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Journal of Contaminant Hydrology

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https://www.readbyqxmd.com/read/29338881/infiltration-behaviour-of-elemental-mercury-dnapl-in-fully-and-partially-water-saturated-porous-media
#1
Andrea D'Aniello, Niels Hartog, Thomas Sweijen, Domenico Pianese
Mercury is a contaminant of global concern due to its harmful effects on human health and for the detrimental consequences of its release in the environment. Sources of liquid elemental mercury are usually anthropogenic, such as chlor-alkali plants. To date insight into the infiltration behaviour of liquid elemental mercury in the subsurface is lacking, although this is critical for assessing both characterization and remediation approaches for mercury DNAPL contaminated sites. Therefore, in this study the infiltration behaviour of elemental mercury in fully and partially water saturated systems was investigated using column experiments...
January 8, 2018: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29329939/enhanced-mobility-of-non-aqueous-phase-liquid-napl-during-drying-of-wet-sand
#2
Dhivakar Govindarajan, Abhijit P Deshpande, Ravikrishna Raghunathan
Enhanced upward mobility of a non aqueous phase liquid (NAPL) present in wet sand during natural drying, and in the absence of any external pressure gradients, is reported for the first time. This mobility was significantly higher than that expected from capillary rise. Experiments were performed in a glass column with a small layer of NAPL-saturated sand trapped between two layers of water-saturated sand. Drying of the wet sand was induced by flow of air across the top surface of the wet sand. The upward movement of the NAPL, in the direction of water transport, commenced when the drying effect reached the location of the NAPL and continued as long as there was significant water evaporation in the vicinity of NAPL, indicating a clear correlation between the NAPL rise and water evaporation...
January 4, 2018: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29269033/effects-of-ph-on-nano-bubble-stability-and-transport-in-saturated-porous-media
#3
Shoichiro Hamamoto, Takato Takemura, Kenichiro Suzuki, Taku Nishimura
An understanding of nano-scale bubble (NB) transport in porous media is important for potential application of NBs in soil/groundwater remediation. It is expected that the solution chemistry of NB water highly influences the surface characteristics of NBs and porous media and the interaction between them, thus affecting the stability and transport characteristics of NB. In this study, in addition to stability experiments, one-dimensional column transport experiments using glass beads were conducted to investigate the effects of pH on the NB transport behavior...
December 7, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29241657/density-driven-transport-of-gas-phase-chemicals-in-unsaturated-soils
#4
Chiu-Shia Fen, Yong-Tai Sun, Yuen Cheng, Yuanchin Chen, Whaiwan Yang, Changtai Pan
Variations of gas phase density are responsible for advective and diffusive transports of organic vapors in unsaturated soils. Laboratory experiments were conducted to explore dense gas transport (sulfur hexafluoride, SF6) from different source densities through a nitrogen gas-dry soil column. Gas pressures and SF6 densities at transient state were measured along the soil column for three transport configurations (horizontal, vertically upward and vertically downward transport). These measurements and others reported in the literature were compared with simulation results obtained from two models based on different diffusion approaches: the dusty gas model (DGM) equations and a Fickian-type molar fraction-based diffusion expression...
December 6, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29224930/transport-of-dissolved-organic-matter-in-boom-clay-size-effects
#5
D Durce, M Aertsens, D Jacques, N Maes, M Van Gompel
A coupled experimental-modelling approach was developed to evaluate the effects of molecular weight (MW) of dissolved organic matter (DOM) on its transport through intact Boom Clay (BC) samples. Natural DOM was sampled in-situ in the BC layer. Transport was investigated with percolation experiments on 1.5cm BC samples by measuring the outflow MW distribution (MWD) by size exclusion chromatography (SEC). A one-dimensional reactive transport model was developed to account for retardation, diffusion and entrapment (attachment and/or straining) of DOM...
December 5, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29224929/anaerobic-biodegradation-of-dissolved-ethanol-in-a-pilot-scale-sand-aquifer-variability-in-plume-redox-biogeochemistry
#6
Heather C McLeod, James W Roy, Gregory F Slater, James E Smith
The use of ethanol in alternative fuels has led to contamination of groundwater with high concentrations of this easily biodegradable organic compound. Previous laboratory and field studies have shown vigorous biodegradation of ethanol plumes, with prevalence of reducing conditions and methanogenesis. The objective of this study was to further our understanding of the dynamic biogeochemistry processes, especially dissolved gas production, that may occur in developing and aging plume cores at sites with ethanol or other organic contamination of groundwater...
December 5, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29198786/the-integrated-contaminant-elution-and-tracer-test-toolkit-icet3-for-improved-characterization-of-mass-transfer-attenuation-and-mass-removal
#7
Mark L Brusseau, Zhilin Guo
It is evident based on historical data that groundwater contaminant plumes persist at many sites, requiring costly long-term management. High-resolution site-characterization methods are needed to support accurate risk assessments and to select, design, and operate effective remediation operations. Most subsurface characterization methods are generally limited in their ability to provide unambiguous, real-time delineation of specific processes affecting mass-transfer, transformation, and mass removal, and accurate estimation of associated rates...
