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Risks posed by vapors are uncertain. Soil profile layering and moisture changes measured at a field site over a year are shown to dramatically alter the movement of hydrocarbon vapors towards the ground surface, and to alter estimates of vapor biodegradation rates. Wherever oxygen was found to be present, hydrocarbon vapors apparently biodegraded.

Vadose Zone Journal May 01, 2005, Vol.4, 225-239. doi:https://doi.org/10.2136/vzj2004.0029

Free draining lysimeters were used to measure drainage, soil moisture, evapotranspiration, soil temperature, and transport of the pesticide methabenzthiazuron. An application of MACRO, MARTHE, TRACE, and ANSWERS to the lysimeter data reveals the conceptual strengths and weaknesses of the different model approaches.

Vadose Zone Journal May 01, 2005, Vol.4, 240-254. doi:https://doi.org/10.2136/vzj2004.0070

An analytic element method for a spherical inclusion of contrasting hydraulic properties in a uniform vertical flow field is presented. The solution requires the numerical matching of both pressure head and normal flux at sphere interface and is iterative due to nonlinearity in the head boundary condition. With contrasting sorptive numbers, reversal of inclusion properties may occur for different background fluxes.

Vadose Zone Journal May 01, 2005, Vol.4, 255-263. doi:https://doi.org/10.2136/vzj2004.0076

Scaling techniques implicitly assume geometric similitude for the soils being scaled; however, the meaning of similar media is not clear. This study shows that similar media can be classified based on the coefficient of variation of standard deviations of soil pore size distributions. A coefficient of variation <10% may be used as a cutoff for similar soils.

Vadose Zone Journal May 01, 2005, Vol.4, 264-270. doi:https://doi.org/10.2136/vzj2004.0113

At a Cretaceous chalk site a range of fracture characterization properties were measured, including origin, orientation, trace length, spacing, coating, connectivity, and hydraulic activity. This information was combined with infrared thermography measurements to determine the main hydraulically active conduits at the site.

Vadose Zone Journal May 01, 2005, Vol.4, 271-280. doi:https://doi.org/10.2136/vzj2004.0074

The guest editor introduces the special section derived from the “Zona No Saturada” 2003 conference in Valladolid, Spain. The studies reported in these articles demonstrate the global growth of vadose zone research.

Vadose Zone Journal May 01, 2005, Vol.4, 281. doi:https://doi.org/10.2136/vzj2005.0037

The kinetics and the equilibria of adsorption and desorption of Arsenate in three Spanish soils are studied. The authors evaluate the effects of temperature and the presence of other ions (phosphate, nitrate, chloride, and sulfate) on the adsorption isotherm of arsenate in soils.

Vadose Zone Journal May 01, 2005, Vol.4, 282-290. doi:https://doi.org/10.2136/vzj2004.0095

A simple method is presented to estimate the soil saturated hydraulic conductivity and the Green-Ampt wetting front suction with the Philip-Dunne falling-head permeameter. Only the times when the permeameter is half full and empty are necessary for the proposed new method, but not the soil moisture increment required by earlier methods.

Vadose Zone Journal May 01, 2005, Vol.4, 291-299. doi:https://doi.org/10.2136/vzj2004.0103

Peculiarities of volcanic soils may influence the movement of solutes through the vadose zone. Bromide transport in a volcanic soil was analyzed by TDR and inverse modeling. Characterization of bromide transport highlighted a delay in bromide breakthrough, which relates to the high Fe and Al oxihydroxides contents typical of these soils.

Vadose Zone Journal May 01, 2005, Vol.4, 300-309. doi:https://doi.org/10.2136/vzj2004.0094

The lattice Boltzmann and Random Walk models are presented for describing pore-scale transport processes. Results show that both approaches are valid alternatives to conventional models.

Vadose Zone Journal May 01, 2005, Vol.4, 310-316. doi:https://doi.org/10.2136/vzj2004.0090

Spatial estimation of the soil water-holding capacity at the regional scale from scarce soil data requires the use of pedotransfer functions and geostatistics. A regional assessment of the average annual water balance in southern Spain suggests that available pedotransfer functions underestimate regional soil water-holding capacity.

Vadose Zone Journal May 01, 2005, Vol.4, 317-328. doi:https://doi.org/10.2136/vzj2004.0099

Nitrogen transformations in soils following urea application were monitored in controlled laboratory batch experiments. Rate data for N transformations and coupled sorption processes were determined from the experimental data and are presented as a function of temperature, soil moisture content, and initial concentration of applied urea.

Vadose Zone Journal May 01, 2005, Vol.4, 329-336. doi:https://doi.org/10.2136/vzj2004.0102

Temporal analysis of profiles of volatile organic compounds within the saturated–unsaturated interface region of a contaminated phreatic aquifer is presented. The profiles were obtained with a passive multilayer sampler that allows detection of differences as great as 24000 micrograms TCE per liter of air between samples located at a vertical interval of only 12 cm.

