Cf. Boutron et al., THE CHANGING OCCURRENCE OF NATURAL AND MAN-DERIVED HEAVY-METALS IN ANTARCTIC AND GREENLAND ANCIENT ICE AND RECENT SNOW, International journal of environmental analytical chemistry, 55(1-4), 1994, pp. 203-209
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.