某石油类污染场地地下水石油烃生物降解的地球化学证据

Geochemical indicators of intrinsic biodegradation in a petroleum hydrocarbon-contaminated aquifer

生物降解地下水石油烃会改变地下水环境的水化学组成,因此可以通过分析污染晕中电子受体、生物降解代谢产物以及重要的地球化学参数量值变化获得生物降解的地球化学证据。本次在对某石油污染场地地质、水文地质条件、污染源污染方式调查基础上,根据地下水样测试结果,详细分析了地下水石油烃污染分布特征、污染晕中指示生物降解作用的电子受体、代谢产物以及重要地球化学参数的空间变化规律,研究结果表明:污染场地内存在氧还原、硝酸盐还原、硫酸盐还原等生物降解作用,其中硫酸盐还原是污染场地地下水石油烃生物降解的优势反应;在沿地下水流向上,TPH浓度、HCO_3^-浓度和碱度逐渐降低,Eh、电子受体(DO、NO_3^-、SO_4^(2-))浓度逐渐升高;在垂直于地下水流向上,从中心向两侧各组分也呈相似的变化规律。

The intrinsic biodegradation of petroleum hydrocarbons in a contaminated aquifer wouldchange the chemical constitution, which can be indicated by various geochemical footprints. The variations of TPH, generation of acceptor reduction and significant geochemical parameters have been analyzed on the ground of geological and hydrogeological conditions of a petroleum hydrocarbon-contaminated site. Results showed that biological degradation existed in contaminated site, such as oxygen reduction, nitrate reduction, sulfate reduction. Meanwhile, sulfate reduction took dominant position in all degradation due to its high concentration at site. Along the groundwater flow, concentration of TPH, HCO3^- and alkalinity decreased, while Eh and concentrations of electron acceptors（ DO, NO3^-, SO4^2- ） gradually increased ; Perpendicular to the groundwater flow from the center to both sides, above variations showed similar trends.