Spatial analysis and risk assessment of potentially toxic elements in agricultural soil downstream of the tungsten mining area in Dayu, China.

Located in the southwest of Jiangxi Province, Dayu County has the most abundant tungsten resources in China. In this paper, 2969 agricultural soil samples were collected downstream of the tungsten mining area in Dayu, and all samples were tested for the contents of potentially toxic elements (PTEs) such as Cd, Pb, Zn, Cr, Cu, Ni, Hg, as well as the mining-related elements W, Sn, Mo and pH. In addition, 135 soil samples were measured for chemical morphology of Cd. The results show that the distribution patterns of Cd, Pb, Zn, Cu and W, Sn, Mo are relatively consistent, which are considered to be affected by upstream mining activities. Hg is possibly overlaying the effects of human production and living activities. Cr and Ni are considered as a natural source. From the perspective of total concentration, the ecological risk of PTEs in the study area was low, with over 80% of the samples being evaluated as safe. However, based on chemical fraction of Cd, more than 75% of the samples were assessed as moderately or severely contaminated. The serious acidification of soil in the study area is the main reason for the increase activity of Cd and its ecological risk. [ABSTRACT FROM AUTHOR]