Geochemical Characteristics Of Heavy Metals In Topsoil Of Shunyi District In Beijing

Soil is an important component of terrestrial ecosystems,which human beings rely for survival and development,and the quality of soil is closely associated with human life.With the rapid development of urbanization and industrialization,the content of heavy metals in soil around the city is also strongly disturbed by human activities,and the suburbs of city are the important agricultural production area for the urban area.Therefore,it is of great theoretical and practical significance to study the geochemical characteristics and environmental quality of heavy metals in soil around cities to ensure the safety of soil environment and human health.This study systematically studied the geochemical characteristics,including spatial distribution,source identification and ecological risk of 8 heavy metals in the topsoil of Shunyi district around Beijing through multivariate statistics and geostatistical analysis.The main conclusions are as follows:Figure out the concentration and spatial distribution characteristics of heavy metals in surface soil in Shunyi district.The mean concentrations of V,Cr,Ni,As,Cd,Zn,Pb and Hg were 68.2,52.1,22.9,8.3,0.153,68.3,23.8 and 0.046mg/kg,respectively.The mean concentrations for eight heavy metals in Shunyi area are all lower than the value of Grade II in Chinese soil quality guidelines.The spatial distribution maps show the“hot spots”of V,Cr,Ni and As are similar and mainly located in the northwest,northeast and central of the study area,are similar to the initial weathering products of Al₂O₃/SiO₂ and Fe₂O₃;high-concentration areas of Cd,Zn and Pb are distributed randomly;high values of Hg mainly scattered in the western of the study area.Sources identification for these metals in the surface soil of Shunyi was performed.By using variogram analysis,Pearson correlation analysis and principal component analysis,it was determined that the elements of V,Cr,Ni and As were primarily originated from the parent material of the soil,and that Cd,Zn and Pb were greatly influenced by industrial activities,agricultural cultivation and traffic emission.Nevertheless,Hg was more weakly related to the above sources,partially due to atmospheric deposition from coal combustion and industrial activities.Furthermore,cluster analysis and redundancy analysis suggested that the elements of V,Cr,Ni and As were closely associated with Fe₂O₃ and Al₂O₃ which undoubtedly originated from parent soils.On the other hand,Cd,Zn and Pb were associated with P,N and TOC which were mainly associated with anthropogenic activity and agricultural cultivation.The results of source identification mentioned above were also supported by the results of anthropogenic contribution calculation.Finally,the environmental quality of the soil of Shunyi was evaluated.Single factor index method?P_i?,Geo-accumulation index(I_geo)and potential ecological risk index?RI?were used to evaluate soil environmental quality in shunyi district.Most of the values of these three methods were not as high as the value of low potential ecological risk in Shunyi district.The results of this study can provide important reference information for the geochemical characteristics of heavy metals in the soil where are similar to Shunyi district...