Characteristics and ecological risk of soil heavy metals of a Tungsten mine in Yudu, Jiangxi Province

The accumulation of heavy metals in soil is generally originated from the persistent exploitation in the mining area, thus clarifying the environmental pollution characteristics of heavy metals in soil and evaluating the ecological risk can provide a basis for monitoring soil environmental quality and preventing soil pollution. A tungsten mine with history of a hundred years in Yudu of southern Jiangxi Province was selected as a case study. Based on the assaying data, single-factor index and Nemerow multifactor index methods were used to assess the quality of soil, then the potential ecological risks of the eight heavy metals were evaluated by Hakanson potential ecological risk index method. The evaluation results show that the single-factor pollution index of Cu, Zn, Cd, Pb and As are 6.74, 3.72, 45.1, 3.36, 8.88, respectively. Cd contributes most to the Nemerow composite pollution index, followed by As, Cu, Pb, and Zn. The average value of the comprehensive potential ecological risk index reaches up to 2065, indicating strong potential hazard. The areas with strong potential heavy metals ecological risk account for 43.89%, which are mainly distributed around mines and their downstream near the river. Correlation analysis of soil heavy metals in the study area shows that Cu, Zn, Cd and Pb are significantly correlated. In conclusion, Cd has a certain potential ecological risk and should be paid more attention, and mineral exploitation activities may be the primary cause of Cu, Zn, Cd, and Pb pollution.