The linkage between uranium, iron and carbon cycling, processes at interfaces: evidences from combined solution chemical and spectroscopic studies
- Autores: Mireia Grivé Solé
- Directores de la Tesis: Jorge Bruno Salgot (dir. tes.), Lara Duro Pérez (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2005
- Idioma: inglés
- Tribunal Calificador de la Tesis: Joan de Pablo Ribas (presid.), Ignaci Casas i Pons (secret.), Ingmar Grenthe (voc.), Carlos Ayora Ibáñez (voc.), Christoph Hennig (voc.)
- Materias:
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- Resumen
The presence of radionuclides in soils and waters due to nuclear waste management facilities and uranium mining tailings is a problem of major environmental concern. The mobility of these radionuclides in oxic groundwaters is linked to the iron cycle and controlled by geochemical processes such as adsorption on major mineral surfaces and precipitation/dissolution.
In this context, iron oxides and oxyhydroxides are of particular importance due to the fact that they are ubiquitous in nature and to their large capacitiy to sorb radionuclides, among them hexavalent uranium. The iron and uranium cycles are linked to the carbon one since aqueous carbonate plays a major role in the transport of radionuclides due to its high affinity to form complexes with some radionuclides, specially with uranium. Furthermore, 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.
The ability to develop adequate models for predicting the fate of inorganic contaminants in surface environments is highly dependent on accurate knowledge of the distribution of these constituents between the solid and solution phases and ultimately on the capability to provide molecular-level information on chemical species distributions in both of these phases. Most of the information we have about interactions of cations or anions at mineral/water interfaces comes from macroscopic measurements. In the last years, efforts to quantify observed sorption reactions at solid/liquid interfaces by means of surface complexation models have been developed. However, it is very difficult to precisely study these sorption reactions without spectroscopic evidence, mainly due to the uncertainty in the definition of the nature of the surface species formed.
