Effects of groundwater fluctuation on migration characteristics and representative elementary volume of entrapped LNAPL

He, Zhennan; Liang, Fachun; Meng, Jia; Li, Naiming

doi:10.1016/j.jhydrol.2022.127833

Cited by 20 publications

(6 citation statements)

References 49 publications

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“…160 A two-dimensional flow chamber was constructed to investigate the effect of GTF on the redistribution of NAPL, and the results indicated that the redistribution of residual contaminants was mainly determined by the fluctuation sequence and enhanced vertical extension and inhibited lateral extension of the NAPL plume was controlled by a rising water table while a falling water table had the opposite effect. 161 The rate of degradation of TCE correlated well with the rate of formation of •OH; specifically, •OH oxidizes TCE and occupies a dominant position in the process. 162 On the contrary, there has been little research on the influence of the hydrodynamic and hydrochemical fields induced by multiple scenarios on the mechanism of migration and transformation of NAPL, and future studies should pay more attention to the process of dissolution and mass transfer of NAPL in variable saturation and heterogeneous porous media.…”

Section: Impacts Of Gtf On the Migration Transformation And Retention...mentioning

confidence: 90%

“…The air entrapment phenomenon was investigated by studying the effect of water table fluctuation on migration of a multicomponent LNAPL (85% hexadecane, 5% toluene, 5% ethylbenzene, and 5% 2-methylnaphthalene on a molar basis) . A two-dimensional flow chamber was constructed to investigate the effect of GTF on the redistribution of NAPL, and the results indicated that the redistribution of residual contaminants was mainly determined by the fluctuation sequence and enhanced vertical extension and inhibited lateral extension of the NAPL plume was controlled by a rising water table while a falling water table had the opposite effect . The rate of degradation of TCE correlated well with the rate of formation of •OH; specifically, •OH oxidizes TCE and occupies a dominant position in the process .…”

Section: Impacts Of Gtf On the Migration Transformation And Retention...mentioning

confidence: 99%

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A Critical Review of Groundwater Table Fluctuation: Formation, Effects on Multifields, and Contaminant Behaviors in a Soil and Aquifer System

Wei,

Chen,

Cao

et al. 2024

Environ. Sci. Technol.

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The groundwater table fluctuation (GTF) zone is an important medium for the hydrologic cycle between unsaturated soil and saturated aquifers, which accelerates the migration, transformation, and redistribution of contaminants and further poses a potential environmental risk to humans. In this review, we clarify the key processes in the generation of the GTF zone and examine its links with the variation of the hydrodynamic and hydrochemistry field, colloid mobilization, and contaminant migration and transformation. Driven by groundwater recharge and discharge, GTF regulates water flow and the movement of the capillary fringe, which further control the advection and dispersion of contaminants in soil and groundwater. In addition, the formation and variation of the reactive oxygen species (ROS) waterfall are impacted by GTF. The changing ROS components partially determine the characteristic transformation of solutes and the dynamic redistribution of the microbial population. GTF facilitates the migration and transformation of contaminants (such as nitrogen, heavy metals, non-aqueous phase liquids, and volatile organic compounds) through colloid mobilization, the co-migration effect, and variation of the hydrodynamic and hydrochemistry fields. In conclusion, this review illustrates the limitations of the current literature on GTF, and the significance of GTF zones in the underground environment is underscored by expounding on the future directions and prospects.

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Section: Impacts Of Gtf On the Migration Transformation And Retention...mentioning

confidence: 90%

Section: Impacts Of Gtf On the Migration Transformation And Retention...mentioning

confidence: 99%

A Critical Review of Groundwater Table Fluctuation: Formation, Effects on Multifields, and Contaminant Behaviors in a Soil and Aquifer System

Wei,

Chen,

Cao

et al. 2024

Environ. Sci. Technol.

