Geochemical characteristics and sources of heavy metal elements in the southern and western surface soils of Fengdu County, Chongqing

Abstract

In order to explore the current situation and sources of heavy metal element pollution in the surface soil of the southern and western parts of Fengdu County, Chongqing. In this paper, the test and analysis results of 2955 surface soil samples collected from the project of "Chongqing Jiaoshi Dam Width, Liziwan Width, etc. a total of five 1:50,000 Land Quality Geological Survey" project were carried out. The single pollution index method and the land accumulation index method were used to evaluate the current status of heavy metal pollution in crops and soil. At the same time, correlation analysis and principal component analysis were performed. The results show that: (1) Compared with the soil heavy metal background in the Three Gorges Reservoir area, the average values of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in the study area are enriched to different degrees, except that the average content of Cr is lower than the background value. Among them, As, Cd and Hg elements were obviously enriched. (2) The calculation results of the single index of heavy metals in the surface soil showed that Cd pollution was the main in the area. Cu was only slightly to slightly polluted, and the number of lightly polluted samples accounted for only 0.07%. (3) The average Igeo trend of heavy metals in surface soil in the region was Cd>Hg>As>Pb>Zn>Cu>Ni>Cr. As, Pb, Zn, Cu, Ni and Cr were mainly non-slightly polluted. Cd and Hg elements were heavily polluted, but the sample accounted for a small proportion. The overall display area is dominated by Cd element pollution. (4) The source analysis results show that As, Cu, Pb, Ni, Zn and Cr in the study area are mainly derived from the earth's crust. Its content is related to the geological setting. The pollution of Hg and Cd is likely to be affected by human activities, mainly from atmospheric deposition.