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Columns::September 22, 2003
UGA, MCG study long-term impact of schizophrenia drugs
Two new faculty members are named Eminent Scholars in molecular genetics, biochemistry
New digital library collection looks at architectural sites, landscapes
Song sung blue: Proposed water projects are bigger threat to local songbirds than timber harvesting
Law professor briefs his students on legal ethics, civil procedure
Retirees
Kudos
Primary messages: Political scientist studies campaign communication strategies of presidential candidates
Movers and shakers
Campus News
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| Geneticist Richard Meagher is working with the city of Danbury, Conn., to remove mercury from soil at an old industrial site. |
Root of the problem
Researchers plant trees that help clean up toxic waste site
By Phil Williams
phil@franklin.uga.edu
Can genetically engineered cottonwood trees clean up a site contaminated with toxic mercury? A team of UGA researchers--in the first such field test ever done with trees--is about to find out.
The results could make clearer the future of phytoremediation--a technique of using trees, grasses and other plants to remove hazardous materials from the soil. On July 16, UGA scientists and city officials in Danbury, Conn., planted, at the site of a 19th-century hat factory in that city, some 60 cottonwoods with a special gene.
“We hope to see a significant difference in the levels of mercury in the soil within 18 months, perhaps as much as a twofold reduction,” says Richard Meagher, professor of genetics.
The field test is a collaboration among UGA, Western Connecticut State University, Applied PhytoGenetics of Athens and the city of Danbury.
While the technology now being used in Danbury does not apply to all sites, mercury pollution is a pervasive problem in Georgia as well as elsewhere. The site of a former chemical factory near Brunswick, for example, is polluted with mercury and other toxic chemicals. Mercury contamination has been reported around the sites of former gold mines in north Georgia, and advisories have been issued during the past decade for mercury-contaminated fish in more than 80 streams, lakes and creeks in the state.
Meagher’s team did the first-ever field trial of a genetically engineered plant to sequester mercury when it grew transgenic tobacco in a New Jersey field trial in 2001, but this is the first such trial using trees, whose larger root systems and year-round life cycle make them better candidates for long-term cleaning of polluted soil.
Phytoremediation is a relatively new field and one gaining international interest. A team of photographers working for National Geographic, for instance, recently spent considerable time with Meagher, filming his work as part of a four-part documentary that will be aired some time next winter.
Meagher has for more than a decade been a pioneer in phytoremediation, and he was the first to demonstrate that a gene called merA can be inserted into plants and used to detoxify mercury in the environment. Since it is an element, mercury cannot be broken down by any plant, but less-toxic forms can be created, and that has been the goal of Meagher’s lab--to find ways to let plants or trees grow on polluted sites, draw such heavy metals as mercury into the plants themselves and then either transpire less-toxic forms of the metal into the air where they are quickly diffused or trap the metal aboveground for later harvest.
The project with Danbury came about because Danbury’s environmental coordinator, Jack Kozuchowski, had in 1977 published an early study that showed how native plants could transfer mercury from contaminated soils into the atmosphere. Kozuchowski, aware of Meagher’s work, convinced officials in Danbury that the so-called Barnum Court site in that town would be a perfect place for a field trial of the genetically engineered trees that Meagher and his collaborator Scott Merkle have developed.
The city was awarded a grant of $55,162 from the Environmental Protection Agency to explore use of the technology, and the trial was set up--though most costs for the work are being born by those involved in it.
“It is our hope that the research will lead to a cleansing of the Barnum Court property so the city can transfer the property for development,” says Mark Boughton, mayor of Danbury.
Meagher’s mercury phytore-mediation technology is exclusively licensed to Applied PhytoGenetics, or ApGen, as it is called, and that Athens company has been instrumental in helping set up the field trial. Meagher is a consultant to and cofounder of ApGen.
Postdoctoral associate Andrew Heaton of Meagher’s lab and another of Meagher’s students traveled to Danbury in July to supervise planting the genetically engineered trees in enclosed plastic containers buried on the site.
Because the mercury on the site ranges, depending on location, from five to more than 300 parts per million, trials were set up to measure the effects of the cottonwood trees on progressively more polluted samples of soil.
Forty-five plots, most planted with four trees each, are located on the site, which is in a mixed-use urban area and whose total area is less than an acre.
Some 15 plots have four merA trees, 15 are non-engineered or “wild-type” trees and 15 received no trees at all, so there are 120 trees in the field test.
The form of mercury at the Danbury site is ionic mercury, a species that can be sequestered and transformed into less-toxic metallic mercury in the transgenic trees and then transpired into the atmosphere.
Several forms of mercury were used in hat-making in the 19th century, and mercury’s toxic effects often sickened workers and led to the phrase “mad as a hatter,” in reference to the process of neurological degeneration that came from working with the metal.
In this part of New England, the symptoms of mercury poisoning were called the “Danbury shakes.”
Meagher’s lab actually has two genes that can effect phytoremediation, merA and merB, but since the merA is active on ionic mercury, the cottonwoods chosen for the Danbury trial express the merA gene.
While the trees at the site will have to be watered, the costs of that pale in comparison to traditional clean-up methods--digging up the polluted soil and hauling it off for storage at another site--at a cost possibly greater than $1 million. |
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