Soil from an abandoned manganese mining area (Hunan, China): significance of health risk from potentially toxic element pollution and its spatial context

We assess the significance of and potential impact on health for residents from pollution from a number of potentially toxic elements (PTEs) (i.e., Mn, Pb, Cu, Zn, Cr, Cd, and Ni) in surface soil from an abandoned manganese mining area in Xiangtan City, Hunan Province, China. The risks were sequentially evaluated using a series of protocols including: the geo-accumulation index (Igeo), pollution load index (PLI), potential ecological risk index (RI), hazard quotient (HQ), hazard index (HI) and carcinogenic risk (CR). The results reveals Mn and Cd were found to be the major pollutants in excess in the soils sampled. The ecological risk assessment identified moderate risks, which were mainly derived from Cd (82.91%). From the health risk assessment, non-carcinogenic risk was absent, with an acceptable level of carcinogenic risk generally in the region although exceedances were identified at a number of locations. Children were found to be more susceptible than adults in terms of non-carcinogenic risks. The soil ingestion pathway is the main route of exposure giving both non-carcinogenic and carcinogenic risks, with Mn the major contributor to non-carcinogenic risk, and Cr and Cd are the major contributor to carcinogenic risk. In addition, three pollution sources were identified through the Pearson correlation coefficient and principal component analysis (PCA), which include: a. mining activities and emissions from related transportation; b. natural background; c. agricultural management and municipal sewage discharge. The study provides more information for the development of the abandoned mining areas and is an example of the prioritization approach for the development and utilization of soil in abandoned mining areas in China.