Partitioning of anthropogenic and natural lead in soils

Industrial pollution and the combustion of leaded petrol have been responsible for a significant increase in Pb concentrations in the atmosphere, which has consequently caused widespread contamination of soils in both rural and urban areas. The introduction of unleaded petrol has reduced Pb levels in aerosols in certain countries, and some studies showed that this is reflected in a recent reduction of Pb concentrations in near surface soil horizons. The effect of soil composition on the chemical partitioning of Pb in soils was evaluated. An understanding of the mechanisms through which Pb, and other heavy metals, were incorporated into the different chemical fractions that comprise the soil has significant implications for the chemical and biological remediation of contaminated soils. Concentrations and isotopic compositions of Pb in soils from Israel and East Europe were used to trace the penetration of anthropogenic Pb through soil profiles and to determine the relative contribution of anthropogenic Pb to the soil. Uncontaminated soil contained ∼ 20 ppm Pb, while Pb concentrations in the top roadside soil range between 100 and 800 ppm with a high proportion of Pb related to the labile soil fractions.