ORIGINAL RESEARCH PAPERS:

Peter Germann, Andreas Helbling, and Tomaso Vadilonga

Rivulet Approach to Rates of Preferential Infiltration
Preferential flow is defined to be between Darcy flow and Richards' flow. The soil water content for transition between preferential flow and Richards' flow is defined as being that where the soil water diffusivity just equals the kinematic viscosity of the soil water. This threshold water content is considered a soil property.
Published online 9 April 2007; doi:10.2136/vzj2006.0115
Vadose Zone J 2007 6: 207-220. [Abstract] [Full Text] [Figures Only] [PDF]  

Barry J. Allred, Jerry M. Bigham, and Glenn O. Brown

The Impact of Clay Mineralogy on Nitrate Mobility under Unsaturated Flow Conditions
Transient unsaturated horizontal column experiments were conducted to assess clay mineralogy impacts on electrostatic processes affecting nitrate mobility. Results indicate anion adsorption is an important process affecting mobility in low pH soils, with limited organic matter, and a clay fraction dominated by kaolinite, while anion exclusion is a key electrostatic interaction influencing mobility in near neutral to high pH soils, especially if significant amounts of montmorillonite are present.
Published online 9 April 2007; doi:10.2136/vzj2006.0064
Vadose Zone J 2007 6: 221-232. [Abstract] [Full Text] [Figures Only] [PDF]  

Kai Uwe Totsche, Steffen Jann, and Ingrid Kögel-Knabner

Single Event–Driven Export of Polycyclic Aromatic Hydrocarbons and Suspended Matter from Coal Tar–Contaminated Soil
Mobile sorbents like (organic) colloids and even larger particles have been identified as transport vehicles for hydrophobic organic contaminants in soil. Results from a field study are presented that show that single and extreme climatic events control the mobilization and relocation of particles and as such the particle-bound contaminants.
Published online 9 April 2007; doi:10.2136/vzj2006.0083
Vadose Zone J 2007 6: 233-243. [Abstract] [Full Text] [Figures Only] [PDF]  

Carlos M. Regalado, Axel Ritter, and Rosa M. Rodríguez-González

Performance of the Commercial WET Capacitance Sensor as Compared with Time Domain Reflectometry in Volcanic Soils
Capacitance sensors are an alternative to dielectric sensors for measuring water content and bulk EC of soil. The capacitance sensor, WET Sensor (Delta-T Devices) is compared with a TDR sensor for measurement of water content and bulk EC of three volcanic soils. The WET Sensor readings required an empirical correction for water content.
Published online 9 April 2007; doi:10.2136/vzj2006.0138
Vadose Zone J 2007 6: 244-254. [Abstract] [Full Text] [Figures Only] [PDF]  

Steven Evett, Nazirbay Ibragimov, Bakhtiyor Kamilov, Yusupbek Esanbekov, Makhsud Sarimsakov, Jamaliddin Shadmanov, Rahmonkul Mirhashimov, Ruzibay Musaev, Tilak Radjabov, and Bahram Muhammadiev

Neutron Moisture Meter Calibration in Six Soils of Uzbekistan Affected by Carbonate Accumulation
The neutron moisture meter was calibrated for irrigation and crop water use research in six Central Asian soils ranging from deep, uniform silt loams of loessial origin to stratified alluvial soils. Presence of a carbonate-rich layer in uniform silt loams necessitated a separate calibration, as did layers with contrasting textures in alluvial soils.
Published online 17 May 2007; doi:10.2136/vzj2006.0155
Vadose Zone J 2007 6: 406-412. [Abstract] [Full Text] [Figures Only] [PDF]  

W. A. P. Waduge, K. Soga, and J. Kawabata

Physical Modeling of LNAPL Source Zone Remediation by Air Sparging
Mass removal behavior of pooled LNAPL by air sparging was investigated using one-dimensional and two-dimensional physical model experiments. The effects of flow rate, flow interruption, NAPL saturation, and soil heterogeneity were examined. The necessity of a rate limited NAPL-gas mass transfer model as a function of NAPL saturation and a threshold saturation is addressed.
Published online 17 May 2007; doi:10.2136/vzj2006.0047
Vadose Zone J 2007 6: 413-422. [Abstract] [Full Text] [Figures Only] [PDF]  

