The research will be presented during the 113th National Geological Society of America meeting in Boston, Nov. 1-10, 2001.

Jackson M. Spain is conducting the research as part of his masters thesis, under the direction of Madeline Schreiber, assistant professor of geological sciences.

Underground storage tanks such as those at service stations sometimes leak, creating underground gas plumes, Spain said. The gas then can get into the groundwater. The most dangerous components of the gasoline are benzene, toluene ethylbenzine, xylenes, or BTEX, because they are most soluble and most likely to get into the groundwater. BTEX, particularly benzene, are carcinogenic.

Bioremediation, which relies on naturally occurring subsurface bacteria to break down contaminants, is an accepted treatment method for cleaning up gasoline spills. The terminal electron accepting process (TEAP) that bacteria use to break down gasoline compounds exerts a strong control on the extent and efficiency of bioremediation. The use of oxygen (aerobic respiration) yields the most energy to the bacteria and thus results in the most complete and rapid bioremediation. When oxygen is not present, bacteria can use other TEAPs, such as nitrate reduction, iron reduction, sulfate reduction, and methanogenesis, to break down gasoline compounds.

"Our study is looking at two specific TEAPs, iron reduction and methanogenesis," Spain said. "Were studying how the heterogeneities of Fe(III) concentrations affect which TEAPs are utilized. Were trying to see if the differences in the Fe(III) concentrations would cause the TEAPs to be used simultaneously instead of sequentially, which is how the theory predicts and how its no
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Contact: Jackson Spain
jspain@vt.edu
540-231-2404
Virginia Tech
8-Nov-2001