Risk Assessment and Source Analysis of Soil Heavy Metal(oid)s Pollution in Beijing, China

Investigating heavy metal(oid)s (HMs) in urban soils is vital to safeguarding human life and health. This study investigated HMs in soils in urban areas of Beijing, assessed their ecological and health risks, and combined principal component analysis, geostatistical analysis, and positive definite matrix factor decomposition models to analyze them retrospectively. Although the Cu, Zn, and Pb in the soils of the study area were all below national quality standards, the average levels were 1.55, 1.17, and 1.21 times higher than the background values for HMs in Beijing soils, respectively, indicating the presence of HMs enrichment in the surface soils. Neither of the nine HMs in this study caused ecological risk. The health risk assessment results show that the nine HMs in this study do not yet pose a non-carcinogenic risk. Ni and Cu have significant carcinogenic effects on humans, and children are more susceptible to carcinogenic risks, with direct ingestion being the main route of HMs exposure. The main sources of HMs pollution in soils are industrial activities, soil-forming matrices and historical sites, which account for 32.89%, 44.16%, and 22.95% of total HMs accumulation respectively. We have found that V, Mn, Co, As, Ni, and Cr are mainly from parent material, Zn and Pb are mainly from industrial emissions, and Cu is from historical remains.