典型地下水浅埋区加油站渗漏污染潜势分析及高潜势验证

地下水浅埋区的加油站油品渗漏可直接对土壤和地下水造成污染. 基于层次分析法对上海市黄浦江上游地区、崇明岛以及长兴岛内的119家加油站进行渗漏污染潜势分析,计算各加油站的LPV(leaking potential value,污染潜势值),并用四分法将119个加油站按LPV分为4个评价等级,有9个加油站LPV很高,3.60≤LPV＜4.07；49个加油站LPV较高,3.18≤LPV＜3.60；47个加油站LPV一般,2.73≤LPV＜3.18；14个加油站LPV较低,2.28≤LPV＜2.73. 针对2个LPV较高的已歇业加油站开展现场打井监测与取样分析.结果表明,这2个加油站的潜水层均出现油品渗漏污染,其中加油岛、管线区以及储油罐区是加油站渗漏污染重灾区,土壤中污染物以苯系物、萘以及总石油烃为主,总石油烃检出率达到71.4%~88.9%；地下水中污染物以总石油烃和MTBE(methyl tert-butyl ether,甲基叔丁基醚)为主,总石油烃检出率达到80.0%~100.0%,MTBE检出率达到33.3%~71.4%,对地下水源污染风险较大. 

Leaking Potential Analysis of Gas Stations and Monitoring of High-Potential-Value Stations in a Typical Shallow Water-Table Area

With the social economic development, gas stations are densely distributed in large cities. Most of gas stations are faced with accidental leaks and spills of the stored products (e.g., gasoline and/or diesel fuel). The leaks and spills have potential risk of pollution to the surrounding environment including soil and groundwater. In the last 30years, the investigation and remediation of the pollution from gas stations has become commonplace in many developed countries such as USA, UK and Japan. However, China initiated this work recently. In order to understand and characterize the pollution potential of gas stations in a typical shallow water-table area, 119gas stations located, and on Chongming Island and Changxing Island of Shanghai, in the upstream region of the Huangpu River, were investigated. The Analytic Hierarchy Process (AHP) method was applied to evaluate the overall leaking potential and to determine the leaking potential value of all selected gas stations. Four leaking potential levels for these gas stations were categoried by quartation method:9stations with extremely-high pollution potential (7.6%), 49stations with high pollution potential (41.2%), 47stations with fair pollution potential (39.5%), and 14stations with low pollution potential (11.7%). To verify actual leakage pollution levels, field monitoring was carried out at two out-of-business gas stations on Chongming Island which were determined to have high pollution potential. The field monitoring results indicated that heavy soil and groundwater pollution existed around the underground storage tank pit, piping area, and fuel dispenser area of these two gas stations. The primary soil contaminants included BTEX (benzene, toluene ethylbenzene, and xylene), naphthalene, and total petrol hydrocarbons (TPH), which were found at detection rates of 71.4%-88.9%. The detection rates for methyl tert-butyl ether (MTBE) and TPH in the groundwater were 33.3%-71.4% and 80.0%-100.0%, respectively.