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  • 1
    Language: English
    In: Journal of Environmental Management, Nov 1, 2015, Vol.163, p.204(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2015.08.025 Byline: Mojtaba G. Mahmoodlu, S. Majid Hassanizadeh, Niels Hartog, Amir Raoof, Martinus Th. van Genuchten Abstract: Permeable reactive barriers are commonly used to treat contaminant plumes in the saturated zone. However, no known applications of horizontal permeable reactive barriers (HPRBs) exist for oxidizing volatile organic compounds (VOCs) in the unsaturated zone. In this study, laboratory column experiments were carried out to investigate the ability of a HPRB containing solid potassium permanganate, to oxidize the vapors of trichloroethylene (TCE), toluene, and ethanol migrating upward from a contaminated saturated zone. Results revealed that an increase in initial water saturation and HPRB thickness strongly affected the removal efficiency of the HPRB. Installing the HPRB relatively close to the water table was more effective due to the high background water content and enhanced diffusion of protons and/or hydroxides away from the HPRB. Inserting the HPRB far above the water table caused rapid changes in pH within the HPRB, leading to lower oxidation rates. The pH effects were included in a reactive transport model, which successfully simulated the TCE and toluene experimental observations. Simulations for ethanol were not affected by pH due to condensation of water during ethanol oxidation, which caused some dilution in the HRPB. Author Affiliation: (a) Utrecht University, Department of Earth Sciences, The Netherlands (b) KWR Watercycle Research Institute, Nieuwegein, The Netherlands (c) Federal University of Rio de Janeiro, Department of Mechanical Engineering, Brazil (d) Department of Watershed and Rangeland Management, Gonbad Kavous University, Iran Article History: Received 5 April 2015; Revised 11 August 2015; Accepted 19 August 2015
    Keywords: Watershed Management – Analysis ; Pollution Control – Analysis ; Volatile Organic Compounds – Analysis ; Toluene – Analysis ; Hydroxides – Analysis ; Vadose Zone – Analysis
    ISSN: 0301-4797
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Journal of Environmental Management, Nov 1, 2015, Vol.163, p.204(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2015.08.025 Byline: Mojtaba G. Mahmoodlu, S. Majid Hassanizadeh, Niels Hartog, Amir Raoof, Martinus Th. van Genuchten Abstract: Permeable reactive barriers are commonly used to treat contaminant plumes in the saturated zone. However, no known applications of horizontal permeable reactive barriers (HPRBs) exist for oxidizing volatile organic compounds (VOCs) in the unsaturated zone. In this study, laboratory column experiments were carried out to investigate the ability of a HPRB containing solid potassium permanganate, to oxidize the vapors of trichloroethylene (TCE), toluene, and ethanol migrating upward from a contaminated saturated zone. Results revealed that an increase in initial water saturation and HPRB thickness strongly affected the removal efficiency of the HPRB. Installing the HPRB relatively close to the water table was more effective due to the high background water content and enhanced diffusion of protons and/or hydroxides away from the HPRB. Inserting the HPRB far above the water table caused rapid changes in pH within the HPRB, leading to lower oxidation rates. The pH effects were included in a reactive transport model, which successfully simulated the TCE and toluene experimental observations. Simulations for ethanol were not affected by pH due to condensation of water during ethanol oxidation, which caused some dilution in the HRPB. Author Affiliation: (a) Utrecht University, Department of Earth Sciences, The Netherlands (b) KWR Watercycle Research Institute, Nieuwegein, The Netherlands (c) Federal University of Rio de Janeiro, Department of Mechanical Engineering, Brazil (d) Department of Watershed and Rangeland Management, Gonbad Kavous University, Iran Article History: Received 5 April 2015; Revised 11 August 2015; Accepted 19 August 2015
    Keywords: Watershed Management – Analysis ; Pollution Control – Analysis ; Volatile Organic Compounds – Analysis ; Toluene – Analysis ; Hydroxides – Analysis ; Vadose Zone – Analysis
    ISSN: 0301-4797
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Journal of Hydrology, October 2018, Vol.565, pp.570-580
