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Journal of Contaminant Hydrology

Paolo Trinchero, Ignasi Puigdomenech, Jorge Molinero, Hedieh Ebrahimi, Björn Gylling, Urban Svensson, Dirk Bosbach, Guido Deissmann
We present an enhanced continuum-based approach for the modelling of groundwater flow coupled with reactive transport in crystalline fractured rocks. In the proposed formulation, flow, transport and geochemical parameters are represented onto a numerical grid using Discrete Fracture Network (DFN) derived parameters. The geochemical reactions are further constrained by field observations of mineral distribution. To illustrate how the approach can be used to include physical and geochemical complexities into reactive transport calculations, we have analysed the potential ingress of oxygenated glacial-meltwater in a heterogeneous fractured rock using the Forsmark site (Sweden) as an example...
April 7, 2017: Journal of Contaminant Hydrology
Geoffrey N Delin, William N Herkelrath
A tracer test was conducted to aid in the investigation of water movement and solute transport at a crude-oil spill site near Bemidji, Minnesota. Time of travel was measured using breakthrough curves for rhodamine WT and bromide tracers moving from the soil surface through oil-contaminated and oil-free unsaturated zones to the saturated zone. Results indicate that the rates of tracer movement were similar in the oil-free unsaturated and saturated zones compared to the oily zones. These results are somewhat surprising given the oil contamination in the unsaturated and saturated zones...
March 29, 2017: Journal of Contaminant Hydrology
L Shawn Matott, Anshuman Singh, Alan J Rabideau
Predictive modeling of the transport and remediation of groundwater contaminants requires an accurate description of the sorption process, which is usually provided by fitting an isotherm model to site-specific laboratory data. Commonly used calibration procedures, listed in order of increasing sophistication, include: trial-and-error, linearization, non-linear regression, global search, and hybrid global-local search. Given the considerable variability in fitting procedures applied in published isotherm studies, we investigated the importance of algorithm selection through a series of numerical experiments involving 13 previously published sorption datasets...
March 21, 2017: Journal of Contaminant Hydrology
YaoQuan Zhou, Michael Cardiff
Non-aqueous phase liquids (NAPLs) have a complex mode of transport in heterogeneous aquifers, which can result in pools and lenses of NAPLs (the "source zone") that are difficult to detect and can cause long-term contamination via slow dissolution into groundwater (the "dissolved plume"). Characterizing the extent and evolution of NAPL contamination within the source zone is a useful strategy for designing and adapting appropriate remedial actions at many contaminated sites. As a NAPL flows into a given aquifer volume, the effective hydraulic conductivity (K) and specific storage (Ss) of the volume changes associated with the viscosity and compressibility of the impinging fluid, meaning that NAPL movement may be detectable with hydraulic testing...
March 21, 2017: Journal of Contaminant Hydrology
Qi Ouyang, Wenxi Lu, Zeyu Hou, Yu Zhang, Shuai Li, Jiannan Luo
In this paper, a multi-algorithm genetically adaptive multi-objective (AMALGAM) method is proposed as a multi-objective optimization solver. It was implemented in the multi-objective optimization of a groundwater remediation design at sites contaminated by dense non-aqueous phase liquids. In this study, there were two objectives: minimization of the total remediation cost, and minimization of the remediation time. A non-dominated sorting genetic algorithm II (NSGA-II) was adopted to compare with the proposed method...
March 14, 2017: Journal of Contaminant Hydrology
Jeff A K Silva, Michelle Crimi, Thomas Palaia, Saebom Ko, Sean Davenport
The methods and results of the first field-scale demonstration of polymer-amended in situ chemical oxidation (PA-ISCO) are presented. The demonstration took place at MCB CAMLEJ (Marine Corps Base, Camp Lejeune) Operable Unit (OU) 15, Site 88, in Camp Lejeune, North Carolina between October and December 2010. PA-ISCO was developed as an alternative treatment approach that utilizes viscosity-modified fluids to improve the in situ delivery and distribution (i.e. sweep-efficiency) of chemical oxidants within texturally heterogeneous contaminated aquifers...
March 14, 2017: Journal of Contaminant Hydrology
Alexander Huizenga, Ryan T Bailey, Timothy K Gates
This study assesses the spatio-temporal patterns of water and nutrient mass exchange in a stream-riparian system of a major river and a contributing tributary in an irrigated semi-arid region. Field monitoring is performed along reaches of the Arkansas River (4.7km) and Timpas Creek (2.0km) in southeastern Colorado during the 2014 growing season, with water quantity and water quality data collected using a network of in-stream sampling sites and groundwater monitoring wells. Mass balance approaches were used to identify temporal and spatial trends in flow, nitrogen (N), and salinity in stream-aquifer exchange...
