加油站的油品渗漏污染调查及健康风险评估

Investigation and assessment:oil leakage contamination at a gas station and the health hazards due to its contamination

为了了解加油站是否存在油品渗漏及其污染情况,选取上海某加油站开展污染调查和研究。调查方法有地质雷达场地初探、PID现场测试与筛选、土壤及地下水样品采集和分析。结果表明,该场地的泵岛和管线区以及废弃储油罐区存在油品渗漏污染,土壤中的污染物以苯系物、多环芳烃以及总石油烃为主,地下水中污染物以甲基叔丁基乙醚和总石油烃为主。此外,基于我国《场地风险评估技术导则(报批稿)》对该场地进行健康风险评估,计算得到场地内苯和乙苯的致癌风险值分别为1.31×10-6和3.59×10-6,均超过人体健康致癌风险可接受水平(10-6)。建议对该场地进行修复,修复优先顺序为乙苯、苯,乙苯和苯的土壤修复限值分别为0.545 mg/kg和0.149 mg/kg。

The present paper aims to report our investigation of the oil leakage and the contamination caused by the leakage by taking a gas station in Shanghai as a case study. In order to figure out what has led to the oil leakage and leakage contamination, we have conducted a contamination investigation on the spot. Before sampling, we had done an initial investigation of the place by using the Ground Penetrating Radar （GPR） as a measuring instrument. The results of the investigation show that the oil＇s hydrocarbon leakage might have occurred in the pump island and pipeline area plus the abandoned oil storage tank area, which were then selected as sampling scope. And, next, we have applied the Photo Ionization Detector （PID） to test and screen the samples on spot and found that there are two points in the sampling scope with the highest PID values which are likely to be the exact point of pollution sources. Following what we have discovered, we have collected the related specifications, soil and groundwater samples and transferred to the laboratory for detailed testing. The testing results reveal that the samples collected from the pump island, the pipeline area and the abandoned oil storage tank area were contaminated to some degree. The main pollutants in the soil prove to be benzene, polycyclic aromatic hydrocarbons （PAHs） and total petroleum hydrocarbon （TPH）. The groundwater was mainly polluted by methyl tert-butyl ether （MTBE） and the total petroleum hydrocarbon （TPH）. It is on the above said investigation that we have conducted a further health risk assessment based on the Technical Guidelines for Risk Assessment of Contaminated Sites in hoping to work out the probability of the potential harms or hazards of such pollutants to human health via different routes of exposure in the soil and shallow groundwater at the contaminated sites, where we have identified benzene, ethyl benzene and naphthalene whose concentration prove to be higher than the screening values. That is to say, the degrees of contamination they result in are to be worried about. The non-carcinogenic hazard quotients of all the concerned contaminants were less than 1, which were at the acceptable risk level. However, the carcinogenic hazardous values of benzene and ethyl benzene turn to be 1.31×10-6 and 3.59×10-6, which are beyond the acceptable risk level （10-6）. Thus, we have suggested that necessary site-work remediation be imposed to the gas station. The remediation priority should be put on ethyl benzene and benzene. The soil remediation limits of ethyl benzene and benzene were found to be 0.545 mg/kg and 0.149 mg/kg.