The linkage between uranium, iron and carbon cycling. Processes at interfaces: evidences from combined solution chemical and spectroscopic studies

Interfacial processes have a critical role in many reactions and phenomena in the environment, including mineral weathering, particle stability in surface waters, transport of chemical species and element cycling in natural environments. In order to predict the environmental impact of human activities such as uranium mining and radioactive waste disposal, it is necessary to understand the migration of actinides, uranium among them, in the environment. Iron oxides and oxyhydroxides are ubiquitous in nature and they are of particular interest due to their large capacity to sorb radionuclides onto their surface. The Fe and U cycles are also linked to the carbon one and aqueous carbonate plays a major role in the transport of radionuclides due to its high affinity to form complexes with hexavalent uranium. On the other hand, dissolved carbonate can compete for the sorption sites of the iron oxides, promoting the dissolution of these oxides and consequently increasing the mobility of the associated radionuclides in natural systems. Our understanding of how radionuclides impact the environment is dependent on our ability to measure chemical reactions at environmental interfaces. (orig.)