三峡库区稻田土壤重金属污染特征及风险评价

以三峡库区(重庆段)12个区县稻田土壤为研究对象，分析了土壤Cd、 Hg、 Pb、 As、 Cr、 Cu、 Zn和Ni含量，采用不同方法评估稻田土壤重金属的污染程度、潜在生态风险和人体健康风险.结果表明，三峡库区稻田土壤8种重金属除Cr外，其它7种重金属平均值均超过三峡库区土壤背景值，且分别有12.32%、 4.35%和2.54%的土壤样品Cd、 Cu和Ni含量超过相关标准的筛选值.8种重金属变异系数为29.08%～56.43%,属于中等及以上强度变异水平，受人为活动影响较大.8种重金属在土壤中均存在污染现象，且有16.30%、 6.52%和2.90%的土壤Cd、 Hg和Pb存在重度污染.同时，土壤Cd和Hg的潜在生态风险较高，整体为中度危害.12个区县中，巫溪县和巫山县污染程度较高，内梅罗综合污染评价为中等污染水平，且综合潜在生态风险也达到中度生态危害水平.健康风险评价结果表明，手口摄入是人体非致癌风险和致癌风险的主要暴露途径.土壤重金属对成人没有非致癌风险(HI<1),但有12.68%的点位对儿童具有非致癌风险(HI>1).土壤重金属对儿童具有致癌风险(TCR=5.75...

Characteristics and Risk Evaluation of Heavy Metal Contamination in Paddy Soils in the Three Gorges Reservoir Area

Soil Cd, Hg, Pb, As, Cr, Cu, Zn, and Ni of 12 districts in the Three Gorges Reservoir area (Chongqing section) were analyzed, and different evaluation methods were used to assess the degree of contamination, potential ecological risk, and human health risk of soil heavy metals in paddy soils. The results showed that the average values of all heavy metals except Cr in paddy soils in the Three Gorges Reservoir area exceeded the background values of soils in the Three Gorges Reservoir area, and the contents of Cd, Cu, and Ni in 12.32%, 4.35%, and 2.54% of the soil samples exceeded the screening values, respectively. The variation coefficients of the eight heavy metals were 29.08%-56.43%, which belonged to the medium and above-intensity variation levels and were influenced by anthropogenic activities. The eight heavy metals were contaminated in the soil, and 16.30%, 6.52%, and 2.90% of the soil Cd, Hg, and Pb were heavily contaminated. At the same time, the potential ecological risk of soil Hg and Cd were in the medium risk level on the whole. Wuxi County and Wushan County had relatively high pollution levels among the 12 districts, the Nemerow pollution index showed a moderate pollution level, and the comprehensive potential ecological risks were also at a moderate ecological hazard level. The results of the health risk evaluation showed that hand-mouth intake was the main exposure path of non-carcinogenic risk and carcinogenic risk. Soil heavy metals presented no non-carcinogenic risk for adults (HI<1), but 12.68% of the sites had non-carcinogenic risk for children (HI>1). As and Cr were the main influencing factors for non-carcinogenic and carcinogenic risks in the study area, and their total contributions to non-carcinogenic and carcinogenic risks were more than 75% and 95%, respectively, which was cause for concern.