Identifying the Signature of the Natural Attenuation of MTBE in Goundwater Using Molecular Methods and "Bug Traps"

EPA Grant Number: R827015C026
Subproject: this is subproject number 026 , established and managed by the Center Director under grant R827015
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: IPEC University of Tulsa (TU)
Center Director: Sublette, Kerry L.
Title: Identifying the Signature of the Natural Attenuation of MTBE in Goundwater Using Molecular Methods and "Bug Traps"
Investigators: Sublette, Kerry L. , Ford, Laura P. , Kolhatkar, R. , Peacock, A. , White, David C
Institution: University of Tulsa
EPA Project Officer: Lasat, Mitch
Project Period: March 1, 2003 through February 28, 2004
RFA: Integrated Petroleum Environmental Consortium (IPEC) (1999) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Targeted Research

Objective:

The use of fuel oxygenates like methyl tert-butyl ether (MTBE) as octane enhancers has greatly muddied the waters, so to speak, in the use of risk-based management of gasoline-contaminated groundwater resulting from leaking underground storage tanks (USTs). In the absence of MTBE a risk-based approach to management of these sites depends on the natural attenuation of the more soluble components of the gasoline (BTEX) through intrinsic bioremediation. Microbial degradation combined with a tendency for these compounds to be somewhat retarded in their movement by interaction with soil organic matter have frequently combined to make risk- based management of these sites both cost-effective and protective of human health and ecological receptors. However, in oxygenated gasoline MTBE is present in higher concentrations that benzene, is more water soluble than BTEX, sorbs weakly to soil and aquifer material, and seems to be more recalcitrant to biodegradation. These properties combine to make MTBE more environmentally persistent than other gasoline components and, therefore, make a risk-based management option more difficult to implement. A defensible risk-based management approach to MTBE contaminated sites would be a major benefit to the domestic petroleum industry. There has been tantalizing field evidence that intrinsic bioremediation of MTBE and its major metabolite, tert-butyl alcohol (TBA), do indeed occur. Most observations link intrinsic bioremediation of these compounds to methanogenic conditions in the subsurface. However, both laboratory microcosm studies and field observations are inconsistent. Some sites appear to support MTBE biodegradation and some do not and the sites are not sufficiently distinct to ascertain why MTBE biodegradation occurs in some cases and not in others. The signature of MTBE biodegradation has yet to be found.

The Science Advisory Board of the U.S. Environmental Protection Agency has recently made three major research recommendations to the EPA Office of Research & Development on the subject of MTBE: 1) Determine the biodegradability of MTBE under various field conditions (for example, various electron acceptors and mixtures of hydrocarbons substrates); 2) Improve the predictability of dissolution rates of MTBE and their fluxes exiting source zones; and 3) Monitor multiple representative and highly characterized sites to provide an information database on indirect measures of MTBE natural attenuation (as has been done with BTEX). Clearly the objective is to provide a scientific basis for risk-based decision making in the management of MTBE plumes. The Board specifically cites the need to determine the "footprint" of MTBE biodegradation.

Approach:

This proposal seeks to address the third recommended research objective with the exception that we seek a direct, not indirect, measure or footprint of MTBE biodegradation. Specifically we propose to search for the signature of MTBE intrinsic bioremediation in the microbial ecology of the contaminated groundwater. BP, in collaboration with EPA, recently conducted an extensive survey of 74 BP retail sites with gasoline spills. Some of these sites indicated MTBE attenuation and others did not. Working with BP we will investigate and compare the in situ microbial ecologies of a subset of these sites using "bug traps" which concentrate organisms for analysis and provide a time-integrated picture of the subsurface microbial community. Further we will supplement this field work with an analysis of the microbial ecology of microcosms currently operated in the laboratory of Dr. Joe Suflita (University of Oklahoma). Microcosms positive for MTBE biodegradation will be sampled using the same bug traps used in the field sampling.

Expected Results:

It is hypothesized that the in situ microbiota contain a signature of past and present MTBE exposure and utilization. A comprehensive measure of the in situ microbial ecology of a site will yield the identity of this signature. We maintain that a definition of MTBE natural attenuation in terms of a site's microbial ecology is direct and definitive, whereas a definition in terms of contaminant chemistry and/or geochemistry or hydrology is indirect and inferential. It is well established that indigenous microbes generate various compounds within their cellular structure (biomarkers) that reflect in situ conditions. Therefore, the microbial community contains a record of the sum microbial response to the environment that is written from changes in the biochemistry of individual organisms. We propose that these responses, in association with knowledge of available electron acceptors and donors of a site, will define the signature of a successful MTBE natural attenuation process.

