Remediation of Trichloroethylene in an Artificial Aquifer with Trees:  A Controlled Field Study

Abstract

Poplar trees have been evaluated in the field for the control of contaminated groundwater movement, but to date, the fate of the contaminants has not been demonstrated. In the present study, we tested a hybrid poplar for the uptake and degradation of trichloroethylene (TCE). Plants were exposed to TCE-contaminated groundwater under field conditions in lined cells for three years. During the growing seasons, the trees were able to remove over 99% of the added TCE. Less than 9% of the TCE was transpired to the atmosphere during the second and third years, and examination of the tissue showed expected metabolites, but at low levels. Chloride did not significantly accumulate in the plant tissues, but chloride ion increased in the soil in amounts that approximately corresponded to TCE loss. These results demonstrate that treatment of TCEcontaminated groundwater with this poplar clone can result in efficient destruction of TCE.

Enhanced phytoremediation of volatile environmental pollutants with transgenic trees

“…Because it has been previously demonstrated that hybrid cottonwood, another kind of poplar, can remove TCE from hydroponic solution (3,18,19), the poor performance of the nontransgenic hybrid poplar in this study was unexpected. However, the hybrid cottonwood (Populus trichocarpa ϫ Populus deltoides) studies were done by using rooted cuttings in flasks with the foliage in open air or in field trials with full-grown trees, whereas this study was conducted with unrooted poplar (Populus tremula ϫ Populus alba) cuttings in sealed vials.…”

Enhanced metabolism of halogenated hydrocarbons in transgenic plants containing mammalian cytochrome P450 2E1

“…Previous work with untransformed poplar trees has shown that chlorinated hydrocarbons such as TCE are taken up along with the water transpired (14). There is little selective uptake of TCE from groundwater; therefore, reductions in the concentration of TCE are insignificant.…”

“…Plants have been shown to take up and, in some cases, to metabolize organic pollutants (6), excess nutrients (6, 7), 2,4,6-trinitrotoluene (TNT) (8,9), and metals (10,11). Work in our laboratory has demonstrated that poplar trees are able to take up and metabolize TCE both under laboratory conditions and in a field test (12)(13)(14).…”

Phytoremediation of Organic Contaminants in Soil and Groundwater

“…The halogenated solvent trichloroethylene (TCE; log K ow = 2.42) is metabolized by cultured cells of poplar (Populus spp.). [42] Newman et al [43] showed remediation of TCE in a controlled field study. Nzengung and Jeffers [14] identified four phytoprocesses involved in the plantmediated transformation of chlorinated organic compounds: www.chemsuschem.org 1) rapid sequestration by partitioning to the lipophilic plant cuticles, 2) phytoreduction to less chlorinated metabolites, 3) phytooxidation, and 4) assimilation into the plant tissue as non-phytotoxic products.…”