Ranger Mine - a uranium mine in Kakadu National Park, Australia.
SYDNEY: Some bacteria have the capacity to stabilise uranium contaminated sites, and if they are used they could reduce the chances of these sites contaminating major waterways and ecosystems, U.S. scientists have said.
Of the millions of tonnes of bacteria living within the Earth's subsurface, some are able to transform the oxidative state of uranium, which defines how the element will interact with oxygen to form various molecules. They change it from the radioactive, toxic and water soluble uranium (VI) to the less soluble, stationary and therefore less harmful uranium (IV) as part of their normal growth.
While this process is relatively well known and has been demonstrated numerous times, until now most studies have occurred in the lab without the added difficulties associated with working in the field. Namely, that uranium isn't the only element that the bacteria affect.
Bacteria causes changes in other elements too
"Bacteria cause chemical changes in several elements, including iron and sulphur," said Ken Kemner, a physicist with the U.S. Department of Energy's Argonne National Laboratory, which is conducting the research.
"Those changes in the iron and/or sulphur geochemistry could cause the uranium to change between soluble and insoluble forms," he said.
The Argonne scientists are studying bacteria at three uranium-contaminated research sites across the United States, one in Colorado and two others at the Pacific Northwest and Oak Ridge National Laboratories in Washington State and Tennessee, respectively. All are relics of the nuclear proliferation of the Cold War era, with the potential for contaminating major waterways.
Not yet ready to unleash on environment
Using the US Department of Energy's Advanced Photon Source (APS) electron accelerator and storage system - which provides the brightest x-ray beams in the Western Hemisphere - the scientists have been able to study the transformation of uranium at the atomic level.
"The [researchers have] 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."
yeah but it is still radioactive
so there may be an unorthodox way to chemically neutralise uranium.
great. but that's never been the issue with the huge volumes of waste produced by uranium mining. the real issue is radiotoxicity, and clearly no chemical agent is going to alter the longevity of this radioactive waste.
the nuclear industry has a tarnished history of promising bold new technological fixes to its unresolved risks and impacts; just around the corner. From electricity 'too cheap to meter'; reactors that eat their own waste, or now, uranium eating bacteria, we shouldn't allow these dreams to sway our judgements on the industry's radioactive realities.
yeah but it was always radioactive
"...clearly no chemical agent is going to alter the longevity of this radioactive waste."
Yes, and therefore it is very clear that mining did not alter the longevity of this radioactive waste either. If you believe the radioactivity of uranium needs to be reduced, there are only two ways to do that:
1) Wait a few billion years.
2) Mine it and burn it in a reactor.
Are you perhaps confusing radioactivity with toxicity?
Uranium-eating bacteria ...
Yes, well, this might be the case in a beaker in a laboratory under controlled conditions, or in a radioactive hot spring to which the bacterium has long ago adapted. However, to suggest that these little critters could rectify a major tailings dam seepage plume that has spread out into the land and aquifers of a world heritage national park located in a monsoonal climate is somewhat fanciful.
Do the mathematics and see what you reckon: 30 years at 100,000 litres/day from a source that contains around 25 mg/litre of uranium is a darned lot of contamination - even if someone actually knew exactly where in the regional environment it had gone.
Another point is that such reactions do not occur as a single process. For example, there is a sulphur-eating bacterium that is commonly used in the mining industry. It certainly does "eat" sulphur, but it does so at the expense of other species. In that case, iron is oxidised and mobilised. The valency of an atom in part decides its bio-availability and chemical toxicity, and there are a lot of other contaminants in uranium tailings. What, for example, would be the effects on other species like radium and other radionuclides that are concentrated in uranium mill tailings? Robert Anitori does not tell us the mechanism of his "cure" and what are the attendant results for other species present.
A further valid point was made in a previous comment on this article. Chemical toxicity is one thing, but radiotoxicity is quite another.
Although I do not say this story makes false statements, I certainly would challenge its application to cleaning up the Ranger tailings mess. And I would have expected a little more critical editorial evaluation of claims like this.
Doctor Wu ... Chartered Chemist and former uranium mine environmental officer.
Editing required
On the third line of the first paragraph, "reducing" should be changed to "reduce". On the fourth line of the second paragraph, the first "with" should be changed to "will".