Water-rock interaction and residence time of groundwater inferred by 234U/238U disequilibria in the Tunisian Continental Intercalaire Aquifer System - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2013

Water-rock interaction and residence time of groundwater inferred by 234U/238U disequilibria in the Tunisian Continental Intercalaire Aquifer System

Résumé

The uranium content and 234U/238U ratios have been measured in more than thirty groundwater samples over the Tunisian part of the Continental Intercalaire (CI) aquifer. In this large artesian aquifer, uranium behavior is mainly controlled by redox front systems. The uranium concentrations vary by 5 orders of magnitude from 10-4 to 20 ppb and the (234U/238U) activity ratio from 1 to 10. Close to CI outcrops in the Dahar Mountains, the stepwise decrease in U concentrations combined with a significant increase of the (234U/238U) ratio up to 10 ("augmenting regime") is followed, downflow by a (234U/238U) decrease up to 3 ("decaying regime"), clearly indicating the occurrence of a redox front. We will discuss the significance of 234U-238U disequilibria in terms of water residence times and its potential to trace water-rock interaction mechanisms.
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Dates et versions

hal-00817841 , version 1 (25-04-2013)

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  • HAL Id : hal-00817841 , version 1

Citer

J.O. Petersen, P. Deschamps, B Hamelin, J. Goncalves, J.L. Michelot, et al.. Water-rock interaction and residence time of groundwater inferred by 234U/238U disequilibria in the Tunisian Continental Intercalaire Aquifer System. Proceedings of the 14th International Symposium on Water-Rock Interaction, WRI 14, Jun 2013, Avignon, France. pp.685-688. ⟨hal-00817841⟩
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