Soil Heavy Metal Pollution and Health Risk Assessment of Abandoned Land in Coal Mining Areas in Xingren County

摘要

Total contents of heavy metals( Pb,Cr,Cd,Hg,As,Cu,Zn,and Ni) in 68 soil samples were determined to evaluate the contamination level of soil from five coal mine areas in Xingren County,Guizhou province.The pollution levels of heavy metals were characterized by anthropogenic influence multiple,and the pollution of heavy metal in soil was evaluated using geo-accumulation index.Based on the health risk models recommended by the U.S.Environmental Protection Agency( US EPA),the health risks of heavy metals in the soils were assessed.The results showed that the abandoned land in the five coal mining areas were contaminated by heavy metals,and the order of pollution levels of eight heavy metals was As>Pb>Cu>Hg>Ni>Cr>Cd>Zn.The soils suffered moderate-heavy pollution from As and Pb,and the contents of As and Pb in the soils were 13.16 and 4.76 times higher than the background values of Guizhou Province,followed by Cu,Hg and Ni,while soil pollution from Cr,Cd and Zn was mild.The order of non-carcinogenic risks of the heavy metals in the soils was As>Pb>Cr>Ni>Cu>Hg>Cd>Zn,and the non-carcinogenic risk value of As was higher than that its threshold value 1,which indicated that As had a high potential health risk to adults and children.The order of carcinogen risks of the four heavy metals was As>Cd>Cr>Ni,and the carcinogenic risk value of As was higher than its threshold value,indicating that As had a high carcinogenic risk to adults and children.The carcinogenic risk values of other three heavy metals(Cd,Cr and Ni)were lower than the threshold value,so they had no carcinogenic risk to human health.Moreover,children were more sensitively affected by heavy metals from the abandoned land.Therefore,the health of children in such areas should be paid more attention to.The HI value of the eight heavy metals to children was seven times higher than that to adults.The contribution rate of HQ_(Asto) HI was about 88%,and the contribution rate of CR_(As) to TCR was about 98%,so As was the most crucial factor influencing non-carcinogenic and carcinogenic risk in the abandoned soils.