Tracing the origin of pollution in French Alpine snow and aerosols using lead isotopic ratios

Fresh snow samples collected at 15 remote locations an aerosols collected a t one location in the French Alps between November 1998 and April 1999 have been analyzed for Pb concentration and isotopic composition by thermal ion ization mass spectrometry. The snow samples contained 19-1300 pg/g of Pb wi th isotopic ratios Pb-206/Pb-207 (Pb-208/Pb-207) of 1.1279-1.1607 (2.3983-2 .4302). Airborne Pb concentrations at one sampling site ranged from 0.42 to 6.0 ng/m(3) with isotopic ratios of 1.1321-1.1427(2.4029-2.4160). Air mass trajectory analysis combined with isotopic compositions of potential sourc e regions did not show discernible evidence of the long-range atmospheric t ransport of pollutants. Isotopic ratios in the Alpine snow samples and thus the free troposphere were generally higher than airborne Pb isotopic ratio s in urban France, which coupled with the relatively high Pb concentrations suggested a regional anthropogenic Pb source, probably Italy but possibly Eastern Europe.