SEASONAL-VARIATIONS IN THE ORIGIN OF LEAD IN SNOW AT DYE-3, GREENLAND

The isotopic composition and concentration of lead has been measured i n fresh and slightly aged snow collected at Dye 3 in southern Greenlan d during one full year. The lead concentration displayed large variati ons ranging from 14-3016 pg/g in April (spring) to 3-6 pg/g in Septemb er (summer) while the isotopic ratios changed in regular manner during the year. The Pb-206/Pb-207 ratios were similar to 1.15 from spring t o mid-summer snow, and increased in late summer to early autumn, reach ing similar to 1.20 in winter. These isotopic data indicate that the l ead in the autumn to winter snow originated in North America, while th at in spring to mid-summer snow is from Eurasia. (C) 1998 Elsevier Sci ence B.V. All rights reserved.