Supplemental Keywords:

Scientific Discipline, Waste, Water, Contaminated Sediments, Remediation, Environmental Chemistry, Oil Spills, Bioremediation, Chemistry and Materials Science, Groundwater remediation, Environmental Engineering, sediment treatment, petroleum, bug traps, natural attenutation, contaminant transport, microbial degradation, leaking underground storage tanks, MTBE, risk management, contaminated sediment, risk assessment model, remediation technologies, petroleum industry, BTEX, chemical contaminants, contaminated soil, hazardous waste, oil spill, groundwater aquifer, contaminated groundwater, hydrocarbons, groundwater contamination, oil removal, crude oil, contaminated aquifers, groundwater, leachate

Progress and Final Reports:

  • Final

  • Main Center Abstract and Reports:

    R827015    IPEC University of Tulsa (TU)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827015C001 Evaluation of Road Base Material Derived from Tank Bottom Sludges
    R827015C002 Passive Sampling Devices (PSDs) for Bioavailability Screening of Soils Containing Petrochemicals
    R827015C003 Demonstration of a Subsurface Drainage System for the Remediation of Brine-Impacted Soil
    R827015C004 Anaerobic Intrinsic Bioremediation of Whole Gasoline
    R827015C005 Microflora Involved in Phytoremediation of Polyaromatic Hydrocarbons
    R827015C006 Microbial Treatment of Naturally Occurring Radioactive Material (NORM)
    R827015C007 Using Plants to Remediate Petroleum-Contaminated Soil
    R827015C008 The Use of Nitrate for the Control of Sulfide Formation in Oklahoma Oil Fields
    R827015C009 Surfactant-Enhanced Treatment of Oil-Contaminated Soils and Oil-Based Drill Cuttings
    R827015C010 Novel Materials for Facile Separation of Petroleum Products from Aqueous Mixtures Via Magnetic Filtration
    R827015C011 Development of Relevant Ecological Screening Criteria (RESC) for Petroleum Hydrocarbon-Contaminated Exploration and Production Sites
    R827015C012 Humate-Induced Remediation of Petroleum Contaminated Surface Soils
    R827015C013 New Process for Plugging Abandoned Wells
    R827015C014 Enhancement of Microbial Sulfate Reduction for the Remediation of Hydrocarbon Contaminated Aquifers - A Laboratory and Field Scale Demonstration
    R827015C015 Locating Oil-Water Interfaces in Process Vessels
    R827015C016 Remediation of Brine Spills with Hay
    R827015C017 Continuation of an Investigation into the Anaerobic Intrinsic Bioremediation of Whole Gasoline
    R827015C018 Using Plants to Remediate Petroleum-Contaminated Soil
    R827015C019 Biodegradation of Petroleum Hydrocarbons in Salt-Impacted Soil by Native Halophiles or Halotolerants and Strategies for Enhanced Degradation
    R827015C020 Anaerobic Intrinsic Bioremediation of MTBE
    R827015C021 Evaluation of Commercial, Microbial-Based Products to Treat Paraffin Deposition in Tank Bottoms and Oil Production Equipment
    R827015C022 A Continuation: Humate-Induced Remediation of Petroleum Contaminated Surface Soils
    R827015C023 Data for Design of Vapor Recovery Units for Crude Oil Stock Tank Emissions
    R827015C024 Development of an Environmentally Friendly and Economical Process for Plugging Abandoned Wells
    R827015C025 A Continuation of Remediation of Brine Spills with Hay
    R827015C026 Identifying the Signature of the Natural Attenuation of MTBE in Goundwater Using Molecular Methods and "Bug Traps"
    R827015C027 Identifying the Signature of Natural Attenuation in the Microbial Ecology of Hydrocarbon Contaminated Groundwater Using Molecular Methods and "Bug Traps"
    R827015C028 Using Plants to Remediate Petroleum-Contaminated Soil: Project Continuation
    R827015C030 Effective Stormwater and Sediment Control During Pipeline Construction Using a New Filter Fence Concept
    R827015C031 Evaluation of Sub-micellar Synthetic Surfactants versus Biosurfactants for Enhanced LNAPL Recovery
    R827015C032 Utilization of the Carbon and Hydrogen Isotopic Composition of Individual Compounds in Refined Hydrocarbon Products To Monitor Their Fate in the Environment
    R830633 Integrated Petroleum Environmental Consortium (IPEC)
    R830633C001 Development of an Environmentally Friendly and Economical Process for Plugging Abandoned Wells (Phase II)
    R830633C002 A Continuation of Remediation of Brine Spills with Hay
    R830633C003 Effective Stormwater and Sediment Control During Pipeline Construction Using a New Filter Fence Concept
    R830633C004 Evaluation of Sub-micellar Synthetic Surfactants versus Biosurfactants for Enhanced LNAPL Recovery
    R830633C005 Utilization of the Carbon and Hydrogen Isotopic Composition of Individual Compounds in Refined Hydrocarbon Products To Monitor Their Fate in the Environment
    R830633C006 Evaluation of Commercial, Microbial-Based Products to Treat Paraffin Deposition in Tank Bottoms and Oil Production Equipment
    R830633C007 Identifying the Signature of the Natural Attenuation in the Microbial Ecology of Hydrocarbon Contaminated Groundwater Using Molecular Methods and “Bug Traps”
    R830633C008 Using Plants to Remediate Petroleum-Contaminated Soil: Project Continuation
    R830633C009 Use of Earthworms to Accelerate the Restoration of Oil and Brine Impacted Sites