Characterization and Ecological Risk Assessment of Toxic Metal Contaminants in the Soil Around the Coal Gangue Hill in Huainan, Central China

To better understand the toxic metal pollution caused by coal mining activities, the concentrations of Ni, Zn, Cr, Cd, Cu, As and Pb in the soil around the coal gangue hill in a coal mine area of Huainan, China were measured, the soil pollution degree was assessed with the single factor index, Nemerow pollution index and potential ecological hazard index method. The descending order of the average concentration is Cr > Zn > As > Ni > Cu > Pb > Cd. The concentrations of toxic metal contaminants in the soil showed distinct spatial distribution differences in different wind directions. The pollution degree is followed the order of downwind direction > upwind direction > control point. The values of Nemerow index and potential ecological risk index are different among different directions and different distances from the coal gangue hill. The ecological risk of toxic metal contaminants in the soil around the mining area in the upwind and downwind directions belonged to slight, Cd and As posing a higher ecological risk than the other elements. Results revealed that the wind direction is important for the distribution of toxic metal contaminants around the coal gangue hill. This study can be used as a scientific reference for the prevention and control of pollution caused by toxic metal contaminants in mining area soil.