Lead contamination and isotopic composition of the bulk and < 2.5 μm fraction of soils in Xuzhou, China

Abstract

Lead contamination is hazardous in urban areas and Pb enrichment in the fine soil particles has important implications for its migration and bioavailability in the soil environment. However, the impact of soil particles on partitioning the pollution sources is seldom addressed in previous studies. In this study, the bulk soil and < 2.5 μm fraction of soil samples selected in Xuzhou (a highly industrialized area), China, reveal the Pb distribution and isotope composition of different soil particles. The results show that the size of the soil particles not only affects the concentration of Pb but also influences the partitioning of anthropogenic Pb due to changes in their Pb isotope compositions. Pb is significantly enriched in the < 2.5 μm fraction with an average enrichment [100 × (Pb in < 2.5 μm fraction − Pb in bulk soil)/Pb in bulk soil] in the concentration of 109%, more than double the bulk concentrations. The isotopic ratios of Pb in bulk soil indicate that the contribution of heavy metals to soil mainly comes from industrial lead and automobile exhaust. For the Pb concentrated in the fine particles, the 206Pb/207Pb values are higher and closer to the isotopic composition of industrial and geological Pb. According to the results of concentration and isotopic composition, an effective remediation method, especially for the fine particles, needs to be developed when restoring the soil.