Annual balance and seasonal variability of sea-air CO2 fluxes in the Patagonia Sea: Their relationship with fronts and chlorophyll distribution

Sea-air differences of CO2 partial pressures (Delta pCO(2)) and surface chlorophyll a (chl-a) concentration have been determined during 22 cruises in various seasons for 2000-2006 over the Patagonia Sea and shelf break. From spring to autumn, the nearshore waters act as a source of atmospheric CO2, while the midshelf and slope are a CO2 sink, leading to highly negative areal means of sea-air CO2 flux and Delta pCO(2). The Delta pCO(2) and CO2 flux in spring reach values of - 67 mu atm and - 7 x 10(-3) mol m(-2) d(-1), respectively, and are close to equilibrium in winter. Sea-air Delta pCO(2) and chl-a over the shelf are negatively correlated, suggesting that photosynthesis is one of the main processes responsible for the large CO2 sequestration. The annual areal mean Delta pCO(2) and sea-air CO2 flux are - 31 mu atm and - 3.7 x 10(-3) mol m(-2) d(-1), respectively, indicating that the Patagonia Sea is one of the strongest CO2 sinks per unit area in the World Ocean.