[Pollution Characteristics, Source Analysis, and Health Risk Assessment of Heavy Metals in Soil and Crops in a...

This study focused on a molybdenum mining area in the Qinling Mountains （Shaanxi segment）. Crop and corresponding soil samples were collected from the vicinity of the mining area, and the concentrations of six heavy metals （Cr, Cu, Zn, As, Cd, and Pb） were determined. Soil heavy metal pollution was assessed using single-factor, comprehensive pollution, and geo-accumulation index methods. The primary sources of soil heavy metals were analyzed using the PMF model. A health risk assessment for soil and crops was conducted using the USEPA model. The results revealed severe pollution of agricultural soils by Cr, Cu, Zn, Cd, and Pb. Among these, Cr may have been primarily sourced from chrombismite nearby mining activities, contributing to 85.1% of the pollution. Cu and As were mainly sourced from agriculture, contributing 50.3% and 70.6%, respectively. Zn and Cd were primarily sourced from natural sources such as metal slag dust and rainwash from the mining area, contributing 73.5% and 48.7%, respectively. Pb was primarily sourced from transportation sources, contributing to 54.7% of the pollution. Crop metal contamination was especially severe for Cr, followed by Pb, whereas As and Cd contamination was relatively lower. Crops were significantly impacted by heavy metal pollution in agricultural soils. The health risk assessment indicated non-carcinogenic and carcinogenic risks for children due to soil heavy metals, whereas adults faced acceptable levels of risk. Both adults and children were exposed to highly significant non-carcinogenic and carcinogenic risks from heavy metals in the crops. Moreover, it is essential to implement effective measures to control heavy metal pollution from tailings to safeguard nearby residents, especially children, from adverse health risks.