New Method for Determining Chemical Species of Uranium in Environmental Samples
Uranium in the environment exists in soluble and insoluble forms. Understanding transformations among these forms is a key aspect to developing models of uranium transport in subsurface environments. Uranyl ion [oxidized, uranium (VII)] is the main soluble form, while the mineral uraninite [reduced, uranium(IV)] is the most prominent insoluble form. Recent research has suggested that uraninite may not be the only reduced form of uranium, with non-crystalline species also present in environmental samples. However, until now it has been difficult to measure the amounts of these species. New DOE research has led to a reliable method for measuring the amounts of crystalline and non-crystalline uranium(IV) in environmental samples. The non-crystalline forms were selectively extracted from environmental samples under alkaline conditions that did not extract the crystalline uraninite, followed by separate measurement of the extracted and unextracted uranium by inductively coupled plasma optical emission spectrometry. The new method will be particularly useful in studying chemical forms of uranium at field sites where interaction of the uranium with minerals and bacteria complicates prediction of uranium movement in the environment.
Alessi, D. S., et al. 2012. “Quantitative Separation of Monomeric U(IV) from UO2 in Products of U(VI) Reduction,” Environmental Science and Technology 46(11), 6150-57. DOI: 10.1021/es204123z.