宝鸡市农村土壤重金属环境质量及风险评价

Environmental quality and risk grade assessment of the farmland pollution by heavy metals in Baoji

目的研究宝鸡农村土壤重金属污染状况及其对农业生产和人体健康的影响,为宝鸡市环境风险预警和土壤环境质量综合治理提供科学依据。方法对采自3个县区30个土壤样品及不同类型作物中的Cu、Pb、Zn、Cd、Ni和Cr 6种重金属元素进行分析,采用单项污染指数法和地积累指数法对土壤环境质量进行评价,运用Hakanson潜在生态风险指数法对土壤环境进行风险评估。结果研究结果表明,宝鸡市农村土壤除Ni外其它元素含量均低于《土壤环境质量标准》的一级标准,眉县横渠镇农田、菜地和林地作物中6种元素含量均未超过相关国家标准。地积累污染指数表明,部分土壤样品中Cu(20%)、Cd(30%)、Cr(30%)和Ni(23.3%)处于轻度污染。潜在生态风险分析显示土壤中除Cd处于低污染生态风险外,其它重金属元素均无生态风险,相关性计算表明Cu和Cr的污染有一定的同源性。结论宝鸡地区农村土壤重金属污染状况各地有所不同,但是整体而言除Cd外,土壤中其它重金属元素的污染均无生态风险,表明宝鸡市相关地区农村土壤样品总体环境风险较低。

Objective—To estimate the status of heavy metal pollution of the farmland in Baoji City,Shaanxi Province,China,to study the influence of the heavy metal pollution on agriculture production and physical health of people and to provide scientific evidence for the environmental risk warning and comprehensive control of farmland environmental quality.Methods—The contents of Cu,Pb,Zn,Cd,Ni and Cr in 30soil samples of different kinds of soils and different types of crops were determined which were collected from 3different regions of Baoji farmland.Single pollution index and geoaccumulation index were used to evaluate the environmental quality of the soils and crops growing on them,and Hakanson potential ecological risk index was also used to assess the risk grade of the farmland which provides agricultural products for people.Results—The results indicated that the contents of the 5 heavy metals except Ni were lower than the primary standard stipulated in Environmental Quality Standard for Soils,the contents of 6above said elements in farmland,vegetable field and woodland plants in Hengqu Town,Meixian County,Baoji didn＇t exceed the relevant standard.Geoaccumulation index showed that the contents of Cu（20%）,Cd（30%）,Cr（30%）and Ni（23.3%）in the soil samples were slightly polluted,potential ecological risk index showed that there was no ecological risk of the heavy metal pollution except Cd,which was in low ecological pollution risk.The correlation analysis indicated that the pollution caused by Cu and Cr has certain homology.Conclusion—The status of heavy metal pollution of farmland was different in different regions of Baoji City.On the whole,there was no ecological risk of heavy metal pollution except Cd,that is to say,the risk of soil environmental quality was low in the related regions of Baoji City.