Isotopic study of lead transfer at the interface soil-plants-atmosphere

Abstract

Soil, rock, plant and rainwater samples have been collected in the evergreen forest of Cameroon and analyzed for their 206Pb/207Pb and 208Pb/207Pb ratios and Pb concentrations. Plant isotopic ratios exhibit the same values than the rains collected at the same site and higher values than the ones observed for surface soils (litter and 20 cm deep). The isotopic composition of rains and plants is in agreement with a mixing model between an anthropogenic end-member and a Saharan particle end-member. This indicates that the enrichment of lead in rainwaters is anthropogenic in origin and that the presence of lead in plants is essentially due to the assimilation of atmospheric lead directly from their leaves and/or from their bark.