A forty year record of mercury in central Greenland snow

Hg has been measured using ultraclean procedures in snow deposited in central Greenland from 1949 to 1989. Concentrations range from less than or equal to 0.05 to 2.0 pg/g (mean : 0.43 pg/g), i.e. values which are orders of magnitude lower than those obtained in earlier studies. It indicates that earlier data were plagued by major contamination problems. Combined estimated contributions from natural Hg sources cannot explain Hg concentrations observed in the snow. It suggests that Hg deposition to the Greenland ice sheet is now significantly influenced by anthropogenic inputs from North America, Asia and Europe linked especially to coal burning and solid waste incineration. Although our data suggest that Hg concentrations were higher in snow dated from the late 1940s to the mid 1960s than in more recent snow, further studies are needed to clearly assess Hg temporal trends.