionally help define the strength and source of lateral carbon input to the Ross Sea. Results from this study will be integrated with other continuing studies to produce a better understanding of biogeochemical cycling in the Ross Sea and in the Southern Ocean in general. ***