Pollution Characteristics and Ecological Risk of Heavy Metals in the Downstream of a Copper-Rich Tailings Pond in Tongling
Metal mine tailings ponds are potential sources of environmental pollution;if improperly disposed of,they will pollute the surrounding environment and pose a serious threat to human health.This study takes five heavy metals(Cu,Zn,Pb,Cd and Cr)in the copper-rich tailings pond in Tongling and its surrounding water and soil as the research objects,and uses BCR step-by-step extrac-tion,leaching tests and two risk assessment models to systematically reveal the pollution characteristics and ecological risks of the five heavy metals.The results showed that the contents of Cd,Cu and Zn in the tailing pond were 13.48,13.18 and 7.03 times higher than the background values of Tongling soil,respectively.The average contents of Cu,Cd and Pb in the soil downstream of the pond exceeded the background values of Tongling soil.The average contents of Cu,Zn,Cd and Pb in river sediments were higher than the background values of sediments in the lower reaches Yangtze River,respectively.The BCR extraction results showed that Cr in the tail-ings pond and downstream soil and river was mainly in the residue state(F4).The acid soluble/exchangeable state(F1)of Cd ac-counted for the highest percentage.In addition,the leaching results of heavy metals showed that the five heavy metals in the tailings were leached at higher rates under strong acid and alkaline conditions.The results calculated by single factor index(Pi)showed that Cu(13.18),Zn(7.03)and Cd(13.4)were at heavy contamination levels.Also,Cd,Cu and Pb in the soil and sediment down-stream of the pond were heavily contaminated.Copper,Zn and Cd in the river water far from the tailings pond were at light contamina-tion levels.The results from risk assessment code(RAC)indicated that Cd in the tailings pond and surrounding soils and sediments ex had the highest potential ecological risk.
NETL
NSTL
万方数据
