广东鼻咽癌高发区土壤-作物系统重金属迁移特征及健康风险评价

为揭示广东鼻咽癌高发区土壤-作物系统重金属迁移特征及健康风险，选择鼻咽癌高发区四会市农田系统为研究对象，采集了稻谷和油麦菜样品及对应的土壤样品，在分析土壤和农作物样品中As、Cu、Hg、Mn、Ni、Pb和Cd这7种重金属含量及化学形态的基础上，采用统计学分析、污染指数评价法、迁移系数法和健康风险评价法等开展土壤-作物系统重金属的迁移特征及健康风险评价.结果表明，研究区农田土壤基本清洁（P_综=0.43）；土壤中Cd和Mn主要以生物可利用态存在，Hg主要以潜在可利用态存在，As、Cu、Ni和Pb主要存在于残渣态中.研究区油麦菜基本安全（P_综=0.48），稻米污染指数（P_综=7.66）高于油麦菜，主要污染元素为Pb（PI=10.25）.研究区土壤中Cd和Cu更容易被油麦菜吸收富集，Cd、Cu和As更容易被稻米吸收富集，农田土壤重金属污染防治工作应特别关注Cd和Cu污染，对于稻田应同时关注As的污染.研究区成人和儿童食用油麦菜的非致癌风险指数（HI）均小于1，总致癌危害指数（Risk）均值小于1×10^-4，食用当地油麦菜的人体健康风险在可接受范围内.当地成人和儿童食用稻米的平均HI指数大于1，主要非致癌因子为Pb，食用稻米的Risk指数均高于1×10^-4，主要致癌因子为As，研究区人群食用当地稻米具有一定的健康风险，且对成人的威胁大于儿童.稻米中的As可能与当地鼻咽癌高发有关.

Transfer Factor and Health Risk Assessment of Heavy Metals in a Soil-Crop System in a High Incidence Area of Nasopharyngeal Carcinoma, Guangdong

In order to reveal the transfer factor and perform health risk assessments of heavy metals in soil-crop systems in the high incidence area of nasopharyngeal carcinoma (NPC) in Guangdong province of China, the farmland system of Sihui City in the high incidence area of NPC was selected as the research object, and rice, lettuce, and corresponding soil samples were collected. As, Cu, Hg, Mn, Ni, Pb, and Cd in the soil and crop samples were analyzed. Based on the contents and chemical forms of seven heavy metals, the environmental pollution, bioavailability, and transfer factors of heavy metals in the soil-crop system were assessed using statistical analyses, pollution index evaluations, and transfer factor methods, and the health risks of adults and children in the study area were assessed using the health risk assessment model recommended by the U.S. Environmental Protection Agency. The results showed that the farmland soil in the study area was basically clean (P=0.43); Cd and Mn mainly existed in a bioavailable state, Hg mainly existed in a potentially available state, and As Cu, Ni, and Pb mainly existed in a residual state. The lettuce was safe (P=0.48), while the pollution index of rice (P=7.66) was higher than that of lettuce, and the main polluting element was Pb (PI=10.25). The results of soil pollution assessments are not completely consistent with those of crop pollution assessments, so they should be combined with the bioavailability of heavy metals and crop effects for correlation analyses. Cd and Cu are more easily absorbed by lettuce, while Cd, Cu, and As are more easily enriched by rice. Special attention should be paid to Cd and Cu pollution in farmland soils, and As pollution should be of focus in paddy fields. In the study area, the non-carcinogenic risk index (HI) value of edible lettuce for adults and children was less than 1 and the average value of the total carcinogenic risk index (Risk) of edible lettuce was less than 1×10^-4. Therefore, the health risk of edible local lettuce was within the acceptable range. The average HI index of rice for adults and children was more than 1 and the main non-carcinogenic factor was Pb; the risk index of rice was more than 1×10^-4, and the main carcinogenic factor was As. Rice consumption in the study area will cause certain health risks, and the threat to adults is greater than that to children. Therefore, As in rice may be related to the high incidence of NPC in Sihui City. It is suggested that the remediation of heavy metals in farmland soils be strengthened or that residents be forbidden to plant or eat local rice and other crops with greater health risks.