小秦岭某金矿区农田土壤重金属污染评价

Assessment of Heavy Metals Contamination of Farmland Soils in Some Gold Mining Area of Xiao Qinling

小秦岭金矿区是中国第二大产金区,金矿开采、选冶活动会将重金属释放到环境中,对土壤环境造成污染。本研究系统采集了133件农田土壤样及邻区非矿业活动区的土壤对照样,结果表明,研究区农田土壤中Hg、Pb、Cd污染明显。以邻区表层土壤重金属含量作为对比评价矿区土壤污染的对比值,除Cr外,Hg、Pb、Cd、Cu、Zn、As累积超标率分别为96.90%、100%、60.10%、12.03%、78.90%、69.17%。Hg、Pb、Cu、Zn、Cd超过国家土壤环境质量二级标准的样本超标率分别为43.16%、12.8%、7.52%、3.01%、2.25%。土壤重金属综合污染指数表明,36.08%的土壤样本受到了轻度以上污染。Hg是农田土壤中最主要的重金属污染物,超标倍数均值为4.71,受Hg污染的农田面积为136.3km2,占到研究区面积的51.76%。土壤污染极其严重,矿区环境污染治理迫在眉睫。

Xiaoqinling gold mining area is the second largest gold mining regions in China. The heavy metals had been released into surrounding by exploitation and selection of gold mining and, the environment has been polluted. On the base of investigation of pollution source, we collected 133 soil samples on the farmland in researching area, and also collected soil samples in the neighbor area without mining pollution as the control. The result shows that contamination of the soil by mining activities was very serious by Cd, Hg and Pb. To compare with the heavy metal concentration of the surface layer soil in neighbor area, we discovered that Hg, Pb, Cd, Cu, Zn and As presented evident accumulation except Cr ,and the excess rate over standard was 96.90, 100, 60.10, 12.03, 78.90 and 69.17% respectively. The integrative pollution index of heavy metals in soil indicates that 36.08% soil samples has been hyper-lightly polluted .Hg is the most serious. The polluted area by Hg is about 136.3km^2, being 51.76% farmland of whole investigative areas.