Researchers, Chrysler Test Trees for TCE Remediation
Purdue
University researchers are collaborating with Chrysler LLC in a project
to use poplar trees to eliminate pollutants from a contaminated site in
north-central Indiana.
The researchers plan to plant transgenic poplars at the site, a
former oil storage facility near Kokomo, Ind., this summer. In a
laboratory setting, the transgenic trees have been shown to be capable
of absorbing trichloroethylene (TCE) and other pollutants before
processing them into harmless byproducts.
Richard Meilan, a Purdue associate professor, is currently at work
to transform one variety of poplar suited to Indiana's climate;
cold-hardy poplars are generally more difficult to alter than the
variety used in a laboratory setting. In a study Meilan co-authored,
published last October in Proceedings of the National Academy of Sciences,
poplar cuttings removed 90 percent of the TCE within a hydroponic
solution in one week. The engineered trees also took up and metabolized
the chemical 100 times faster than unaltered hybrid poplars.
Meilan said he thinks the transgenic poplars will be able to remove
the TCE from the site, which was contaminated by tainted oil stored
there in the 1960s. The chemical, used as an industrial solvent and
degreaser, lies within 10 feet of the surface, making it accessible to
poplar roots, he said.
Planting transgenic trees in the field remains controversial, Meilan
said, primarily due to concerns that inserted genes, or transgenes,
might escape and incorporate into natural tree populations.
Meilan has applied for a permit to grow transgenic poplars in a
field, or non-laboratory, setting from the Animal and Plant Health
Inspection Service, the government organization responsible for
regulating such research activities, he said.
In order to comply with permit guidelines and to protect the
environment, Meilan's team will take measures to prevent any plant
material from leaving the site and will remove the trees after three
years, short of the five it takes for poplars to reach sexual maturity,
he said.
Besides their use in phytoremediation, or pollution removal, poplars
have promise as a feedstock for cellulosic ethanol. To investigate
their potential in this area, the U.S. Department of Energy awarded a
$1.3 million grant to Meilan and two colleagues.