Laboratory investigation on the retention performance of a soil–bentonite mixture used as an engineered barrier: insight into the effects of ionic strength and associated heavy metal ions

He, Qi; He, Yong; Hu, Huiping; Lou, Wei; Zhang, Zhao; Zhang, Ke-neng; Chen, Yong-Gui; Ye, Weimin; Sun, Jun

doi:10.1007/s11356-023-25780-5

Cited by 14 publications

(4 citation statements)

References 39 publications

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“…The rapid industrialization in China has served as a catalyst for socioeconomic advancement; however, at same time, it has led to the contamination of groundwater environments with heavy metals [3]. The transport of heavy metals contaminants in groundwater is an imperceptible, prolonged, challenging-to-detect, and reversible phenomenon [4]. Among them, Chromium (Cr) groundwater contamination often stems from the unregulated disposal of chromium slag and the seepage of leachate from slag piles.…”

Section: Introductionmentioning

confidence: 99%

Surrogate-Based Uncertainty Analysis for Groundwater Contaminant Transport in a Chromium Residue Site Located in Southern China

Zou,

Yousaf,

Yang

et al. 2024

Water

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Numerical modeling is widely acknowledged as a highly precise method for understanding the dynamics of contaminant transport in groundwater. However, due to the intricate characteristics of environmental systems and the lack of accurate information, the results are susceptible to a significant degree of uncertainty. Numerical models must explicitly consider related uncertainties in parameters to facilitate robust decision-making. In a Chromium Residue Site located in southern China (the study area), this study employed Monte Carlo simulation to assess the impact of variability in key parameters uncertainty on the simulation outcomes. Variogram analysis of response surface (VARS), global sensitivity analysis, and an XGBoost (version 2.0.0)-based surrogate model was employed to overcome the substantial computational cost of Monte Carlo simulation. The results of numerical simulation indicate that the contaminant is spreading downstream towards the northern boundary of contaminated site near Lianshui River, threatening water quality. Furthermore, migration patterns are complex due to both downstream convection and upstream diffusion. Sensitivity analysis identified hydraulic conductivity, recharge rate, and porosity as the most influential model parameters, selected as key parameters. Moreover, uncertainty analysis indicated that the variability in key parameters has a minimal impact on the simulation outcomes at monitoring wells near the contaminant source. In contrast, at wells positioned a considerable distance from the contaminant source, the variability in key parameters significantly influences the simulation outcomes. The surrogate model markedly mitigated computational workload and calculation time, while demonstrating superior precision and effectively capture the non-linear correlations between input and output of the simulation model.

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Section: Introductionmentioning

confidence: 99%

Surrogate-Based Uncertainty Analysis for Groundwater Contaminant Transport in a Chromium Residue Site Located in Southern China

Zou,

Yousaf,

Yang

et al. 2024

Water

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“…Dutta et al [ 34 ] and Nartowska et al [ 35 ] suggest that at low concentrations of metal salts in bentonites, bentonite quality affects clay permeability, while at higher concentrations, it becomes the dominant factor. He et al [ 36 ] propose that, in low-permeability soils, solute transport results from the interaction of adsorption and diffusion forces, with solution molarity playing a significant role. For instance, increased Zn retention was observed with increasing ionic strength of the solution.…”

Section: Introductionmentioning

confidence: 99%

Mobility of Zn and Cu in Bentonites: Implications for Environmental Remediation

Nartowska,

Podlasek,

Vaverková

et al. 2024

Materials

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The aim of this study was to evaluate the mobility of copper (Cu) and zinc (Zn) and their impact on the properties of bentonites and unfrozen water content. Limited research in this area necessitates further analysis to prevent the negative effects of metal interactions on bentonite effectiveness. Tests involved American (SWy-3, Stx-1b) and Slovak (BSvk) bentonite samples with Zn or Cu ion exchange. Sequential extraction was performed using the Community Bureau of Reference (BCR) method. Elemental content was analyzed via inductively coupled plasma optical emission spectrometry (ICP-OES). Unfrozen water content was measured using nuclear magnetic resonance (1H-NMR) and differential scanning calorimetry (DSC). Results showed a significant influence of the main cation (Zn or Cu) on ion mobility, with toxic metal concentrations increasing mobility and decreasing residual fractions. Mobile Zn fractions increased with larger particle diameters, lower clay content, and shorter interplanar spacing, while the opposite was observed for Cu. Zn likely accumulated in larger clay pores, while Cu was immobilized in the bentonite complex. The stability of Zn or Cu ions increased with higher clay content or specific surface area. Residual Zn or Cu fractions were highest in uncontaminated bentonites with higher unfrozen water content, suggesting the potential formation of concentrated solutions in sub-zero temperatures, posing a threat to the clay–water environment, especially in cold regions.

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“…The contaminant transport in groundwater flow systems is a concealed, long-term, invertible process that has become a serious environmental problem and poses threats to sustainable development [ 1 , 2 , 3 , 4 ]. Understanding the dynamic characteristics of contaminant migration and retention is crucial for pollution assessment and contaminant remediation in soils, sites, and groundwater.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, regardless of the dynamic governing equations and solution Toxics 2023, 11, 438 2 of 25 methods, numerical modeling is confronted with the non-uniqueness of simulation results, which limits the accuracy of simulation results. Aiming to generate accurate and meaningful simulation results, extensive efforts have been made in model calibration [2,[14][15][16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Efficient Calibration of Groundwater Contaminant Transport Models Using Bayesian Optimization

Deng

Zhou

et al. 2023

Toxics

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Numerical modeling is a significant tool to understand the dynamic characteristics of contaminants transport in groundwater. The automatic calibration of highly parametrized and computationally intensive numerical models for the simulation of contaminant transport in the groundwater flow system is a challenging task. While existing methods use general optimization techniques to achieve automatic calibration, the large numbers of numerical model evaluations required in the calibration process lead to high computing overhead and limit the efficiency of model calibration. This paper presents a Bayesian optimization (BO) method for efficient calibration of numerical models of groundwater contaminant transport. A Bayes model is built to fully represent calibration criteria and derive the objective function for model calibration. The efficiency of model calibration is made possible by the probabilistic surrogate model and the expected improvement acquisition function in BO. The probabilistic surrogate model approximates the computationally expensive objective function with a closed-form expression that can be computed efficiently, while the expected improvement acquisition function proposes the most promising model parameters to improve the fitness to the calibration criteria and reduce the uncertainty of the surrogate model. These schemes allow us to find the optimized model parameters effectively by using a small number of numerical model evaluations. Two case studies for the calibration of the Cr(VI) transport model demonstrate that the BO method is effective and efficient in the inversion of hypothetical model parameters, the minimization of the objective function, and the adaptation of different model calibration criteria. Specifically, this promising performance is achieved within 200 numerical model evaluations, which substantially reduces the computing budget for model calibration.

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Laboratory investigation on the retention performance of a soil–bentonite mixture used as an engineered barrier: insight into the effects of ionic strength and associated heavy metal ions

Cited by 14 publications

References 39 publications

Surrogate-Based Uncertainty Analysis for Groundwater Contaminant Transport in a Chromium Residue Site Located in Southern China

Surrogate-Based Uncertainty Analysis for Groundwater Contaminant Transport in a Chromium Residue Site Located in Southern China

Mobility of Zn and Cu in Bentonites: Implications for Environmental Remediation

Efficient Calibration of Groundwater Contaminant Transport Models Using Bayesian Optimization

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