STABLE LEAD-ISOTOPE RATIOS IN ALASKAN ARCTIC AEROSOLS

Aerosol samples collected at Barrow, Alaska, during February and March 1990 were found to have uniform stable lead isotope compositions. The mean Pb-208/Pb-207 ratio was 2.423 +/- 0.009 and the mean Pb-206/Pb-2 07 ratio was 1.161+/-0.014. The latter ratio is essentially the same a s that obtained from an earlier study of aerosols at two Canadian stat ions in the High Arctic and is typical of but not unique to, Eurasian sources of atmospheric lead. Further discriminating power was availabl e in this study through the inclusion of Pb-208/Pb-207 ratios, which p rovided additional evidence that the former Soviet Union and eastern E urope are major contributors to atmospheric particulate lead in the Al askan Arctic, accounting for around two-thirds of the particulate lead measured at Barrow. The remaining third of the lead is attributed to west European sources. There was no evidence for a substantial North A merican component, other than local contamination.