The study of Hawkings et al. (2021) presents concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream fjords based on samples collected during summer ablation seasons. It is shown that concentrations of dissolved mercury are among the highest recorded in natural waters and mercury yields from these glacial catchments are two orders of magnitude higher than from Arctic rivers.

High dissolved mercury concentrations were found to persist across salinity gradients of fjords. These results suggest a geological source of mercury at the ice sheet bed. The high concentrations of mercury and its large export to the downstream fjords have important implications for Arctic ecosystems.

The results highlight an urgent need to better understand mercury dynamics in ice sheet runoff under global warming.

According to the CLEFSA network, this issue is characterized with a high impact and likelihood of emergence, and given the increasing relevance of the oceans as food and feed sources.