    Description: The macroscopic effects of soil textural heterogeneity and fine-scale soil layering on unsaturated flow remain poorly understood. In this study we used the Discrete Element Method (DEM) to numerically generate artificial particle packings of heterogeneous sands from which the pore structure can be extracted. Packings were generated from known grain size distributions following sand grain mixing and fine-scale profile layering. Five sands with different mean grain sizes were used to investigate the effects of heterogeneity on their pore structure, including changes in the permeability and soil water retention (SWR). Heterogeneous media were created by mixing a relatively fine sand with coarser sands. In addition, we created layered media having sharp as well as transitional interfaces between the two sand samples. Mixing fine and coarse sand caused reductions in the average pore body and pore throat sizes of the coarser sands, and hence also in their intrinsic permeability. The layered media with a transitional interface showed lower porosities at the interface because of penetration of small particles into the larger pores, while the porosities increased at sharp interfaces. The nonlinear relationships between permeability and the average pore body and throat radii were explored using different unimodal sands. Mixing fine and coarse sand caused a decrease in the capillary pressure at a given water content of the new medium, and hence larger values of the van Genuchten parameter. The SWRCs of the layered soils with a sharp interface were best described using bimodal functions. Sharp interfaces caused a non-monotonic change in the drainage curve due to discrepancies between the pore throat radii of the two adjacent sands. This change was influenced by of the sands used for the layered media. In contrast to the sharp interface, a monotonic (smooth) change in the drainage curve was observed for two sands having small differences in their values. The study gave considerable insight into how particle heterogeneity and layering affects the hydraulic properties of unsaturated media.
    Keywords: Soil Water Retention Curve (Swrc) ; Intrinsic Permeability ; Heterogeneous Sands ; Discrete Element Method ; Pore Structure ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 4
    Language: English
    In: Journal of Hydrology, 2011, Vol.399(1), pp.93-99
    Description: ► We assess influence of soil CaCO on soil water retention characteristics of calcareous soils. ► We derive specific pedotransfer functions PTFs for calcareous soils. ► The derived point and parametric PTFs provide better accuracy than Rosetta PTFs. The unsaturated soil hydraulic properties are needed for many different applications in soil hydrology. Pedotransfer functions (PTFs) have proven to be useful to indirectly estimate these parameters from more easily obtainable soil data. Until now no studies have been conducted to derive or verify PTFs for calcareous soils, which hydraulically may not behave the same as non-calcareous soils. The objectives of this study were to assess the influence of soil CaCO on the soil water retention characteristics of some calcareous soils, and to derive PTFs for these soils. Two data sets were used to derive and evaluate the established PTFs. Data set 1 containing 220 samples was employed as a calibration set for multiple linear regression. An independent data set containing 55 soil samples from a different location served to verify the derived PTFs. No significant difference in accuracy was found between the PTFs with and without CaCO in terms of estimating specific soil water retention values or the van Genuchten soil hydraulic parameters. Compared with the Rosetta PTFs of , the derived point and parametric PTFs provided better accuracy with average values of 0.028 and 0.107 cm cm , respectively.
    Keywords: Calcareous Soils ; Pedotransfer Function ; Soil Hydraulic Properties ; Water Retention Curve ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 5
    Language: English
    In: Journal of hydrology, 2011, Vol.399(1), pp.93-99
    Description: The unsaturated soil hydraulic properties are needed for many different applications in soil hydrology. Pedotransfer functions (PTFs) have proven to be useful to indirectly estimate these parameters from more easily obtainable soil data. Until now no studies have been conducted to derive or verify PTFs for calcareous soils, which hydraulically may not behave the same as non-calcareous soils. The objectives of this study were to assess the influence of soil CaCO₃ on the soil water retention characteristics of some calcareous soils, and to derive PTFs for these soils. Two data sets were used to derive and evaluate the established PTFs. Data set 1 containing 220 samples was employed as a calibration set for multiple linear regression. An independent data set containing 55 soil samples from a different location served to verify the derived PTFs. No significant difference in accuracy was found between the PTFs with and without CaCO₃ in terms of estimating specific soil water retention values or the van Genuchten soil hydraulic parameters. Compared with the Rosetta PTFs of , the derived point and parametric PTFs provided better accuracy with average RMSE values of 0.028 and 0.107cm³ cm⁻³, respectively. ; Includes references ; p. 93-99.
