Phytoremediation: Using Plants To Clean Up Soils

When it comes to helping clean up soils contaminated with heavy and toxic metals, nature has ARS plant physiologist Leon V. Kochian to thank. 

During 13 years of research at the U.S. Plant, Soil, and Nutrition Laboratory at Ithaca, New York, Kochian has become an authority on mechanisms used by certain plants to take up essential mineral nutrients and toxic heavy metals from soils. He has also characterized strategies some plants use to tolerate toxic soil environments.

Kochian is an international expert on plant responses to environmental stress, plant mineral nutrition, and use of plants to clean up or remediate soils contaminated with heavy metals and radioisotopes.

Besides providing important new information on how to use plants in this practical way, Kochian's research may also shed light on an important nutritional concern: how to prevent toxic metals from entering the food chain.

"One of the primary ways toxic heavy metals, such as cadmium, get in food is through plant uptake—the metal is taken up by the roots and deposited in edible portions," he says.

"Contaminated soils and waters pose major environmental, agricultural, and human health problems worldwide," says Kochian. "These problems may be partially solved by an emerging new technology—phytoremediation."

"Green" Technology: Simple Concept and Cost-Effective

Phytoremediation is the use of green plants to remove pollutants from the environment or render them harmless.

"Current engineering-based technologies used to clean up soils—like the removal of contaminated topsoil for storage in landfills—are very costly," Kochian says, "and dramatically disturb the landscape."

Kochian's cost-effective "green" technology uses plants to "vacuum" heavy metals from the soil through their roots. He says, "Certain plant species—known as metal hyperaccumulators—have the ability to extract elements from the soil and concentrate them in the easily harvested plant stems, shoots, and leaves. These plant tissues can be collected, reduced in volume, and stored for later use."

While acting as vacuum cleaners, the unique plants must be able to tolerate and survive high levels of heavy metals in soils—like zinc, cadmium, and nickel...

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