W. A. Agyare, S. J. Park, and P. L. G. Vlek

Artificial Neural Network Estimation of Saturated Hydraulic Conductivity
Estimation of saturated hydraulic conductivity using an artificial neural networks (ANN) method is investigated employing a combination of readily measured soil parameters and terrain attributes. We show that using terrain attributes can improve the estimation, which highlights the need for some measured data for good ANN topsoil saturated hydraulic conductivity estimation.
Published online 17 May 2007; doi:10.2136/vzj2006.0131
Vadose Zone J 2007 6: 423-431. [Abstract] [Full Text] [Figures Only] [PDF]  

TECHNICAL NOTES:

H. Hardelauf, M. Javaux, M. Herbst, S. Gottschalk, R. Kasteel, J. Vanderborght, and H. Vereecken

PARSWMS: A Parallelized Model for Simulating Three-Dimensional Water Flow and Solute Transport in Variably Saturated Soils
This article describes, proves the reliability and shows the performance of a parallel code for solving water flow and solute transport in unsaturated conditions: PARSWMS.
Published online 9 April 2007; doi:10.2136/vzj2006.0156
Vadose Zone J 2007 6: 255-259. [Abstract] [Full Text] [Figures Only] [PDF]  

BOOK REVIEWS:

William W. Woessner

Applied Flow and Solute Transport Modeling in Aquifers: Fundamental Principles and Analytical and Numerical Methods
by Vedat Batu. Taylor & Francis Group, CRC Press, Boca Raton, FL. 2005. Hardcover, 667 pp. ISBN 0-8493-3574-4.
Published online 9 April 2007; doi:10.2136/vzj2006.0163br
Vadose Zone J 2007 6: 260. [Full Text] [PDF]  

Zhiming Lu and Dongxiao Zhang

Stochastic Methods in Subsurface Contaminant Hydrology
Edited by Rao S. Govindaraju. ASCE Press, Reston, VA. 2002. Hardcover, 410 pp. ISBN 0-7844-0532-8.
Published online 9 April 2007; doi:10.2136/vzj2006.0165br
Vadose Zone J 2007 6: 261-262. [Full Text] [PDF]  

Linda S. Lee

Environmental Organic Chemistry, 2nd Edition
by Rene P. Schwarzenbach, Philip M. Gschwend, and Dieter M. Imboden. John Wiley & Sons, Wiley-Interscience, Hoboken, NJ. 2003. Paperback, 1313 pp. ISBN-0-471-35750-2.
Published online 9 April 2007; doi:10.2136/vzj2007.0023br
Vadose Zone J 2007 6: 263-264. [Full Text] [PDF]  

Anthony O'Geen

Soils: Genesis and Geomorphology
by Randall Schaetzl and Sharon Anderson, Cambridge University Press, New York. 2005. Hardcover. 817 pages. ISBN 0-521-81201-1.
Published online 9 April 2007; doi:10.2136/vzj2007.0030br
Vadose Zone J 2007 6: 265. [Full Text] [PDF]  

SPECIAL SECTION: SOIL BIOPHYSICS:

Alvin J.M. Smucker and Jan W. Hopmans

Preface: Soil Biophysical Contributions to Hydrological Processes in the Vadose Zone
The editors introduce the five featured papers derived from the symposium "Soil Biophysics: A Challenging Interface." A better understanding of the interaction between the soil physical and biological realms is needed to improve vadose zone modeling and advance the field of soil ecology.
Published online 17 May 2007; doi:10.2136/vzj2007.0057
Vadose Zone J 2007 6: 267-268. [Abstract] [Full Text] [PDF]  

Alain Pierret, Claude Doussan, Yvan Capowiez, François Bastardie, and Loïc Pagès

Root Functional Architecture: A Framework for Modeling the Interplay between Roots and Soil
Root-soil interactions involve a myriad of interwoven physical, chemical, and biological processes that we mostly know about from disciplines operating independently. This fragmented knowledge needs to be integrated through a unifying framework. In this review, we show how the concept of root functional architecture can be used to this end.
Published online 17 May 2007; doi:10.2136/vzj2006.0067
Vadose Zone J 2007 6: 269-281. [Abstract] [Full Text] [Figures Only] [PDF]  

