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At least 73 records · Page 4Linked to original sources
USGS1997

Occurrence of the gasoline oxygenate MTBE and BTEX compounds in municipal stormwater in the United States, 1991-95

The U.S. Geological Survey (USGS) sampled stormwater in 16 cities and metropolitan areas that are required to obtain permits to discharge stormwater from their municipal storm-sewer system into surface water. Concentrations of 62 volatile organic compounds (VOCs), including methyl tert-butyl ether (MTBE) and BTEX (benzene, toluene, ethylbenzene, and total xylene) compounds, were measured in 592 stormwater samples collected in these cities and metropolitan areas from 1991 through 1995. MTBE was the seventh most frequently detected VOC in municipal stormwater. In decreasing order, the most frequently detected VOCs were toluene, total xylene, chloroform, total trimethylbenzene, tetrachloroethene, and naphthalene. MTBE was detected in 6.9 percent (41 of 592) of stormwater samples collected. When detected, concentrations of MTBE ranged from 0.2 to 8.7 micrograms per liter (??g/L), with a median of 1.5 ??g/L. All detections of MTBE were less than the lower limit of the U.S. Environmental Protection Agency's (USEPA) draft drinking water lifetime health advisory (20 ??g/L). Eighty-three percent of all detections of MTBE in stonnwater were in samples collected during October through March of each year (1991-95), which corresponds with the expected seasonal use of oxygenated gasoline in areas where carbon monoxide exceeds established air-quality standards. The median concentration of MTBE and benzene for all samples was statistically different and higher in samples collected during October through March than samples collected during April through September. Sixty-six percent of all MTBE: detections occurred with BTEX compounds, and a proportionate increase in concentrations was found when these compounds occurred together. Detected concentrations of toluene and total xylene ranged from 0.2 to 6.6 ??g/L and 0.2 to 15 ??g/L with median concentrations of 0.3 and 0.4 ??g/L, respectively.

ACS Division of Environmental Chemistry, Preprints↗
USGS1997

Preliminary assessment of the occurrence and possible sources of MTBE in groundwater in the United States, 1993-1994

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 1993-94 as part of the U.S. Geological Survey's National Water-Quality Assessment Program. Samples were collected from 5 drinking-water wells, 12 springs, and 1g3 monitoring wells in urban areas. No MTBE was detected in drinking-water wells. At a reporting level of 0.2 ??g/L, MTBE was detected most frequently in shallow groundwater from urban areas (27% of 210 wells and springs sampled in 8 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 9 areas). Only 3% of the shallow wells sampled in urban areas had concentrations of MTBE that exceed 20 ??g/L, which is the estimated lower limit of the United States Environmental Protection Agency draft lifetime 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 xylenes (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 nonpoint sources, such as recharge of precipitation and storm-water runoff.

ACS Division of Environmental Chemistry, Preprints↗
USGS2001

Biodegradation of MTBE by indigenous aquifer microorganisms under artificial oxic conditions

The hypothesis that artificial oxic conditions will lead to MTBE biodegradation by indigenous microorganisms in anoxic, gasoline-contaminated aquifers was examined by adding oxygen in the form of a metal peroxide slurry to an anoxic part of gasoline-contaminated aquifer in South Carolina. Field observations of relatively rapid aerobic MTBE biodegradation following oxygen addition suggest that the indigenous bacteria have become acclimated not only to mg/L concentrations of MTBE in the gasoline plume, but also to periodic delivery of oxygen by recharge events. Significant natural attenuation of MTBE could occur if the oxygen limitations naturally associated with gasoline releases can be removed, either under natural conditions where discharging anoxic groundwater comes into contact with oxygen, or artificial conditions where oxygen can be added to aquifers containing mg/L concentrations of MTBE. This final solution might be an effective strategy for intercepting characteristically long MTBE plumes, particularly at sites not characterized by groundwater discharge to land surface. This is an abstract of a paper presented at the 222nd ACS National Meting (Chicago, IL 8/26-30/2001).

ACS Division of Environmental Chemistry, Preprints↗