Pollution Status, Risk Assessment, and Source Identification of Heavy Metals in Farmland Topsoil of Mining Area Along the Yangtze River, East China

This study evaluates the pollution status, ecological risks, health risks, and sources of heavy metals from farmland in a mining city located in the Yangtze River basin, East China. A total of 2361 samples of topsoil were collected and analyzed for the concentration of five heavy metals and pH. The Nemerow index was used to assess integrated pollution, while absolute principal component scores-multiple linear regression (APCS-MLR) was used to identify the sources of heavy metals. The results revealed that, excluding Hg and Cr, the concentrations of Cd, As, and Pb in some samples exceeded intervention values, with Cd concentrations in 19.7% of samples surpassing this threshold. Based on the Nemerow index, 68.8% of sites were contaminated, with 27.4% classified as heavily polluted, indicating significant pollution in this area. Cd posed the primary ecological risk, with 19.8% of sites at high risk or above, also presenting carcinogenic risks to adults. Additionally, As exceeded safety thresholds for hazard quotient (HQ = 1) and carcinogenic risk (CR = 1 × 10−4). APCS-MLR revealed that heavy metals in farmland were mainly influenced by mining, agricultural activities, and natural soil-forming processes. This study offers insights into farmland heavy metal management and highlights industrial pollution sources in mining areas.