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NATURAL BIODEGRADATION OF NTBE ON A SITE ON LONG ISLAND, NY: SYMPOSIUM
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NRMRL-ADA-00170 Kolhatkar, R., Wilson*, J.T., and Hinshalwood, G. "Natural Biodegradation of NTBE on a Site on Long Island, NY." In: 6th Intl. In-Situ and On-Site Symposium on Bioremediation of MTBE, Alcohols, and Ethers, Battelle, The Sixth International Symposium, San Diego, CA, 6/4-7/01. 1, 6, 2001, 43-50. In a plume of gasoline contamination on Long Island, New York, the concentration of MTBE attenuated significantly in certain wells that were down gradient of the source, while the concentration of methane did not attenuate significantly. Near the source, the mingled plume of BTEX and MTBE was uniformly methanogenic. Down gradient of the source BTEX was completely depleted and the MTBE plume was resolved into two distinct regions, a shallow region with high concentrations of methane (>0.5 mg/liter) and a deeper region with low concentrations of methane. Rates of natural biodegradation were calculated for wells that were in the shallow methanogenic plume. The rate of MTBE attenuation with distance (0.0067 per foot) was estimated as the negative of the slope of an exponential regression of MTBE concentration with distance along the flow path. The average ground water seepage velocity at the site is near 700 feet per year. Using this attenuation rate in the approach of Buscheck and Alcantar (1995), a first order biodegradation rate constant for MTBE was estimated at 5.2 per year (95% confidence interval of 2.2 to 8.2 per year). At this site, MTBE attenuation appears to be strongly correlated to methanogenic conditions in the ground water. Although MTBE is depleted in the shallower methanogenic zone, it persists in a deeper zone in the aquifer where methane is absent. Although the research described in this manuscript has been supported by the United States Environmental Protection Agency through in- house task 5857 (Natural Attenuation of MTBE) at the R. S. Kerr Environmental Research Center, it has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred.