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Journal of Contaminant Hydrology

Zhenhui Li, Cheng You, Matthew Gonzales, Anna K Wendt, Fei Wu, Susan L Brantley
No abstract text is available yet for this article.
November 8, 2017: Journal of Contaminant Hydrology
Alper Elçi
Groundwater vulnerability assessment studies are essential in water resources management. Overlay-and-index methods such as DRASTIC are widely used for mapping of groundwater vulnerability, however, these methods mainly suffer from a subjective selection of model parameters. The objective of this study is to introduce a calibration procedure that results in a more accurate assessment of groundwater vulnerability. The improvement of the assessment is formulated as a parameter optimization problem using an objective function that is based on the correlation between actual groundwater contamination and vulnerability index values...
November 6, 2017: Journal of Contaminant Hydrology
Qi Ouyang, Wenxi Lu, Tiansheng Miao, Wenbing Deng, Changlong Jiang, Jiannan Luo
In this study, we aimed to develop an optimal groundwater remediation design for sites contaminated by dense non-aqueous phase liquids by using an ensemble of surrogates and adaptive sequential sampling. Compared with previous approaches, our proposed method has the following advantages: (1) a surrogate surfactant-enhanced aquifer remediation simulation model is constructed using a Gaussian process; (2) the accuracy of the surrogate model is improved by constructing ensemble surrogates using five different surrogate modelling techniques, i...
November 6, 2017: Journal of Contaminant Hydrology
Agnieszka Herzyk, Lucas Fillinger, Michael Larentis, Shiran Qiu, Piotr Maloszewski, Marko Hünniger, Susanne I Schmidt, Christine Stumpp, Sviatlana Marozava, Peter S K Knappett, Martin Elsner, Rainer Meckenstock, Tillmann Lueders, Christian Griebler
Microbial communities are the driving force behind the degradation of contaminants like aromatic hydrocarbons in groundwater ecosystems. However, little is known about the response of native microbial communities to contamination in pristine environments as well as their potential to recover from a contamination event. Here, we used an indoor aquifer mesocosm filled with sandy quaternary calciferous sediment that was continuously fed with pristine groundwater to study the response, resistance and resilience of microbial communities to toluene contamination over a period of almost two years, comprising 132days of toluene exposure followed by nearly 600days of recovery...
October 31, 2017: Journal of Contaminant Hydrology
Aitor Iraola, Paolo Trinchero, Mikko Voutilainen, Björn Gylling, Jan-Olof Selroos, Jorge Molinero, Urban Svensson, Dirk Bosbach, Guido Deissmann
Field investigation studies, conducted in the context of safety analyses of deep geological repositories for nuclear waste, have pointed out that in fractured crystalline rocks sorbing radionuclides can diffuse surprisingly long distances deep into the intact rock matrix; i.e. much longer distances than those predicted by reactive transport models based on a homogeneous description of the properties of the rock matrix. Here, we focus on cesium diffusion and use detailed micro characterisation data, based on micro computed tomography, along with a grain-scale Inter-Granular Network model, to offer a plausible explanation for the anomalously long cesium penetration profiles observed in these in-situ experiments...
October 18, 2017: Journal of Contaminant Hydrology
Derya Ayral-Cinar, Avery H Demond
Diffusion is regarded as the dominant transport mechanism into and out of low permeable subsurface lenses and layers in the subsurface. But, some reports of mass storage in such zones are higher than what might be attributable to diffusion, based on estimated diffusion coefficients. Despite the importance of diffusion to efforts to estimate the quantity of residual contamination in the subsurface, relatively few studies present measured diffusion coefficients of organic solutes in saturated low permeability soils...
September 23, 2017: Journal of Contaminant Hydrology
Yu Chen, Yaofa Li, Albert J Valocchi, Kenneth T Christensen
We employed the color-fluid lattice Boltzmann multiphase model to simulate liquid CO2 displacing water documented in experiments in a 2D heterogeneous micromodel at reservoir pressure conditions. The main purpose is to investigate whether lattice Boltzmann simulation can reproduce the CO2 invasion patterns observed in these experiments for a range of capillary numbers. Although the viscosity ratio used in the simulation matches the experimental conditions, the viscosity of the fluids in the simulation is higher than that of the actual fluids used in the experiments...
