Research On Spatial Distribution And Pollution Evaluation Of Heavy Metal In Soil Of Yindu Mining Area Based On GIS

With the continuous development of human mining,the impact of mining on the surrounding soil is increasing,resulting in higher levels of heavy metals in the soil than in its original value,resulting in the pollution of heavy metal elements in the soil;once the soil is contaminated,it will have a serious impact on plants,animals and human society.By analyzing the spatial distribution and pollution of heavy metals in soil,it can provide important theoretical basis for mine ecological management,development and utilization,and treatment and prevention of mining areas.This paper takes the Yindu mining area of Chifeng City,Inner Mongolia as the research object,analyzes the spatial variation structure,distribution characteristics and pollution status of six heavy metal elements in the 82 soil sample collection sites in the mining area,and uses geostatistics combined with GIS to visualize the spatial distribution and pollution of heavy metals.The specific main conclusions are as follows:(1)Six kinds of superficial heavy metal elements,in terms of content,except for Cr,the maximum values of the other five elements are all higher than the national secondary standard values,followed by Cd>As>Pb>Hg>Ni in order from high to low;In terms of variation,all of the six kinds of heavy metal elements have variations.The order of the variation intensity from high to low is Cd>Pb>As>Hg>Ni>Cr,and both approximate log-normal distribution;the optimal theory of spatial variability According to the model,Pb,Cd,and Hg conform to the linear model,Cr conforms to the spherical model,and Ni and As conform to the Gaussian model.(2)The results of spatial distribution of heavy metal content in shallow layers show that the content of Cd and As in the entire mining area exceeds the national secondary standard value;most of Pb and Hg exceed the national secondary standard value;Ni is extremely small and exceeds the national secondary standard value;Cr does not exceed the national secondary standard value.(3)Shallow soil pollution: The single evaluation results showed that Cd and As are heavy pollution elements,Pb is moderate pollution elements,Hg is light pollutionelements,Cr and Ni are safety elements;and the integrated pollution assessment of Nemerow shows that The over-standard rate of comprehensive pollution was100%;and the pollution load index evaluation results showed that the shallow soil was moderately polluted.(4)Deep soil pollution: The single evaluation results showed that As is a moderately polluting element,Cd is a lightly polluting element,and Hg,Pb,Ni,and Cd are safe elements;the integrated assessment of Nemerow shows that the comprehensive pollution exceeds the standard rate.41.46%;The pollution load index evaluation results show that deep soil belongs to no pollution.(5)There are many factors that cause heavy metal pollution in shallow soils.,There are mainly four kinds: wind dust,rainwater leaching,ore splashing,and soil backfill.