Oxygenates

Gasoline oxygenates have been used in gasoline primarily to improve octane, reduce vehicular emissions and comply with the oxygen requirements of the 1990 Clean Air Act Amendments. While there are many different gasoline oxygenates the ones most commonly used in US gasolines are methyl tert-butyl ether (MTBE) and ethanol (EtOH). Tert-butyl alcohol (TBA) is both a trace component found in fuel grade MTBE, and is also a metabolite of MTBE biodegradation. API groundwater research has focused on understanding the fate, transport and remediation of these compounds, with special focus on the factors influencing their biodegradation.

This page is a portal to technical information on fuel oxygenates in soil and groundwater.  Reports and presentations on API-sponsored research are provided for various aspects of risk-based decision-making.

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Technical Protocol for Evaluating the Natural Attenuation of MtBE

 
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File Size: 3.0 MB
Date: May 2007
License: Free

May 7, 2007 - This technical protocol addresses data collection, evaluation, and interpretation procedures that consider the physical, chemical and biological properties of MtBE and other oxygenates and degradation byproducts.  A tiered approach is provided that can be used by stakeholders to interpret several lines of evidence to evaluate natural attenuation on a site-specific basis.  Several resources are provided to support an MNA evaluation, including:  

• a review of basic scientific principles relevant to the evaluation of MtBE  natural attenuation, including biodegradation and physicochemical attenuation mechanisms;
  
• a discussion of data that can be used to assess MtBE (and other oxygenates or degradation byproducts) natural attenuation;   
  
• technical references for relevant chemical properties, analytical methods, and field sampling techniques;  
  
• guidance for data quality assurance and interpretation, including statistical analysis; and
  
• guidance on the presentation of natural attenuation data/information to facilitate regulatory and other stakeholder review and acceptance of MNA remedies.

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MTBE and TBA Biodegradation
September 25, 2006 - For the last several years, Dr. Mike Hyman has researched the diversity of pathways of aerobic MTBE and TBA oxidation(metabolism vs cometabolism).  His work has helped identify the enzymes responsible for initiating these processes at the molecular level and led to a better understanding of how distinct microbial processes can contribute to MTBE and TBA degradation in gasoline-impacted groundwater. Click below to download Dr. Mike Hyman's Physiological and Enzymatic Diversity of Aerobic MTBE Biodegradation Processes from the Second European MTBE Conference in Barcelona, Spain.

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File Size: 2.0 MB
Version Date: November 2004
License: Free

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Research in Progress
May 9, 2007 - API has several oxygenate-related publications scheduled for completion in 2007 including:

• Use of Compound Specific Isotope Analyses (CSIA) as an In-situ Indicator of MtBE Biodegradation
  
  
• Technical Manual on the Design and Operation of Ex-Situ Biological Treatment of Oxygenate Impacted Groundwater
  

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Site Characterization
Strategies for Characterizing Subsurface Releases of Gasoline Containing MTBE

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Solute Plume Migration: Assessment Significance
and Implications for Characterization and Monitoring of "Diving Plumes"

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File Size: 5.5 MB
OS: PC/Mac | License: Free

Download Bulletin
File Size: 2.6 MB
Version Date: April 2006
OS: PC/Mac | License: Free

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Remediation
Groundwater Remediation Strategies Tool

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Analytical Methods
Papers and websites on analytical methods for detecting various oxygenates



 

TBA Hazard Narrative

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File Size: 584 KB
Version Date: October 2005
OS: PC/Mac | License: Free

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FAQs
The following API Soil and Groundwater Research bulletins cover provide basic information about oxygenate behavior in groundwater:

Answers to Frequently Asked Questions About Ethanol Impacts to Groundwater:

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File Size: 260 KB
Version Date: December 2003
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Ten Frequently Asked Questions About MTBE in Water:

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File Size: 40 KB
Version Date: March 1998
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Fate and Transport
Laboratory studies on the behavior of subsurface fuel releases:

The Impact of Gasohol and Fuel-Grade Ethanol on BTX and Other Hydrocarbons in Ground Water:

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File Size: 768 KB
Version Date: December 2005
OS: PC/Mac | License: Free

Dissolution of MTBE from a Residually Trapped Gasoline Source:

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File Size: 248 KB
Version Date: September 2000
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Small Releases
Modeling studies to evaluate the potential for groundwater impacts from small mass or volume releases from fuel storage systems: 

Evaluation of Small-Volume Releases of Ethanol-Blended Gasoline at UST Sites:

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File Size: 180 KB
Version Date: October 2003
OS: PC/Mac | License: Free

Simulation of Transport of Methyl Tert-Butyl Ether (MTBE) to Groundwater from Small-Volume Releases of Gasoline in the Vadose Zone:

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File Size: 192 KB
Version Date: June 2000
OS: PC/Mac | License: Free

Maximum Potential Impacts of Tertiary Butyl Alcohol (TBA) on Groundwater from Small-Volume Releases of Ethanol-Blended Gasoline in the Vadose Zone:

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File Size: 324 KB
Version Date: January 2005
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Evaluation of Potential Vapor Transport to Indoor Air Associated with Small-Volume Releases of Oxygenated Gasoline in the Vadose Zone:

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File Size: 308 KB
Version Date: January 2005
OS: PC/Mac | License: Free