September 23, 2017: Journal of Contaminant Hydrology
Vahid Nourani, Shahram Mousavi, Fahreddin Sadikoglu, Vijay P Singh
This study developed a new hybrid artificial intelligence (AI)-meshless approach for modeling contaminant transport in porous media. The key innovation of the proposed approach is that both black box and physically-based models are combined for modeling contaminant transport. The effectiveness of the approach was evaluated using experimental and real world data. Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) were calibrated to predict temporal contaminant concentrations (CCs), and the effect of noisy and de-noised data on the model performance was evaluated...
September 21, 2017: Journal of Contaminant Hydrology
Jonghyun Lee, Massimo Rolle, Peter K Kitanidis
Most recent research on hydrodynamic dispersion in porous media has focused on whole-domain dispersion while other research is largely on laboratory-scale dispersion. This work focuses on the contribution of a single block in a numerical model to dispersion. Variability of fluid velocity and concentration within a block is not resolved and the combined spreading effect is approximated using resolved quantities and macroscopic parameters. This applies whether the formation is modeled as homogeneous or discretized into homogeneous blocks but the emphasis here being on the latter...
September 15, 2017: Journal of Contaminant Hydrology
Gianluca Boccardo, Eleonora Crevacore, Rajandrea Sethi, Matteo Icardi
In the upscaling from pore to continuum (Darcy) scale, reaction and deposition phenomena at the solid-liquid interface of a porous medium have to be represented by macroscopic reaction source terms. The effective rates can be computed, in the case of periodic media, from three-dimensional microscopic simulations of the periodic cell. Several computational and semi-analytical models have been studied in the field of colloid filtration to describe this problem. They typically rely on effective deposition rates defined by complex fitting procedures, neglecting the advection-diffusion interplay, the pore-scale flow complexity, and assuming slow reactions (or large Péclet numbers)...
September 13, 2017: Journal of Contaminant Hydrology
Richard J Watts, Miao Yu, Amy L Teel
The activation of peroxymonosulfate by iron (II), iron (III), and iron (III)-EDTA for in situ chemical oxidation (ISCO) was compared using nitrobenzene as a hydroxyl radical probe, anisole as a hydroxyl radical+sulfate radical probe, and hexachloroethane as a reductant+nucleophile probe. In addition, activated peroxymonosulfate was investigated for the treatment of the model groundwater contaminants perchloroethylene (PCE) and trichloroethylene (TCE). The relative activities of hydroxyl radical and sulfate radical in the degradation of the probe compounds and PCE and TCE were isolated using the radical scavengers tert-butanol and isopropanol...
September 8, 2017: Journal of Contaminant Hydrology
Bagus P Muljadi, Branko Bijeljic, Martin J Blunt, Adam Colbourne, Andy J Sederman, Mick D Mantle, Lynn F Gladden
We present an experimental and numerical study of transport in carbonates during dissolution and its upscaling from the pore (∼μm) to core (∼cm) scale. For the experimental part, we use nuclear magnetic resonance (NMR) to probe molecular displacements (propagators) of an aqueous hydrochloric acid (HCl) solution through a Ketton limestone core. A series of propagator profiles are obtained at a large number of spatial points along the core at multiple time-steps during dissolution. For the numerical part, first, the transport model-a particle-tracking method based on Continuous Time Random Walks (CTRW) by Rhodes et al...
September 1, 2017: Journal of Contaminant Hydrology
Asaf Ben Neriah, Amir Paster
Application of short-duration pulses of high air pressure, to an air sparging system for groundwater remediation, was tested in a two-dimensional laboratory setup. It was hypothesized that this injection mode, termed boxcar, can enhance the remediation efficiency due to the larger ZOI and enhanced mixing which results from the pressure pulses. To test this hypothesis, flow and transport experiments were performed. Results confirm that cyclically applying short-duration pressure pulses may enhance contaminant cleanup...
