Abstract: In order to clearly understand the heavy metal pollution and potential ecological risk of farmland soil around the ancient copper mine site in Daye City,and provide scientific basis for heavy metal remediation technology in farmland soil, in this study,the single factor pollution index method,Nemerow comprehensive pollution index method and Hakanson potential ecological risk index method were used to evaluate the heavy metal pollution status and potential ecological risk of farmland in this area,and the spatial distribution of heavy metal pollution and potential ecological risk was drawn by ArcGIS. The results showed that the average value of heavy metals in the region was higher than the soil background value of Daye City,and the problem of excessive soil heavy metals was obvious. Among the 60 samples,the heavy pollution rates of Cu and Cd were as high as 35% and 32% respectively. Especially,the potential ecological risk caused by Cd was very serious,and more than 35% of the soil samples were in high potential ecological risk and above. The comprehensive evaluation results showed that 38% of the sample soil was in severe pollution,and 23% of the sample soil was in high potential ecological risk and above. The spatial distribution characteristics of most heavy metal contents and potential ecological risks were high in the central area of the mining area and gradually decreased in the outward area,indicating that mining dust,mining wastewater and ore transportation in mining activities were the main causes of heavy metal pollution and potential ecological risks. In addition,some villagers used mine soil as farmland soil also caused the transfer of core mining soil to a certain extent.

Key words: ancient copper mine site,farmland soil,heavy metals,pollution investigation,assessment