Objetivo The remediation of uranium-contaminated sediments and aquifers remains a major environmental challenge, yet the processes that control uranium speciation and mobility in the subsurface remain largely unknown. In anoxic systems, two major processes may lead to uranium reduction: direct electron transfer via bacterial metabolism or indirect electron transfer from microbially- reduced metals. Our initial experiments confirm that bacterial reduction of U(VI) may lead to the stable mineral uraninite (UO2), but in some cases a non-uraninite U(IV) species is produced. This species has been dubbed ‘monomeric U(IV)’ due to the absence of a feature in the x-ray absorption spectrum that is characteristic of the U-U interaction found in uraninite. The presence of this monomeric U(IV) species is an important development because is expected to be less stable than uraninite. Thus, its formation may have critical implications for predicting uranium immobilization in the subsurface. Here we propose an interdisciplinary project, utilizing tools from microbiology, geochemistry, and spectroscopy, to determine the conditions that mediate the formation of non-uraninite U(IV). We will initially conduct batch experiments with several bacterial species, both in the presence and absence of iron as an electron acceptor, and monitor the production of iron and uranium precipitates. Using a suite of tools including transmission electron microscopy, selected area electron diffraction, Mössbauer spectroscopy, and extended x-ray absorbance fine structure, we will identify the speciation of reduced uranium and the mechanisms that control its reduction. Based on these results, we will conduct a series of uranium flow-through column studies to more closely simulate natural conditions. The results of these studies will help in planning environmental remediation strategies at uranium-contaminated locations and in nuclear repository design. Ámbito científico natural sciencesearth and related environmental sciencesgeochemistrynatural sciencesbiological sciencesmicrobiologybacteriologynatural sciencesphysical sciencesopticsmicroscopyelectron microscopynatural sciencesphysical sciencesopticsspectroscopyabsorption spectroscopy Programa(s) FP7-PEOPLE - Specific programme "People" implementing the Seventh Framework Programme of the European Community for research, technological development and demonstration activities (2007 to 2013) Tema(s) FP7-PEOPLE-2009-IIF - Marie Curie Action: "International Incoming Fellowships" Convocatoria de propuestas FP7-PEOPLE-2009-IIF Consulte otros proyectos de esta convocatoria Régimen de financiación MC-IIF - International Incoming Fellowships (IIF) Coordinador ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE Aportación de la UE € 174 065,20 Dirección BATIMENT CE 3316 STATION 1 1015 Lausanne Suiza Ver en el mapa Región Schweiz/Suisse/Svizzera Région lémanique Vaud Tipo de actividad Higher or Secondary Education Establishments Contacto administrativo Rizlan Bernier-Latmani (Prof.) Enlaces Contactar con la organización Opens in new window Sitio web Opens in new window Coste total Sin datos