Alvin J.M. Smucker, Eun-Jin Park, Jose Dorner, and Rainer Horn

Soil Micropore Development and Contributions to Soluble Carbon Transport within Macroaggregates
Micropores within soil aggregates control the diffusion and retention of carbon compounds, contaminants, plant nutrients, and microbial communities. Natural drying and wetting expands intra-aggregate storage capacities. We suggest these natural drying and wetting processes augment the spatial distributions of both substrates and microbes within newly developed micropore networks.
Published online 17 May 2007; doi:10.2136/vzj2007.0031
Vadose Zone J 2007 6: 282-290. [Abstract] [Full Text] [Figures Only] [PDF]  

Michael F. Allen

Mycorrhizal Fungi: Highways for Water and Nutrients in Arid Soils
Mycorrhizal fungal hyphae bridge gaps across soil pores. These bridges may reduce tortuosity forming highways for rapid nutrient and water flux. Water can flow bidirectionally, from soil to hypha to plant or plant to hypha to soil (hydraulically lifted water), depending on the gradient in water potential.
Published online 17 May 2007; doi:10.2136/vzj2006.0068
Vadose Zone J 2007 6: 291-297. [Abstract] [Full Text] [Figures Only] [PDF]  

Dani Or, Sachin Phutane, and Arnaud Dechesne

Extracellular Polymeric Substances Affecting Pore-Scale Hydrologic Conditions for Bacterial Activity in Unsaturated Soils
We examine morphological changes in the extracellular polymeric substance (EPS) matrix under varying hydration states, its role in maintenance of aquatic microhabitats and facilitating nutrient diffusion under desiccated conditions, and potential modification of macroscopic hydrologic properties of host porous media.
Published online 17 May 2007; doi:10.2136/vzj2006.0080
Vadose Zone J 2007 6: 298-305. [Abstract] [Full Text] [Figures Only] [PDF]  

A. Massoudieh, A. Mathew, E. Lambertini, K. E. Nelson, and T. R. Ginn

Horizontal Gene Transfer on Surfaces in Natural Porous Media: Conjugation and Kinetics
A new modeling approach to quantify conjugation and its kinetics in natural porous media is introduced and tested. It accounts for the transport of bacteria in bulk fluid, interaction with solid surfaces, conjugation in both planktonic and sessile states, and time lags observed experimentally via an exposure-time approach.
Published online 17 May 2007; doi:10.2136/vzj2006.0069
Vadose Zone J 2007 6: 306-315. [Abstract] [Full Text] [Figures Only] [PDF]  

SPECIAL SECTION: SAVANNAH RIVER SITE:

J. C. Seaman, B. B. Looney, and M. K. Harris

Research in Support of Remediation Activities at the Savannah River Site
The guest editors introduce the articles featured in the special section and provide a history of the Savannah River Site, as well as a description of its lithology and hydrostatigraphy. Production and refinement of nuclear materials has resulted in complex mixtures of contaminants at the site, but also in advances in environmental research and remediation, often through active interdisciplinary collaboration with researchers from other USDOE facilities, academic and federal institutions, and commercial entities.
Published online 17 May 2007; doi:10.2136/vzj2007.0044
Vadose Zone J 2007 6: 316-326. [Abstract] [Full Text] [Figures Only] [PDF]  

Todd C. Rasmussen and Thomas L. Mote

Monitoring Surface and Subsurface Water Storage Using Confined Aquifer Water Levels at the Savannah River Site, USA
A confined aquifer at the Savannah River Site behaves as a large (natural) weighing lysimeter, responding quickly to precipitation and to changes in overlying soil moisture storage on the scale of hectares. Candidate aquifers for serving as regional lysimeters include those in poorly consolidated media remotely located from human disturbances.
Published online 17 May 2007; doi:10.2136/vzj2006.0049
Vadose Zone J 2007 6: 327-335. [Abstract] [Full Text] [Figures Only] [PDF]  

