某铅锌矿周边地区大米重金属污染评价及膳食暴露风险评估

Pollution evaluation and dietary exposure risk assessment of heavy metals in rice from a lead-zinc ore mine

采集了广东某铅锌矿周边90个水稻样品,分析籽实大米中重金属Cd、Cr、Pb、As和Zn的含量,采用单项污染指数和内梅罗综合污染指数评价大米的污染情况,并应用美国环境保护署的多介质暴露评价模型(MMSOILS模型)对重金属经大米摄入带来的健康风险进行评估。大米重金属Cd、Cr、Pb、As、Zn的平均含量分别为0.4098、0.4727、0.1746、0.0401和15.8100 mg/kg,仅有Cd和Pb超标,超标率分别为83.33%和31.11%。Cd、Cr、Pb和As的平均单项污染指数分别为2.0490、0.4727、0.8732和0.2006,表明大米受到一定的Cd污染。综合污染指数表明有17.78%的大米样品未受污染,45.56%、24.44%和12.22%的大米样品分别受到轻度污染、中度污染和重度污染。各重金属中仅有Cd和Cr的日摄入剂量超过USEPA的参考标准(RfD),其平均风险商(HQ)分别为2.740和1.0533,表明当地居民有一定的经大米摄入重金属Cd和Cr的风险。

90 rice samples were collected from a Lead-zinc mine located in Guangdong province, the contents of cadmium （ Cd ）, chromium （ Cr ）, lead （ Pb ）, arsenic （ As ） and zinc （ Zn ） in rice were analyzed. The pollution situation was evaluated by single factor pollution index and N. L. Nemerow comprehensive pollution index, and the intake healthy risk of heavy metals from rice ingestion was assessed by a multimedia exposure assessment model （ the MMSOILS model ） promoted by USEPA. The average concentrations of Cd, Cr, Pb, As and Zn in rice were 0.4098, 0.4727, 0.1746, 0.0401, 15.8100 mg/kg, respectively. Only the levels of Cd and Pb exceeded the standard, and the over standard rates were 83.33% and 31.11%, respectively. The average single factor pollution index of Cd, Cr, Pb, As were 2.0490, 0.4727, 0.8732 and 0.2006, respectively, suggesting the rice were polluted by Cd in some extent. Comprehensive pollution index indicated that 17.78% of the rice samples were uncontaminated, 45.56% were slightly polluted, 24.44% were moderate polluted, and 12.22% were heavily polluted. Among the study elements, only the daily intake dose of Cd and Cr exceeded the USEPA reference standard dose （ RfD ） , with hazard quotients （ HQ ） of 2.740 and 1.0533, respectively, indicating the local residents were experiencing certain Cd and Cr exposure risk from rice ingestion.