Sea-air CO2 fluxes and pCO2 variability in the Northern Antarctic Peninsula during three summer periods (2008–2010)

Abstract

This work aimed to improve the understanding of the role played by surface waters in controlling the carbon dioxide partial pressure (pCO2) and sea-air CO2 fluxes in the Northern Antarctic Peninsula (NAP) region. Physical, chemical and biological measurements were made on board the Brazilian RV NApOc. Ary Rongel during the austral summers of 2008, 2009 and 2010. The study region included the southern portion of Drake Passage, Bransfield Strait and the northwestern Weddell Sea. The variability in seawater pCO2 and sea-air CO2 fluxes was investigated by quantifying the relevant biological, physical and thermodynamic effects. Considerable variability in the seawater pCO2 was found at both spatial and interannual scales. Biological activity was the dominant process that removed inorganic carbon from the surface waters throughout most of the region, especially in areas with strong diatom blooms in the Weddell Sea and areas dominated by cryptophytes in Bransfield Strait. Features such as glacial meltwater discharges, fronts, eddies, thermodynamic effects and stratification of the mixing layer also modified these distributions. Overall, the surface waters in the study area represented a sink of atmospheric CO2 in the summers of 2008 and 2010, with average CO2 fluxes of − 1.0mmol CO2 m−2d−1 and − 2.4mmol CO2 m−2d−1, respectively. In the summer of 2009, the region was a weak source of CO2 to the atmosphere, with an average CO2 flux of 0.2mmol CO2 m−2d−1. This result suggests that the physical processes prevailed over the biological activity at that time, mainly in Bransfield Strait.