September 1, 2017: Journal of Contaminant Hydrology
Colby M Steelman, Dylan R Klazinga, Aaron G Cahill, Anthony L Endres, Beth L Parker
Fugitive methane (CH4) leakage associated with conventional and unconventional petroleum development (e.g., shale gas) may pose significant risks to shallow groundwater. While the potential threat of stray (CH4) gas in aquifers has been acknowledged, few studies have examined the nature of its migration and fate in a shallow groundwater flow system. This study examines the geophysical responses observed from surface during a 72day field-scale simulated CH4 leak in an unconfined sandy aquifer at Canadian Forces Base Borden, Canada, to better understand the transient behaviour of fugitive CH4 gas in the subsurface...
August 30, 2017: Journal of Contaminant Hydrology
M Korfanta, T Babadagli, K Develi
Surface roughness and flow rate effects on the solvent transport under miscible conditions in a single fracture are studied. Surface replicas of seven different rocks (marble, granite, and limestone) are used to represent different surface roughness characteristics each described by different mathematical models including three fractal dimensions. Distribution of dyed solvent is investigated at various flow rate conditions to clarify the effect of roughness on convective and diffusive mixing. After a qualitative analysis using comparative images of different rocks, the area covered by solvent with respect to time is determined to conduct a semi-quantitative analysis...
August 26, 2017: Journal of Contaminant Hydrology
Mackenzie M Cremeans, J F Devlin
Distributions of flow across the groundwater-surface water interface should be expected to be as complex as the geologic deposits associated with stream or lake beds and their underlying aquifers. In these environments, the conventional Darcy-based method of characterizing flow systems (near streams) has significant limitations, including reliance on parameters with high uncertainties (e.g., hydraulic conductivity), the common use of drilled wells in the case of streambank investigations, and potentially lengthy measurement times for aquifer characterization and water level measurements...
November 2017: Journal of Contaminant Hydrology
S Collins, R Singh, A Rivas, A Palmer, D Horne, A Manderson, J Roygard, A Matthews
Intensive agricultural activities are generally associated with nitrogen leaching from agricultural soils, and this nitrogen has the potential to percolate and contaminate groundwater and surface waters. We assessed surface water and groundwater interactions, and nitrogen leaching and its potential attenuation in shallow groundwater in the lower Rangitikei River catchment (832km(2)), New Zealand. We combined regional- and local-scale field surveys and experiments, nutrient budget modelling, and hydraulic and geochemical methods, to gain an insight into leaching, transformation and transport of nitrogen via groundwaters to the river in the study area...
November 2017: Journal of Contaminant Hydrology
Derya Aydin Sarikurt, Cagri Gokdemir, Nadim K Copty
The rate of interphase mass transfer from non-aqueous phase liquids (NAPLs) entrapped in the subsurface into the surrounding mobile aqueous phase is commonly expressed in terms of Sherwood (Sh) correlations that are expressed as a function of flow and porous media properties. Because of the lack of precise methods for the estimation of the interfacial area separating the NAPL and aqueous phases, most studies have opted to use modified Sherwood expressions that lump the interfacial area into the interphase mass transfer coefficient...
November 2017: Journal of Contaminant Hydrology
V Rønde, U S McKnight, A Th Sonne, N Balbarini, J F Devlin, P L Bjerg
No abstract text is available yet for this article.
November 2017: Journal of Contaminant Hydrology
Jina Jeong, Eungyu Park, Weon Shik Han, Kue-Young Kim, Seong-Chun Jun, Sungwook Choung, Seong-Taek Yun, Junho Oh, Hyun-Jun Kim
In this study, a data-driven method for predicting CO2 leaks and associated concentrations from geological CO2 sequestration is developed. Several candidate models are compared based on their reproducibility and predictive capability for CO2 concentration measurements from the Environment Impact Evaluation Test (EIT) site in Korea. Based on the data mining results, a one-dimensional solution of the advective-dispersive equation for steady flow (i.e., Ogata-Banks solution) is found to be most representative for the test data, and this model is adopted as the data model for the developed method...
November 2017: Journal of Contaminant Hydrology
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