某加油站地下水基础环境调查及健康风险评估

Basic Environmental Survey and Heath Risk Assessment on Groundwater Pollution from a Petrol Station

本文以某地下水源保护区内一加油站为典型案例。通过对典型加油站场地及周边水工环地质条件的调查,分析该场地浅层地下水水质特征,建立水流数值模型和溶质运移模型对地下水流场及特征污染物运移进行模拟预测,并在此基础上评价特征污染物对下游水源井所在地周边人群的健康风险。调查结果表明:该加油站监测井地下水质量为V类,有机污染的主要特征指标为甲基叔丁基醚(MTBE);对特征污染物MTBE运移模拟预测可知:800d后,距加油站最近的下游水源井一级保护区内潜水中MTBE将可被检出,1500d后,距加油站最近的下游水源井北侧潜水MTBE浓度将会达到0.04mg/L的水平;健康风险评估的结果显示,该加油站对下游水源井造成的MTBE污染所引发的致癌风险会达到1.2E-06,超过了人体健康致癌风险可接受水平1.0E-06,对人体健康存在风险。该场地关注污染物MTBE的地下水风险控制值应在0.033mg/L以下。

In this paper,a petrol station in a groundwater source protection area is taken as a typical study case.Through the investigation of the petrol station site and its surrounding the hydrogeology conditions,it researches the shallow groundwater quality characteristics,establishes the flow numerical model and solute transport model to simulate and forecast the groundwater flow field and pollutant migration characteristics.The health risk evaluation is studied based on the characteristics of pollutants for water wells located downstream of the peripheral populations.The investigation results show that the groundwater quality in the petrol station monitoring well belongs to Grade V;the main characteristics organic pollution index is MTBE.The pollutant MTBE migration is simulated and predicted:after 800 days,in I-leveled water source protection area from the nearest downstream water wells to the petrol station,the pollutant MTBE in phreatic zone will be detected;after 1500 days,on the north side of the nearest downstream water wells,the MTBE concentration will reach 0.04mg/L.Health risk assessment show that the MTBE pollution carcinogenic risk from the petrol station will reach 1.2E-06,beyond the human health risk of cancer acceptable level of 1.0E-06.The MTBE concentration in the groundwater should be controlled less than 0.033mg/L.