重金属在铅锌冶炼厂内的空间分布及污染评价

Contamination assessment and spatial distribution of heavy metals in lead-zinc smelting plant

对陕西省西部某铅锌冶炼厂界内土壤及杂草中的重金属含量进行测定,分析土壤及杂草中重金属含量。结果表明:土壤已受到Pb,Zn,Cu,As,Cd和Hg的严重污染,冶炼厂区内杂草的Pb,Zn,Cu,Cr,As,Cd和Hg含量都远远超过蔬菜中重金属食品卫生标准限值,土壤中重金属在空间分布上存在局部富集现象。从水平分布上看,土壤中重金属主要集中在铅锌冶炼企业的核心生产岗位,其最大富集系数高达111.8;从垂直分布上看,方差分析表明,土层深度对土壤重金属含量影响显著,土壤中重金属在土壤表层、中层、深层均可实现累积,主要富集在土壤表层,其厂区内重金属Pb,Zn,Cd和Hg富集系数平均值已高达98.8,61.3,334.1,55.9。利用重金属富集系数研究厂区内杂草对重金属富集程度,说明土壤-植物系统中重金属迁移的规律。最后,采用Hakanson潜在生态危害指数法,评价了土壤铅的生态风险,评价结果表明,在土壤中重金属大量富集的区域,存在强生态风险,这意味着铅锌冶炼企业厂界内土壤中重金属因局部富集而引起的生态风险必须引起高度的关注。

In this study, heavy metals in the soil and weeds which were obtained as samples on a lead and zinc smelter in western Shaanxi Province were determined and analyzed. The results showed that： the soil has already being polluted seriously by Pb, Zn, Cu, As, Cd and Hg. The contents of above-mentioned heavy met- als which are determined from the weeds of the smelter are far more than food hygiene standard limits of the vegetables; the spatial distribution of heavy metals in the soil shows a kind of phenomenon which is enriched partly. Judging from the horizontal distribution, the heavy metals in the soil are mainly concentrated in the lead-zinc smelting plant＇s core production units. The maximum enrichment factor is up to 111.8 ; from the ver- tical distribution point of view, analysis of variance showed that soil depth affected significantly on soil heavy metals. The heavy metals can accumulate in surface layer, middle layer and deep layer of the soil, which are mainly concentrated in the soil surface. In this factory, the average value of enrichment factor about Pb, Zn, Cd, and Hg are as high as 98.8,61.3,33d. 1,55.9. Additionally, the regular pattern of soil-plant system mi- gration is indicated by studying the heavy metal enrichment of weeds in factory region via the enrichment factor method. Finally, the ecological risk of soil lead was evaluated by using Hakanson potential ecological risk in- dex method, the evaluation results shows that there is a strong ecological risk in the region which a large num- ber of heavy metals are enriched in soil, it means that the ecological risk caused by local enrichment of heavy metals which is existed in the interior of the lead and zinc smelter must be taken serious account.