Contamination and Health Risk Assessment of Heavy Metal Pollution in Soils Developed from Different Soil Parent Materials

Accurate risk assessment of heavy metal pollution in soil is a prerequisite for environmental and human health protection. Due to the spatial heterogeneity in the environment, biased results can be obtained when uniform background values are introduced in regional heavy metal pollution assessment. In this study, considering the heavy metal background variation in different regions, 209 surface samples and 18 deep samples were collected from soils developed from different parent materials. In addition, the pollution level, environmental, and health risks and spatial pattern were analyzed. The results indicated that the overall mean concentrations of Cr, Pb, As, Cd, and Hg were 60.02, 39.79, 14.32, 0.38, and 0.18 mg/kg, respectively. Moreover, heavy metals exhibited significantly different pollution levels and environmental risks among soils developed from the different parent materials: due to the higher accumulation and toxicity response coefficients for Cd, Hg, and As, heavy metal pollution and ecological risks in soils developed from plain river alluvium and granite eluvium were higher than those in soils developed from the other parent materials. Regarding human health risks, ingestion was found to be the main exposure pathway, and children exhibited higher noncarcinogenic and carcinogenic risks than the adults. Heavy metal pollution in soils developed from granite eluvium indicated a significantly higher health risk than those in soils developed from the other parent materials due to higher As accumulation. The assessment index spatial distributions revealed that high-risk areas mainly occurred in the eastern broad valley plain, central river valley plain, and northwestern mountain areas, demonstrating that due to intensive human activities, heavy metal accumulation in these areas yielded higher risks. When formulating soil pollution prevention measures, attention should be directed toward high-risk areas to achieve sustainable environmental development.