PHYTOREMEDIATION OF TOXIC WASTE SITES

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We plan to determine the ability of plants to remediate toxic waste sites. In prototype experiments, we will focus on the ability of polar trees to detoxify trichloroethylene (TCE). Poplars are able to grow in the presence of high levels of TCE and to transpire and metabolize the compounds. TCE is converted to trichloroethanol, trichloroacetic acid, and two polar compounds whose structures will be determined. We will determine which clones metabolize the largest proportion of TCE absorbed by the plants. The extent of metabolism will be augmented by introducing genes which are known to metabolize TCE. Laboratory studies of the uptake and metabolism of TCE will use gas-tight glass apparatuses with separate chambers for roots and crowns in order to determine the fate of 100: of the material administered. The best clones will be studied in greenhouse-scale experiments to determine their ability to absorb and detoxify TCE. Finally, field studies will be conducted in collaboration with the Occidental Chemical Corporation at a site at the Port of Tacoma. These field studies will take place for 2 to 4 years, will be heavily instrumented, will determine the ability of the plants to take up and detoxify TCE, and will measure the extent of transpiration of the compound. In conjunction with these studies, we will collaborate with Dr. Leah Bauer, USDA, East Lansing, MI, to determine the effect of the ingestion of chicks to determine whether there is any effect on these animals. We will also investigate whether we can use the ability of plants to metabolize. TCE to chlorinated products as an environmental biomarker of the extent of below-ground TCE contamination. Plant tissue from a range of sites will be analyzed for TCE metabolites and compared to known levels of TCE contamination. The use of plants to remediate pollution meets the mandate of the NIEHS to attenuate adverse effects of toxic materials on human health. This approach serves as a "green solution" to pollution abatement and is expected to meet with public approval.