Trace element analysis and associated risk assessment in mining area soils from Zhexi river plain, Zhejiang, China

The topography of southern China is mainly comprised of farmlands, woodlands, and rivers around the mining areas. Edible bamboo woodland soil and water may be the main focus of the potential metal risk to food safety and human health in the typical southern mining areas, at the source of the Qujiang River. A total of 24 samples from 12 farmland and woodland sites (around the mine area) were collected to measure the concentrations of nine trace elements (Cu, Cd, Cr, Mn, Pb, Zn, Ca, Mg, and Al). These elements are toxic to human health. The results showed that most of the metal concentrations in both woodland and farmland study areas exceeded the reference value for the soils of Zhejiang Province. The correlation, cluster, and multiple principal (F. Chen et al., 2010) component analyses revealed that the enrichment of metals like Pb, Cd, Zn, and Cu were a result of mixed inputs from agrochemical sources, tailing heaps, and mining transportation into farmland. In woodland soils, Cr might be defined as a natural component, and Mn concentration was dominated by both natural and anthropogenic factors. Especially in the Q12 study area the highest metal concentrations might be influenced by anthropogenic mining activities. Heavy metal contamination was evaluated through risk assessment (Nemero synthesis index). For the farmland soils, almost all the areas were polluted except the Q4 area. In addition, four areas could be marked as severely polluted. Moreover, 75% of the woodland study areas were severe in pollution. The results highlight that environmental impact assessment of mining will provide a basis for the effective governance of the polluted areas in the future.