Superfund Research Program
Phytoremediation of Toxic Wastes
Project Leader: Lee A. Newman (University of South Carolina)
Grant Number: P42ES004696
Funding Period: 1995 - 2006
Final Progress Reports
Year: 2005 1999
The goals of this project continue to be development of phytoremdiation methods for important toxicants found at hazardous waste sites. Dr. Newman and her research team have successfully screened a number of plants, evergreen and deciduous, trees and herbaceous plants, and have found that the metabolism of trichloroethylene (TCE) occurs in all plants tested. This has the potential to have a significant impact on those sites where both remediation and concurrent restoration is desired.
Project researchers previously found that the incorporation of mammalian p450 genes into poplar trees and tobacco results in increased catabolic activity 20 fold against TCE and other halogenated aliphatic hydrocarbons such as carbon tetrachloride, chloroform, benzene, and toluene. Experiments with tobacco plants modified with human cytochrome P450 2E1 have shown that the transgenic plants remove carbon tetrachloride, chloroform, TCE, benzene, and toluene at rates that are at least 20 times higher than the wild type vector control plants. Perchloroethylene (PCE), which is not a substrate for 2E1, was not removed faster. Anomalously, methyl chloroform, which is metabolized by 2E1 in the human liver, was also not significantly removed. Experiments with transgenic INRA aspen transformed with rabbit 2E1 are underway. Project researchers developed a method to screen for native plant genes involved in TCE metabolism, and believe that they have identified several candidate plant genes. They are currently screening both knock-out plants and overexpressing plants to better understand the role of these genes in TCE metabolism.
Work on this project has lead to the project working as consultants at the Del Monte Fresh Fruit Corporation to remediate ethylene dibromide, TCE remediation projects for the Undersea Naval Warfare Center at Keyport, the Department of Energy, and the state of Oregon, a dichloropropane and nitrate site for Simplot in Oregon, a formaldehyde site for Grays Harbor County, and a trichloroethane site for the state of Oregon. The Keyport Naval site is a listed Superfund site, and one of the DOE sites was listed by both CERCLA and RCRA. The DOE at the Savannah River Site has also funded work to look at the role of plants in natural attenuation.