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True Green Report
The Bringing a little "Cottony-Softness" to Toxic Wastelands
by Matthew Macdonald
January 12, 2004
A new program in Connecticut is bringing some cottony-softness to the harsh field of toxic wasteland clean up.
In a new experiment, scientists from the University of Georgia are introducing genetically modified cotton plants into a soil that has toxic levels of mercury. The plants have added genes that enable them to live in mercury-contaminated soil. This new gene allows the plant to soak up the mercury into the cotton tree, thus removing the toxin from the soil.
This has drastic implications for governments looking to clean up toxic wastelands. The cost of planting some genetically modified cotton plants is minuscule compared to the current methods of soil decontamination. In Danbury, Connecticut the city is looking to use such advancements to cut down on the exorbitant costs of cleaning some of their contaminated soils from the days when they were home to the ‘hatting’ industry. ‘Hatting’ was the making of hats, which used harsh chemicals, including mercury, in the formation process.
"Excavation, removal and replacement of the toxic soil would cost $543,000 [US], the cottonwood trees cost us next to nothing," Jack Kozuchowski, Danbury's Environmental Director told the science magazine Popular Science.
Phytoremediation is the use of plants to neutralize or remove contaminants from soil or water. With such measurable advantages for governments, phytoremediation is receiving a lot more attention.
Most plants cannot live in soil that is heavily contaminated by mercury, however there are some bacteria that can. Scientists have isolated the genes in these bacteria that give them this natural resistance. The genetically modified cotton plants have the genes MerA and MerB inserted in them. These genes produce enzymes, which are involved in mercury decontamination. Dr. Richard Meagher, at the University of Georgia, has written numerous papers on the field of phytoremediation. "These two enzymes are critical to various strategies of engineered mercury phytoremediation," says Meagher.
One of the big advantages of the cotton trees is that they take 5 years to reach sexual maturity. Thus the experiment/treatment can be completed long before any threat of mass reproduction by the plant --a major criticism of most genetically modified plants.
One concern is that the plants can transpire the mercury into the air through their leaves. However the amount and chemical form of the mercury poses a much-decreased toxicity compared to leaving it in the soil. Prior to the enzymes acting on the soil the mercury can be ‘biomagnified’ (increased) by six to eight orders of magnitude. The mercury that is released via the leaves is not biomagnified in its new form.
Even in Canada, phytoremediation is getting a lot of attention. The Department of Defence is funding numerous projects in the field through the Royal Military College; and there are numerous graduate programs throughout other Canadian universities as well.
With such attention to this interesting field, phytoremediation scientists are showing that the harsh world of chemical decontamination can have a cottony-soft edge.
Matthew Macdonald is a Christianity & Culture and Life Science student at the University of Toronto. His areas of interests include Politics, interactions between Church and Politics, Science, Toxicology and Pharmacology. He can be reached via email: matt@macdonald.ca