    ISSN: 0022-1694
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 6
    Language: English
    In: Journal of Environmental Management, 01 November 2015, Vol.163, pp.204-213
    Description: Permeable reactive barriers are commonly used to treat contaminant plumes in the saturated zone. However, no known applications of horizontal permeable reactive barriers (HPRBs) exist for oxidizing volatile organic compounds (VOCs) in the unsaturated zone. In this study, laboratory column experiments were carried out to investigate the ability of a HPRB containing solid potassium permanganate, to oxidize the vapors of trichloroethylene (TCE), toluene, and ethanol migrating upward from a contaminated saturated zone. Results revealed that an increase in initial water saturation and HPRB thickness strongly affected the removal efficiency of the HPRB. Installing the HPRB relatively close to the water table was more effective due to the high background water content and enhanced diffusion of protons and/or hydroxides away from the HPRB. Inserting the HPRB far above the water table caused rapid changes in pH within the HPRB, leading to lower oxidation rates. The pH effects were included in a reactive transport model, which successfully simulated the TCE and toluene experimental observations. Simulations for ethanol were not affected by pH due to condensation of water during ethanol oxidation, which caused some dilution in the HRPB.
    Keywords: Horizontal Permeable Reactive Barrier ; Potassium Permanganate ; VOC Vapors ; Unsaturated Zone ; Diffusion ; Environmental Sciences ; Economics
    ISSN: 0301-4797
    E-ISSN: 1095-8630
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  • 7
    Language: English
    In: Journal of Environmental Management, 2015, Vol.163, pp.204-4797
    Description: Permeable reactive barriers are commonly used to treat contaminant plumes in the saturated zone. However, no known applications of horizontal permeable reactive barriers (HPRBs) exist for oxidizing volatile organic compounds (VOCs) in the unsaturated zone. In this study, laboratory column experiments were carried out to investigate the ability of a HPRB containing solid potassium permanganate, to oxidize the vapors of trichloroethylene (TCE), toluene, and ethanol migrating upward from a contaminated saturated zone. Results revealed that an increase in initial water saturation and HPRB thickness strongly affected the removal efficiency of the HPRB. Installing the HPRB relatively close to the water table was more effective due to the high background water content and enhanced diffusion of protons and/or hydroxides away from the HPRB. Inserting the HPRB far above the water table caused rapid changes in pH within the HPRB, leading to lower oxidation rates. The pH effects were included in a reactive transport model, which successfully simulated the TCE and toluene experimental observations. Simulations for ethanol were not affected by pH due to condensation of water during ethanol oxidation, which caused some dilution in the HRPB.
    Keywords: Diffusion ; Horizontal Permeable Reactive Barrier ; Potassium Permanganate ; Unsaturated Zone ; Voc Vapors ; Environmental Engineering ; Waste Management And Disposal ; Management, Monitoring, Policy And Law
    ISSN: 0301-4797
    Source: NARCIS (National Academic Research and Collaborations Information System)
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  • 8
    Language: English
    In: Ground water, 2011, Vol.49(2), pp.286-94
    Description: Accurate estimates of groundwater recharge are essential for effective management of groundwater, especially when supplies are limited such as in many arid and semiarid areas. In the Hebei Plain, China, water shortage is increasingly restricting socioeconomic development, especially for agriculture, which heavily relies on groundwater. Human activities have greatly changed groundwater recharge there during the past several decades. To obtain better estimates of recharge in the plain, five representative sites were selected to investigate the effects of irrigation and water table depth on groundwater recharge. At each site, a one-dimensional unsaturated flow model (Hydrus-1D) was calibrated using field data of climate, soil moisture, and groundwater levels. A sensitivity analysis of evapotranspirative fluxes and various soil hydraulic parameters confirmed that fine-textured surface soils generally generate less recharge. Model calculations showed that recharge on average is about 175 mm/year in the piedmont plain to the west, and 133 mm/year in both the central alluvial and lacustrine plains and the coastal plain to the east. Temporal and spatial variations in the recharge processes were significant in response to rainfall and irrigation. Peak time-lags between infiltration (rainfall plus irrigation) and recharge were 18 to 35 days in the piedmont plain and 3 to 5 days in the central alluvial and lacustrine plains, but only 1 or 2 days in the coastal plain. This implies that different time-lags corresponding to different water table depths must be considered when estimating or modeling groundwater recharge.