November 23, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29223368/transport-of-polymer-stabilized-nano-scale-zero-valent-iron-in-porous-media
#8
Pulin K Mondal, Paul D Furbacher, Ziteng Cui, Magdalena M Krol, Brent E Sleep
This study presents a set of laboratory-scale transport experiments and numerical simulations evaluating carboxymethyl cellulose (CMC) polymer stabilized nano-scale zero-valent iron (nZVI) transport. The experiments, performed in a glass-walled two-dimensional (2D) porous medium system, were conducted to identify the effects of water specific discharge and CMC concentration on nZVI transport and to produce data for model validation. The transport and movement of a tracer lissamine green B® (LGB) dye, CMC, and CMC-nZVI were evaluated through analysis of the breakthrough curves (BTCs) at the outlets, the time-lapsed images of the plume, and retained nZVI in the sandbox...
November 21, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29217310/about-the-connectivity-of-dual-scale-media-based-on-micro-structure-based-regional-analysis-of-nmr-flow-propagators
#9
Yong Zheng, Igor Shikhov, Louis Kpamsar Gbayan, Ji-Youn Arns, Christoph H Arns
The characterisation of heterogeneous porous media at multiple length scales typically requires the classification of structure at some scale to allow the calculation of effective transport properties at a scale relevant for macroscopic description. While such a classification may be derived from various imaging methods, a shortcoming is often the simultaneous characterisation of the connectivity between regions representing different micro-structure. In this work we combine NMR based flow propagators with the simulations performed on corresponding reconstructed structure, and relate the NMR measurements to their simulated global and local representations to study fluid transport locally and the exchange between micro- and macro-porous regions...
November 20, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29289350/enhanced-reductive-de-chlorination-of-a-solvent-contaminated-aquifer-through-addition-and-apparent-fermentation-of-cyclodextrin
#10
William James Blanford, Michael Philip Pecoraro, Rebecca Heinrichs, Thomas Bernhard Boving
In a field study, aqueous cyclodextrin (CD) was investigated for its ability to extract chlorinated volatile organic compounds (cVOC), such as trichloroethylene (TCE), 1,1,1-trichloroethane (TCA), and dichloroethene (DCE) through in-situ flushing of a sandy aquifer. After cessation of aquifer flushing, a plume of CD was left. Changes in CD, cVOC, and inorganic terminal electron acceptors (TEAs) (DO, nitrate, sulfate, iron) were monitored in four rounds of wellwater sampling (20, 210, 342, and 425days after cessation of active pumping)...
November 14, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29157733/using-environmental-isotopes-along-with-major-hydro-geochemical-compositions-to-assess-deep-groundwater-formation-and-evolution-in-eastern-coastal-china
#11
Naizheng Xu, Jianshi Gong, Guoqiang Yang
Hydrochemical analysis and environmental isotopic tracing are successfully applied to study groundwater evolution processes. Located in eastern China, the Jiangsu Coastal Plain is characterized by an extensively exploited deep groundwater system, and groundwater salinization has become the primary water environmental problem. This paper provides a case study on the use of a hydrochemical and environmental isotopic approach to assess possible mixing and evolution processes at Yoco Port, Jiangsu Province, China...
November 14, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29174719/contaminant-source-identification-using-semi-supervised-machine-learning
#12
Velimir V Vesselinov, Boian S Alexandrov, Daniel O'Malley
Identification of the original groundwater types present in geochemical mixtures observed in an aquifer is a challenging but very important task. Frequently, some of the groundwater types are related to different infiltration and/or contamination sources associated with various geochemical signatures and origins. The characterization of groundwater mixing processes typically requires solving complex inverse models representing groundwater flow and geochemical transport in the aquifer, where the inverse analysis accounts for available site data...
November 8, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29129334/calibration-of-groundwater-vulnerability-mapping-using-the-generalized-reduced-gradient-method
#13
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
https://www.readbyqxmd.com/read/29128132/application-of-ensemble-surrogates-and-adaptive-sequential-sampling-to-optimal-groundwater-remediation-design-at-dnapls-contaminated-sites
#14
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
https://www.readbyqxmd.com/read/29167020/laboratory-validation-of-a-point-velocity-probe-for-measuring-horizontal-flow-from-any-direction
#15
B Gibson, J F Devlin
The point-velocity probe (PVP) quantifies groundwater speed and flow direction, i.e., velocity, at the centimeter scale. The first probe designs required that the flow direction be known a priori, within about 100° in order to position the probe during installation. This study introduces and assesses a '360° PVP' that measures flow from any direction without foreknowledge of the groundwater velocity. In tests conducted in a Nested Storage Tank (NeST) aquifer simulator packed with sand, PVP-measured velocities matched expected velocities within ±9° in direction and ±15% in magnitude, on average, consistent with previously reported PVP performances in laboratory studies...
October 31, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29128133/response-and-recovery-of-a-pristine-groundwater-ecosystem-impacted-by-toluene-contamination-a-meso-scale-indoor-aquifer-experiment
#16
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
https://www.readbyqxmd.com/read/29128134/corrigendum-to-searching-for-anomalous-methane-in-shallow-groundwater-near-shale-gas-wells-j-contam-hydrol-195-december-2016-23-30
#17
Zhenhui Li, Cheng You, Matthew Gonzales, Anna K Wendt, Fei Wu, Susan L Brantley
No abstract text is available yet for this article.
December 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/29050851/validation-of-a-new-device-to-quantify-groundwater-surface-water-exchange
#18
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
https://www.readbyqxmd.com/read/29033220/transport-and-potential-attenuation-of-nitrogen-in-shallow-groundwaters-in-the-lower-rangitikei-catchment-new-zealand
#19
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
https://www.readbyqxmd.com/read/29033219/sherwood-correlation-for-dissolution-of-pooled-napl-in-porous-media
#20
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
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