Heavy metal pollution characteristics and source analysis of water drainage from a mine in Inner Mongolia

Heavy metal pollution evaluation and its source analysis are essential to mine water reuse and protection of ecological environment in mining areas. The objective of this paper is to study heavy metal pollution characteristics and source of heavy metal in mine water. A coal mine from Inner Mongolia Province was chosen as the study area and 49 water samples including surface water, quaternary groundwater, confined groundwater and mine water were collected. Primarily, we detected the concentrations of Zn, Pb, Fe, Mn, As, Cu, Cd, Cr, Hg and Se of water samples to explore heavy metal pollution characteristics and excessive situation. And then, HPI(Heavy-metal Pollution Index) model was established to evaluate the degree of mine water heavy metal pollution. At last, mathematical statistics, heavy metal concentration box-plot and heavy metal leaching tests of coal/roof were used to analyze heavy metal source. The results show that the concentration of Zn, Pb, Fe, Mn and As exceeded their standard value. And the exceeding rate of Fe and Zn both reach 100% with the highest over-standard rate. Six of the seven water samples HPI value exceed the critical value of 100. It means mine water heavy metal pollution is serious, generally. The pb and As in mine water is mainly from the leakage of oil substances of coal mining and transportation machinery, while Mn is mainly from aquifer Ⅲ, and Fe and Zn from aquifer Ⅲ, and iron and manganese bearing minerals leaching of coal seam. This conclusion will provide a basis for prevention and treatment of heavy metal pollution in mine water.