典型有色金属矿业城市零星菜地蔬菜重金属污染及健康风险评估

Contamination and Health Risk for Heavy Metals via Consumption of Vegetables Grown in Fragmentary Vegetable Plots from a Typical Nonferrous Metals Mine City

在铜陵惠溪河流域及铜陵有色金属冶炼厂周边零星菜地,选择35个点位采集8种蔬菜(226颗)及相应的土样,在对重金属As、Ni、Cu、Pb、Cd和Zn含量分析测试的基础上,开展蔬菜重金属污染评价、富集能力分析及健康风险评估.结果表明:①研究区土壤重金属污染严重,As、Ni、Cu、Pb、Cd和Zn平均含量分别达96.96、56.64、1 247.82、313.59、6.743和600.96 mg·kg-1,均显著高于铜陵市土壤元素背景值;②8种蔬菜重金属综合污染指数平均值,均超过重污染等级阈值3.0,达重污染水平;③蔬菜对Zn富集能力最强,其次是Ni和Cu,对As、Pb、Cd等的富集系数相对较小,蔬菜中6种重金属污染程度排序为Ni>Zn>Cu>Pb>As>Cd;④蔬菜重金属As、Ni、Cu、Pb、Cd和Zn相应的THQ值分别为17.92、1.01、10.14、0.73、0.21和1.93,其中As和Cu的非致癌风险贡献率最大,分别为56.10%和31.75%,是研究区蔬菜重金属危害的最重要元素;⑤成人经蔬菜途径进入人体的As、Ni、Cu、Pb、Cd和Zn,分别为324.38、1 211.25、24 326.25、176.25、12.75和34 800μg·d-1;⑥蔬菜中As的目标致癌风险TR达8.06×10-3,远超过美国环保署(US EPA)推荐的可接受风险10-6～10-4和国际辐射防护委员会(ICRP)推荐的最大可接受风险值5.0×10-5,表明长期食用这些蔬菜可能带来较高的健康风险.

A systematic survey of As, Ni, Cu, Pb, Cd and Zn concentrations in eight kinds of vegetables （involving 226 samples） and their corresponding soils at 35 sampling sites in the fragmentary vegetable plots of a typical nonferrous metals mine city, Tongling, was carried out for assessing heavy metal pollution, bio-accumulation ability and potential health risk to local inhabitants due to exposure via consumption of vegetables. The results showed that： （1） The soils of the studied vegetable plots were seriously contaminated by heavy metals and the mean concentrations of As, Ni, Cu, Pb, Cd and Zn reached 96. 96, 56.64, 1 247.82, 313.59, 6. 743 and 600.96 mgokg , respectively, all significantly exceeding the soil background value of Tongling city; （2） The mean values of integrated pollution index corresponding to eight varieties of vegetables were all higher than the threshold value （ i. e. 3. 0） of heavy pollution ; （3） In general, the largest bioaccumulation factor of heavy metals in vegetables was As, followed by Ni and Cu, and the order of pollution degree of heavy metals in vegetables was Ni 〉 Zn 〉 Cu 〉 Pb 〉 As 〉 Cd ; （4） The target hazard quotients （THQs） of As, Ni, Cu, Pb, Cd and Zn were 17.92, 1.01, 10.14, 0. 73, 0.21 and 1.93, respectively. Arsenic and copper were the major risk contributors for inhabitants since the THQs of them respectively mounted to 56. 10% and 31.75% of the total THQ value according to the average vegetable consumption; （5） The estimated daily intake （DI） of As, Ni, Cu, Pb, Cd and Zn from vegetables was 324. 38, 1 211.25, 24 326. 25, 176.25, 12.75 and 34 800μg·d^- 1 for adult residents, respectively; and （6）The target cancer risk （TR） of vegetables polluted by As to individual human health was 8.06 ×10 -3, significantly higher than the management standard （ i. e. 10 -6-10 -4 ） of United States Environmental Protection Agency （US EPA） and the standard （ i. e. 5.0 × 10-5 ） of International Commission on Radiological Protection （ICRP） , indicating that it was quite unsafe for the general population to consume vegetables from the studied fragmentary plots.