基于MCDA模型的危险废物填埋场地下水污染风险分级

Risk Ranking for Groundwater Pollution from Hazardous Waste Landfills by MCDA Model

基于对风险全过程控制的思想,利用层次分析法,构建了综合考虑危险废物填埋场自身属性、污染场地水文地质条件以及污染受体等因素的危险废物填埋场地下水污染风险分级指标体系,该体系共包括14项指标;并采用MCDA(multi-criteria decision analysis,多准则决策分析)模型,对我国37个危险废物填埋场(不包括港澳台数据,下同)地下水污染风险进行了分级研究.结果表明:14项风险分级指标之间具有很好的独立性,指标体系能够较为完整、准确地反映危险废物填埋场对地下水的污染风险程度;37个危险废物填埋场地下水污染风险可分为高、中、低3个级别,其中81%处于中、低级风险级别;地下水中特征污染物ρ(Cr)监测值与风险分级分值的距平指数为0.802 9,验证了风险分级结果的可靠性;同时采用MDCA模型对风险分级指标权重的敏感性进行分析,验证了风险分级过程中指标权重赋值的准确性,并降低了指标权重赋值过程中的不确定性,进一步提高了分级结果的可靠性.风险分级结果在一定程度上可为危险废物填埋场地下水污染风险管理提供依据.

A large number of hazardous waste landfills have become major potential pollution sources for groundwater in China. It is very important for guaranteeing groundwater environmental safety that the landfills are effectively supervised. Based on the total process analysis of risk control, an index system of risk ranking for groundwater pollution was established by applying analytic hierarchy process （AHP）. The related hazardous waste landfill attributes, hydrogeological conditions and receptors were considered, including 14 risk ranking indexes. The risk ranking for groundwater pollution of the landfills was studied by using the multi-criteria comprehensive decision analysis model （MCDA）, and the method was applied to 37 hazardous waste landfills in China （data of Hong Kong, Macao and Taiwan not included）. The results showed that in the index system of risk ranking, 14 indicators had good independence, and the index system was more complete and could accurately reflect the risk of groundwater pollution in hazardous waste landfills. The risk levels of groundwater pollution of 37 hazardous waste landfills could be divided into three levels：high, medium and low, of which 81% were in the middle and low risk level; the relative coefficient of the standardized anomalies of the monitoring concentration of Cr and the risk score was 0.8029.Thus, the result of risk ranking was basically consistent with the actual results of on-site monitoring of characteristic contamination. With the application of MCDA model in the analysis of weight sensitivity of risk ranking index to verify the accuracy of the index weight assignment in the risk ranking process, the uncertainty in the process of the index weight assignment was reduced, and the reliability of the risk ranking results was improved. The risk ranking might provide a reference to the risk management for groundwater contamination of hazardous waste landfills.