ISOTOPIC COMPOSITION AS AN INDICATOR OF ORIGIN OF LEAD ACCUMULATIONS IN SURFACE SOILS

Surface accumulation of lead in urban soils is a well-known phenomenon but its marked accumulation in remote, upland areas is less well documented. Such enrichments (up to 500 mg/kg) could be a potential hazard to grazing sheep. Lead isotope ratios determined by thermal ionization mass spectrometry are reported for three soil profiles from remote, upland areas with highly enriched surface concentrations of lead. Isotope ratios in recent rainwater samples from six widely dispersed sites in Scotland are also discussed. Lead in current rainwater samples has very low isotope ratios indicating its likely origin from petrol-derived sources. The ratios in soil surface horizons are not as low as those in current rainwater samples which suggests that lead accumulated over many decades is derived from both petrol-derived sources and also from other industrial emissions such as smelting and steel production. © 1992, Taylor & Francis Group, LLC. All rights reserved.