THE CHANGING OCCURRENCE OF NATURAL AND MAN-DERIVED HEAVY-METALS IN ANTARCTIC AND GREENLAND ANCIENT ICE AND RECENT SNOW

A record of the past and recent changes in the large scale atmospheric cycles of Pb and other heavy metals can be found in the successive da ted ice and snow layers stored in the Antarctic and Greenland ice caps . Deciphering these frozen archives has however been possible only whe n using sophisticated ultrasensitive and ultraclean analytical techniq ues. The available data have allowed to demonstrate that the atmospher ic cycles of heavy metals have been highly dependent upon climate duri ng pre-pollution times. During the last few centuries, they have been significantly altered by man. This is especially the case for Pb, whos e concentrations were found to have strongly increased in Greenland ic e and snow from several millennia ago to the mid 1960's, then to have decreased from the late 1960's to present.