Chlorinated Solvents Contamination

Chlorinated solvents have properties that make them useful for degreasing fats, oils, waxes, and resins. They are used widely and have been manufactured in large quantities. Some chlorinated solvents are dichloromethane, tetrachloroethene, trichloroethane, and tricholoroethene. The U.S. production of these compounds in 1980 were 255,000, 347,000, 314,000, and 121,000 metric tons, respectively.

Chlorinated solvents in general are harmful to human and ecological health. They can cause or are suspected of causing cancer, and are toxic or harmful to aquatic organisms.

Spills and leaks of chlorinated solvents have caused widespread subsurface contamination in the environment. Commonly these contaminants are present in the subsurface in the form of non-aqueous phase liquids (NAPL, the bulk chemical product), as dissolved contaminants in ground water, associated with aquifer sediments, and as vapors in the unsaturated zone. Because the density of these NAPL’s is greater than water, they tend to sink in ground water systems, which results in a complex dispersal and plume patterns, long-term sources in the subsurface, and difficult clean-up. Under the proper conditions, biodegradation and volatilization can contribute significantly to the removal of chlorinated solvents from the subsurface, making natural attenuation a potentially important remediation alternative.

The project activities undertaken fall into 2 general categories: Plume-scale research at representative contamination sites, and research on microbial degradation pathways for chlorinated solvents. More information is provided on these activities as follows:

Plume-Scale Research at Representative Contamination Sites

Chlorinated Solvents in Fractured Sedimentary Rock -- Naval Air Warfare Center (NAWC) Research Site, West Trenton, New Jersey

Field Investigation of Natural Attenuation of Chlorinated Solvents -- Picatinny Arsenal, New Jersey

Microbial Degradation Pathways for Chlorinated Solvents

Microbial Degradation of Chloroethenes in Ground Water Systems

Application of Molecular Methods in Microbial Ecology to Understand the Natural Attenuation of Chlorinated Solvents

Program Headlines Related to Chlorinated Solvents Contamination

• New Report Presents a Framework for Assessing the Sustainability of Monitored Natural Attenuation
• New Version of NAS (Natural Attenuation Software) Available
• RDX Biodegradation Under Metal-Reducing Conditions
• History and Ecology of Chloroethene Biodegradation–A Review
• The Changing Face of Microbial Communities in Contaminant Plumes
• Software Provides Estimates of How Long it Will Take for Remediation Efforts to Achieve Their Goals
• Effect of Terminal Electron Accepting Conditions on Chloroethene Oxidation
• Anaerobic Oxidation of Vinyl Chloride Under Humic-Acids-Reducing Conditions
• Aerobic Microbial Mineralization of Dichloroethene as the Sole Carbon Substrate
• Microbial Oxidation of Vinyl Chloride Under Iron-Reducing Conditions
• Role of Acetogens in Anaerobic Oxidation of VInyl Chloride
• SERDP Invests in Technologies Developed by the Toxics Program
• DNAPL Removal Key to Accelerated, Less Expensive Remediation
• Relying on Nature to Clean Up Contaminated Ground Water
• USGS Scientists Contribute to the Landmark " Treatise on Geochemistry"

Fact Sheets

• Bioremediation--Nature's Way to a Cleaner Environment: USGS Fact Sheet FS-O54-95
• Contaminant Sorption by Soil and Bed Sediment is there a Difference?: USGS Fact Sheet FS-087-00

Meetings and Conferences

• USGS and Virginia Tech present the NGWA's short course "Estimating Times of Remediation Associated with Monitored Natural Attenuation and Contaminant Source Removal," Tucson, Ariz., March 17-18, 2008

New Publications

Upcoming Publications

• Biological degradation of chloroethenes: Bradley, P.M., and Chapelle, F.H., in SERDP/ESTCP Monograph on Remediation of Dissolved-Phase Chlorinated Solvents: (IN PRESS).
• Biochemical indicators for the bioavailability of natural dissolved organic carbon in ground water: Chapelle, F.H., Bradley, P.M., Goode, D.J., Tiedeman, C., Lacombe, P.J., Kaiser, K., and Benner, R., Ground Water (IN PRESS).

Newly Published

• Redox processes and water quality of selected principal aquifer systems: McMahon, P.B., and Chapelle, F.H., 2008, Ground Water, v. 46, no. 2, p. 259-271, doi:10.1111/j.1745-6584.2007.00385.x.
• Anoxic mineralization--Environmental reality or experimental artifact?: Bradley, P.M., Chapelle, F.H., and Löffler, F.E., 2008, Ground Water Monitoring and Remediation, v. 28, no. 1, p. 47-49, doi:10.1111/j.1745-6592.2007.00186.x.