汽油添加剂甲基叔丁基醚(MTBE)污染的植物修复

摘要

Methyl tert-butyl ether (MTBE) is the most commonly used gasoline oxygenate in the North American's fuelindustry. Due to its high solubility in water and low sorption tendency in soils, MTBE has become one of the most commoncontaminants in urban groundwater. This paper examined the potential for phytoremediation of MTBE within a carefullydesigned bioreactor. Pre-rooted willow trees (Salix alba) were kept in an Erlenmeyer flask of 500 mL with 450 mL spikedaqueous solution for 12 d. MTBE and the main metabolite TBA were measured by GC/FID. Willow tree uptake tests indicatedthat the removal of MTBE mass in aqueous solution through willow tree activities was found in the range of 24.84～53.27 % at15 @ ～25 @ over a 12-day period of exposure. The fraction of MTBE (%) removed from the aqueous solution by willow treeswas positively correlated to tree transpiration (mg). Neither TBA, nor any other possible metabolite of MTBE was tracked inthis test, indicating phytovolatilization is the dominant mechanism for phytoremediation of MTBE. Results of the bench-scalestudies indicated that a large fraction of MTBE was released into the air without any conversion through willow trees over ashort period of time, however MTBE will be susceptible to photooxidation and does not become an air quality concern.Therefore, it is to conclude that phytoremediation is an effective method to clean the soil and groundwater contaminated withMTBE.%甲基叔丁基醚(MTBE)是北美燃料市场最常用的汽油添加剂.由于其在土壤中的不吸附性和极高的水溶性,MTBE已成为一种蔓延性的地下水污染物.本实验用一自行设计的植物反应器来观察和测定在不同温度条件下柳树(Salixalba)对MTBE污染水溶液的修复潜力.长出新根须和嫩叶的柳树枝条在一容积500mL的锥型瓶中生长12 d(其中MTBE溶液450 mL)来观察MTBE对柳树生长的影响,同时测定柳树对MTBE的吸收和降解.MTBE及其主要降解产物叔丁基醇(TBA)用气相色谱来检测.本实验结果表明在为期12 d的时间内,水溶液中24.84～53.27%MTBE可以通过柳树的蒸腾作用去除.同时在15℃～25 ℃的温度范围内,MTBE的去除率(%)和柳树的蒸腾量(g)之间存在着明显的线性关系.由于没有发现TBA和其它可能的降解产物,植物挥发是MTBE植物修复技术中主要的作用机理尽管植物在MTBE污染的修复过程中只是起着中间传输媒介的作用,大量的MTBE通过植物的蒸腾作用以气态的形式释放到大气中,但由于MTBE在气态下的光氧化非常快,MTBE不会造成空气污染.我们认为植物修复技术对MTBE污染的土壤和地下水仍不失为一个有效的修复手段.