BTEX在乙醇汽油和传统汽油污染地下水中的衰减行为对比

地下燃油储藏罐泄漏造成苯、甲苯、乙苯和二甲苯（BTEX）影响生态环境和公众健康的问题一直备受关注，随着乙醇汽油的推广使用，乙醇对BTEX修复策略的影响成为需要重视的新问题.为揭示乙醇汽油污染地下水中BTEX的衰减行为，本文通过室内两个独立砂槽投注实验和近3年的监测，对比了乙醇汽油和传统汽油中BTEX自然衰减和基于硫酸盐-硝酸盐补充的增强生物修复行为.结果表明，传统汽油BTEX自然衰减较快，乙醇汽油BTEX自然衰减较慢，一级衰减速率常数分别为0.0055~0.0329 d^-1和0.0045~0.0124 d^-1；苯衰减最快，其次为甲苯.补充硫酸盐和硝酸盐能促进生物修复，单独补充硫酸盐时其利用率为89.7%~92.9%，同时补充硝酸盐时硫酸盐利用被抑制，硝酸盐利用率为79.9%~87.2%.水位波动会促进BTEX溶解和迁移，增大质量通量.乙醇汽油不仅能消耗更多电子受体，使得BTEX衰减被抑制，而且可能会扩大水位波动引起的增溶效应.

Comparison of BTEX attenuation behaviors between ethanol gasoline and tradition gasoline in contaminated groundwater

Leakages of underground fuel storage tanks that cause the impacts of benzene, toluene, ethylbenzene, and xylene (BTEX) on the ecological environment and public health have been commonly concerned. With the increasing utilization of ethanol gasoline, the ethanol influence on the remediation of BTEX in groundwater is a new problem, requiring more understandings. To gain insight into the behaviors of BTEX attenuation in groundwater contaminated by ethanol gasoline, sand-tank injection experiments were performed. Traditional gasoline and ethanol gasoline were injected into two separate sand tanks, respectively. Natural attenuation and enhanced bioremediation of BTEX based on sulfate and nitrate amendments were monitored for about three years. The results showed that the attenuation of BTEX in traditional gasoline was faster than that in ethanol gasoline. The first-order decay rate constants were 0.0055~0.0329 d^-1 and 0.0045~0.0124 d^-1, respectively. Benzene attenuation was the fastest, followed by toluene attenuation. The addition of sulfate and nitrate could enhance the bioremediation. The utilization rate of sulfate reached 89.7%~92.9% when it was added alone, which could be inhibited when nitrate was added simultaneously. The utilization rate of nitrate was 79.9%~87.2%. Water level fluctuation promoted BTEX dissolution and migration, causing the increase in mass flux. Ethanol not only preferentially consumed more available electron receptors that could otherwise enhance BTEX biodegradation, but also likely stimulated BTEX solubilization caused by water level fluctuation.