Abstract:

The partial pressure of CO₂ in surface water (pCO₂^sw) measured within the Canadian Arctic Archipelago (CAA) and Baffin Bay was highly variable with values ranging from strongly undersaturated (118 µatm) to slightly supersaturated (419 µatm) with respect to the atmospheric levels (~386 μatm) during summer and autumn 2011. During summer, melting sea ice contributed to cold and fresh surface water and enhanced the ice-edge bloom, resulting in strong pCO₂^sw undersaturation. Coronation Gulf was the only area with supersaturated pCO₂^sw, likely due to warm CO₂-enriched freshwater input from the Coppermine River. During autumn, the entire CAA (including Coronation Gulf) was undersaturated, despite generally increasing pCO₂^sw. Coronation Gulf was the one place where pCO₂^sw decreased, likely due to seasonal reduction in discharge from the Coppermine River and the decreasing sea surface temperature. The seasonal summer-to-autumn increase in pCO₂^sw across the archipelago is attributed in part to the continuous uptake of atmospheric CO₂ through both summer and autumn and to the seasonal deepening of the surface mixed layer, bringing CO₂-rich waters to the surface. These observations demonstrate how freshwater from sea ice melt and rivers affect pCO₂^sw differently. The general pCO₂^sw undersaturation during summer-autumn 2011 throughout the CAA and Baffin Bay give an estimated net oceanic sink for atmospheric CO₂ over the study period of 11.4 mmol CO₂ m⁻² d⁻¹, assuming no sea-air CO₂ flux exchange across the sea-ice covered areas.

Continental Shelf Research. Volume 156, 15 March 2018, Pages 1-10.https://doi.org/10.1016/j.csr.2018.01.006