Heavy metal pollution and ecological risk assessment of Datun basin in the Gejiu tin mining area, Yunnan Province

Heavy metals in the soil body will directly affect the safety of agricultural production, and investigation of the pollution level in different cultivated land types and soil types will provide the basis for the reduction of the above ecological risk. The authors investigated the heavy metal content in different land use and soil types through field work and laboratory analysis. Pollution assessment was conducted using a single factor index and Nemerow pollution index, and ecological risk assessment was also carried out based on potential ecological risk index. The results show that As and Cd are the most important pollution factors among As, Cd, Cu, Cr, Ni, Pb and Zn elements. The contribution of As and Cd to the pollution level is 97%, with the contribution of Cd reaching 68%. The contribution of As and Cd to ecological risk is 87%, with Cd alone contributing 68%. In addition, the pollution level and ecological risk of heavy metals in dry land is greater than those in paddy field, and the pollution level and ecological risk of heavy metals are also greater in red soil than in cerra rossa. Spatially, the pollution level of heavy metals in Datun basin of the Gejiu mining area generally shows a decreasing trend from southwest to northeast.