Preliminary Assessment of the Occurrence and Possible Sources of MTBE in Groundwater in the United States, 1993−1994

Abstract

The 1990 Clean Air Act Amendments require fuel oxygenates to be added to gasoline used in some metropolitan areas to reduce atmospheric concentrations of carbon monoxide or ozone. Methyl tert-butyl ether (MTBE) is the most commonly used fuel oxygenate and is a relatively new gasoline additive. Nevertheless, out of 60 volatile organic chemicals analyzed, MTBE was the second most frequently detected chemical in samples of shallow ambient groundwater from urban areas that were collected during 1993−1994 as part of the U.S. Geological Survey's National Water-Quality Assessment program. Samples were collected from five drinking water wells, 12 springs, and 193 monitoring wells in urban areas. No MTBE was detected in drinking water wells. At a reporting level of 0.2 μg/L, MTBE was detected most frequently in shallow groundwater from urban areas (27% of 210 wells and springs sampled in eight areas) as compared to shallow groundwater from agricultural areas (1.3% of 549 wells sampled in 21 areas) or deeper groundwater from major aquifers (1.0% of 412 wells sampled in nine areas). Only 3% of the shallow wells sampled in urban areas had concentrations of MTBE that exceed 20 μg/L, which is the estimated lower limit of the United States Environmental Protection Agency draft drinking water health advisory. Because MTBE is persistent and mobile in groundwater, it can move from shallow to deeper aquifers with time. In shallow urban groundwater, MTBE generally was not found with benzene, toluene, ethylbenzene, or xylene (BTEX) compounds, which commonly are associated with gasoline spills. This disassociation causes uncertainty as to the source of MTBE. Possible sources of MTBE in groundwater include point sources, such as leaking storage tanks, and non-point sources, such as recharge of precipitation and stormwater runoff.

Enthalpies of Formation and Bond Dissociation Energies of Lower Alkyl Hydroperoxides and Related Hydroperoxy and Alkoxy Radicals

“…Methyl hydroperoxide, CH 3 OOH, has been the subject of numerous publications [20][21][22][23][24] since a comprehensive review by Dorofeeva et al in 2001. 25 They concluded that ∆H f (298.15K) ) -139.0 ( 5.0 kJ mol -1 represented the best estimate from values which ranged from -122 to -143 kJ mol -1 .…”

An Experimental Study of Phytoremediation of Methyl-tert-butyl Ether (MTBE) in Groundwater

“…Volume Two (Squillace et al, 1996). The results show that, of the 60 volatile organic compounds (VOCs) analyzed, MTBE was the second most frequently detected compound.…”

Trace Analysis of Methyl Tert‐butyl Ether in Water Samples Using New Ultrasound‐assisted Dispersive Liquid‐liquid Microextraction and Gas Chromatography‐flame Ionization Detection

“…The high solubility of MTBE in water, combined with its high concentration in some gasoline, can result in high concentrations of MTBE in surface water, ground water and storm water. 2,3 Currently, the most common method for the determination of MTBE is purge-and-trap preconcentration, followed by GC analysis. Purge-and-trap/GC instrumentation is expensive, technically sophisticated and time-consuming to operate.…”