DECREASE IN ANTHROPOGENIC LEAD, CADMIUM AND ZINC IN GREENLAND SNOWS SINCE THE LATE 1960S

MORE than twenty years ago, Patterson and co-workers 1 showed that evidence of lead concentrations in Greenland ice and snow had increased about 200-fold since ancient times. From their results, they concluded that more than 99% of this highly toxic metal in the global troposphere of the Northern Hemisphere originated from human activities in the mid 1960s-mainly from the use of alkyl-leaded petrol. At least in part because of this evidence, the United States and other countries limited the use of lead additives in petrol from about 1970. Here we report that, as a result of these policy initiatives, lead concentrations in Greenland snow have decreased by a factor of 7.5 over the past twenty years. We also show that over the same time period, cadmium and zinc concentrations have decreased by a factor of 2.5.