大邑铅锌矿区土壤和蔬菜重金属污染现状及评价

Status Quo and Evaluation of Heavy Metal Pollution of Vegetables and Soils in Dayi Lead-Zinc Mining Area,China

研究了四川省大邑县铅锌矿区附近土壤和蔬菜中Pb、Zn、Cr和Cd含量,采用单因子污染指数法和综合污染指数法评价铅锌矿区附近土壤重金属污染状况。结果表明,铅锌矿矿口以及选矿厂周边土壤重金属富集因子均超过1,距选矿厂距离≤20 m的3个土壤样点Pb、Zn和Cd的单因子污染指数和综合污染指数较高,土壤污染程度为重污染,选矿厂周边土壤重金属污染在水平层次的空间分布上表现出异质性。选矿厂周边蔬菜地下部分重金属含量普遍高于地上部分,不同重金属在蔬菜可食用部分的转移因子总体由大到小依次为Cd、Zn、Pb和Cr。选矿厂周边蔬菜地土壤与蔬菜中Pb、Zn、Cd和Cr含量之间无显著相关性,但土壤中Pb、Zn和Cd含量3者之间在α=0.01水平上显著相关。

Samples of the soils in the vicinity of the Dayi Pb-Zn mining area, Sichuan and the vegetable growing thereon were collected for analysis of contents of Pb, Zn, Cr and Cd, and further for evaluation of heavy metals pollution of the soil using the single factor pollution index and comprehensive pollution index methods. Results show that enrichment factor of the heavy metals exceeded 1 in both the soil near（≤20 m） the pithead and the soil near the ore dressing plant. Soils at Sampling sites X1, X2, and X3 near the gate of the ore dressing plant were all quite high in single factor pollution index of Pb,Zn,and Cd as well as in comprehensive pollution index, which indicates that the soil is severely polluted with heavy metals. Heavy metal pollution in the soil around the ore dressing plant varied spatially at a horizontal level. The vegetables growing in the vicinity of the ore dressing plant had morehihger heavy metal contents in the under ground part than in the above ground part. Transfer factors of the different heavy metals in edible parts of the vegetables were varied and showing an order of Cd 〉 Zn 〉 Pb 〉 Cr. No significant relationship was found between the soil and the vegetable in terms of Pb, Zn, Cd and Cr concent, but the correlations between Pb, Zn and Cd were significant in the soil（α ＝0.01）.