SEASONAL-VARIATIONS IN HEAVY-METALS CONCENTRATIONS IN PRESENT-DAY GREENLAND SNOW

Thirty six snow samples collected from a 1.6 m snow pit in central Gre enland, have been analysed for Pb, Cd, Zn, Cu and other species using ultraclean analytical procedures. They cover continuously a 2 year tim e period from summer 1992 to spring 1990, with sub-seasonal resolution . Pronounced seasonal variations of the concentrations are observed fo r all four heavy metals, with low values in winter, and much higher co ncentrations not only in spring but also in summer. The factors of var iations are 75 for Pb, 31 for Cd, 22 for Zn and 48 for Cu. Estimates o f the contributions from natural sources show that anthropogenic contr ibutions are dominant for Pb, Cd and Zn while a significant fraction o f Cu derives from rock and soil dust in part of the samples. Our data confirm that the high altitude central areas of the Greenland ice shee t remain isolated from the highly polluted air masses of the Arctic ba sin in winter. The enhanced concentrations observed in the summer laye rs are attributed to inputs from pin point sources in high latitude co ntinental areas. Copyright (C) 1996 Elsevier Science B.V.