Source Apportionment Of Regional Soil Heavy Metal Pollution

Heavy metals in soil can pose a great threat to ecosystem and human health.The problem of heavy metal pollution in soil caused by the rapid development process has aroused widespread concern all over the world.It was very important for our ecological environment construction to identify and quantify the sources and risks of heavy metal pollution in soil and formulate soil pollution prevention and control measures.In this paper,Qujiang District,a typical industrial production area,was taken as the research area,and eight kinds of heavy metals,such as Hg,As,Pb,Cd,Cu,Ni,Cr and Zn,were taken as the research objects.By means of statistical analysis,spatial analysis,source apportionment and risk assessment,the pollution characteristics,pollution sources,spatial distribution and influencing factors of soil heavy metals in the research area were explored,and the ecological and health risk levels caused by specific sources were evaluated.It provided reference for the prevention and control of soil pollution.(1)In this study,single factor index method,comprehensive pollution index method and ground accumulation index method were used to evaluate the pollution status of heavy metals in soil in the study area.The results showed that eight kinds of heavy metals in the soil in the study area were enriched to varying degrees,and the average content was higher than the local soil background value.Compared with the risk screening values in "Soil Environmental Quality Risk Control Standard for Agricultural Land Soil Pollution(Trial)"(GB 15618-2018),the pollution of Cd and As was relatively serious,with an average content of 2.05 times and 1.08 times of the corresponding screening values.The over-standard points of Cd,As and Pb were in the top three,accounting for 36.06%,30.77% and 22.12% respectively.(2)The inverse distance weighted interpolation method was used to characterize the spatial distribution characteristics of soil heavy metals in the study area.The results showed that the spatial distribution characteristics of eight kinds of soil heavy metals were different.The spatial distribution trends of Cd,Pb and Zn were similar.The highvalue areas were concentrated in the north-central part of the study area,the high-value areas of As were mainly distributed in the south-central part,and the high-value areas of Cu were located in the middle part.The spatial distribution trends of Ni and Cr were relatively scattered,and there was no obvious high-value area.(3)Based on the comprehensive source apportionment method of positive definite matrix factorization(PMF),geostatistics method and Geodetector model,the pollution sources of heavy metals in soil in the study area were explored.The sources of heavy metal pollution in soil mainly come from natural sources and anthropogenic sources,with the contribution rates of 33.1% and 66.9% respectively.Anthropogenic sources included traffic sources,atmospheric deposition,industrial activities dominated by metal mining and dressing,and industrial activities dominated by metal products,with the contribution rates of 22.9%,16.3%,15.1% and 12.6% respectively.Hg,Cr and Ni were mainly influenced by natural sources,such as organic matter,altitude and pH value.As was related to industrial activities,mainly metal mining and dressing.Cd and Cu were superimposed by natural sources and man-made sources.The accumulation of Pb and Zn can be attributed to traffic sources.(4)The results of risk assessment showed that the high potential ecological risk area in the study area was located in the north-central part,and the soil heavy metal Cd contributes the highest ecological risk,while the other seven heavy metals had low potential ecological risks.In the study area,the carcinogenic risk of heavy metals in soil to children and adults was at an acceptable level,but the potential non-carcinogenic risk to children was higher than the acceptable value.Among all exposure routes,the health risk from oral intake was the greatest,and the industrial activities mainly in metal mining and dressing were the most important areas for follow-up management and control.In this study,the heavy metals in the soil in the study area were explored from the perspectives of pollution identification,cause analysis and risk assessment,and a set of combined source analysis technology was formed,which can provide reference for soil prevention and control in other regions of China.