贵州万山汞矿区某农田土壤重金属污染特征及来源解析

研究采集万山汞矿区典型农田土壤样品,分析测试其Hg、As、Cd、Cr、Pb、Cu、Zn、Ni含量,利用综合污染指数法、地累积指数法和潜在生态危害指数法评估农田土壤的污染状况及生态风险,结合相关分析和主成分分析解析农田土壤中重金属的来源。结果表明,该农田土壤Hg、As、Cd、Cr、Pb、Cu、Zn、Ni的平均含量分别为4.29、117.6、0.43、59.06、48.99、43.77、29.13、18.80 mg kg~(-1)。土壤重金属综合污染指数为7.16,表明该农田土壤重金属重度污染,其中100%的位点Hg、As重度污染,66.7%的位点Pb轻度污染,25%的位点Cd轻度污染。土壤重金属的综合潜在生态危害指数为469.0,生态风险强,Hg对综合潜在生态危害指数的贡献率为78.30%,是该农田土壤生态风险的主要来源。该农田中重金属的来源包括:交通运输源、矿业污染源、农业污染源和自然活动源,主要污染物Hg来源于矿业活动,As来源于交通运输和矿业活动,Cd来源于农业活动,Pb来源于交通运输。

Pollution Characteristics and Sources of Heavy Metals in Farmland Soil in Wanshan Mining Areas,Guizhou Province

In this study,a total of 12 soil samples were collected from a typical farmland field in Wanshan Mining area.Concentrations of Hg,As,Cd,Cr,Pb,Cu,Zn and Ni were determined by atomic fluorescence spectrometry (AFS) and inductively coupled plasma-mass spectrometry (ICP-MS),respectively.Pollution characteristics of heavy metals in the farmland soils were evaluated through comprehensive pollution index,geoaccumulation index (Igeo),potential ecological risk index (RI).Correlation analysis and principal component analysis (PCA) were applied to identify the sources of 8 heavy metals in the farmland soil.The results showed that the average concentrations of Hg,As,Cd,Cr,Pb,Cu,Zn and Ni were 4.29,117.6,0.43,59.06,48.99,43.77,29.13 and 18.80 mg kg-1,respectively.The comprehensive pollution index of heavy metals was 7.16,indicating that the farmland soil was seriously contaminated.All soil samples were seriously polluted by Hg and As,66.7％ were slightly contaminated by Pb and 25％ were slightly polluted by Cd.According to the RI (469.0),the ecological risk of the farmland soils was serious.The contribution of Hg to the RI was 78.30％.Hence Hg was the main component contributing to potential ecological risk.The 8 heavy metals in the farmland soil were mainly from vehicular transport,mining,agricultural production and natural source.The principal pollutant Hg was from mining,As was related to vehicular transport and mining,Cd involved with agricultural production and Pb derived from vehicular transport.