Deep underground, where sunlight never reaches and oxygen is scarce, ordinary bacteria may be carrying out an unexpected chemical trick. Give the microbes a simple food source called glycerol, and they can help pull dissolved uranium out of contaminated mine water. In laboratory experiments using real mine water, researchers found that roughly 90 to 95 percent of dissolved uranium was removed over several weeks, while part of the uranium became locked into a rare pentavalent form that can remain remarkably stable.
The finding matters because uranium does not always remain safely buried inside rocks. Mining can expose uranium-bearing minerals to water and alter the metal's chemical state.
