Upwelling coastal margins are regions of intense carbon cycling, air-sea gas exchange, and redox chemistry where the sea floor, ocean interior, and air-sea interface are closely coupled. In this research, a multidisciplinary team from Oregon State University, University of Washington, University of Chicago, Princeton University, and Columbia University will conduct a coordinated study of transport and biogeochemical reaction rates within the bottom boundary layer, and of exchanges across the boundaries between coastal and open ocean; the sea surface and atmosphere; and the water column and seafloor. They hypothesize that net carbon fluxes in these settings are governed by the juxtaposition of physical transport and chemical reaction in the bottom boundary layer. They will address questions such as how much of the net community carbon production is ultimately sequestered in the ocean interior and how does this happen, how do large, fast-growing coastal diatoms responsible for the high net community production meet their iron demands, and how much mobilized iron and methane reaches illuminated depths and/or the sea-surface and outgases to the atmosphere.
These goals will be accomplished with a field program off the Oregon coast that will include the following: (1) high-resolution surveys of the distributions of temperature, salinity, velocity, carbon (inorganic pCO2 and TCO2, and particulate and dissolved organic carbon), methane, and iron in the water column; (2) deliberate multiple-tracer releases in the bottom boundary layer to examine physical transport processes, illumination history, and air-sea gas exchange; (3) direct measurement using benthic flux chambers of transport between the sediments and the boundary layer; (4) measurement of reactivity of organic matter, iron and methane in the boundary layer using incubations and compound specific markers. Data-synthesis, carbon-budgeting, and modeling efforts will integrate all the field data, incorporate reaction and transport rates, and generate predictive capabilities that can extend our results to other upwelling systems.
Among the broader impacts, the research will produce several technological developments that will have multi-disciplinary applications in earth science. Eight graduate students from five institutions will participate in this project, producing either master's degrees or the foundations for doctoral dissertations. Undergraduate students will participate in the laboratory and fieldwork. Outreach activities include participation of reporters and adult educators on the expeditions, as well as working with the State of Oregon's Ocean Sciences and Math Collaborative program that provides learning activities linking ocean sciences with real life issues and reaches an underserved population of adult learners.
