Contamination Of Soil Nutrients And Heavy Metals In Mine Of InnerMongolia Grassland

Heavy metal contamination in agricultural soils have received a great deal of attention in the past decades, yet little is known about how mining activities would affect soil properties in the grassland areas. In the grasslands, the pollution caused by mining could not only change soil nutrient conditions but also pose great threats to food safety through the potential accumulation of heavy metals from soil to forage grasses and livestock. Examining the status of soil nutrients and heavy metal contents in the grasslands with intensive mining activities is of great importance in order to ensure the food safety and ecological stability of grasslands. In this study, we collected soil samples around a large opencast coal mine (Shengli West No.1 Coal Mine), a tin-copper mine and a lead-zinc mine located in the central area of Inner Mongolia grasslands. We then analyzed the contents of major nutrients and heavy metals in these samples, as well as their spatial variation from mine centers to the adjacent natural grasslands. The degree of contamination was evaluated through single factor index, Nemerow index and potential ecological risk index. Based on these assessments, we proposed appropriate methods of soil remediation for these areas.Our results showed that the degree of heavy mental contamination and the status of soil nutrients varied among the three mines. The contents of Cr, Cu, Zn,Cd and Pb differed significantly among the sites with different distances from the center of the lead-zinc mine; the contents of Cu, As and Sn also showed spatial variation around the tin-copper mine; For the coal mine, only the contents of Zn varied at different distances from the mine center. In terms of soil nutrients, the contents of available K, organic matter and available P were significantly affected by the operations of the lead-zinc mine, while the contents of organic matter and available N varied among sites around the coal mine, and the contents of available K and available N were significantly affected by the operations of the tin-copper mine. Based on our evaluation, all major nutrients except available P were above the medium level in the soils around these mines.According to the heavy metal pollution assessments,on the basis of Single factor pollution index and Nemerow index, lead-zinc mine and coal mine has yet to cause pollution,but tin-copper mine have appeared different degrees of pollution at different sites.On the basis of Potential ecological risk index, lead-zinc mine and coal mine belong to light pollution,but the tin-copper mine was the most contaminated area among all three mines(Cd pollution is most serious), especially at the site S2 which is 45 m away from the center of the tin-copper mine with strong ecologital harm should be management.