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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.

Item Type:	Refereed Article
Keywords:	Labrador Sea, carbon cycling
Research Division:	Earth Sciences
Research Group:	Oceanography
Research Field:	Biological oceanography
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the earth sciences
UTAS Author:	Strutton, PG (Professor Peter Strutton)
ID Code:	80210
Year Published:	2009
Web of Science® Times Cited:	18
Deposited By:	IMAS Research and Education Centre
Deposited On:	2012-10-24
Last Modified:	2022-08-29
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