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 CO 2 partial pressures (Δ p CO 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 CO 2 , while the midshelf and slope are a CO 2 sink, leading to highly negative areal means of sea‐air CO 2 flux and Δ p CO 2 . The Δ p CO 2 and CO 2 flux in spring reach values of −67 μ atm and −7 × 10 −3 mol m −2 d −1 , respectively, and are close to equilibrium in winter. Sea‐air Δ p CO 2 and chl‐ a over the shelf are negatively correlated, suggesting that photosynthesis is one of the main processes responsible for the large CO 2 sequestration. The annual areal mean Δ p CO 2 and sea‐air CO 2 flux are −31 μ atm and −3.7 × 10 −3 mol m −2 d −1 , respectively, indicating that the Patagonia Sea is one of the strongest CO 2 sinks per unit area in the World Ocean.