Sorption properties of peat's organic matter for U and $^{226}$Ra in mining areas

G. Bordelet (1) , C. Beaucaire (1) , M. Descostes (2) , V. Phrommavanh (3)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 Groupe AREVA
3 AREVA

The environmental footprint of former uranium mining activities is a major concern for AREVA who is in charge of monitoring these ancient mining sites. In order to limit the radiological impact on the biosphere we must have a good knowledge of the chemical properties controlling the migration of uranium (U) and its decay products, in particular radium ($^{226}$Ra). This present study is focused on an acidic peat land typical of those found in the vicinity of former mining sites in the Limousin region (France). Peat is a complex material which combines in various proportions, many components such as organic compounds (humic and fulvic acids, organic acids, bacteria, fungi) and mineral phases (clay minerals, oxides), each having their own specific reactivity and influence on U(VI) and $^{226}$Ra behavior.This study aims to acquire the sorption properties of U(VI) and $^{226}$Ra on natural organic matter from peat. According to the ion exchange formalism frequently used to describe the sorption behavior of clay-minerals, oxides and more generally soils, the peat sorption properties were successfully determined, i.e. the amount of sorption site types and their selectivity towards U(VI) and $^{226}$Ra. These sorption parameters would then be implemented in geochemical models used for the environmental impact assessment of mining sites.

Mots clés: uranium; radium; peat; sorption; modelling; ion-exchange; uranium mines

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique Nucléaire Théorique [nucl-th]

G. Bordelet, C. Beaucaire, M. Descostes, V. Phrommavanh. Sorption properties of peat's organic matter for U and $^{226}$Ra in mining areas. International conference contaminated sites - 2015, May 2015, Bratislava, Slovakia. ⟨cea-02500840⟩