The presence of sea ice impedes the breakdown of toxic mercury compounds in the ocean, according to a study published online in Nature Geoscience. These findings suggest that the continued loss of Arctic sea ice this century will accelerate the breakdown of toxic mercury compounds in surface waters.

David Point and colleagues analysed the chemical composition of mercury in seabird eggs, to ascertain the composition of mercury in sea water. They show that the breakdown of mercury compounds by sunlight is reduced in regions with extensive sea-ice cover. Atmospheric deposition of mercury has increased threefold since pre-industrial times, and is particularly pronounced in the Arctic.