Puzzled by uranium

In sites scattered across the Earth, the extraction and processing of uranium for nuclear fuel and weapons has left aquifers contaminated. Immobilizing the contaminant through the action of bacteria has been considered a potential solution to limit its transport away from the contamination site. A recent article by Professor Rizlan Bernier-Latmani and collaborators, published last week in Geochimica et Cosmochimica Acta, points to new unknowns and paints a more complex picture. Less than a year ago, the nuclear power industry had the wind in its sails, thanks to increasing global energy consumption and public support for carbon neutral power generation. Then came Fukushima. Although the future of nuclear energy has become less certain - Switzerland and Germany have decided to abandon it altogether - demand for uranium is not expected to decrease; besides its use as an energy source, uranium is in high demand for its military and medical applications. And while a significant fraction of uranium used today is recovered from decommissioned Russian nuclear submarines, those stocks will eventually become exhausted, renewing the need to mine for the radioactive metal. Uranium is a naturally occurring radioactive element that can be found in low concentrations throughout the earth's crust. Extracted from uranium ore, most commonly uraninite (UO2), it becomes a hazardous contaminant when mined and processed, since this produces soluble oxidized uranium, U(VI). Once released, it quickly reaches groundwater, threatening potential subsurface sources of drinking water. Ultimately, it makes its way to rivers. So how could the uranium be kept from reaching the groundwater?