GREENLAND SNOW AND ICE CORES - UNIQUE ARCHIVES OF LARGE-SCALE POLLUTION OF THE TROPOSPHERE OF THE NORTHERN-HEMISPHERE BY LEAD AND OTHER HEAVY-METALS

Since the pioneering work of C. Patterson and his coworkers, great imp rovements have been made in our understanding of the changing occurren ce of heavy metals in the dated snow and ice archives deposited in Gre enland. The available reliable data, which have been obtained using im proved ultraclean and ultrasensitive analytical procedures, confirm th at Pb, Cd, Zn, and Cu concentrations markedly increased in Greenland s now during the period from the industrial revolution more than 200 yea rs ago to about the mid-1960s. The sharpest increase is clearly observ ed for Pb, mainly as a consequence of the introduction of Pb alkyl add itives in gasoline, as confirmed by recent isotopic and speciation stu dies. During the past two decades, a clear decrease has been documente d, following the great improvements made in the control of industrial emissions and the strong decline in the use of Pb alkyl additives.