Lead Contamination and Source Characterization in Soils Around a Lead–Zinc Smelting Plant in a Near-Urban Environment in Baoji, China

Economic reforms in China since 1978 have promoted nationwide socioeconomic advancement but led to a considerable amount of environmental pollution. The distribution and sources of Pb in a typical peri-urban industrial part of Baoji, China, were assessed by determining the Pb contents and isotopic compositions in 52 topsoil samples from the study area. The topsoil samples were polluted averagely with 40.88 mg Pb kg⁻¹, was 1.86 times higher than the Pb content of local background soil (22.04 mg kg⁻¹). Pb isotopic compositions were determined by analyzing samples prepared using total digestion and acid extraction methods. Radiogenic isotopes contributed more to the Pb concentrations in the acid extracts than in the total digests. This was shown by the ^207/206Pb and ^208/206Pb ratios, which were 0.845–0.88 and 2.088–2.128, respectively, in the acid extracts and 0.841–0.875 and 2.086–2.125, respectively, in the total digests. This indicates that anthropogenic sources of Pb could be identified more sensitively in acid extracts than in total digests. The Pb isotope ratios showed that burning coal and smelting ore are the predominant anthropogenic sources of Pb in the study area, i.e., a lead–zinc smelter and a coking plant are major sources of Pb in the study area.