POSTINDUSTRIAL REVOLUTION CHANGES IN LARGE-SCALE ATMOSPHERIC-POLLUTION OF THE NORTHERN-HEMISPHERE BY HEAVY-METALS AS DOCUMENTED IN CENTRAL GREENLAND SNOW AND ICE

Pb, Zn, Cd and Cu have been measured using ultraclean procedures in va rious sections of a 70.3-m snow/ice core covering the past 220 years ( including the Industrial Revolution) drilled at Summit, central Greenl and. These time series are the first reliable ones ever published for Zn, Cd, and Cu; for Pb they ate the first verification of the pioneeri ng data published more than two decades ago by C. Patterson and his co workers [Murozumi et al., 1969]. For all four heavy metals, concentrat ions are found to have markedly increased up until the 1960s and 1970s before decreasing significantly during the following few decades. The timing and the amplitude of the observed changes differ significantly however from one metal to another. Comparison with concentration valu es obtained by analyzing ancient Holocene ice dated 7760 years B.P., t hat is, before humans started to impact on the atmosphere, show that n o detectable increase occurred for Zn, Cd, and Cu before the Industria l Revolution. On the other hand, PE,concentrations were already one or der of magnitude above natural values in late 18th century ice. Cumula tive deposition of heavy metals to the whole Greenland ice cap since t he Industrial Revolution ranges from 3200 t for Pb to 60 t for Cd.