POWRE: An Arctic Ocean Time-Series of Dissolved Inorganic Carbon

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POWRE: An Arctic Ocean time-series of dissolved inorganic carbon The goal of this research project is to evaluate seasonal patterns of biological production and respiration in the central Arctic Ocean with an emphasis on predicting the direction and extent of air-sea carbon exchange. This research would complement funded research at a year-long field-station (SHEBA) established in the perennial ice pack along the eastern edge of the Beaufort Sea. For the first time ever with modern methods, oceanographers will observe nearly all major components of the central Arctic marine carbon cycle with at least weekly resolution over an entire year. Funded Principle Investigators, Wheeler et al. and Welch et al., will measure dissolved oxygen and nutrients, particulate and dissolved organic carbon, autotrophic and heterotrophic biomass (ranging from picoplankton to polar bears), and primary and secondary production and respiration rates. These measurements will be made in the context of a larger surface heat budget experiment (NSF-SHEBA, DOE-ARM, NASA-FIRE, ONR-HLP) where many biogeochemically-relevant physical parameters will be monitored throughout the year. Two key parameters, total dissolved inorganic carbon (CT) and alkalinity (AT), needed to complete the carbon budget and link the Arctic Ocean ecosystem to the global carbon cycle, are as yet missing from the funded plan. This proposal is designed to provide these missing links. I propose to use weekly depth profiles of CT and AT in Arctic surface waters to detect the biological transformations of carbon between the dissolved inorganic (DIC) and organic carbon (OC) pools, specifically the extent of net primary production during the photic period, respiration rates during the dark wintertime, and the effect of springtime ice algae on near-surface DIC concentration. By measuring both CT and AT, we can calculate pCO2, needed to estimate gas exchange, and also use alkalinity as a tracer for contributions from rivers, sea-ice, and other water masses. While perennially ice-covered seas have been historically considered `net heterotrophic` ecosystems, these estimates have typically relied on summertime measurements. With a data set covering an entire annual cycle, we (myself and my collaborators) propose to test the following hypotheses: that 1) autotrophy exceeds heterotrophy during parts of the year, 2) a seasonal offset exists between autotrophic and heterotrophic production, 3) wintertime heterotrophy is supported by DOC produced locally during the spring and early summer, and 4) local production and respiration balance on an annual basis. By providing the link between biological processes and pCO2, my data would allow us to test additionally whether this region of perennially-ice covered Arctic seas (net heterotrophic, net autotrophic, or balanced) is, on an annual basis, a source or sink for atmospheric CO2. The POWRE award would have a significant impact on the career of Dr. Yager. As a new investigator, this award will provide an opportunity to enhance her research activities through access to state-of-the-art oceanographic field equipment and the opportunity to collaborate with an internationally known team of oceanographers.