| Farmland soil around a molybdenum mining area in Weinan, Shaanxi Province, was selected as the research object. The concentrations of eight heavy metals (Cd, Hg, As, Cr, Pb, Cu, Ni, and Zn) in the soil were analyzed. The single-factor pollution index, the Nemerow comprehensive pollution index, and the geo-accumulation index (Igeo) were used to evaluate pollution levels of heavy metals. The potential ecological risk index was used to assess ecological risk in the study area. The results showed that the average concentrations of the eight heavy metals exceeded the soil background values, whereas Cd and Zn showed serious pollution, with average values of 0.27 and 158.21 mg/kg, respectively, exceeding the risk screening values for agricultural land. According to the Nemerow index, Pb, Cu, Hg, Ni, Cr, and As were at a light pollution level, whereas the index values for Cd and Zn were 4.74 and 3.33, respectively, indicating heavy pollution. The average geo-accumulation indices of Cd, Zn, and Pb were 0.62, 0.44, and 0.09, respectively, corresponding to mild to moderate pollution levels. The potential ecological risk index indicated that the potential ecological risk of soil heavy metals around the mining area was at a medium level. Cd was the primary pollution factor and the major contributor to ecological risk. Monitoring, control, and restoration should be strengthened to safeguard long-term soil health. |
