西南某铅锌矿区农田土壤重金属空间主成分分析及生态风险评价

以西南某铅锌矿区周边农田土壤作为研究对象,采集土壤表层(0~20 cm)149个土壤样品,分析测定了As、Cd、Cr、Cu、Hg、Ni、Pb、Zn共8种重金属含量.采用多元统计分析,揭示了研究区农田土壤重金属污染的主要来源及各元素之间的相关性;并应用Hakanson潜在生态风险指数法,对农田土壤生态风险进行评价.结果表明,研究区农田土壤重金属Cd、Pb、Zn含量相对处于极高水平,均值分别为15.56、419.4、933.4 mg·kg~(-1),污染十分严重;Hg和As的均值分别为0.13 mg·kg~(-1)和37.3 mg·kg~(-1),属于中度污染;Cu、Ni、Cr的均值分别为26.1、14.3、33.4 mg·kg~(-1),未超过云南省土壤环境背景值;多元统计分析结果显示Cd、Pb、Zn、Hg、As这5种元素来源相似,主要来源于矿山开采和工业活动;Cu、Ni、Cr这3种元素来源相似,主要是自然来源;研究区综合潜在生态风险指数RI的均值为2 294.8,整体上处于极高生态风险水平.矿区开采和工业活动对农田土壤造成了严重的重金属污染.

Principal Component Analysis and Ecological Risk Assessment of Heavy Metals in Farmland Soils around a Pb-Zn Mine in Southwestern China

The farmland soil around a Pb-Zn mine in southwestern China was studied. One hundred forty-nine surface soil samples were taken from 0-20 cm depth, and the contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were tested. The correlations among these heavy metals were studied with multivariate analysis, and the potential sources of the metals were identified. The environmental risk of the metals was evaluated with the Potential Ecological Risk Index method. The results showed that the amounts of Cd, Pb, and Zn were at relatively high level, with average concentrations of 15.56, 419.4, and 933.4mg·kg^-1 respectively, indicating the soil was heavily polluted. The average concentrations of Hg and As were 0.13 and 37.3mg·kg^-1, suggesting moderate soil pollution. The average concentrations of Cu, Ni, and Cr were lower than Yunnan soil background values. The multivariate analysis suggested that the sources of Cd, Pb, Zn, Hg, and As were similar and came mainly from smelting activities in the mining area. The sources of Cu, Ni, and Cr were similar and can be attributed to natural sources. The comprehensive potential ecological risk index was 2294.8, which suggested a high potential ecological risk. In general, the farmland soils in the research area were polluted seriously by the mining and industrial activities.