Speciation Analysis and Risk Assessment of Heavy Metals in the Soil of a Lead-Zinc Mining Area

This is a paper in the field of mining environmental engineering. Heavy metal pollution in soil has a long-time impact, with high biological toxicity and serious threat on human health. In order to study the present situation of soil heavy metal pollution in a lead-zinc mining area and assess its risk, a lead-zinc mining area was taken in Jiangxi as the study object, and the speciation contents of heavy metal elements (Cu, Pb, Zn, Cd) in the soil samples of a lead-zinc mining area were analyzed by themodified BCR successive extraction, and the correlation of heavy metal elements was studied. The environmental risk of heavy metal elements was evaluated by the method of risk assessment coding (RAC) and ratio of secondary phase and primary phase(RSP). The results showed that: The Cu, Zn, Cd and Pb elements in the soil of the lead-zinc mining area exceeded the standard, and the Cu, Zn and Pb elements were mainly in residual state. Compared with Cu, Zn and Pb, Cd element had a higher content of acid extractable state, and its bioavailability was strong, so the pollution of Cd element was serious. The residual-state contents of Cu, Zn and Pb in the soil samples of the mining area were significantly positively correlated with the total contents, while the residual-state contents of Cd were not significantly correlated with the total contents. The contents of Cu, Zn, Cd and Pb in the acid extractable state were significantly positively correlated, but the contents of acid extractable state was negatively correlated with pH value. The conclusion of risk assessment coding method and ratio method of secondary phase and primary phase was relatively consistent, which showed that the pollution of Cd element was serious with a high environmental risk, while that of Cu, Pb, Zn elements was relatively light with a low environmental risk. This paper is expected to provide reference for the prevention and control of soil heavy metal pollution in the lead-zinc mining area.