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IMPACT OF ETHANOL ON THE NATURAL ATTENUATION OF MTBE IN A NORMALLY SULFATE-REDUCING AQUIFER
Citation:
MACKAY, D., N. DE SIEYES, M. EINARSON, K. FERIS, A. PAPPAS, I. WOOD, L. JACOBSON, L. JUSTICE, M. NOSKE, J. T. WILSON, C. J. ADAIR, AND K. SCOW. IMPACT OF ETHANOL ON THE NATURAL ATTENUATION OF MTBE IN A NORMALLY SULFATE-REDUCING AQUIFER. ENVIRONMENTAL SCIENCE AND TECHNOLOGY. American Chemical Society, Washington, DC, 41(6):2015-2021, (2007).
Impact/Purpose:
Journal article published
Description:
Two side-by-side experiments were conducted in an MTBE-contaminated aquifer at a former service station site to determine the effect of ethanol release on the fate of pre-existing MTBE contamination. On one side, we injected groundwater amended with 1-3 mg/L benzene, toluene, and o-xylene (abbreviated BToX) and on the other side the injected groundwater was amended with the same concentrations of BToX, as well as 470 mg/L ethanol. The fates of BToX are addressed in a companion paper. No MTBE transformation was observed on the side without ethanol. On the ethanol-impacted side, MTBE was biotransformed to TBA under the 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 biotransformation was less than 2 months after start of the experiments and the pseudo-first-order reaction rate was 0.046 d-1. In general, 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 zone beyond the reach of inhibitory effects such as those caused by high concentrations of ethanol.
