Pollution characteristics of heavy metal(loid)s in soil in China: Implications for health risk assessment and temporal trend analysis

The ecological and human health risks associated with heavy metal(loid)s (HMs) have attracted much attentions worldwide. In this study, 153 topsoil samples were collected across China in 2019, aiming to investigate the HMs pollution characteristics. The soil samples were collected from areas such as parks, schools, communities, and rural regions, which were far away from pollution sources of HMs. In order to study the temporal trend of pollution, related studies from 2000 to 2015 in China were also summarized. The findings indicated that Cd, Cu, Zn, and Pb were the major HMs with the mean concentrations of Cd, Cu, Zn, and Pb were 0.40, 36.5, 107, and 33.5 mg/kg, respectively. High background values and metal processing resulted in high total concentrations of Cd, As, Cr, and V especially in Southwest China (such as Guizhou and Yunnan provinces). The result of the Positive Matrix Factorization (PMF) model indicated the primary source of HMs was natural source (45.3%), followed by traffic source (20.6%), industrial source (17.3%), and agricultural source (16.8%). The health risk assessment of HMs indicated that non-carcinogenic risks were minimal, however, carcinogenic risks (95th) for As, Cr, and Cd should attract attentions. Compared with the measurements from 2000 to 2015, the pollution levels of HMs showed a decreasing trend in China in 2019, which indicated the effectives on HMs control along with the implementation of the control policy on soil in China.