The seasonal cycle of carbonate system processes in Ryder Bay, West Antarctic Peninsula

Legge, O.J., Bakker, D.C.E., Meredith, M., Venables, H.J., Brown, P.J., Jones, E.M. and Johnson, Martin T. (2017) The seasonal cycle of carbonate system processes in Ryder Bay, West Antarctic Peninsula. Deep-Sea Research Part II: Topical Studies in Oceanography, 139. 167–180. ISSN 0967-0645

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    Abstract

    The carbon cycle in seasonally sea-ice covered waters remains poorly understood due to both a lack of observational data and the complexity of the system. Here we present three consecutive seasonal cycles of upper ocean dissolved inorganic carbon (DIC) and total alkalinity measurements from Ryder Bay on the West Antarctic Peninsula. We attribute the observed changes in DIC to four processes: mixing of water masses, air-sea CO2 flux, calcium carbonate precipitation/dissolution and photosynthesis/respiration. This approach enables us to resolve the main drivers of the seasonal DIC cycle and also investigate the mechanisms behind interannual variability in the carbonate system. We observe a strong, asymmetric seasonal cycle in the carbonate system, driven by physical processes and primary production. In summer, melting glacial ice and sea ice and a reduction in mixing with deeper water reduce the concentration of DIC in surface waters. The dominant process affecting the carbonate system is net photosynthesis which reduces DIC and the fugacity of CO2, making the ocean a net sink of atmospheric CO2. In winter, mixing with deeper, carbon-rich water and net heterotrophy increase surface DIC concentrations, resulting in pH as low as 7.95 and aragonite saturation states close to 1. We observe no clear seasonal cycle of calcium carbonate precipitation/dissolution but some short-lived features of the carbonate time series strongly suggest that significant precipitation of calcium carbonate does occur in the Bay. The variability observed in this study demonstrates that changes in mixing and sea ice cover significantly affect carbon cycling in this dynamic environment. Maintaining this unique time series will allow the carbonate system in seasonally sea-ice covered waters to be better understood.

    Item Type: Article
    Additional Information: Under a Creative Commons Attribution 4.0 International license
    Uncontrolled Keywords: carbon cycle,polar waters,seasonality,sea ice,time series
    Faculty \ School: Faculty of Science > School of Environmental Sciences
    Faculty of Science
    Related URLs:
    Depositing User: Pure Connector
    Date Deposited: 21 Nov 2016 17:00
    Last Modified: 11 Apr 2019 14:57
    URI: https://ueaeprints.uea.ac.uk/id/eprint/61433
    DOI: 10.1016/j.dsr2.2016.11.006

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