Chemical contamination of Antarctic snow: The case of lead

Snow samples were collected from surface layers of the Hercules Neve (Victoria Land, East Antarctica) during the austral summer 1993-1994 in the framework of the: Italian Scientific Expeditions to Antarctica. To avoid contamination stringent ultraclean field procedures were applied and carefully precleaned Teflon PTFE containers were used. Lead concentration was determined directly on melted snow and without any preconcentration step by differential pulse anodic stripping voltammetry inside a clean chemistry laboratory (Class 100). Metal fallout fluxes were calculated using corresponding annual accumulation rates. Results showed that during the previous decade the lead content of Antarctic snow had decreased markedly, particularly from about 8.4 pg g(-1) in 1986 to 2.5 pg g(-1) in 1991, with metal flux declining from 184 to 34 pg cm(-2) year(-1) in the same period. This trend, which confirms previous results obtained in other sites of Victoria Land (McCarthy Ridge and Styx Glacier plateau), has been related to the corresponding decrease in the consumption of lead as a gasoline additive in the countries of the southern hemisphere. (C) 1997 Academic Press.