Carbon Dioxide Flux at the Water–Air Boundary at the Continental Slope in the Kara Sea

The values and direction of carbon dioxide flux in the area of the continental slope in the north of the Kara Sea (St. Anna Trough) are calculated based on field studies in 2020 within the Siberian Arctic Sea Ecosystems program. The existence of a stable frontal zone in this area has been confirmed, which is formed by an alongslope current and limits the northward spread of surface waters freshened by the continental runoff. The simultaneous analysis of the carbonate system in the upper sea layer and the CO₂ concentration in the surface air layer shows the CO₂ flux with a rate of 0.2 to 22 mmol/m² day to be directed from the atmosphere into the water in the area of the outer shelf, which is affected by the river runoff, and in the area of the continental slope, which is beyond this effect. The highest rates of CO₂ absorption by the sea surface layer are localized above the continental slope. Local processes in the area of the slope frontal zone determine the CO₂ emission into the atmosphere with a rate of 0.34 mmol/m² day.