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“…In the case of small-volume LNAPL spills, the LNAPL may be trapped in the soil pores of the vadose zone. However, for sufficient LNAPL spills, an immobile residual phase may form along the migration pathway, accumulating primarily at the groundwater table [ 4 ]. Then, LNAPL spreads along the direction of groundwater flow.…”

Section: Introductionmentioning

confidence: 99%

Assessing the Natural Source Zone Depletion of a Petroleum-Contaminated Clayey Soil Site in Southern China Combining Concentration Gradient Method and Metagenomics

Xu,

Zhang,

Ning

et al. 2024

Life

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Natural source zone depletion (NSZD) is the main process of LNAPL (Light Non-Aqueous Phase Liquid) removal under natural conditions. The NSZD rates assessed ranged from 0.55 to 11.55 kg·m−2·a−1 (kilograms per square meter per year) in previous studies. However, most of these data were obtained from sandy sites, with few clayey sites. To gain knowledge of NSZD in clayey soil sites, the study assessed the NSZD of a petroleum hydrocarbon-contaminated clayey soil site in China, combining the concentration gradient method with metagenomic sequencing technology. The results show that the abundance of methane-producing key enzyme mcrA gene in the source zone was more abundant than in background areas, which suggests that there was methanogenesis, the key process of NSZD. The concentration gradients of oxygen and carbon dioxide existed only in shallow soil (<0.7 m), which suggests that there was a thin methane oxidation zone in the shallow zone. The calculated NSZD rates range from 0.23 to 1.15 kg·m−2·a−1, which fall within the moderate range compared to previous NSZD sites. This study expands the knowledge of NSZD in clayey soil and enriches the attenuation rate data for contaminated sites, which is of significant importance in managing petroleum contaminants.

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“…Specifically, researchers had treated the permeability domain of porous medium as a "black-box" model and described the flow within the porous medium at the macroscopic scale by combining Darcy's law and measuring parameters such as pressure difference, flow rate, etc. For pore-scale imbibition laws, the main method is to use pore-scale multiphase flow simulation to obtain the spatial distribution of velocity and pressure fields, and then to analyze the laws of fluid flow in the pore space (Golparvar et al, 2018;Ramstad and Berg, 2019;He et al, 2022aHe et al, , 2023Liang et al, 2023;Zou et al, 2023). This approach has become an important tool, in addition to laboratory physical experiments, in the study of microscopic seepage mechanism in reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Numerical methods to simulate spontaneous imbibition in microscopic pore structures: A review

Zhou,

Guan,

Zhao

et al. 2024

Capillarity

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Spontaneous imbibition, as a fundamental flow phenomenon, is widely utilized in fossil energy production, carbon dioxide and underground hydrogen storage. With the development of computing, the exploration of flow laws of spontaneous imbibition has evolved from macroscopic theoretical models to pore-scale numerical analysis. Currently, the solutions for multiphase flow in pore media mainly consider the volume of fluid and the phase field, and have been classed into level set methods based on macroscopic Navier-Stokes equations and the Shan-Chen, free energy, color gradient, and phase-field methods based on mesoscopic lattice Boltzmann equations. However, no comprehensive review article has summarized the strengths and limitations of these methods. Therefore, this work focuses on critically reviewing and commenting on the fundamentals and limitations of porescale models applied to spontaneous imbibition. In addition, recent works applying these methods are systematically reviewed. Our study aims to provide the scientific community with an expert opinion to understand the basic methods for solving the existing problems of spontaneous imbibition in porous media. Future research directions are suggested, namely, focusing on developing the reconstruction pore medium algorithms, establishing modeling methods for non-stationary states, exploring the flow laws in mixed wetting conditions, linking macroscopic and microscopic flow laws, and developing models for coupled multiphase flow numerical computation with machine learning. Overall, this review provides a comprehensive understanding of spontaneous imbibition simulation methods, promotes a thorough knowledge of spontaneous imbibition in porous media, provides guidance on exploring flow laws, and inspires researchers to give more credit to spontaneous imbibition studies.

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Effects of groundwater fluctuation on migration characteristics and representative elementary volume of entrapped LNAPL

Cited by 20 publications

References 49 publications

A Critical Review of Groundwater Table Fluctuation: Formation, Effects on Multifields, and Contaminant Behaviors in a Soil and Aquifer System

A Critical Review of Groundwater Table Fluctuation: Formation, Effects on Multifields, and Contaminant Behaviors in a Soil and Aquifer System

Assessing the Natural Source Zone Depletion of a Petroleum-Contaminated Clayey Soil Site in Southern China Combining Concentration Gradient Method and Metagenomics

Numerical methods to simulate spontaneous imbibition in microscopic pore structures: A review

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