矿业活动影响区稻田土壤和稻米中重金属含量及健康风险

探讨了南丹矿业活动对周边稻田土壤和稻米中重金属含量的影响,并评估当地居民通过稻米摄入重金属的健康风险.对位于矿业影响区车河镇、大厂镇、长老乡以及对照区六寨镇的4个典型村庄居民进行为期3 d的入户膳食调查,同时采集稻田土壤样品56个和稻米样品90个,用原子荧光形态分析仪(AFS-9700)、石墨炉原子吸收分光光谱仪(AA 700)和电感耦合等离子发射光谱仪(Optima 7000)测定其重金属含量,并通过污染指数法和重金属摄入量评价居民膳食暴露的健康风险.结果表明,矿业活动影响区稻田土壤As、Sb、Cd、Pb、Cu和Zn的几何平均值分别为58.1、16.4、1.22、49.1、52.1和271mg·kg~(-1),除Pb外,其他元素均显著高于对照区稻田土壤相应重金属含量(P0.05),Nemero综合指数(PN)为3.14,属于重度污染水平.六寨、车河、大厂和长老地区稻米样品中Cd含量均超出标准限值,超出倍数分别为2.23、4.40、3.81和3.52倍,As也存在严重超标现象;居民Cd的摄入量高于FAO/WHO提出的重金属人均日摄入可允许限量标准(PTDI).说明南丹矿业活动对周边稻田土壤和稻米及人群健康的危害明显大于对照区人群,食用当地稻米对人体存在较大的健康风险.

Concentrations and Health Risk Assessments of Heavy Metal Contents in Soil and Rice of Mine Contaminated Areas

Nandan County is famous for its mining of nonferrous metals. In order to investigate the effects of mining activities on the soil and rice and to evaluate the health risk of the exposure of typical local inhabitants to heavy metals via consumption of rice, a consecutive 3-day household diet survey in four villages in Nandan was conducted. Liuzhai is an uncontaminated contrast area, and Chehe, Dachang, and Zhanglao are contaminated areas. The data for rice consumption rates were obtained. At the same time, 56 soil samples from rice fields and 90 rice samples were collected for the analysis of As, Sb, Cd, Pb, Cu, and Zn. In addition, the potential health risk of the exposure of local people to heavy metals via consumption of the rice was assessed using the pollution index method and the data from the intake of heavy metals. Results showed that the mean contents of As, Sb, Cd, Pb, Cu, and Zn were 58.1, 16.4, 1.22, 49.1, 52.1, and 271 mg·kg^-1 in the soil samples from contaminated areas, with higher pollution risks than from the control area for soil heavy metal contents. The Nemero comprehensive contamination index (P_N) was 3.14, a heavy pollution grade. Cd contents in rice in Liuzhai, Chehe, Dachang, and Zhanglao were 2.23 times, 4.40 times, 3.81 times, and 3.52 times higher than those of GB 2762-2017.The content in rice exceeds the standard in all four areas. The daily intake (DI) of Cd in the four areas was higher than the provisional tolerable daily intake (PTDI) established by FAO/WHO. This indicates that Cd and As are the major heavy metal elements posing health risks to the health of the inhabitants in the mining areas and that the inhabitants in the mining areas are facing severe risks of exposure to heavy metals.