    Keywords: Water Movements ; Environmental Monitoring -- Methods
    ISSN: 0017467X
    E-ISSN: 1745-6584
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  • 9
    Language: English
    In: Ground Water, Jan-Feb, 2013, Vol.51, p.9(4)
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1111/j.1745-6584.2012.01018.x/abstract Byline: Vedat Batu(*) , Martinus Th. van Genuchten(1), John C. Parker(2) ***** No abstract is available for this article. ***** Author Affiliation: (1)Department of Mechanical Engineering, COPPE/LTTC, Federal University of Rio de Janeiro, UFRJ, Rio de Janeiro, RJ 21945-970, Brazil. (2)Department of Civil and Environmental Engineering, University of Tennessee at Knoxville, Knoxville, TN 37996. Correspondence: (*) URS Corporation, 100 South Wacker Drive, Chicago, IL 60606; vedat_batu@urscorp.com
    Keywords: Mechanical Engineering
    ISSN: 0017-467X
    Source: Cengage Learning, Inc.
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  • 10
    Language: English
    In: Journal of Contaminant Hydrology, Sept, 2013, Vol.152, p.12(6)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jconhyd.2013.06.002 Byline: Gholamreza Sadeghi, Jack F. Schijven, Thilo Behrends, S. Majid Hassanizadeh, Martinus Th. van Genuchten Abstract: Knowledge of virus removal in subsurface environments is pivotal for assessing the risk of viral contamination of water resources and developing appropriate protection measures. Columns packed with sand are frequently used to quantify attachment, detachment and inactivation rates of viruses. Since column transport experiments are very laborious, a common alternative is to perform batch experiments where usually one or two measurements are done assuming equilibrium is reached. It is also possible to perform kinetic batch experiments. In that case, however, it is necessary to monitor changes in the concentration with time. This means that kinetic batch experiments will be almost as laborious as column experiments. Moreover, attachment and detachment rate coefficients derived from batch experiments may differ from those determined using column experiments. The aim of this study was to determine the utility of kinetic batch experiments and investigate the effects of different designs of the batch experiments on estimated attachment, detachment and inactivation rate coefficients. The experiments involved various combinations of container size, sand-water ratio, and mixing method (i.e., rolling or tumbling by pivoting the tubes around their horizontal or vertical axes, respectively). Batch experiments were conducted with clean quartz sand, water at pH7 and ionic strength of 20mM, and using the bacteriophage PRD1 as a model virus. Values of attachment, detachment and inactivation rate coefficients were found by fitting an analytical solution of the kinetic model equations to the data. Attachment rate coefficients were found to be systematically higher under tumbling than under rolling conditions because of better mixing and more efficient contact of phages with the surfaces of the sand grains. In both mixing methods, more sand in the container yielded higher attachment rate coefficients. A linear increase in the detachment rate coefficient was observed with increased solid-water ratio using tumbling method. Given the differences in the attachment rate coefficients, and assuming the same sticking efficiencies since chemical conditions of the batch and column experiments were the same, our results show that collision efficiencies of batch experiments are not the same as those of column experiments. Upscaling of the attachment rate from batch to column experiments hence requires proper understanding of the mixing conditions. Because batch experiments, in which the kinetics are monitored, are as laborious as column experiments, there seems to be no major advantage in performing batch instead of column experiments. Article History: Received 18 March 2013; Revised 11 June 2013; Accepted 13 June 2013
    Keywords: Water Resources
    ISSN: 0169-7722
    Source: Cengage Learning, Inc.
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