Pollution Characteristics And Lead Isotope Source Apportionment For Heavy Metals In Atmosphere-Plant-Soil System Around Xinqiao Mining Area In Tongling

Tongling is a famous mining city in the middle and lower reaches of the Yangtze river and an important nonferrous metal base in China.Due to the intensification of mining and metal smelting activities,heavy metals enter the environment and cause pollution.In this study,the XinQiao mining area of Tongling was selected as the research area,and the surrounding plants(crops,vegetables,medicinal plant Fengdan)were taken as the research object to explore the enrichment characteristics and migration rules of heavy metals Cu,Zn,Cr,Cd and Pb in the atmosphere-plant-soil system.The sources of heavy metal pollution in plants were analyzed by multivariate statistical analysis and Pb isotope tracer technology,which provided basic data and scientific basis for local prevention and control of heavy metal pollution.The main conclusions of this study were as follows:(1)The pH value of the rhizospheric soils and profile soils were generally neutral,and Cu,Zn,Cd and Pb were seriously polluted.The soil pollution around XiangSi river and XinQiao river basin were higher than that in ShengChong river basin and Shun 'an river basin.Cd pollution was the most serious,while Cr pollution was relatively small.The morphotometry results of heavy metals showed that Cd had the highest extractable acid state and the highest ecological risk.(2)Heavy metals Cr,Cd,Pb,Cu and Zn in atmospheric dustfall were seriously polluted.The pollution level was Zn>Cd>Cu>Pb>Cr.(3)Rice and corn were polluted by Cr,vegetables by Pb,Cd and Cr,and Fengdan by Cd and Cr.The result of risk assessment of plants showed that the THQ value of Cr,Cd and Pb elements in vegetables and Cr elements in corn kernels,rice kernels and Fengdan were greater than 1,indicating that Cr was the main pollutant of human health risk.Long-term consumption of plants in mining areas will cause harm to local human health.(4)A multivariate statistical analysis was used to trace the pollution sources of atmospheric dustfall,plants and soils.The results showed that Zn,Cd,Pb and Cu in the samples had similar geochemical behaviors in pollution sources,migration and distribution characteristics,while Cr sources may be different.(5)Pb isotope tracing research showed that Pb in the rhizospheric soils of the mining area mainly came from coal combustion(50%),natural rock source(25%)and artificial ore source(25%),with the characteristics of three-terminal element mixing.Pb in atmospheric dustfall in Tongling mining area mainly came from artificial ore source(46.67%)and traffic emission(53.33%).The Pb in edible part of plants came from diesel oil(85%)and rhizospheric soil(15%).The Pb in inedible part of plants ame from diesel oil(60%)and rhizospheric soil(40%).Compared with the inedible tissues,the automobile exhaust contributed more to the accumulation of lead in the edible tissues of plants.