Vadose Zone Journal May 01, 2005, Vol.4, 337-344. doi:https://doi.org/10.2136/vzj2004.0100

An automated laboratory apparatus used to study the hydraulic properties of variably saturated porous media is described. Accurate temporal measures of temperature, water content, and soil suction inside the sample can be made. A unique feature of the apparatus is that it is capable of quantifying behavior for media undergoing shrinkage or swelling.

Vadose Zone Journal May 01, 2004, Vol.4, 345-353. doi:https://doi.org/10.2136/vzj2004.0105

The optimal well locations and flow rates to maximize mass removal of subsurface contaminants using bioventing systems, subject to certain physical and budgetary constraints, were explored. Wells placed on the centerline of the contaminant plume achieved best results. Findings were applied to a field case study.

Vadose Zone Journal May 01, 2005, Vol.4, 354-359. doi:https://doi.org/10.2136/vzj2004.0055

Random walk may be an efficient numerical method to simulate solute transport in saturated or unsaturated porous material. Topics covered in this review include theoretical aspects of the methods, various numerical implementations including reactive transport, and continuous time and time domain random walk.

Vadose Zone Journal May 01, 2005, Vol.4, 360-379. doi:https://doi.org/10.2136/vzj2004.0125

The soil water retention characteristic is predicted based on the microscopic structure of the pore space. Three different models having different complexity are compared: a Lattice-Boltzmann simulation, a pure geometric approach, and a network model.

Vadose Zone Journal May 01, 2005, Vol.4, 380-388. doi:https://doi.org/10.2136/vzj2004.0114

A genetic optimization algorithm and a probability distribution function were applied to air permeability vs. volumetric water data derived from a sandstone core sample to estimate the pore size distribution and pore configuration of the sandstone. The derived pore information was used to predict the water retention curve for the sandstone.

Vadose Zone Journal May 01, 2005, Vol.4, 389-397. doi:https://doi.org/10.2136/vzj2004.0116

Measured data from a high time-resolution tracer microlysimeter experiment were accurately reproduced by simulations using an improved version of MACRO. Parameter identification with the GLUE procedure adequately constrained the mass exchange coefficient, indicating that it would be identifiable in inverse procedures.

Vadose Zone Journal May 01, 2005, Vol.4, 398-406. doi:https://doi.org/10.2136/vzj2004.0137

The impact of the growth of Pseudomonas fluorescens on the hydraulic properties of variably saturated porous media was studied using packed laboratory columns. A numerical model of coupled fluid flow and multicomponent mass transport was used to simulate measured moisture content, water pressure, biomass concentrations, and effluent fluxes.

Vadose Zone Journal May 01, 2005, Vol.4, 407-417. doi:https://doi.org/10.2136/vzj2004.0087

Relationships between simulated evaporation and transpiration and the pore-size distribution index across dissimilar soil textures were used to estimate evaporation and transpiration for a range of potential rates in initially wet soils. The results were found useful in quantifying spatial variability of evaporation and transpiration in the field.

Vadose Zone Journal May 01, 2005, Vol.4, 418-427. doi:https://doi.org/10.2136/vzj2004.0119

A new method is presented for measuring the air permeability of soil columns and cores. Dry air is pumped through an initially wet soil sample, which completely dries coarse-textured samples within 1 to 2 d. Concurrently, water content and air pressure measurements are collected to enable calculation of air permeability.

Vadose Zone Journal May 01, 2005, Vol.4, 428-433. doi:https://doi.org/10.2136/vzj2004.0092

ORIGINAL RESEARCH

Buckingham's methodical development of an unsaturated flow theory from first principles facilitates a grasp that one seldom gets from textbooks. While providing a dynamical basis for studying soil moisture, Buckingham understood the problem well enough to be skeptical about its mathematical tractability. Soil physics education is incomplete without a reading of Buckingham's enjoyable masterpiece.

Vadose Zone Journal May 01, 2005, Vol.4, 434-441. doi:https://doi.org/10.2136/vzj2004.0126

Book Reviews

Vadose Zone Journal May 01, 2005, Vol.4, 442. doi:https://doi.org/10.2136/vzj2003.0016br
Vadose Zone Journal May 01, 2005, Vol.4, 443-444. doi:https://doi.org/10.2136/vzj2004.0001br
Vadose Zone Journal May 01, 2005, Vol.4, 445. doi:https://doi.org/10.2136/vzj2004.0002br
Vadose Zone Journal May 01, 2005, Vol.4, 446. doi:https://doi.org/10.2136/vzj2004.0004br
Vadose Zone Journal May 01, 2005, Vol.4, 447. doi:https://doi.org/10.2136/vzj2004.0007br
Vadose Zone Journal May 01, 2005, Vol.4, 448. doi:https://doi.org/10.2136/vzj2004.0012br
Vadose Zone Journal May 01, 2005, Vol.4, 449. doi:https://doi.org/10.2136/vzj2004.0013br
Vadose Zone Journal May 01, 2005, Vol.4, 450. doi:https://doi.org/10.2136/vzj2004.0014br
Vadose Zone Journal May 01, 2005, Vol.4, 451. doi:https://doi.org/10.2136/vzj2005.0002br
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