title: Impact of ethanol on the natural attenuation of MTBE in a normally sulfate-reducing aquifer.
abstract: Side-by-side experiments were conducted in an aquifer contaminated with methyl-tert-butyl ether (MTBE) at a former fuel station to evaluate the effect of ethanol release on the fate of pre-existing MTBE contamination. On one side, for approximately 9 months we injected groundwater amended with 1-3 mg/L benzene, toluene, and o-xylene (BToX). On the other side, we injected the same, adding approximately 500 mg/L ethanol. The fates of BToX in both sides ("lanes") were addressed in a prior publication. No MTBE transformation was observed in the "No Ethanol Lane." In the "With Ethanol Lane", MTBE was transformed to tert-butyl alcohol (TBA) underthe methanogenic and/or acetogenic conditions induced by the in situ biodegradation of the ethanol downgradient of the injection wells. The lag time before onset of this transformation was less than 2 months and the pseudo-first-order reaction rate estimated after 7-8 months was 0.046 d(-1). Our results imply that rapid subsurface transformation of MTBE to TBA may be expected in situations where strongly anaerobic conditions are sustained and fluxes of requisite nutrients and electron donors allow development of an active acetogenic/methanogenic zone beyond the reach of inhibitory effects such as those caused by high concentrations of ethanol.
authors.affiliation: Department of Land, Air & Water Resources, University of California, Davis, USA. dmmackay@ucdavis.edu
authors.forename: Doug
authors.initials: D
authors.lastname: Mackay
authors.forename: Nick
authors.initials: N
authors.lastname: de Sieyes
authors.forename: Murray
authors.initials: M
authors.lastname: Einarson
authors.forename: Kevin
authors.initials: K
authors.lastname: Feris
authors.forename: Alex
authors.initials: A
authors.lastname: Pappas
authors.forename: Isaac
authors.initials: I
authors.lastname: Wood
authors.forename: Lisa
authors.initials: L
authors.lastname: Jacobson
authors.forename: Larry
authors.initials: L
authors.lastname: Justice
authors.forename: Mark
authors.initials: M
authors.lastname: Noske
authors.forename: John
authors.initials: J
authors.lastname: Wilson
authors.forename: Cherri
authors.initials: C
authors.lastname: Adair
authors.forename: Kate
authors.initials: K
authors.lastname: Scow
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D001554:Benzene; D001673:Biodegradation, Environmental; D002140:California; D004787:Environmental Pollution / Q000517:prevention & control*; D000431:Ethanol / Q000378:metabolism*; D005618:Fresh Water / Q000737:chemistry* / Q000382:microbiology; D007700:Kinetics; D008738:Methyl Ethers / Q000378:metabolism*; D014050:Toluene; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D014992:Xylenes
chemical_list: D008738:Methyl Ethers; D014874:Water Pollutants, Chemical; D014992:Xylenes; C043243:methyl tert-butyl ether; D014050:Toluene; D000431:Ethanol; D001554:Benzene; C026114:2-xylene