Degradation rates of benzene, toluene and o-xylene in a normally sulfate-reducing aquifer: Impact of ethanol in a controlled field experiment

Since May 2004, side-by-side field experiments have been conducted to evaluate the impact of ethanol on the natural attenuation of BTEX and MTBE. The motivation for this work is the increasing use of ethanol-containing gasoline (gasohol) and the concern that spills of gasohol will result in significant alteration of the subsurface redox conditions and consequent impacts of the fate of other fuel components. The experiments are conducted at Site 60, Vandenberg Air Force Base, CA, at which leaking UST and/or piping resulted in the generation of a plume of petroleum hydrocarbons and MTBE. Emphasis was placed on the areal contour plots of the solutes. Estimation of bulk reaction rates for BTX in Lanes A and B were presented. Preliminary estimates suggested that the apparent half-life of benzene was in the order of 10-20 times longer in the ethanol-impacted lane compared to the lane not impacted by ethanol. However, estimated half lives depended on the choice of methods and wells used for the estimation. This is an abstract of a paper presented at the Petroleum Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Assessment, and Remediation Conference (Costa Mesa, CA 8/8-19/2005).