The distribution regularity and accumulation risk of heavy metals in water and soil along the Hengshi River in the Dabaoshan mining area, Guangdong Province

The study of the release，migration and accumulation characteristics of heavy metals by mining activities is of important significance for the prevention and control of environmental pollution of soil and water in the mining area. In this paper, through collection of soil and water samples along the Hengshi River during the survey of Dabaoshan mining pollution and with the soil control values of the study area and the national environment quality as the evaluation standard, the authors studied migration and accumulation characteristics of heavy metals in the Dabaoshan mining area. The result shows that the soil heavy metal elements along the Hengshi River mainly come from mining activities of acid waste water emissions, the concentrations of soil Cd, Pb, Cu and Zn are higher than the local control values, showing obvious accumulation characteristics, with Cd, Cu content exceeding the national standard of soil environmental quality. Heavy metal accumulation in soil and its level of risk degree show decreasing characteristics from the source to the downstream area. Liangqiao Village and Shuilouxia Village are areas of high risk in soil heavy metals; Yanghe River-Lianxin Village area has no risk in spite of some accumulation of heavy metals; Shangba Village is located in medium risk zone of the accumulation of soil heavy metals; Xiaba Village is located in low risk zone. The research results provide an important basis for the prevention and control of heavy metal pollution in mining areas.