三峡水库消落带不同水位高程土壤汞风险评价

Risk Assessment of Mercury in Soil at Different Water-level Altitudes in Drawdown Areas of Three Gorges Reservior

以三峡水库消落带为研究区域,采集重庆涪陵、万州等9个区县不同水位高程共81个样点的土壤,分析其总汞含量与分布特征,并采用美国环保署推荐的健康风险评价模型,对不同水位高程土壤中汞进行健康风险评价。结果表明:三峡库区消落带土壤汞含量为(40.5±5.0)^(113.7±46.3)μg/kg,平均值为(68.5±22.7)μg/kg。不同水位高程土壤汞的平均含量为155~165m高程(79.4±18.4)μg/kg>145~155m高程(66.9±14.6)μg/kg>165~175m高程(59.2±13.3)μg/kg。单因子污染指数评价结果显示,不同水位高程土壤汞均未超过土壤环境质量标准的一级标准,但有80.2%的采样点土壤汞含量超过三峡库区土壤背景值。健康风险评价结果表明,儿童比成人更易受到土壤汞含量的影响。成人和儿童在不同水位高程所受的土壤汞年风险系数均小于美国环保署推荐的最大可接受风险水平,不会对人体健康产生非致癌风险。

The characterization and the health risk assessment of Hg in soils at different water-level altitudes in the drawdown areas of Three Gorges Reservior were studied. Samples were collected from eighty one sampling points covering nine districts or counties in Chongqing. Hg concentrations were measured to investigate their distribution and evaluate their risk to human health. The US EPA Health Risk Assessment Model was employed to evaluate the non-carcinogenic risks of Hg in soils to child and adult, respectively. The results showed that the Hg concentration ranged from （40.5±5.0） μg/kg to （113.7±46.3） μg/kg, with an average of （68.5±22.7） μg/kg. The order for average contents of Hg in soils of different water- level altitudes was 155±165 m（79.4±18.4） μg/kg ）145〉155 m（66.9±14.6） μg/kg ）165±175 m（59.2 ± 13.3） μg/kg. According to the single factor pollution index, Hg concentrations in soils at different water-level altitudes in the Three Gorges Reservior were lower than the primary standard of Environmental Quality Standard for soils, however 80.2% of Hg contents which were higher than the soil background value in the Three Gorges Reservoir Region. Health risk assessment showed children were more easily affected by Hg in soils. The non-cancerous average risk index for children and adult health were less than the standard value of US EPA, which implied a non-carcinogenic risk to the health of the residents.