Section Navigation. Facebook Twitter LinkedIn Syndicate. Minus Related Pages. Links with this icon indicate that you are leaving the CDC website. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website. These pulses, which possibly are caused by the infiltration of rain water or rising groundwater levels, may necessitate frequent groundwater sampling to determine actual MTBE concentrations and levels of risk to downgradient receptors.
The frequency of sampling can be determined based on the velocity of the groundwater and the number of monitoring wells EPA Another consideration in characterizing MTBE plumes is the potential for the plumes to dive. Because MTBE does not sorb to aquifer material and because there may be little biological degradation in some plumes, MTBE plumes can become very long.
The longer the plume, the more likely that it will dive below the screen of conventional monitoring wells. Plumes can dive deeper into an aquifer by different mechanisms: they can be buried by recharge of precipitation, moving down to the aquifer from the surface, and they also tend to flow around clay layers and through sand or gravel layers.
If the layers that control flow of groundwater dive into the aquifer, so will the plume EPA and Weaver and Wilson ITRC suggests several reasons for the studies' findings, including the potential for biodegradation not specifically examined in the studies , but cautions that the site characterizations might be faulty.
ITRC offers the following observations:. Microcosm studies and DNA fingerprinting are expensive tests that can be used to indicate if biodegradation is occurring or has the potential to occur. Alternatively, Wilson et al. While analysis for biogeochemical footprints can show biodegradation and aquifer impact for a gasoline spill as a whole, they generally cannot be used as an indicator of what is happening specifically to MTBE Wilson et al.
Weaver and J. Wilson L. EPA F, 5 pp, Analytical Methodologies for Fuel Oxygenates. EPA F, 2 pp, Holopainen, S. Nousiainen, and M. Talanta A membrane-extraction module coupled to IMS is a time- and cost-effective analysis method because sampling can be performed in a single procedure and from different natural water matrices within a few minutes.
Consequently, IMS combined with membrane extraction is suitable not only for waterworks and other online applications but also in the field for monitoring the quality of drinking and natural water.
LBNL, 28 pp, The decay of MTBE in the blood was assessed by fitting the post-exposure data to a 2- or 3-exponential model that yielded residence times tau of min, min, and h as measured by alveolar breath, and 5 min, 60 min, and 32 h as evaluated from venous blood measurements. Based on observations of lower than expected blood and breath MTBE during uptake and a decreasing blood-to-breath ratio during the post-exposure decay period, we hypothesize that the respiratory mucous membranes were serving as a reservoir for the retention of MTBE.
The Agency is continuing to review and update its analysis of the potential health risks posed by MTBE. Once MTBE contaminates a drinking water source, its chemical nature makes it difficult, expensive, and time-consuming to remediate. For example, it is much harder and more expensive to remove MTBE from drinking water than it is to remove other organic components of gasoline.
Interstate Technology Regulatory Council Fuel Oxygenates D. Barcelo ed. Springer, New York.
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