Air-sea CO₂fluxes along the coast of Chile: From CO₂outgassing in central northern upwelling waters to CO₂uptake in southern Patagonian fjords

Carbon system parameters measured during several expeditions along the coast of Chile (23°S-56°S) have been used to show the main spatial and temporal trends of air-sea CO 2 fluxes in the coastal waters of the eastern South Pacific.Chilean coastal waters are characterized by strong pCO 2 gradients between the atmosphere and the surface water, with high spatial and temporal variability.On average, the direction of the carbon flux changes from CO 2 outgassing at the coastal upwelling region to CO 2 sequestering at the nonupwelling fjord region in Chilean Patagonia.Estimations of surface water pCO 2 along the Patagonian fjord region showed that, while minimum pCO 2 levels (strong CO 2 undersaturation) occurs during the spring and summer period, maximum levels (including CO 2 supersaturation) occur during the austral winter.CO 2 uptake in the Patagonia fjord region during spring-summer is within the order of -5 mol C m -2 yr -1 , indicating a significant regional sink of atmospheric CO 2 during that season.We suggest that the CO 2 sink at Patagonia most probably exceeds the CO 2 source exerted by the coastal upwelling system off central northern Chile.