Abstract: We investigated the contents of heavy metals, including Cd, Cr, Ni, Cu, Zn, Pb, As and Se, in coal (coal gangue) and soil around coal mining area in the upper reaches of Guancheng River in Zhijin County, Guizhou, and analyzed their potential sources. The status of soil contamination by heavy metals and potential risks were evaluated by single-factor pollution index, Nemerow multi-factor index, geo-accumulation index and potential ecological risk index. The results showed that contents of Cr, Se and Pb in coal (coal gangue) were higher than the global mean value in the coal. The contents of Ni, Cu, Zn and Cd were higher than global and national mean values, respectively. Except Pb, the average contents of Cd, Se, Cr, Zn, As, Cu in soil were higher than soil background values of in Guizhou, especially for Cd, Se and Cu. Soils in the study area were characterized by rich selenium (or excessive amounts of selenium) and high content of cadmium, with the occurrence of acidification. The sources of Cd, Cr, Ni, Zn and Se in soils were similar, which was related with coal mining activities. The evaluation results of singlefactor pollution index showed that the order of pollution of heavy metals in soil was Cd>Cu>Ni>Zn>Cr>As>Pb, and the comprehensive pollution of heavy metals in soils was at severe pollution level. Environmental risks of Cr, Ni, Cu, Zn, As and Pb in soils were slight, but environmental risk of Cd was high. The results of four evaluation methods were similar. The single-factor pollution index and geoaccumulation index for Cd were the highest. Meanwhile, the pollution level and potential ecological harm of Cd were the highest. Therefore, Cd made the greatest contribution to the potential ecological risk index.

Key words: Gentiana rigescens, bioclimatic characteristics, ecological niche model., geographical distribution, medicinal plant resources