重庆市加油站周边浅层地下水中石油烃污染调查与特征分析

为了解加油站运营对周边浅层地下水环境质量的影响,随机选择了12个正常运营20年以上的加油站,在加油站上游和下游共布设了27口地下水监测井,对地下水中石油烃、苯系物、萘、1,2-二氯乙烷和甲基叔丁基醚开展了水质监测。结果表明,石油烃在地下水中的检出率较高,为96.3%,检出浓度为4.2~544.7μg/L,检出组分主要为柴油烃中的C26和C20,检出率分别达到了88.9%和77.8%;汽油烃的有效组分C6~C9未检出,作为汽油添加剂的1,2-二氯乙烷和甲基叔丁基醚在地下水中存在,检出率分别为96.3%和22.2%,检出浓度分别为1.7~30.9μg/L和3.8~30.9μg/L。其中,11.1%的监测井中甲基叔丁基醚浓度超过了EPA推荐的饮用水安全的浓度限值(20μg/L),3.7%的监测井中1,2-二氯乙烷浓度超过了《地表水环境质量标准》(GB 3838-2002)中"集中式生活饮用水地表水源地特定项目标准限值"规定的30μg/L。总体而言,石油烃、苯系物、1,2-二氯乙烷和甲基叔丁基醚的含量远低于油品渗(泄)漏导致的污染水平。

Investigation on pollution characteristics of petroleum hydrocarbon in shallow groundwater around gas stations

In order to monitor the organic pollution in shallow groundwater of gas stations in Chongqing,27 groundwater sample sites around 12 gas stations which have been operated more than 20 years in western Chongqing were proposed.Total petroleum hydrocarbon(TPH),benzene,naphthalene,1,2-dichloroethane(1,2-DCA) and methyl tert-butyl ether(MTBE) were monitored.The results show that major typical pollutants in the shallow groundwater of gas stations are TPH,1,2-DCA and MTBE.The detection rate of TPH is 96.3% with concentration range from 4.2μg/L to 544.7μg/L,and the main chemical components of TPH are detected with n-alkanes of C20 and C26.1,2-DCA is detected in 26 groundwater samples,accounting the rate for 96.3%.The concentration of 1,2-DCA is ranged from 1.7μg/L to 30.9μg/L.The concentrations of 1,2-DCA exceed the standard of centralized drinking water in Surface Water Environment Quality Standard(GB3838-2002) for 3%.MTBE is found in 6 shallow groundwater samples which accounting the rate for 22.2% with concentration varies from 3.8μg/L to 30.9μg/L.And the concentrations exceed the safe drinking water standard of EPA for 20μg/L.Comparing with the results of other researches,the pollution status of TPH,BTEX,MTBE and naphthalene in shallow groundwater of Chongqing is lower than those caused by oil leakage.