The Impact of Coal Mining on Soil Nutrients and Heavy Metals in Rainfed Farmland in Arid Grassland Area

Coal mining has an important impact on the surrounding rainfed farmland. In order to clarify the effects of coal mining on soil nutrients and heavy metals content in arid grassland area, the soil nutrients (organic matter, total N, total P, total K and pH) and heavy metals (Pb, Cd, Cr, Cu, Zn, Ni, Hg) were measured in the rainfed farmland around Dingjiagou Coal Mine in Yijin Holuo Banner, Ordos City. The relationship between soil nutrients and heavy metals and the sources of heavy metal pollution were analyzed. The results show that coal mine had a great influence on soil nutrient and heavy metal content in 0-10 cm rainfed farmland around the mining area, and caused the decrease of organic matter and total N content in soil; in the range of 500 m around the coal mine, the contents of heavy metals Cu and As in soil were higher than CK; in the range of 2 500 m around the coal mine, the contents of Pb and Cr in soil were higher than CK. Soil organic matter and total N contents were lower than those of CK at 1 250 m range around the coal mine, and were negatively correlated with the contents of Pb, Cr, Cu and As in the soil; Zn mainly came from transportation; Ni mainly came from agricultural production activities; Cd and Hg came from natural soil parent materials and anthropogenic activity outside coal mine. Therefore, the pollution of Pb, Cr, Cu and As from coal mines should be controlled when the rainfed farmland in this area is to be protected.