Bugs boost Cold War clean-upBacteria could scrub uranium from sites
contaminated decades ago.
13
October 2003
BETSY MASON
 |
| Traditional clean-up
techniques can expose workers to toxic levels of
radioactive uranium. |
| ©
SPL | | |
Uranium-contaminated groundwater can be cleaned up by
resident microbes, say microbiologists1.
Cold War-era uranium processing has left contaminated
sites across the United States and the world.
Traditional pump-and-treat methods can take decades and
expose workers to toxic levels of uranium. Now a better
solution is being proposed by Robert Anderson, of the
University of Massachusetts Amherst, and his
colleagues.
Anderson's team has found a way to encourage microbes
called Geobacter to convert soluble uranium to insoluble
uraninite. Uraninite stays put instead of mixing with
water used for drinking or irrigation. "I think this is
something we might be using in the near future," says
Anderson.
"This is a major step," agrees Jonathan Istok of
Oregon State University in Corvallis, who has had
similar success in using microbes to mop up both uranium
and another element, technetium. "We're pretty close to
being able to apply this to the real world," he says.
Divide and rule
Geobacter are best known as iron-eaters, but in 1991
team member Derek Lovley, also at Amherst, proved that
the bugs could metabolize uranium in the laboratory2.
The bacteria turn up in sediments across the United
States, but usually in small quantities. Anderson's team
stimulated the bugs to multiply in a contaminated
underground aquifer in Colorado by injecting acetate, a
favourite nutrient.
|
We're pretty close to being able
to apply this to the real world |
|
Jonathan Istok
Oregon
State
University | | |
Within days the Geobacter population boomed, and
soluble uranium levels began to drop. After 50 days, 70%
of the uranium had been converted into uraninite.
The site used in the study was contaminated by low
levels of uranium from mining residue. The team hopes
that the technique might eventually be used to clean
heavily contaminated sites, such as those run by the US
Department of Energy, which funded the research. "We
know these organisms can grow in extremely high
concentrations of uranium," says Lovley. | 
