ABSTRACT
From the large amount of work carried out on snow and ice samples, it has been possible to extract only very limited information on historical changes in global heavy metal pollution. Melting and movement of water and impurities within the snow will confuse the picture in all but the highest, coldest mountain glaciers and the polar ice caps. Contamination can be introduced at every stage from before the snow falls until the analysis is complete. In central Antarctica and Greenland, the ice is several kilometers thick and it may be possible to obtain useful information over more than 500,000 years. In Greenland, it was found that the ratio of snow concentration to air concentration was a factor of five to ten lower for Pb than for crustal elements and other heavy metals. The relationship between air and snow concentrations depends on the mechanisms by which particles are incorporated into snow.
