Dimethyl sulfide concentrations and fate in first-year sea ice, under-ice surface waters, snow and melt ponds in June 2015, offshore Qikiqtarjuaq, Davis Strait

In polar regions, sea ice is a major player in biogeochemical cycles, including the cycling of biogenic sulfur. Dimethyl sulfide (DMS) is the most abundant gaseous precursor of atmospheric sulfate aerosols in remote marine regions. Pristine atmospheric conditions over the polar regions make DMS-derived aerosols significant in cloud formation processes. Most climatology-derived estimates consider that DMS fluxes above ice-covered waters are non-existent, typically because of the paucity of sea ice-related data. However, recent studies have shown that sea ice, through its liquid brine micro-structure, can exchange gases with both the ocean and the atmosphere. The fate of the DMS produced during ice-related blooms in the Arctic, especially the potential diffusion of DMS through the ice and eventually toward the atmosphere, has never been documented in the Arctic. The aim of this study is to fill this gap of knowledge. This study reports on the vertical distribution of DMS in Arctic first-year ice (FYI) during the transition between early and advanced melt periods, when there is a shift from the gravity drainage phase to the vertical stabilization phase of the brine network within sea ice. Measurements of DMS in snow, in melt ponds, and in under-ice water were carried out to provide a broad picture of the different ice-related sources of DMS in the Arctic.