March 8, 2017: Journal of Contaminant Hydrology
N Seetha, Amir Raoof, M S Mohan Kumar, S Majid Hassanizadeh
Transport and deposition of nanoparticles in porous media is a multi-scale problem governed by several pore-scale processes, and hence, it is critical to link the processes at pore scale to the Darcy-scale behavior. In this study, using pore network modeling, we develop correlation equations for deposition rate coefficients for nanoparticle transport under unfavorable conditions at the Darcy scale based on pore-scale mechanisms. The upscaling tool is a multi-directional pore-network model consisting of an interconnected network of pores with variable connectivities...
March 6, 2017: Journal of Contaminant Hydrology
Jennifer D Arthur, Noah W Mark, Susan Taylor, J Šimunek, M L Brusseau, Katerina M Dontsova
The explosive 2,4,6-trinitrotoluene (TNT) is currently a main ingredient in munitions; however the compound has failed to meet the new sensitivity requirements. The replacement compound being tested is 2,4-dinitroanisole (DNAN). DNAN is less sensitive to shock, high temperatures, and has good detonation characteristics. However, DNAN is more soluble than TNT, which can influence transport and fate behavior and thus bioavailability and human exposure potential. The objective of this study was to investigate the environmental fate and transport of DNAN in soil, with specific focus on sorption processes...
March 1, 2017: Journal of Contaminant Hydrology
Jun Dong, Bowen Li, Qiburi Bao
Mg(OH)2 dissolves slowly and can provide a long-term source of alkalinity, thus a promising alternative reagent for the in situ remediation of heavy metal polluted groundwater. However, the application of Mg(OH)2 on in situ reactive zone (IRZ) for heavy metal polluted groundwater has never been investigated. In this study, the behaviors of heavy metals in a Mg(OH)2 IRZ were monitored for 45d. The heavy metals show a sequential precipitation by modified Mg(OH)2 due to the difference of Ksp. Column tests were conducted to investigate the temporal and spatial distribution of heavy metals in Mg(OH)2 IRZ and evaluate the stabilization effect for multi-heavy metal polluted groundwater...
February 24, 2017: Journal of Contaminant Hydrology
Paul W Reimus, Bill W Arnold
Four different tracer methods were used to estimate groundwater flow velocity at a multiple-well site in the saturated alluvium south of Yucca Mountain, Nevada: (1) two single-well tracer tests with different rest or "shut-in" periods, (2) a cross-hole tracer test with an extended flow interruption, (3) a comparison of two tracer decay curves in an injection borehole with and without pumping of a downgradient well, and (4) a natural-gradient tracer test. Such tracer methods are potentially very useful for estimating groundwater velocities when hydraulic gradients are flat (and hence uncertain) and also when water level and hydraulic conductivity data are sparse, both of which were the case at this test location...
February 20, 2017: Journal of Contaminant Hydrology
Lichun Wang, M Bayani Cardenas
Understanding transport in rough fractures from non-Fickian to Fickian regimes and the prediction of non-Fickian transport is critical for the development of new transport theories and many practical applications. Through computational experiments that fall within the macrodispersion regime, we first simulated and analyzed solute transport through synthetic rough fractures with stationary geometrical properties (i.e., fracture roughness σb/〈b〉 and correlation length λ, where b refers to aperture with its standard deviation σb and arithmetic mean 〈b〉) across increasing fracture longitudinal transport domain length L, with L/λ ranging from 2...
February 4, 2017: Journal of Contaminant Hydrology
Mark C Padgett, Geoffrey R Tick, Kenneth C Carroll, William R Burke
The influence of chemical structure on NAPL mixture nonideality evolution, rate-limited dissolution, and contaminant mass flux was examined. The variability of measured and UNIFAC modeled NAPL activity coefficients as a function of mole fraction was compared for two NAPL mixtures containing structurally-different contaminants of concern including toluene (TOL) or trichloroethene (TCE) within a hexadecane (HEXDEC) matrix. The results showed that dissolution from the NAPL mixtures transitioned from ideality for mole fractions >0...
