No 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 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.

No abstract

No abstract

Chromophoric dissolved organic matter (CDOM), the optically active fraction of dissolved organic matter, is primarily generated by pelagic organisms in the open ocean. In this study, we experimentally determined the quantity and spectral quality of CDOM generated by bacterioplankton using two different substrates (with and without photoproducts) and by Antarctic krill Euphausia superba and evaluated their potential contributions to CDOM dynamics in the peninsular region of the Southern Ocean. CDOM was generated by bacteria in all experiments, and the presence of photoproducts influenced both the quantity and the spectral quality of the resultant CDOM. We confirmed a direct link between bacterial production and CDOM generation, which yielded in situ CDOM duplication times from 31 to 33 d. Antarctic krill as a direct source of CDOM was also confirmed experimentally. We estimated that CDOM generation by krill would lead to CDOM duplication times from 0.48 to 0.80 d within krill swarms. Our findings highlight the potential significance of bacteria and Antarctic krill swarms in the generation of CDOM and underscore the dynamic nature of CDOM in this area.