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CORVALLIS - Sometimes the Earth's smallest organisms can be called upon to carry out some of the world's largest and most ominous tasks, like stopping the spread of radioactive nuclear waste in groundwater.

The U.S. Department of Energy has just awarded researchers at Oregon State University $1.3 million to further explore how bacteria commonly found in soils can be tapped to stop the subsurface spread of radionuclides like uranium and technetium.

Throughout the Cold War, these radioactive compounds were improperly disposed of during nuclear warhead production and are now dissolved in groundwater. They have been silently spreading into miles-long, underground plumes, making cleanup efforts complicated and tremendously costly.

"Many of these contaminated sites are miles across," said Jack Istok, a professor of environmental engineering at OSU. "Because the amount of waste is so large, and the contaminated sites so vast, it would cost trillions of dollars - fractions of the gross national product - to clean it all up using traditional methods. So the Department of Energy is looking for cheaper cleanup alternatives."

Cleanup is not quite the right term, Istok admits, because uranium and other long-lived radionuclides are impossible to scrub from the earth, at least until they naturally decay, which can take up to a few billion years.

"Uranium has a half-life of a billion years," Istok said. "In a billion years, half of what's here now will still be here."

But Istok and OSU colleague Jennifer Field, a professor of environmental microbiology and toxicology, are at the cutting edge of a plan to enlist the help of billions of bacteria to contain the toxins and keep them from contaminating any more groundwater.

Earlier this year, Istok and his team proved for the first time in field tests that a certain community of metal-reducing bacteria can in fact halt the spread of nuclear waste. Their breakthrough research results led to the U.S. Department of Energy grant.

"We are the first people to do this - to show in the ground that you can get the bacteria to grow and stop the spread of uranium and technetium," Istok said. "Nobody else is doing this kind of testing in the field."

Istok says the procedure is quite simple. By feeding the bacteria a biodegradable solution of glucose or ethanol, the tiny organisms quickly reproduce, triggering a chemical change in the soil that causes the radionuclides in the groundwater to precipitate and adhere to the soil where they stay put instead of continuing to spread. The groundwater, now free of the toxic waste, continues on its way.

Istok and his interdisciplinary team of researchers, students, and scientists at OSU, the University of Oklahoma, Pacific Northwest National Labs and Oak Ridge National Labs will now engineer a full-scale onsite drip system to feed the bacteria and further enhance the effectiveness of this groundbreaking technology.

Istok hopes his team's work will lead to installation of a large-scale, cost-effective cleanup operation, perhaps as close to home as nearby Hanford, located just up the Columbia River from Portland.

"This is very important, because so many sites exist all over the world," Istok said. "And the waste is continuing to spread."