Distribution of uranium in soil profiles of Bahia State, Brazil

In the present work we study five soil profiles and explain the measured uranium concentrations on the basis of an isovolumetric reasoning. The results show that, despite an important loss of uranium to the outgoing solutions when the parent rock is transformed into alterite and soil, the relative concentration in the residual soil increases. To improve our knowledge of the distribution of uranium in the components of the soil, we measured its concentrations in clays and heavy minerals, which are the main bearers of uranium. To explain the phenomena of adsorption and desorption of uranium in clays, we performed, in the laboratory, lixiviation experiments on soil samples washed by water enriched in organic and mineral matter.