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Small-Volume Releases of Gasoline in the Vadose Zone: Impact of the Additives MTBE and Ethanol on Groundwater Quality

Lookup NU author(s): Professor David WernerORCiD


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A controlled gasoline spill experiment was performed under outdoor conditions typical for winter in temperate regions to study the fate of methyl tert-butyl ether (MTBE), ethanol, benzene, and selected other petroleum hydrocarbons. Artificial gasoline containing MTBE and ethanol (5% w/w of each) was placed at a defined depth into a 2.3 m thick unsaturated zone of alluvial sand overlying a gravel aquifer in a lysimeter. During an initial period of 41 days without recharge, MTBE and hydrocarbon vapors migrated by vapor-phase diffusion to groundwater, while ethanol vapors were naturally attenuated. In a subsequent period of 30 days with 5-mm daily recharge, all soluble compounds including ethanol were transported to the groundwater. Ethanol disappeared concomitantly with benzene and all other petroleum hydrocarbons except isooctane from the aerobic groundwater due to biodegrada tion. MTBE persisted for longer than 6 months at concentrations larger than 125 000 g L-1. No evidence for MTBE biodegradation was found, whereas >99.6% of ethanol removal from the lysimeter was due to biodegradation. It is concluded that MTBE-free gasoline would be less harmful for groundwater resources and that ethanol is an acceptable substitute.

Publication metadata

Author(s): Dakhel N, Pasteris G, Werner D, Höhener P

Publication type: Article

Publication status: Published

Journal: Environmental Science & Technology

Year: 2003

Volume: 37

Issue: 10

Pages: 2127-2133

ISSN (print): 0013-936X

ISSN (electronic): 1520-5851

Publisher: American Chemical Society


DOI: 10.1021/es026442n

Notes: Because of concerns like those voiced in this publication MTBE is banned as a gasoline additive in some parts of the world (e.g. California) and ethanol is gaining in importance.


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