Kinetics of incongruent dissolution of carbonates in a Chalk aquifer using reverse flow modelling
Gillon, Marina | Renard, François | Crançon, Pierre | Aupiais, Jean | Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH) ; Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | DAM Île-de-France (DAM/DIF) ; Direction des Applications Militaires (DAM) ; Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
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Показать больше [+] Меньше [-]Английский. s u m m a r y Water–rock interactions are major processes that control the solute transfer (from natural or anthropo-genic sources) in aquifers. In carbonate aquifers, these water–rock interactions are mainly characterised by the incongruent dissolutions of carbonates. The in situ quantification of these reactions is few studied. In the present paper, we provide a new quantification of the kinetic rates of simultaneous incongruent dissolution of composite carbonate and dolomite in a Chalk aquifer. The approach is based on a mass-balance model used to calculate the rates of mineral dissolution and precipitation along a 500 m to 4 km flow path starting at the groundwater divide line. The groundwater transfer times between the groundwater divide line and the wells are calculated thanks to flow and transport modelling, used in a backward particle tracking mode. The uncertainties on porosity, dispersivity and transmissivity are taken into account. The rates are found ranging between 1.5 Â 10 À5 and 1.5 Â 10 À4 mol C5 chalk L À1 w yr À1 for the composite carbonate dissolution, between 1.0 Â 10 À7 and 3.0 Â 10 À6 mol dolomite L À1 w yr À1 for the dolomite dissolution and between 1.0 Â 10 À5 and 1.5 Â 10 À4 mol calcite L À1 w yr À1 for the calcite precipitation. The results highlight the importance of physical and geological properties of the aquifer.
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