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

Abstract

[1] 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 CO2 fluxes in the coastal waters of the eastern South Pacific. Chilean coastal waters are characterized by strong pCO2 gradients between the atmosphere and the surface water, with high spatial and temporal variability. On average, the direction of the carbon flux changes from CO2 outgassing at the coastal upwelling region to CO2 sequestering at the nonupwelling fjord region in Chilean Patagonia. Estimations of surface water pCO2 along the Patagonian fjord region showed that, while minimum pCO2 levels (strong CO2 undersaturation) occurs during the spring and summer period, maximum levels (including CO2 supersaturation) occur during the austral winter. CO2 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 CO2 during that season. We suggest that the CO2 sink at Patagonia most probably exceeds the CO2 source exerted by the coastal upwelling system off central northern Chile.