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Environmental Health - Toxic Substances

Toxics Program Remediation Activities

Using Phytoremediation to Control Fuel Oxygenate Plumes in Northern Climates

  • Testing of Remediation Technologies
  • Natural Attenuation Evaluation
Location Flathead Indian Reservation, Ronan, Montana
Technology Phytoremediation
  • Fuel Oxygenates
    • Methyl tert-butyl ether (MTBE)
    • Non-MTBE ethers (tert-amyl methyl ether TAME, diisopropyl ether DIPE, ethyl tert-butyl ether ETBE )
    • Tert-amyl alcohol (TAA), and tert-butyl alcohol (TBA)
  • Hydrocarbons

USGS scientists and their partners are testing the use of phytoremediation in northern climates (nontemperate) to contain and remediate a subsurface plume of gasoline located near Ronan, Montana, on the Flathead Indian Reservation. At the site, an underground storage tank leaked an estimated 10,000 gallons of gasoline that contained BTEX and various fuel oxygenates, such as MTBE. Although the tank has been removed, free product is still present in the subsurface at the site, creating a plume that has migrated from the gasoline station, under Highway 93, and terminates at Spring Creek, about 450 meters away.

root ball
The root ball of each poplar tree was dipped in a solution of mycorrhizae to inoculate the new trees with beneficial microbial populations to assist in water uptake. More Photos

The objective of the test is to see if phytoremediation in this northern climate, where it is not uncommon for the top foot of soil to freeze during winter months, could stop the contamination plume from discharging into Spring Creek. To achieve this, water-loving trees (poplars) were planted to capture ground water and dissolved contaminants. The trees planted in 2001 by the USGS at the toe of the plume did not survive the winter. The high rate of mortality was most likely due to planting small, 6-inch cuttings, without a large root mass. In 2002, much larger, 6-foot trees with a substantial root ball were planted. Future monitoring results will be useful in determining the viability of using phytoremediation in this part of the U.S. to control plume migration.

A secondary objective of the project is to test the ability of new analytical methods to measure the concentrations of alternative fuel oxygenates (non-MTBE ethers and polar fuel compounds) in contaminated ground water. Project scientists in conjunction with scientists from the U.S. Geological Survey's National Water Quality Laboratory, the Oregon Graduate Institute, and the University of Oklahoma successfully measured alternative fuel oxygenates (tert-amyl methyl ether TAME, diisopropyl ether DIPE, ethyl tert-butyl ether ETBE, tert-amyl alcohol TAA, and tert-butyl alcohol TBA) in water. The data from this project will enable the scientists to evaluate and compare the natural attenuation of alternative oxygenates to MTBE. The comparison will be aided by the analysis of the composition of stable-isotopes of carbon and hydrogen in the oxygenates. Changes in carbon and hydrogen isotopes will help identify biodegradation reactions of the oxygenates in ground water. This information can be used by resource managers to evaluate using proposed alternatives to MTBE as oxygenates in gasoline.

In addition to the above work, the scientists conducted an investigation to determine the ability of the subsurface microorganisms at the site to degrade MTBE during the winter when ground water temperatures range from 5° Celsius (C) 41° Fahrenheit (F) to 14°C (57.2°F). Because microbial activity often decreases with decreasing temperatures, the scientific and engineering communities have assumed that biodegradation rates are low or insignificant at such cold temperatures. The scientists conducted laboratory microcosm studies on the sediment samples from the Ronan site and the Almena Agricenter Site in northern Kansas, and demonstrated that the microbial communities present at the sites can biodegrade MTBE at temperatures as cold as 4°C (39.2°F). These results indicate that microbial degradation can continue to contribute to the natural attenuation of MTBE in ground water even during winter cold-temperature conditions.

More Information
Contact James Landmeyer, USGS, South Carolina Water Science Center, Columbia, SC,
Links USGS Phytoremediation Information

Toxics Program Information on Remediation of Fuel Oxygenates

USGS Information on Fuel Oxygenates

Back to Toxics Program Remediation Activities Index

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Page Last Modified: Tuesday, 30-Jul-2013 12:23:12 EDT