This proposal seeks support for the principal investigators' participation in the multi-investigator, international North Water Polynya Program organized by Canada. The larger project will test hypotheses for the formation of the polynya, and this proposal will supply Geochemical tracer measurements that are important in gaining an understanding of the present-day ecosystem dynamics and their relations to polynya size and formation processes. Specifically, the Geochemical tracer work addresses two classes of processes operating with the North Water polynya: 1) the sinking flux of particulate organic carbon (POC), and 2) net community production and carbon cycling. The sinking flux of POC will be quantified based on the water column distributions of the natural U-238 series radionuclide Th-237. The distribution of nutrients, oxygen and dissolved inorganic carbon (DIC) in the water column will be used to deduce the net biological production of the North Water ecosystem. Dissolved organic carbon will be measured to examine the partitioning between the DOC and POC pools. The principal investigators have been invited to participate in the 1998 Canadian-sponsored cruise to the polynya. Both spatial and temporal variability in the Geochemical tracers will be addressed in the proposed sampling scheme.
