东洞庭湖沉积物重金属污染及生态-健康风险

沉积物是水体中重金属污染的源和汇，为探究东洞庭湖最新的沉积物重金属污染状况、生态风险及健康风险，采集东洞庭湖湿地保护核心区、城陵矶港口区、航道区、城镇居民区、旅游区、农场和芦苇场7个功能区63个表层沉积物样品，测定As等10种重金属的含量，并采用地累积指数法、富集因子法和Hakanson潜在生态风险指数法以及美国EPA健康风险评价法对其污染程度和人体暴露风险进行评估。结果表明，As、Cd、Cr、Co、Cu、Mn、Ni、Pb、Sr和Zn的平均含量分别为14.53、6.49、70.39、19.66、27.91、933.26、42.36、41.48、93.83 mg·kg^-1和164.91 mg·kg^-1。地累积指数评价结果显示，Cd处于偏重度污染程度等级（I_geo=3.39），其余均为轻度污染（0<I_geo<1）；富集因子法评价结果表明，Cd为中度富集（EF=2.78），其余重金属均为轻度富集（EF<1）；潜在生态风险指数法评价结果显示，Cd的风险程度为极高风险（Eⁱ_r=662.13），其余重金属均为低风险（Eⁱ_r<10）；从不同功能区来看，重金属潜在生态风险由高到低排序为：湿地保护核心区>芦苇场>航道区>旅游区>农场>城镇居民区>城陵矶港口区，表明重金属更易于在植物根际土壤中沉积与滞留。健康风险评价结果表明，表层沉积物对成人的非致癌指数均在可接受范围内（HI<1），而As、Cd、Pb对儿童造成的非致癌风险在沿东洞庭湖东岸的航道区超过了可接受水平。综合来看，与已报道的国内其他浅水湖泊相比，东洞庭湖表层沉积物的重金属污染处于较高污染水平。

Sediment heavy metal pollution and its ecological and health risk assessment in the East Dongting Lake, China

The concentrations of 10 heavy metals were determined in 65 surface sediment samples collected at East Dongting Lake, including seven functional wetland protection areas, Chenglingji port, a waterway area, urban residential area, tourist area, farmland, and a reed field. The pollution status and human exposure risk of heavy metals in different functional areas were evaluated using the geoaccumulation index, enrichment factor, potential ecological risk index, and health risk assessment method in accordance with the characteristics of human exposure parameters. The results showed that the average concentrations of As, Cd, Cr, Co, Cu, Mn, Ni, Pb, Sr, and Zn were 14.53, 6.49, 70.39, 19.66, 27.91, 933.26, 42.36, 41.48, 93.83 mg·kg^-1, and 164.91 mg·kg^-1, respectively. The overall pollution status of heavy metals was relatively severe compared to that in other shallow lakes in China. The evaluation results of the geoaccumulation index showed that the pollution level of Cd was severe(I_geo=3.39); however, all other metal levels were relatively mild. The evaluation of the enrichment factor index demonstrated that, except for the remarkable enrichment of Cd(EF=2.78), the other nine metals were all at mild enrichment levels(EF<1). The potential ecological risk index assessment suggested that the potential ecological risk of Cd was extremely high(Eⁱ_r=662.13), whereas the other nine metals were at a mild level(Eⁱ_r <10). Ecological risk assessment results from different functional areas ranked in the descending order were as follows:wetland protection area > reed field > waterway area > tourist area > farmland > urban residential area > Chenglingji port area. Human health risk assessment results showed that the non-carcinogenic indices for adults were all within the acceptable range(HI<1). However, the non-carcinogenic risks of As, Cd, and Pb to children exceeded the acceptable level in the waterway area along East Dongting Lake. In summary, the heavy metal pollution in the surface sediments of East Dongting Lake is severe.