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Transfert de solutés réactifs dans la zone non-saturée des sols à différentes échelles d'observation.

Abstract : The transfer of contaminants in the unsaturated zone of soils is driven by numerous mechanisms. Field studies are sometimes difficult to set up, and so the question is raised about the reliability of laboratory measurements for describing a field situation.
The nuclear powerplant at Brennilis (Finistère, France) has been chosen to study the transfer of strontium, cobalt and inert tracers in the soil of this industrial site. Several observation scales have been tested (batch, stirred flow-through reactor, sieved-soil column, unrepacked or repacked soil-core lysimeter, field experiments) in order to determine, at each scale, the factors that influence the transfer of these contaminants, then to verify the adequacy between the different observation scales and their field representativity.
Regarding the soil hydrodynamic properties, the porosity, the water content in the field, the pore water velocity at the water content in the field, the saturation hydraulic conductivity and the dispersion coefficient of this embanked soil are spatially less heterogeneous than those of agricultural or non-anthropic soils. The results obtained with lysimeter and field experiments suggest that hydrodynamics of this unstructured soil can be studied on a repacked sample if the volume is high compared to the rare big-size stones.
Regarding the chemical soil-contaminant interactions, cobalt and strontium isotherms are non-linear at concentration higher than 10-4 mol.L-1, cobalt adsorption and desorption are fast and independent on pH. On the contrary, at concentration lower than 3.5x10-6 mol.L-1, cobalt and strontium isotherms are linear, cobalt desorption is markedly slower than adsorption and both cobalt partition coefficient at equilibrium and its reaction kinetics are highly pH-dependent. For both elements, the results obtained with batch, stirred flow-through reactor and sieved-soil column are in adequacy. However, strontium batch adsorption measurements at equilibrium do not make possible to describe the results of field transfer experiments.
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Contributor : Guillaume Limousin <>
Submitted on : Sunday, February 4, 2007 - 12:33:39 PM
Last modification on : Thursday, November 19, 2020 - 3:54:29 PM
Long-term archiving on: : Wednesday, April 7, 2010 - 2:38:27 AM

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  • HAL Id : tel-00128889, version 1

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Guillaume Limousin. Transfert de solutés réactifs dans la zone non-saturée des sols à différentes échelles d'observation.. Hydrologie. Université Joseph-Fourier - Grenoble I, 2006. Français. ⟨tel-00128889⟩

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