Spatial patterns of potentially hazardous metals in paddy soils in a typical electrical waste dismantling area and their pollution characteristics

Environmental pollution caused by electrical waste (E-waste) dismantling has attracted much attention from environmental researchers in China and worldwide. A total of 90 topsoil samples, 10 soil profile samples and 14 groundwater samples, were collected from a typical E-waste dismantling area in southeastern China. The spatial and vertical variations of potentially hazardous metals (PHM) in paddy soils and their potentially ecological risks were studied. The results showed that the mean total concentrations of five PHM (Cd, Cu, Pb, Zn and Ni) in paddy soils were 0.38, 35.13, 35.40, 121.38 and 28.13 mg kg−1, respectively. The total Cd, and Pb concentrations in paddy soils had strong variability coefficients of 121.05% and 109.38%, respectively. Compared with the background values in Zhejiang province, the PHM were enriched in paddy soils. Part of the study area was seriously contaminated by these metals. The soil was contaminated with Cd, with high Pi Ave value (>1). The shallow groundwater was also contaminated by Cd in the E-waste dismantling area. Results of vertical variations of PHM in soils revealed significant accumulation of PHM in the topsoil (0-20 cm, 20-40 cm). Soil pH and organic matter (SOM) was significantly correlated with most of the total PHM in soils. Kriging interpolation and Moran's I were used to identify the contaminated hotspots of these PHM. It was found that high soil Cd, Cu, Ni, Zn were located in Da Xi and Zhe Guo towns, which was attributed to E-waste dismantling and other anthropogenic activities. Soil Ni was mainly influenced by the parent material. The PHM in soils may pose a potential threat to local ecosystem and human health.