Argonne scientists seek natural remediation for uranium-rich sites

Mar 19, 2010
Argonne scientists Ken Kemner (right) and Ed O’Loughlin work to better understand exactly how bacteria chemically changes uranium. Photo by George Joch / courtesy Argonne National Laboratory.

While most of us are focused on life above ground, scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory are trying to understand the drama unfolding beneath our feet.

Their work centers on the more than billions of tons of bacteria living within the Earth’s subsurface, below the root zone, and how they change the of the rocks and minerals they touch, including . The result could prove useful in a surprising way.

Scientists know some bacteria can change Uranium (VI)—which is radioactive, toxic and water-soluble—into the more insoluble, stationary and thus less harmful Uranium (IV).

What they don't know is how to harness this so it could help reduce the danger posed by the more than 1,000 uranium-contaminated sites scattered across the nation.

Some of these sites—relics of the Cold War era—are near major waterways, including the Colorado, Tennessee and Columbia Rivers, making their remediation a high priority for the DOE.

Uranium (VI) can be transported by groundwater, so wherever water goes, the uranium goes with it. The key is to make it immobile, to stop it before it's introduced into the and ultimately to humans.

Certain species of bacteria can do just that.

"We know that some bacteria turn uranium into rock form so that it can't move," said Ken Kemner, an Argonne physicist. "That could be critical for some of these sites.

But the process isn't without a few kinks. That's because uranium isn't the only element that bacteria can change—and this is where a seemingly simple process grows complicated.

"Bacteria cause chemical changes in several elements, including iron and sulfur," Kemner said. "And those changes in the iron and/or sulfur could cause the uranium to change between soluble and insoluble forms."

It's these problems that Kemner and a team of Argonne microbiologists, chemists, physicists and geochemists are trying to figure out. They're working to find a way to enhance the stability of the immobile form of uranium while many other processes are occurring.

"We want to know why and how this happens, so that we might one day use this process to our advantage in terms of cleaning up sites contaminated with heavy metals and radioactive elements," Kemner said.

The Argonne team is part of the DOE’s efforts in Subsurface Biogeochemical Research, which performs some of the basic research needed to tackle some of the country's most challenging environmental cleanup problems.

Argonne scientists are uniquely positioned because they have access to the laboratory's Advanced Photon Source (APS). The APS provides the brightest x-ray beams in the Western Hemisphere, allowing scientists to understand uranium's transformation at the atomic level.

Argonne researchers recently published two papers on the topic. Both appeared in the journal Environmental Science and Technology, and both focused on uranium immobilization. The first was published in January 2010 and the second a month later.

In the first study, Argonne's team used the APS to better understand the chemical transformations of uranium and iron. In the second study, scientists used the APS to investigate how iron helps to chemically transform and immobilize uranium underground.

While Kemner and his associates conduct much of their research in the laboratory, they are also part of research teams that work out in the field. The teams study bacteria at three uranium-contaminated research sites across the country: one in Colorado and two others at Pacific Northwest and Oak Ridge National Laboratories.

Their findings are promising.

"The Department has successfully demonstrated in some pilot studies that this really works," Kemner said. "But we don't understand it enough that we can go off into the environment and routinely employ the bacteria on a larger scale."

Kemner emphasizes that the research is not focused on creating new bacteria and releasing them into the environment, as some critics have feared.

"We are working only with the indigenous population," he said. "We have all the we need underground to do the job."

Argonne's most recent papers on this topic are available online from the journal Environmental Science and Technology, here and here.

Explore further: Pact with devil? California farmers use oil firms' water

Related Stories

Patience pays off with methanol for uranium bioremediation

Feb 23, 2009

The legacy of nuclear weapons and nuclear energy development has left ground water and sediment at dozens of sites across the United States and many more around the world contaminated with uranium. The uranium is transported ...

Scientists find safer ways to detect uranium minerals

Nov 21, 2006

The threat of "dirty" bombs and plans to use nuclear power as an energy source have driven Queensland University of Technology scientists to discover a new, safer way of detecting radioative contamination in the ground. Professor ...

Recommended for you

Stronger action needed to transform the UK's energy system

39 minutes ago

An ambitious policy package is essential for the UK to transform its energy system to achieve the deep reductions in carbon emissions required to avoid dangerous climate change, according to research led by UCL scientists. ...

Gimmicks and technology: California learns to save water

Jul 03, 2015

Billboards and TV commercials, living room visits, guess-your-water-use booths, and awards for water stinginess—a wealthy swath of Orange County that once had one of the worst records for water conservation ...

Cities, regions call for 'robust' world climate pact

Jul 03, 2015

Thousands of cities, provinces and states from around the world urged national governments on Thursday to deliver a "robust, binding, equitable and universal" planet-saving climate pact in December.

Will climate change put mussels off the menu?

Jul 03, 2015

Climate change models predict that sea temperatures will rise significantly, including in the tropics. In these areas, rainfall is also predicted to increase, reducing the salt concentration of the surface ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Mar 19, 2010
Bio Leaching is already used on some gold and copper deposits. This is very exciting technology as it reduces the contaminantes on the tailings and slimes dumps.

Bio-leaching bacteria requires a controlled temperature on the dump for effective operation. How are they going to achieve that with an in situ operation?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.