Project Summary (2000-2006)

The purpose of this project is to explore the use of plants to remediate toxic solvent spills, particularly trichloroethylene (TCE), in the environment. Previous work has focused on the hybrid poplar species H-11-11, Populus trichocarpa X P. deltoides. Over the past four years, this hybrid has exhibited favorable cultivation and growth characteristics at a test site, and has removed 98-99% of the TCE in the influent water. Analysis of the planted soil versus controls showed an increase in chloride that is equivalent to the amount of TCE added to the cells, indicating that the TCE has been extensively mineralized. The contribution of soil bacteria to the degradation is negligible, and during 1998 there was no detectable TCE transpired by the trees. Additional studies have indicated that the detritus from TCE treated poplars is harmless to several insects tested. Researchers have also had preliminary success with the introduction of genes for a degradative enzyme, cytochrome P450 IIE1. These plants formed up to 35 times as much of the first degradative product of TCE. Future work will use 14C-labeled TCE to measure the rate of uptake and the fate of the carbon in the TCE. Researchers are also developing a repertoire of plants to detoxify a variety of common pollutants in a variety of geographic areas.