Fluxes of Dissolved Inorganic, Dissolved Organic and Particulate Carbon Associated with Water Masses of the Arctic Ocean Based on Samples from the 1996 U.S.N. Pargo Cruise

Proposal No: OPP- 9622621 Principal Investigator: Sambrotto, Raymond ABSTRACT The recent use of the U.S. Navy's atomic submarine Pargo for non-military scientific exploration in the Arctic has opened a new dimension in the oceanography of the least-sampled ocean basin. Samples obtained from the first such cruise allowed me to add significant details to the 3-dimensional analysis of dissolved inorganic carbon (DIC) in the Arctic ocean, a region that may play a much greater role in the carbon dynamics of the world ocean than has been appreciated. Based on samples brought back from the 1996 science cruise of the Pargo, the proposed project will make additional measurements of DIC and add new and critical measurements of dissolved organic carbon (DOC) and particulate carbon (PC). These measurements will qualify the inorganic and organic carbon pools associated with waters in the Canada, Makarov, Amundsen and Nansen basins as well as shelf and upper slope waters of the Chukchi region that appear to be the site of entry for a huge amount of carbon to the upper halocline of adjacent waters. The fall timing of the 1996 Pargo cruise is ideal for the latter measurements because it coincides with the end of the productive season and the beginning of the cooling and sinking of shelf waters into adjacent basins. Spatial changes in the carbon pools will be analyzed with respect to geochemical tracer data such as tritium and 3He collected from the Pargo and other Arctic cruises to estimate the rates of change associated with each pool. Such rates are critical for understanding the Arctic's role in the carbon cycle at the world ocean and global scale. As one of the atmospheric constituents that is prominent in the heat budget of the lower atmosphere, carbon dioxide has received increasing scrutiny to assess the non-human induced factors that influence its abundance. The Arctic Ocean is currently poorly characterized in this respect but is a potentially important link in the dyn amics of the ocean's carbon cycle. First order questions include the size of the carbon reservoirs associated with the unique water masses of the Arctic, the water mass formation rates, and the changes, if any, that can be expected in these cold reservoirs if climate change brings about a warning in this region.