矿山环境土壤重金属污染潜在生态风险评价模型探讨

Potential Ecological Risk Assessment Model for Heavy Metal Contamination of Agricultural Soils in Mining Areas

Weeks(2005)提出有关土壤污染的生态风险"层叠式(Tiered approach)"评价框架,有关各层次的评价技术是当前环境科学研究的热点。针对矿山环境土壤重金属污染生态风险特征,提出矿山环境土壤重金属污染潜在生态风险评价模型,属于Tire 1层次评价模型。根据矿山环境土壤重金属污染生态风险特征,遵循生态风险评价中的熵原理和证据权重原则,用土壤中重金属的浓度风险表征污染指数(Cfi);以其环境生物可利用性表征毒性响应系数(Tbi),以对污染指数进行修正;以重金属元素的生物毒性响应因子(Tie)为权重,提出矿山环境土壤重金属污染潜在生态风险评价模型:RI=Σmi=1Eir其中,Eir=Tie×Tbi×Cif;RI表示土壤中多种重金属潜在生态风险指数;Eri为元素i的潜在风险因子;Cfi=Ci/Coi,Ci为土壤中重金属浓度实测值,Cio为计算所需要的参照值。Tib=(Rbi/Pbi)1/2,Rbi为样品中某元素生物可利用相态占总含量的百分比,Pib为参照土壤的相应比值。

The aim of this work was to develop a potential ecological risk index to be used as a diagnostic tool for heavy metal contaminated agricultural soils control purposes in mining areas. Taking consideration that the mainroad for ecological risk of heavy metal contamination of soil is soil-vegetation-man. The environmental bioavailability largely determines the environmental impact of metal contaminated soils. Using environmental bioavailability explain the environmental toxicity sensitivity of the heavy metals in the soil-vegetation-man ecological system. The model is following：RI=∑^m i=1 E^ri,with E^ri=C^if×T^ib×T^ie.RI= the requested potential ecological risk index for soil; E^ri = the potential ecological risk factor for the given substance （i） ;C^if=the degree of contamination,C^if=C^i/C^io,C^i=the metal concentration in the soil,C^io = the metal concentration for samples from referring area;T^ic= the element toxic-response factor for the given substance;Zn=1,Pb=4, Cd=15, Cu=2, Cr=11, Ni=3.T^ib=（R^ib/P^ib）^1/2;T^ib= the environment bioavailbability ratio factor,T^ib=（R^ib/P^ib）^1/2,R^ib=[ water soluble fraction ＋ exchangeable fraction/total concentration of the metal in soil ] （ 100% ] for the samples of contaminated soil, P^ib =[ water soluble fraction ＋ exchangeable fraction/total concentration of the metal in soil] × 100% ] for samples from referring area.