Morphological distribution and risk assessment of soil heavy metals in the Belly of the Three Gorges Reservoir area in Chongqing-A Case Study of Fengdu

Abstract

The study of the morphological distribution and pollution risk of heavy metals in the hinterland of the Three Gorges Reservoir area in Chongqing can be used to provide data support for soil pollution prevention and control, ecological environment safety risk control and agricultural healthy development in the region. In this paper, Fengdu County, the hinterland of the Three Gorges Reservoir Area in Chongqing, was taken as the study area. The total amount and morphology of 8 heavy metal elements in the surface soil of agricultural land were analyzed and determined. The geocumulative index method was used to evaluate the pollution degree. The risk assessment coding method is used to evaluate the potential risk level. The results showed that the average contents of heavy metal elements As, Hg, Cu and Cr in the soil in the study area were relatively low. The average contents of Cd, Zn, Pb and Ni were higher than those in the Three Gorges Reservoir area. The mean value of Cd content was 1.71 times that of the background value. Cd in the soil heavy metal form is dominated by ion exchange state. The proportion of carbonate-bound state and iron-manganese bound state is relatively high. The proportion of bioavailable state was 46.36%, and the biological activity was strong. The other elements are mainly in the stable residue state. The results of the geoaccumulation index method showed that Cd was mainly mild pollution level. The other elements are mainly clean and pollution-free levels. The evaluation results of the risk assessment coding method showed that the risk of Cd contamination was the highest, and the risk of contamination of other elements was relatively low. On the whole, there is a certain degree of potential pollution risk in the soil Cd in the study area. Attention needs to be paid to the prevention and control of Cd.