不同方式处置的疏浚沉积物重金属生态风险评价对比

以山东沂河沉积物处置示范工程为例，分别对经土工管袋填埋和减量化隔离处置3年后的沉积物生态风险进行跟踪评价，以探究不同处置方式对沉积物重金属安全性的影响。对2种处置方式下沉积物中Cr、As、Zn、Cu、Cd、Pb和Hg的总量及赋存形态进行分析，并采用浸出毒性法、风险评价编码法（RAC）和潜在生态风险指数法（PERI）进行生态风险和环境安全性评估。结果表明:2种沉积物处置场地内沉积物As、Cd和Hg总量超过GB 15618—2018《土壤环境质量 农用地土壤 污染风险管控标准（试行）》的风险筛选值；2种场地内沉积物中Zn和Hg的形态分布存在较大差异；浸出毒性实验表明，土工管袋填埋处置Cr、As和Cu浸出毒性高于减量化隔离处置，而Zn则相反。综合浸出毒性法、RAC和PERI的结果，经土工管袋填埋处置后沉积物重金属的生态风险相对较高。在选择何种方式对疏浚沉积物进行异位处理时，应综合权衡各个方面因素，以确保环境效益和经济效益的最大化。

COMPARISON OF ECOLOGICAL RISK ASSESSMENT OF HEAVY METALS IN DREDGED SEDIMENT TREATED BY DIFFERENT METHODS

Taking the sediment disposal demonstration project of Yihe River in Shandong province as an example, the ecological risks of sediment after three years of geo-textile tube landfill and reduction disposal were tracked to explore the effects of different disposal methods on the safety of heavy metals in sediments. The total concentrations and geochemical fractions of Cr, As, Zn, Cu, Cd, Pb, and Hg in sediments by the two disposal methods were analyzed. Meanwhile, their ecological risks and environmental safety were assessed by leaching toxicity method, risk assessment code (RAC), and potential ecological risk index method (PERI). The obtained results showed total concentrations of As, Cd, and Hg in sediments from two different disposal sites exceeded the risk screening value of the Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land (GB 15618-2018). The geochemical fraction distribution of Zn and Hg in the sediments of the two sites was quite different, and the difference was mainly related to the differences of two disposal methods. The leaching toxicity test showed that the leaching toxicity of Cr, As, and Cu in geo-textile tube landfill was higher than that in reduction disposal, while the leaching toxity of Zn was on the contrary. According to the results of leaching toxicity, RAC, and PERI, the ecological risk of geo-textile tube landfill was relatively higher. In order to maximize the environmental and economic benefits, it was necessary to weigh all aspects of factors when choosing which way to treat the dredged sediments.