Modeling reactive transport in non-ideal aqueous–solid solution system

Shao, Haibing; Dmytrieva, Svitlana V.; Kolditz, Olaf; Kulik, Dmitrii A.; Pfingsten, Wilfried; Kosakowski, Georg

doi:10.1016/j.apgeochem.2009.04.001

Cited by 60 publications

(59 citation statements)

References 42 publications

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“…2 with previous results (Shao et al, 2009a) shows that the mobility of aqueous radium is considerably lower if cation exchange reactions in addition to solid solution formation is considered. Even with a limited amount of clay (Mont/ water ratio of 0.1 in Fig.…”

Section: Discussionsupporting

confidence: 67%

“…Resultant concentrations of chemical species are then passed to the subsequent time step. Details regarding code development and verification can be found in Shao et al (2009a).…”

Section: Governing Equationsmentioning

confidence: 99%

“…In such geotechnical systems, chemical interactions between radionuclides and clay minerals determine the retention e38 H. Shao et al co-precipitation, and that it will be three orders of magnitude higher if only a pure RaSO 4 phase is considered. Shao et al (2009a) numerically analyzed non-ideal aqueous-solid solution systems with both Ba-Sr-Ra carbonate and Ba-Sr-Ra sulfate formations. They concluded that the re-partitioning of radium from carbonate to sulfate may cause a strong retardation effect on Ra.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the competition between solid solution formation and cation exchange on the retardation of aqueous radium in an idealized bentonite column

et al. 2009

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Clays and clay rocks are considered viable geotechnical barriers in radioactive waste disposal. One reason for this is the propensity for cation exchange reactions in clay minerals to retard the migration of radionuclides. Although another retardation mechanism, namely the incorporation of radionuclides into sulfate or carbonate solid solutions, has been known for a long time, only recently has it been examined systematically. In this work, we investigate the competitive effect of both mechanisms on the transport of radium (Ra) in the near-field of a low-and intermediate level nuclear waste repository. In our idealized geochemical model, numerical simulations show that barium (Ba) and strontium (Sr) needed for Ra sulfate solid solutions also partition to the cation exchange sites of montmorillonite (Mont), which is the major mineral constituent of bentonite that is used for tunnel backfill. At high Mont content, most Ra tends to attach to Mont, while incorporation of Ra in sulfate solid solutions is more important at low Mont content. To explore the effect of the Mont content on the transport of radium, a multi-component reactive transport model was developed and implemented in the scientific software OpenGeoSys-GEM. It was found that a decrease of fixation capacity due to low Mont content is compensated by the formation of solid solutions and that the migration distance of aqueous Ra is similar at different Mont/ water ratios.

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Section: Discussionsupporting

confidence: 67%

“…Resultant concentrations of chemical species are then passed to the subsequent time step. Details regarding code development and verification can be found in Shao et al (2009a).…”

Section: Governing Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling the competition between solid solution formation and cation exchange on the retardation of aqueous radium in an idealized bentonite column

et al. 2009

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“…In this work we investigate the porosity evolution at a generic interface between clay and cement containing materials with novel reactive transport codes that use the chemical GEM method for the calculation of thermodynamic equilibria 14) . The use of GEM method in reactive transport codes is a step to a more realistic description of complex geochemical systems.…”

Section: Introductionmentioning

confidence: 99%

Evolution of a Generic Clay/Cement Interface: First Reactive Transport Calculations Utilizing a Gibbs Energy Minimization Based Approach for Geochemical Calculations

Kosakowski

Blum

Kulik

et al. 2009

JESSS

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The long-term evolution of deep geological repositories for nuclear waste is governed by geochemical processes in conjunction with mass and energy transport. A key role for the design of the multi-barrier system is the knowledge of long term changes at the interfaces between different materials. We investigate the porosity evolution at a generic interface between clay and cement containing materials. We use novel reactive transport codes that couple a Gibbs Energy Minimization (GEM) chemical equilibrium thermodynamic solver with mass transport solvers. Our simulations show that in the cementitious material, the porosity is increased due to the dissolution of portlandite. At the interface, the porosity is strongly reduced in the clay and cement compartment due to calcite precipitation and due to the precipitation of C-S-H solid solution. The time for clogging the interface is highly variable and depends on transport conditions and on the geochemical setup.

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“…OGS has been successfully applied in different fields like water resources management, hydrology, geothermal energy, energy storage, CO 2 storage, and waste deposition Shao et al, 2013;Gräbe et al, 2013;Wang et al, 2017). In the field of hydrology / hydrogeology, OGS has been applied to various topics such as regional groundwater flow and transport (Sun et al, 2011;Selle et al, 2013), contaminant hydrology (Beyer et al, 2006;Walther et al, 2014), reactive transport (Shao et al, 2009;He et al, 2015), and sea 20 water intrusion , etc. -Calculate model-wide and detailed water balances in both time and space.…”

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confidence: 99%

Improved representation of groundwater at a regional scale – coupling of mesocale Hydrologic Model (mHM) with OpeneGeoSys (OGS)

Jing¹,

Heße²,

Wang³

et al. 2017

Preprint

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Abstract. Most of the current large scale hydrological models do not contain a physically-based groundwater flow component. The main difficulties in large-scale groundwater modeling include the efficient representation of unsaturated zone flow, the characterization of dynamic groundwater-surface water interaction and the numerical stability while preserving complex physical processes and high resolution. To address these problems, we propose a highly-scalable coupled hydrologic and groundwater model (mHM#OGS) based on the integration of two open-source modeling codes: the mesoscale hydrologic 5 Model (mHM) and the finite element simulator OpenGeoSys (OGS). mHM#OGS is coupled using a boundary condition-based coupling scheme that dynamically links the surface and subsurface parts. Nested time stepping allows smaller time steps for typically faster surface runoff routing in mHM and larger time steps for slower subsurface flow in OGS. mHM#OGS features the coupling interface which can transfer the groundwater recharge and river baseflow rate between mHM and OpenGeoSys.Verification of the coupled model was conducted using the time-series of observed streamflow and groundwater levels. More-10 over, we force the transient model using groundwater recharge in two scenarios: (1) spatially variable recharge based on the mHM simulations, and (2) spatially homogeneous groundwater recharge. The modeling result in first scenario has a slightly higher correlation with groundwater head time-series, which further validates the plausibility of spatial groundwater recharge distribution calculated by mHM in the mesocale. The statistical analysis of model predictions shows a promising prediction ability of the model. The offline coupling method implemented here can reproduce reasonable groundwater head time series 15 while keep a desired level of detail in the subsurface model structure with little surplus in computational cost. Our exemplary calculations show that the coupled model mHM#OGS can be a valuable tool to assess the effects of variability in land surface heterogeneity, meteorological, topographical forces and geological zonation on the groundwater flow dynamics. 1Geosci. Model Dev. Discuss., https://doi

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Modeling reactive transport in non-ideal aqueous–solid solution system

Cited by 60 publications

References 42 publications

Modeling the competition between solid solution formation and cation exchange on the retardation of aqueous radium in an idealized bentonite column

Modeling the competition between solid solution formation and cation exchange on the retardation of aqueous radium in an idealized bentonite column

Evolution of a Generic Clay/Cement Interface: First Reactive Transport Calculations Utilizing a Gibbs Energy Minimization Based Approach for Geochemical Calculations

Improved representation of groundwater at a regional scale – coupling of mesocale Hydrologic Model (mHM) with OpeneGeoSys (OGS)

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