G. P. Flach, K. P. Crapse, M. A. Phifer, L. B. Collard, and L. D. Koffman

An Unsteady Dual Porosity Representation of Tritium Leaching from Buried Concrete Rubble
Buried concrete rubble from building demolition comprises a heterogeneous mixture of coarse aggregate sizes, shapes, and internal contamination distributions. A novel technique for approximating an arbitrary three-dimensional shape with a one-dimensional slab thickness is developed for use in an unsteady dual-porosity transport model.
Published online 17 May 2007; doi:10.2136/vzj2006.0051
Vadose Zone J 2007 6: 336-343. [Abstract] [Full Text] [Figures Only] [PDF]  

Deniz I. Demirkanli, Fred J. Molz, Daniel I. Kaplan, Robert A. Fjeld, and Steven M. Serkiz

Modeling Long-Term Plutonium Transport in the Savannah River Site Vadose Zone
To understand Pu migration in natural conditions, long-term experiments were conducted in field lysimeters. Measured activity distributions after 11 yr were not explainable using advection-dispersion concepts alone. However, they are explained using a two-species transport model with redox reactions on mineral surfaces.
Published online 17 May 2007; doi:10.2136/vzj2006.0042
Vadose Zone J 2007 6: 344-353. [Abstract] [Full Text] [Figures Only] [PDF]  

S. M. Serkiz, W. H. Johnson, L. M. Johnson Wile, and S. B. Clark

Environmental Availability of Uranium in an Acidic Plume at the Savannah River Site
Uranium availability in porewater/soil samples from an impacted aquifer at the Savannah River Site was investigated via sequential extractions. Hydrologic regime, source proximity, and weathering were examined. Vadose-zone soils exhibited a lower uranium availability than saturated with field-derived partition coefficient for U (0.1-300 L/kg) correlated to pH.
Published online 17 May 2007; doi:10.2136/vzj2006.0072
Vadose Zone J 2007 6: 354-362. [Abstract] [Full Text] [Figures Only] [PDF]  

J. C. Seaman, P. M. Bertsch, and D. I. Kaplan

Spatial and Temporal Variability in Colloid Dispersion as a Function of Groundwater Injection Rate within Atlantic Coastal Plain Sediments
A field study was conducted to evaluate the impact of pump-and-treat remediation activities on colloid generation for injection rates ranging from 19 to 132 liters per minute. Turbidity varied greatly between sampling wells and zones within a given well (<1-740 NTU), with the two closest sampling wells displaying the greatest response to increases in injection rate.
Published online 17 May 2007; doi:10.2136/vzj2006.0048
Vadose Zone J 2007 6: 363-372. [Abstract] [Full Text] [Figures Only] [PDF]  

J. C. Seaman, P. M. Bertsch, M. Wilson, J. Singer, F. Majs, and S. A. Aburime

Tracer Migration in a Radially Divergent Flow Field: Longitudinal Dispersivity and Anionic Tracer Retardation
Radial, forced-gradient hydrologic tracer experiments were conducted using tritium, bromide, and two fluorobezoates to evaluate longitudinal dispersivity. Dispersivities ranged greatly between wells located at similar distances and different sampling zones within a given well, and the anionic tracers were found to be retarded when compared with tritium.
Published online 17 May 2007; doi:10.2136/vzj2006.0109
Vadose Zone J 2007 6: 373-386. [Abstract] [Full Text] [Figures Only] [PDF]  

Karin T. Rebel, Susan J. Riha, Derek Karssenberg, and Jery R. Stedinger

Simulating Tritium Fluxes in the Vadose Zone under Transient Saturated Conditions
Tritium was used as a tracer to study the significance of lateral flow on plant solute uptake on Coastal Plain soils in South Carolina. The results suggest that locally, lateral solute flow may be important, but on an area average it does not have a large impact on plant solute uptake.
Published online 17 May 2007; doi:10.2136/vzj2005.0113
Vadose Zone J 2007 6: 387-396. [Abstract] [Full Text] [Figures Only] [PDF]  

Christine Switzer and David S. Kosson

Soil Vapor Extraction Performance in Layered Vadose Zone Materials
A series of field tests and mass transfer model simulations were used to evaluate a soil vapor extraction system addressing a trichloroethylene source at the Savannah River Site. Diffusion model simulations compare well with the location of a dense non-aqueous-phase liquid source detected during the course of operation.
Published online 17 May 2007; doi:10.2136/vzj2005.0131
Vadose Zone J 2007 6: 397-405. [Abstract] [Full Text] [Figures Only] [PDF]  

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