February 3, 2017: Journal of Contaminant Hydrology
Saliha Najib, Ahmed Fadili, Khalid Mehdi, Joëlle Riss, Abdelhadi Makan
This study aims to identify groundwater salinization origin and to determine seawater intrusion extension toward the inland in Chaouia, Morocco. To reach these objectives, firstly, 46 groundwater samples were analyzed for major chemical elements during January 2012 and, secondly, 10 electrical resistivity tomography (ERT) profiles were performed perpendicularly to the coastal fringe. Statistical analysis provided the distinction between three Clusters reflecting different hydrochemical processes. Cluster I and Cluster II-a showed a high water electrical conductivity (EC) (from 2...
January 31, 2017: Journal of Contaminant Hydrology
Alba Grau-Martínez, Clara Torrentó, Raúl Carrey, Paula Rodríguez-Escales, Cristina Domènech, Giorgio Ghiglieri, Albert Soler, Neus Otero
Anaerobic batch and flow-through experiments were performed to assess the capacity of two organic substrates to promote denitrification of nitrate-contaminated groundwater within managed artificial recharge systems (MAR) in arid or semi-arid regions. Denitrification in MAR systems can be achieved through artificial recharge ponds coupled with a permeable reactive barrier in the form of a reactive organic layer. In arid or semi-arid regions, short-term efficient organic substrates are required due to the short recharge periods...
January 22, 2017: Journal of Contaminant Hydrology
Elias Hideo Teramoto, Hung Kiang Chang
Mass transfer of light non-aqueous phase liquids (LNAPLs) trapped in porous media is a complex phenomenon. Water table fluctuations have been identified as responsible for generating significant variations in the concentration of dissolved hydrocarbons. Based on field evidence, this work presents a conceptual model and a numerical solution for mass transfer from entrapped LNAPL to groundwater controlled by both LNAPL saturation and seasonal water table fluctuations within the LNAPL smear zone. The numerical approach is capable of reproducing aqueous BTEX concentration trends under three different scenarios - water table fluctuating within smear zone, above the smear zone and partially within smear zone, resulting in in-phase, out-of-phase and alternating in-phase and out-of-phase BTEX concentration trend with respect to water table oscillation, respectively...
January 18, 2017: Journal of Contaminant Hydrology
Ronald W Falta, Wenwen Wang
A semi-analytical approximation for transient matrix diffusion is developed for use in numerical contaminant transport simulators. This method is an adaptation and extension of the heat conduction method of Vinsome and Westerveld (1980) used to simulate heat losses during thermally enhanced oil recovery. The semi-analytical method is used in place of discretization of the low permeability materials, and it represents the concentration profile in the low permeability materials with a fitting function that is adjusted in each element at each time-step...
January 11, 2017: Journal of Contaminant Hydrology
Iason Verginelli, Oriana Capobianco, Niels Hartog, Renato Baciocchi
In this work we introduce a 1-D analytical solution that can be used for the design of horizontal permeable reactive barriers (HPRBs) as a vapor mitigation system at sites contaminated by chlorinated solvents. The developed model incorporates a transient diffusion-dominated transport with a second-order reaction rate constant. Furthermore, the model accounts for the HPRB lifetime as a function of the oxidant consumption by reaction with upward vapors and its progressive dissolution and leaching by infiltrating water...
January 10, 2017: Journal of Contaminant Hydrology
Thanasis Mpouras, Maria Chrysochoou, Dimitris Dermatas
In this study the removal of hexavalent chromium (Cr(6+)) by serpentine sediments was investigated in order to delineate Cr(6+) sorption behavior in aquifers with ultramafic geologic background. Batch experiments were conducted in order to determine the influence of several parameters on Cr(6+) removal, including the pH of the sediment solution, mineralogy, sediment's particle size and Cr(6+) initial concentration. The results showed that Cr(6+) removal was due to both adsorption and reduction phenomena. Reduction was attributed to the presence of a magnetic fraction in the sediment, mostly related to magnetite, which contributed almost 50% of the total removal in the pH range 3-7...
January 5, 2017: Journal of Contaminant Hydrology
Adam Dettmer, Raymond Ball, Thomas B Boving, Naima A Khan, Tanner Schaub, Nilusha Sudasinghe, Carlos A Fernandez, Kenneth C Carroll
Recalcitrant organic groundwater contaminants, such as 1,4-dioxane, may require strong oxidants for complete mineralization. However, their efficacy for in-situ chemical oxidation (ISCO) is limited by oxidant decay and reactivity. Hydroxypropyl-β-cyclodextrin (HPβCD) was examined for its ability to stabilize aqueous-phase ozone (O3) and prolong oxidation potential through inclusion complex formation. Partial transformation of HPβCD by O3 was observed. However, HPβCD proved to be sufficiently recalcitrant, because it was only partially degraded in the presence of O3...
January 2017: Journal of Contaminant Hydrology
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