One of the major problems plaguing uranium mines, nuclear waste dumps and areas where depleted uranium was widely used in munitions during wars is the leaking of radioactive materials into the ground which wind up polluting the ground water underneath the dump. This pollution can make its way through the water table to the site of wells that supply drinking water or into surface water, posing a threat to the people in the area. One of the worst examples of this is at the Hanford Nuclear Reservation where millions of gallons of radioactive liquid from nuclear bomb manufacture were poured into unlined dirt trenches and allowed to soak into the soil. This happened decades ago but radioactive materials are still moving through the ground and out into the Columbia River. Various schemes have been proposed and some are being tested to halt this leakage but none are guaranteed to work.
Now a research team at the School of Environmental and Biological Sciences at Rutgers University have found a soil bacteria of a type called betaproteobacteria in an old uranium mine in Rifle, a town near Denver, Colorado which may be the answer to this problem. There have been suggestions that bacteria could be used for radioactive pollution cleanup, but this is the first betaproteobacteria that has been found that can utilize oxygen or uranium for the energy needed to drive metabolism. This is unique. Other types of metal consuming bacteria exist but they cannot consume oxygen as an alternative energy source and must rely on metals such as iron.
If the new betaproteobacteria is utilizing uranium for energy, the uranium is immobilize in the soil. After this betaproteobacteria interacts with uranium compounds dissolved in water, the uranium is precipitated out of solution and turned into solid uranium nanoparticles no longer dissolved in the water. This means that the uranium cannot be carried out of the ground and contaminate drinking water.
Considering the thousands of sites around the world that have soil contaminated with radioactive materials, this betaproteobacteria could be used for what is called bioremediation to lock the radioactive contamination in the soil and prevent ground water from carrying it to the surface. While chemical solutions have been researched for immobilizing radioactive materials in soil, these chemicals are toxic and expensive to deploy in large areas. It would be much better to use an existing soil betaproteobacteria for such work.
Metastudies of epidemiological data have shown that there is no safe level for radioactive materials in the environment. Even the natural background radiation from natural uranium in the soil is a threat to human health. Natural background radiation varies from place to place. If an effective and inexpensive bioremediation process could be developed based on the new betaproteobacteria, it might make sense to apply it in places where the natural background radiation is highest even though no human activity contributed to the level of radiation.
Rutgers University School of Environmental and Biological Sciences:
