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Sea surface pCO2 and carbon export during the Labrador Sea spring-summer bloom: An in situ mass balance approach
journal contributionposted on 2023-05-17, 13:45 authored by Martz, TR, DeGrandpre, MD, Peter StruttonPeter Strutton, McGillis, WR, Drennan, WM
We report depth-resolved in situ time series of the partial pressure of CO2 (pCO2) and other carbon-related parameters spanning the development and decline of a high-latitude phytoplankton bloom. A suite of sensors was deployed on a mooring in the Labrador Sea from June to August 2004. The study became quasi-Lagrangian when the mooring broke free in late June. Measured parameters included pCO2, chlorophyll a fluorescence, beam c, optical backscatter, and photosynthetically active radiation. During the bloom, the pCO2 was drawn down from 330 to 260 μatm, corresponding to a 70 μmol kg-1 decrease of dissolved inorganic carbon (DIC). One-dimensional model results suggest that the observed drawdown was primarily driven by local processes and contributions from horizontal advection were minimal. A mass balance using the DIC and particulate organic carbon found that 47 mmol C m-2 d-1 of DIC was assimilated into biomass. The bloom biomass was not remineralized in the mixed layer but was rapidly exported below 35 m within 15 days of the bloom. As a consequence, the large air-sea pCO2 gradient persisted, and approximately 30% of the DIC was regained through air-sea exchange by the end of the study. It is likely that all of the exported organic matter, corresponding to 5.4 +- 1.9 Tg of carbon, was replaced by atmospheric pCO2 prior to the onset of deep convective mixing.
Publication titleJournal of Geophysical Research-Space Physics
Department/SchoolInstitute for Marine and Antarctic Studies
PublisherAmer Geophysical Union
Place of publication2000 Florida Ave Nw, Washington, USA, Dc, 20009
Rights statementCopyright 2009 American Geophysical Union.