Environmental Impact Assessment Of Heavy Metal Pollution In Soil Around Tailings Pond Under Rainfall Condition Based On GIS

This thesis focuses on the heavy metal pollution of soil in the environmental impact assessment of mines,and uses GIS technology and analytic hierarchy process to conduct an exploration and study on the quantitative assessment of soil environmental pollution in mines.Based on the environmental assessment data of mine planning in Nanjing area,the thesis takes Cu2+ as an example,combined with the regression prediction model of the total amount of copper under rainfall conditions,and the mathematical model of soil adsorption of Cu2+.This thesis uses GIS spatial analysis technology to explore the prediction methods of the heavy metal pollution range and pollution intensity of the soil around the mine under rainfall conditions,and tries to find a pollution prediction model and technical route suitable for the accuracy level of the mine planning EIA.(1)Considering the two pollution pathways of surface temporary water flow and river pollution of heavy metal tailings under rainfall conditions,based on the principle of conservation of matter and a one-dimensional mathematical model of water quality,a mathematical model of soil adsorption of Cu2+ under rainfall conditions is deduced and established.(2)Using topographic slope,rainfall intensity,soil p H,organic matter content and other five influencing factors of soil adsorption of Cu2+ as quantitative analysis indicators,the adsorption coefficient k is introduced as the adsorption capacity of the soil to the unit concentration of Cu2+ under the combined action of five factors in the mathematical model.(3)Based on GIS hydrological analysis technology,the D8 single flow direction algorithm using GIS to extract water flow direction is proposed,combined with GIS buffer analysis,layer overlay analysis and other functions to predict the pollution range of the tailings pond on the surrounding soil under rainfall conditions.(4)Based on the analytic hierarchy process to determine the weight of the influence of various factors on the soil adsorption of Cu2+,combined with the pollution range of the tailings pond to the surrounding soil,under the premise of a given total amount of Cu2+ pollutants released by the tailings pond,the Cu2+ adsorption coefficient k after distance attenuation is calculated.(5)Based on the grid calculation function of GIS,combined with the regression prediction model of the total amount of copper in the soil under rainfall conditions,the prediction of the relative enrichment of the total amount of copper in the soil around the two tailings ponds in Nanjing is realized.Combined with the mathematical model of soil adsorption of Cu2+ under rainfall conditions,the prediction of the relative amount of soil adsorption of Cu2+ is realized.