Reactive transport modelling of groundwater chemistry in a chalk aquifer at the watershed scale

Autor: L. De Windt, Pierre Crançon, Arnaud Mangeret
Přispěvatelé: Centre de Géosciences (GEOSCIENCES), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), 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), Mines Paris - PSL (École nationale supérieure des mines de Paris)
Rok vydání: 2012
Předmět:
010504 meteorology & atmospheric sciences
[SDE.MCG]Environmental Sciences/Global Changes
Dolomite
Incongruent dissolution
Alkalinity
Reactive transport
Aquifer
Soil science
engineering.material
010502 geochemistry & geophysics
Sensitivity and Specificity
01 natural sciences
Calcium Carbonate
chemistry.chemical_compound
Dual porosity
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry
Vadose zone
Water Movements
Environmental Chemistry
Groundwater
0105 earth and related environmental sciences
Water Science and Technology
Calcite
Hydrology
geography
geography.geographical_feature_category
Hydrochemistry
6. Clean water
Kinetics
Infiltration (hydrology)
Models
Chemical
Carbon dioxide
chemistry
Illite
engineering
Thermodynamics
France
Water Pollutants
Chemical
Geology
Environmental Monitoring
Zdroj: Journal of Contaminant Hydrology
Journal of Contaminant Hydrology, Elsevier, 2012, 138-139, pp.60-74. ⟨10.1016/j.jconhyd.2012.06.004⟩
Journal of Contaminant Hydrology, 2012, 138-139, pp.60-74. ⟨10.1016/j.jconhyd.2012.06.004⟩
ISSN: 0169-7722
DOI: 10.1016/j.jconhyd.2012.06.004
Popis: Appendix A. Supplementary data : Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.jconhyd.2012.06.004; International audience; This study investigates thermodynamics and kinetics of water-rock interactions in a carbonate aquifer at the watershed scale. A reactive transport model is applied to the unconfined chalk aquifer of the Champagne Mounts (France), by considering both the chalk matrix and the interconnected fracture network. Major element concentrations and main chemical parameters calculated in groundwater and their evolution along flow lines are in fair agreement with field data. A relative homogeneity of the aquifer baseline chemistry is rapidly reached in terms of pH, alkalinity and Ca concentration since calcite equilibrium is achieved over the first metres of the vadose zone. However, incongruent chalk dissolution slowly releases Ba, Mg and Sr in groundwater. Introducing dilution effect by rainwater infiltration and a local occurrence of dolomite improves the agreement between modelling and field data. The dissolution of illite and opal-CT, controlling K and SiO2 concentrations in the model, can be approximately tackled by classical kinetic rate laws, but not the incongruent chalk dissolution. An apparent kinetic rate has therefore been fitted on field data by inverse modelling: 1.5×10−5 molchalkL −1wateryear −1. Sensitivity analysis indicates that the CO2 partial pressure of the unsaturated zone is a critical parameter for modelling the baseline chemistry over the whole chalk aquifer.
Databáze: OpenAIRE
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