Marine Science Faculty Publications

Fco2 Variability at the Cariaco Tropical Coastal Upwelling Time Series Station

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Air-sea exchange, Cariaco Basin, fCO2, Oceanographic time series, Upwelling

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Monthly seawater pH and alkalinity measurements were collected between January 1996 and December 2000 at 10°30′N, 64°40′W as part of the CARIACO (CArbon Retention In A Colored Ocean) oceanographic time series. One key objective of CARIACO is to study temporal variability in Total CO 2 (TCO2) concentrations and CO2 fugacity (fCO2) at this tropical coastal wind-driven upwelling site. Between 1996 and 2000, the difference between atmospheric and surface ocean CO 2 concentrations ranged from about - 64.3 to + 62.3 μatm. Physical and biochemical factors, specifically upwelling, temperature, primary production, and TCO2 concentrations interacted to control temporal variations in fCO2. Air-sea CO2 fluxes were typically depressed (0 to + 10 mmol C m- 2 day- 1) in the first few months of the year during upwelling. Fluxes were higher during June-November (+ 10 to 20 mmol C m- 2 day- 1). Fluxes were generally independent of the slight changes in salinity normally seen at the station, but low positive flux values were seen in the second half of 1999 during a period of anomalously heavy rains and land-derived runoff. During the 5 years of monthly data examined, only two episodes of negative air-sea CO2 flux were observed. These occurred during short but intense upwelling events in March 1997 (-10 mmol C m - 2 day- 1) and March 1998 (- 50 mmol C m- 2 day- 1). Therefore, the Cariaco Basin generally acted as a source of CO2 to the atmosphere in spite of primary productivity in excess of between 300 and 600 g C m - 2 year- 1.

Citation / Publisher Attribution

Marine Chemistry, v. 97, issue 3-4, p. 245-261