Smart Kd-values, their uncertainties and sensitivities - Applying a new approach for realistic distribution coefficients in geochemical modeling of complex systems

Stockmann, Madlen; Schikora, J.; Becker, Dirk-A.; Flügge, Joh.; Noseck, Ulrich; Brendler, Vinzenz

doi:10.1016/j.chemosphere.2017.08.115

Cited by 27 publications

(18 citation statements)

References 16 publications

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“…77,78 The combination of such statistical 29,39 and (the presented) spectroscopy strategies will strengthen predictive modelling of the long-term behaviour of elements of interest, including moving toward "smart" K D values. 79,80 Such predictive modelling can assist with extrapolating results from elevated concentrations (required for EXAFS analyses) to more environmentally relevant/trace concentrations. We suggest that the presented information on the Sr and Cs speciation within a composite clayey soil (including the complete results from the adsorption experiments at trace and elevated concentrations on these solids, Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Such (evidence-based) modelling efforts will enable Please do not adjust margins Please do not adjust margins predicting the long-term behaviour of Sr and Cs at a wide range of concentrations, and enable predicting the impacts of any environmental engineering strategies at contaminated legacy sites. 80,81 Such predictive modelling is essential in the design of evidence-based engineering strategies for the remediation and long-term management of contaminated (legacy) sites. 19…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Emerging investigator series: a holistic approach to multicomponent EXAFS: Sr and Cs complexation in clayey soils

Bots

Comarmond

Payne

et al. 2021

Environ. Sci.: Processes Impacts

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Emerging investigator series: a holistic approach to multicomponent EXAFS: Sr and Cs complexation in clayey soils

Bots

Comarmond

Payne

et al. 2021

Environ. Sci.: Processes Impacts

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“…Currently, UNiSeCs II is being applied for calculating look-up tables of distribution coefficients similar to the "smart K d " concept [66], containing values for possible combinations of the relevant soil parameters. Within the ongoing joint project Trans-LARA, these tables are intended to be used for hydrological simulations of radionuclide migration from groundwater to the upper soil horizon and also for biosphere simulations with Ecolego [1] to estimate the radiation burden of the human population after the contamination of agricultural soils.…”

Section: Discussionmentioning

confidence: 99%

A consistent model for estimating the partitioning of Am, Pu and Se in agricultural soils

Hormann

2021

J Radioanal Nucl Chem

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The component additive model UNiSeCs II for simulating the physicochemical behaviour of the radionuclides americium, plutonium and selenium in agricultural soils is presented. The model is validated by estimating the distribution coefficients (Kd) of these elements measured in batch experiments from the literature. For all three elements, the resulting average relative deviations from the experimental values are smaller than a factor of 2.5. This indicates that the model has the potential to significantly improve the predictions of radioecological models that normally use tabulated Kd values from the IAEA which are known to have large uncertainties. Using UNiSeCs II, the soil solution parameters most important for the partitioning of Am, Pu and Se are identified by single parameter variations.

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“…The varying mineralogy of the Opalinus Clay is implemented in the simulations with a bottom-up approach [27,28]. The amount of sorption of contaminants in heterogeneous formations can be determined by the additive sorption on individual minerals.…”

Section: Integrating Sorption Processesmentioning

confidence: 99%

“…The distribution coefficient K d (m 3 /kg) is defined by the ratio between the amount of a species adsorbed on the solid phase and the amount present in the liquid phase. The K d is calculated in PHREEQC for each facies depending on the geochemical and mineralogical conditions following Stockmann et al [28]. In the literature, sorption of uranium on Opalinus Clay is commonly modeled using only the clay minerals illite and montmorillonite [32][33][34][35].…”

Section: Integrating Sorption Processesmentioning

confidence: 99%

Surrogate Model for Multi-Component Diffusion of Uranium through Opalinus Clay on the Host Rock Scale

Hennig

Kühn

2021

Applied Sciences

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Multi-component (MC) diffusion simulations enable a process based and more precise approach to calculate transport and sorption compared to the commonly used single-component (SC) models following Fick’s law. The MC approach takes into account the interaction of chemical species in the porewater with the diffuse double layer (DDL) adhering clay mineral surfaces. We studied the shaly, sandy and carbonate-rich facies of the Opalinus Clay. High clay contents dominate diffusion and sorption of uranium. The MC simulations show shorter diffusion lengths than the SC models due to anion exclusion from the DDL. This hampers diffusion of the predominant species CaUO2(CO3)32−. On the one side, species concentrations and ionic strengths of the porewater and on the other side surface charge of the clay minerals control the composition and behaviour of the DDL. For some instances, it amplifies the diffusion of uranium. We developed a workflow to transfer computationally intensive MC simulations to SC models via calibrated effective diffusion and distribution coefficients. Simulations for one million years depict maximum uranium diffusion lengths between 10 m and 35 m. With respect to the minimum requirement of a thickness of 100 m, the Opalinus Clay seems to be a suitable host rock for nuclear waste repositories.

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Smart Kd-values, their uncertainties and sensitivities - Applying a new approach for realistic distribution coefficients in geochemical modeling of complex systems

Cited by 27 publications

References 16 publications

Emerging investigator series: a holistic approach to multicomponent EXAFS: Sr and Cs complexation in clayey soils

Emerging investigator series: a holistic approach to multicomponent EXAFS: Sr and Cs complexation in clayey soils

A consistent model for estimating the partitioning of Am, Pu and Se in agricultural soils

Surrogate Model for Multi-Component Diffusion of Uranium through Opalinus Clay on the Host Rock Scale

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