Arctic System Science/Shelf-Basin Interactions

Project Description
The Western Arctic Shelf-Basin Interactions (SBI) project focuses on shelf, shelf break and upper-slope water mass and ecosystem modifications, material fluxes and biogeochemical cycles. The geographical focus is on the Chukchi and Beaufort Seas and adjacent upper slopes, with the aim of generalization of the results into Pan Arctic and global models. The overarching goal of the SBI project is to understand the physical and biogeochemical processes that link the Arctic shelves, slopes, and deep basins. Relevant to this proposal, the SBI project will focus on a) biogeochemical modifications of Pacific water over the Beaufort and Chukchi shelf and slope regions, with emphasis on carbon and nitrogen; and b) comparative analysis of the findings over the broad Chukchi shelf and narrow Beaufort shelf and adjacent slopes to facilitate integration of the Western Arctic into a Pan-Arctic perspective. We will support the goals of SBI by evaluating the processes of carbon and nitrogen transport, exchanges and transformations in the regions of interest. Our specific interests will be: a) determination of mass transport and fate of carbon and nitrogen associated with the volume transports calculated by SBI collaborators; b) interpretation of carbon and nitrogen spatial distributions and temporal variability relative to biological and physical conditions; c) evaluation of partitioning of organic matter between dissolved and particulate phases; d) determination of net community production and itÂ’s fate as DOM, suspended POM, and sinking POM; e) determination of C:N stoichiometry as a complement to biological studies, particularly in relation to community structure and seasonal progression of intense phytoplankton blooms in the Chukchi and Beaufort Seas; and f) evaluation of the contribution of DOM vs. POM to apparent oxygen utilization (AOU) development in the Arctic halocline and export from the shelf. We will measure the full suite of carbon and nitrogen variables in survey mode. These include dissolved organic carbon (DOC), particulate organic carbon (POC) and dissolved inorganic carbon (DIC), as well as dissolved organic nitrogen (DON) and particulate organic nitrogen (PON). Dissolved inorganic nitrogen (DIN), a required variable, will be measured by the Category 2 hydrographic team contracted by SBI. We will also measure alkalinity to aid in identification of water masses, and the seawater pCO2 (e.g., ?pCO2) of the surface water to estimate air/sea flux of CO2). DOC, DIC, total alkalinity, and seawater pCO2 will be determined at sea. DON, PON, and POC will be analyzed at our shore labs. We require that 4 individuals from our groups (2 for organic variables and 2 for inorganic variables) join each of two 6-week processes cruises each summer (2002 and 2004). Synthesis of data will progress throughout the five-year project, culminating in the overarching final year synthesis. We anticipate ongoing synthesis and modeling collaborations with other funded SBI groups, including the physical oceanographic and tracer groups, the service groups and biological studies groups.

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