Sources Of Heavy Metals In Rainwater Runoff From Antimony Mining Areas And Antimony Migration In Soil And Risk Assessment

Surface runoff from many mining areas contains high concentrations of heavy metal elements.Clarifying the source of heavy metal elements in surface runoff from mining areas,establishing their migration model in soil,and evaluating their pollution risk in soil are of positive significance for the prevention and control of heavy metal pollution.After hundreds of years of development of mining in Xikuangshan,Hunan Province,surface runoff contains high concentrations of heavy metal elements.In this paper,taking the antimony mining area of Xikuangshan as the research area,in order to analyze the sources of six heavy metal elements including antimony,copper,zinc,cadmium,nickel and lead in 204 surface runoff samples,the concentration of heavy metal elements in surface runoff samples was analyzed using correlation analysis,cluster analysis and principal component analysis were used to determine the composition of each source;a three-dimensional migration model of antimony with the highest average concentration in the soil was constructed in the surface runoff samples of the study area.Based on the model,the diffusion of antimony in soil at different depths at different time points was analyzed,and the pollution degree and human health risk of the study area at different times were assessed.The main research contents and results completed are:(1)Four main sources of six heavy metal pollutions including antimony,copper,zinc,cadmium,nickel and lead in surface runoff samples from antimony mining areas were analyzed.The results show that source 1 is a mixed source from the atmosphere,traffic and soil,and the load is mainly from nickel,cadmium and lead;source 2 is the zinc smelting industry,and the load is mainly from zinc and cadmium;source 3 is agricultural activity,and the load mainly comes from copper and lead;Source 4 is the antimony smelting industry,and the load is mainly from antimony and zinc.(2)A three-dimensional migration model of antimony in the soil from surface runoff in the study area of Xikuangshan antimony mining area was constructed.First,Hydrus-1D was used for all sampling points to establish a one-dimensional migration model of antimony in soil,then kriging interpolation was used to establish a two-dimensional model,and two-dimensional models were stacked to establish a three-dimensional migration model of antimony in soil.(3)Based on the constructed three-dimensional migration model of antimony in soil,the relationship between antimony concentration and time at depths of 3 meters and 6 meters in soil was analyzed.The results show that the functions of antimony concentration and time at the soil depths of 3 meters and 6 meters are similar to the "S"-shaped curve: that is,at the beginning of the calculation period,at the depths of 3 meters and 6 meters,the antimony concentration rises slowly,and then rises rapidly;At about 1500 days,when the concentration was close to the antimony concentration in the surface runoff,the rising speed gradually slowed down.(4)Based on the constructed three-dimensional migration model of antimony,the Nemerow index was used to evaluate the degree of antimony contamination in the soil at depths of 3 m and 6 m in the study area at different time points.After the 160-day calculation period,the pollution level at a depth of 3 meters was more serious;on the 260 th day,most areas at a depth of 6 meters were seriously polluted.(5)Based on the constructed three-dimensional migration model of antimony,the noncarcinogenic health risks of antimony in the 3-meter and 6-meter soils of the study area at different time points to residents were evaluated by the non-carcinogenic risk index.From the160 th day of the calculation period,most of the areas at a depth of 3 meters in the soil have non-carcinogenic health risks;from the 260 th day,more than half of the areas at a depth of 6meters in the soil have non-carcinogenic risks.In this paper,the sources of antimony,copper,zinc,cadmium,nickel,and lead in surface runoff samples from antimony mining areas were determined by multivariate statistical methods,a three-dimensional migration model of antimony in soil was constructed,and the pollution of antimony in soil at different depths and time was evaluated.In order to provide effective data reference and technical support for decision-making on the prevention and control of heavy metal pollution in Xikuangshan mine soil.