不同环境下土壤作物系统中重金属元素迁移分配特点

Accumulation and partitioning of some heavy metals in soil-crop system under different environmental impacts

不同环境中重金属的积累特点及其向食物的迁移可能导致对人类健康的不同影响。文章对苏南某市典型乡镇工业环境中的农田表层土壤重金属污染积累进行了分析,并参照国家土壤环境质量二级标准进行重金属污染的单因子和综合因子评价。结果表明,工业环境中农田土壤表层重金属元素的富集系数和重金属DTPA有效态含量显著高于非工业环境,说明工业化发展是土壤重金属积累的主要因素,同时土壤的基本理化性质对土壤重金属的富集有一定的影响。不同种类农产品对重金属的富集能力表现为叶菜类>籽实类>根菜类>水稻籽粒,重金属元素中Cd、Zn、Cu较易在农产品中积累。应该注意工业发展对农田土壤的重金属污染以及对人类食物安全的可能影响。

The accumulation and transfer of heavy metals through soil-plant-food-human under different environment may cause difference in health risks for people. Sampling of topsoil and crops grown on them from typical farms and determination of their heavy metal contents were conducted in a municipality from southern Jiangsu, China. The results indicated that enrichment index and DTPA extractable pool of heavy metals in topsoil under industrial environment significantly increased compared to under non-industrial environment while concentration of heavy metal was basically below the guideline limit of the State Soil Environmental Quality Category II. It seems that contents of the heavy metals in topsoil were governed primarily by the pollution input under industry development. On the other hand, soil physical and chemical properties could play a considerable role in their transfer. The heavy metals accumulation in crops was as follows： leafy vegetables〉grain cereals〉 root and tuber crops. Among the studied heavy metals, accumulation ofCd, Cu and Zn were more apparent than of the others in crop organs. Attention should be paid to the soil pollution and the potential impacts on human food security of heavy metals while the industry is developing in this area.