Intrinsic Bioremediation of Petroleum Hydrocarbons in a Gas Condensate-Contaminated Aquifer

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• 作者：Lisa M. Gieg ; Ravindra V. Kolhatkar ; Michael J. McInerney ; Ralph S. Tanner ; Steve H. Harris ; Jr. ; Kerry L. Sublette ; and Joseph M. Suflita
• 刊名：Environmental Science & Technology
• 出版年：1999
• 出版时间：August 1, 1999
• 年：1999
• 卷：33
• 期：15
• 页码：2550 - 2560
• 全文大小：151K
• 年卷期：v.33,no.15(August 1, 1999)
• ISSN：1520-5851

文摘

A study was designed to determine if the intrinsicbioremediation of gas condensate hydrocarbons representedan important fate process in a shallow aquifer underlyinga natural gas production site. For over 4 yr, changes inthe groundwater, sediment, and vadose zone chemistry inthe contaminated portion of the aquifer were interpretedrelative to a background zone. Changes included decreaseddissolved oxygen and sulfate levels and increasedalkalinity, Fe(II), and methane concentrations in thecontaminated groundwater, suggesting that aerobicheterotrophic respiration depleted oxygen reserves leavinganaerobic conditions in the hydrocarbon-impactedsubsurface. Dissolved hydrogen levels in the contaminatedgroundwater indicated that sulfate reduction andmethanogenesis were predominant biological processes,corroborating the geochemical findings. Furthermore, 10-1000-fold higher numbers of sulfate reducers andmethanogens were enumerated in the contaminatedsediment relative to background. Putative metaboliteswere also detected in the contaminated groundwater,including methylbenzylsuccinic acid, a signature intermediateof anaerobic xylene decay. Laboratory incubationsshowed that benzene, toluene, ethylbenzene, and each ofthe xylene isomers were biodegraded under sulfate-reducing conditions as was toluene under methanogenicconditions. These results coupled with a decrease inhydrocarbon concentrations in the contaminated sedimentconfirm that intrinsic bioremediation contributes to theattenuation of hydrocarbons in this aquifer.