地下水石油烃生物降解作用研究

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,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变化规律,通过计算矿物饱和指数和采用含水层介质X射线矿物衍射方法研究了污染晕中矿物沉淀反应,计算了含水层的氧化容量。结果表明：由于SO42-背景浓度值较高,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;菱铁矿、黄铁矿和FeS的沉淀反应是HS-、Fe2＋浓度异常的原因;SO42-的氧化容量在含水层中的氧化容量（OXC）所占比例最大,可进一步推断硫酸盐还原反应是引起污染场地地下水石油烃生物降解的优势反应。

Monitoring Biodegradation in a Petroleum Hydrocarbon-contaminated Aquifer

The geochemical indicators of biodegradation at a petroleum hydrocarbon-contaminated site,including variations in total petroleum hydrocarbon（TPH）,acceptor reduction,and other important geochemical parameters,were determined from an analysis of the geological and hydrogeological conditions at the site.Speciation calculations and SEM-EDS（Scanning Electron Microscopy Combined with Energy Dispersive X-ray Spectroscopy） analysis were used to identify secondary minerals precipitating within the plume.Redox zones within the aquifer were delineated on the basis of the oxidation capacity（OXC） of the aquifer sediments.The results show that the concentration of TPH and HCO3–,as well as alkalinity,decreased in the direction of groundwater flow,while Eh and the concentrations of electron acceptors（DO,NO3–,and SO42–） gradually increased.Sulfate reduction was the dominant reaction associated with the biodegradation due to its high concentration at the site.Concentrations of HS– and Fe2＋ were lower than background levels due to the precipitation of siderite,pyrite,and FeS.Oxidized SO42– made the greatest contribution to OXC,and this suggests that deoxidation of sulfate was the major cause of biodegradation here.