Seasonal variability of net sea-air CO(2) fluxes in a coastal region of the northern Antarctic Peninsula

We show an annual overview of the sea-air CO(2) exchanges and primary drivers in the Gerlache Strait, a hotspot for climate change that is ecologically important in the northern Antarctic Peninsula. In autumn and winter, episodic upwelling events increase the remineralized carbon in the sea surface, leading the region to act as a moderate or strong CO(2) source to the atmosphere of up to 40 mmol m(–2) day(–1). During summer and late spring, photosynthesis decreases the CO(2) partial pressure in the surface seawater, enhancing ocean CO(2) uptake, which reaches values higher than − 40 mmol m(–2) day(–1). Thus, autumn/winter CO(2) outgassing is nearly balanced by an only 4-month period of intense ocean CO(2) ingassing during summer/spring. Hence, the estimated annual net sea-air CO(2) flux from 2002 to 2017 was 1.24 ± 4.33 mmol m(–2) day(–1), opposing the common CO(2) sink behaviour observed in other coastal regions around Antarctica. The main drivers of changes in the surface CO(2) system in this region were total dissolved inorganic carbon and total alkalinity, revealing dominant influences of both physical and biological processes. These findings demonstrate the importance of Antarctica coastal zones as summer carbon sinks and emphasize the need to better understand local/regional seasonal sensitivity to the net CO(2) flux effect on the Southern Ocean carbon cycle, especially considering the impacts caused by climate change.