Elements and Pb isotopic composition as evidence for contaminant-metal dispersal in surficial soil and sediment of drinking water source in Beijing, China.

Abstract

Pb pollution in soils and sediments has adverse effects on human health and the environment. Identifying and quantifying the relative contribution of Pb pollution sources are key issues to control Pb pollution. In this study, U, Th and Pb concentration, Pb enrichment coefficient and Pb isotopic composition in the sediment and surface soil samples of the Miyun Reservoir and its upstream Chaohe, Baihe and Tanghe River were analysed to determine the source and relative contribution of Pb pollution. Results show a significant enrichment of Pb in the sediments of the Baihe River (2.7 ± 0.9). The enrichment of Pb in the soils in Baihe (8.0 ± 10.5) and Tanghe (313.3 ± 1139.4) is more obvious, and Pb is unevenly distributed in the soil in the Tanghe Basin. In general, soil is more seriously affected by human activities than sediment. The Pb isotope ratio indicates that mining activities and natural background are the main sources of Pb in soil and sediment. Based on the binary mixture model, the average contribution rate of mining activities to Pb pollution in the sediment is 21.5%, of which the contribution rates in the Miyun Reservoir, Chaohe, Baihe and Tanghe River are 14.86%, 17.20%, 41.03% and 26.32%, respectively. The average contribution rate of mining activities to soil Pb is 43.1%, among which the contribution rates in the Chaohe River Basin, Baihe River Basin and Tanghe River Basin are 58.79%, 60.98% and 36.24%, respectively. In summary, soils and sediments in the basin are affected by mining activities to varying degrees. Nevertheless, natural background is still the main source of Pb in the sediments in the basin and in soil in the Tanghe River. Mining activities are the main sources of Pb in soils in the Chaohe and Baihe River.