Variações da pCO2 ao longo de um transecto longitudinal plataforma continental - oceano em 34,5°S no Atlântico sudoeste.

Abstract

The South Atlantic Ocean is recognized as an important global sink of atmospheric CO2, however, there are still uncertainties about CO2 dynamics and the influence of physical processes. This study evaluated the variation of high-resolution in situ pCO2 and net CO2 fluxes in the air-sea interface region along latitude 34.5° S in the Southwest Atlantic during autumn 2018 and winter 2019. Measurements of temperature, salinity, dissolved oxygen, CO2 mole fraction, and nutrients over the continental shelf and open ocean were performed in the region. In the autumn of 2018, the shelf region acted as a source of CO2 to the atmosphere and the open ocean acted as a sink, with median fluxes of 3.2 mmol CO2 m-2.d-1 and -2.5 mmol CO2 m-2.d-1 (according to Wanninkhof, 2014), respectively. However, in winter 2019 there was a release of CO2 from the ocean to the atmosphere along the entire transect, with a median flux of 1.5 mmol CO2 m-2.d-1. Different from the general sense that the ocean region behaves as an important CO2 sink, it was possible to evidence in winter 2019, the region acting as a source of CO2 to the atmosphere, being hydrodynamic processes, biological activity, and mesoscale features, such as vortices and ocean fronts, the main drivers of the variations found in sea pCO2.