PHYTOREMEDIATION OF TRICHLOROETHANOL AND CARBON TETRACHLORIDE: RESULTS FROM BENCH TO FIELD
|L.A. Newman1, C. Bod2, N. Choe1, R. Crampton3, R. Cortellucci4, D. Domroes4, S. Doty1, J. Duffy4, G. Ekuan2, D. Fogel2, R. Hashmonay3, P. Heilman2, D. Martin1, I.A. Muiznieks1, T. Newman5, M. Ruszaj4, T. Shang1, B. Shurtleff1, S. Stanley1, S.E. Strand6, X. Wang6, J. Wilmouth1, M. Yost3, and M.P. Gordon1, 1Department of Biochemistry, Box 357350, University of Washington, Seattle, WA 98195, 2Washington State University, Puyallup Re-search and Extension Center, Puyallup, WA, 3Depanment of Environmental Health, University of Washington, Seattle, WA 98195, 40ccidental Chemical, 2801 Long Road, Grand Island, New York 14072, 5Occidental Chemical, 605 E Alexander Ave, Tacoma, WA 98421, 6College of Forest Resources, University of Washington, Seattle, WA 98195||
Remediation of contaminated sites using plants, or phytoremediation, is one of the most promising new technologies for remediation. As with any new technology, solid data concerning the efficacy of this needs to be produced before commercial groups are willing to implement the technology. This work shows that axenic poplar cell cultures produced from hybrid poplar H-11-11 (Populus trichocarpa x P. deltoides) are capable of independently oxidizing trichloroethylene (TCE) to expected metabolites.
It also demonstrates that young rooted cuttings, when placed in metabolic chambers, are capable of taking up and transpiring both TCE and carbon tetrachloride (CT). These tests were then stepped up to a pilot scale remediation project that allows for the testing of multiple species of trees and contaminants under field conditions closely simulating what would be seen on a contaminated site. Two different trees are currently tested on the site, H-11-11 and Black Locust sp.
The hybrid poplars were exposed to TCE for two growing seasons, and to CT for one growing season. After two years exposure to TCE, the data shows that hybrid poplars were able to remove over 97% of the TCE from the water stream. Additionally, at dose concentrations up to 50ppm, there is no apparent affect on the growth of the trees. Tissue analysis shows only low levels of accumulation of TCE metabolism intermediates. At the end of the one-year exposure to CT, the trees were capable of removing 95% of CT from the water stream.
However, there was a higher susceptibility to the toxic effects of CT. Measurements of transpiration levels of both compounds are much lower than seen in the bench scale studies. Black locusts have been exposed to TCE for one growing season, and these studies will continue to better determine their field applicability. Continued use of bench and pilot scale facilities will allow the testing of different species of plants challenged with a wide range of chemicals.
Key words: phytoremediation, poplar, tri-chloroethylene, carbon tetrachloride
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