The Effect of Molecular Size on Diffusion Characteristics in Soil

Barraclough, D.; Nye, P. H.

doi:10.1111/j.1365-2389.1979.tb00962.x

Cited by 33 publications

(7 citation statements)

References 13 publications

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“…This is high compared with values measured in unsaturated soils (e.g. Porter et af., 1960; Barraclough & Tinker, 1981) but very close to the value found by Barraclough & Nye (1979) in a saturated sandy loam. Nye & Tinker (1977) quoted saturated soil fi values between 0.4 and 0.7.…”

Section: Nitrate Difusion In Small Aggregatessupporting

confidence: 84%

Measurement and simulation of anion diffusion in natural soil aggregates and clods

Addiscott

Thomas

Janjua

1983

Journal of Soil Science

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The diffusion of indigenous nitrate from small (< 5 mm) aggregates of a clay-loam soil, and added bromide from larger (30-70 mm) clods of a sandy clay, were studied under saturated conditions. The time (20.5) taken for half the diffusional solute loss to occur from the small aggregates was well related to the square of the aggregate radius (a2). The impedance factor Ui, of 0.54 calculated from the t0.5 v. a2 relationship gave satisfactory results in simulations of the measured Mt/M, v. time curves.L0.5 was also well related to a2 for the clods, but thefc values calculated from it were not only very large (>0.9) but also decreased with increasing clod size, possibly because of anion exclusion effects.The model simulated bromide diffusion from chalk cubes of mixed sizes better when computations were made for each size than when a single volume-averaged size was taken.

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Section: Nitrate Difusion In Small Aggregatessupporting

confidence: 84%

Measurement and simulation of anion diffusion in natural soil aggregates and clods

Addiscott

Thomas

Janjua

1983

Journal of Soil Science

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“…When solute diffusion coefficients obtained from a large number of experiments (Barraclough & Nye, ; Barraclough & Tinker, ; Conca, ; Graham‐Bryce, ; Jurinak et al, ; Klute & Letey, ; Mehta et al, ; Olesen & Kemper, ; Patil et al, ; Porter et al, ; Rökens & Bruce, ; Rowell et al, ; Sadeghi et al, ; Schaefer et al, ; So & Nye, ; Warncke & Barber, ; Civilian Radioactive Waste Management System Management and Operating Contractor (CRWMS M&O) , ; Conca & Wright, ; Hu & Wang, ; Haggerty, ; Haggerty et al, ; Letey & Klute, ; Klute & Letey, ; Sallam et al, ; Mehta et al, ; Rinaldi & Cuestas, ) were compared with the moisture content directly with no attempt to estimate a threshold Hunt, Ghanbarian, & Ewing (), the result, shown in Figure , was that D pm / D w ≈ θ 1.96 , an exponent very close to 2. When the data for each porous medium were analyzed separately, however, in the same fashion as the gas diffusion coefficient Ghanbarian et al, , the result obtained followed equation .…”

Section: Constitutive Relationships For the Unsaturated Zonementioning

confidence: 99%

Flow, Transport, and Reaction in Porous Media: Percolation Scaling, Critical‐Path Analysis, and Effective Medium Approximation

Hunt

Sahimi

2017

Reviews of Geophysics

141

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We describe the most important developments in the application of three theoretical tools to modeling of the morphology of porous media and flow and transport processes in them. One tool is percolation theory. Although it was over 40 years ago that the possibility of using percolation theory to describe flow and transport processes in porous media was first raised, new models and concepts, as well as new variants of the original percolation model are still being developed for various applications to flow phenomena in porous media. The other two approaches, closely related to percolation theory, are the critical‐path analysis, which is applicable when porous media are highly heterogeneous, and the effective medium approximation—poor man's percolation—that provide a simple and, under certain conditions, quantitatively correct description of transport in porous media in which percolation‐type disorder is relevant. Applications to topics in geosciences include predictions of the hydraulic conductivity and air permeability, solute and gas diffusion that are particularly important in ecohydrological applications and land‐surface interactions, and multiphase flow in porous media, as well as non‐Gaussian solute transport, and flow morphologies associated with imbibition into unsaturated fractures. We describe new applications of percolation theory of solute transport to chemical weathering and soil formation, geomorphology, and elemental cycling through the terrestrial Earth surface. Wherever quantitatively accurate predictions of such quantities are relevant, so are the techniques presented here. Whenever possible, the theoretical predictions are compared with the relevant experimental data. In practically all the cases, the agreement between the theoretical predictions and the data is excellent. Also discussed are possible future directions in the application of such concepts to many other phenomena in geosciences.

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“…It is important because it is directly related to the polymer length: the longer the polymer, the greater the molecular weight (Green et al 2000). Polymers with lower molecular weights may not have chain lengths that are sufficiently long to bind together the relatively small number of clay particles present (Levy and Agassi 1995); polymers with very high molecular weights may be too large to penetrate soil voids (Barraclough and Nye 1979). The molecular weight is not important in clayey soils because the clay particles are close enough together that even short polymer lengths can bind them (Green et al 2000, Levy andAgassi 1995).…”

Section: Soil Conditionersmentioning

confidence: 99%

Effectiveness of best management practices that have application to forest roads: a literature synthesis

Edwards¹,

Wood²,

Quinlivan³

2016

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Literature describing the effectiveness of best management practices (BMPs) applicable to forest roads is reviewed and synthesized. Effectiveness is considered from the perspective of protecting water quality and water resources. Both paved and unpaved forest roads are considered, but BMPs that involve substantial engineering are not considered. Some of the BMPs included are commonly used on roads; others are used less often. The synthesis focuses on quantitative BMP effectiveness and descriptions of processes or characteristics that influenced the effectiveness. Qualitative results and observations not supported by data are excluded. Most of the effectiveness results describe sediment losses and sediment delivery, but there is also some coverage of chemicals used as BMPs, such as dust palliatives and soil conditioners. Chapters and subheadings are based on how or where protection is provided, or type of BMP. The final chapter provides information on research needs and potential direction of BMP implementation in the future. Although there remains a great need to quantify BMP effectiveness more rigorously across more physiographic, topographic, climate, and soil conditions, the data provided in this synthesis give road and watershed managers and landowners a starting place for evaluating and selecting BMPs.

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The Effect of Molecular Size on Diffusion Characteristics in Soil

Cited by 33 publications

References 13 publications

Measurement and simulation of anion diffusion in natural soil aggregates and clods

Measurement and simulation of anion diffusion in natural soil aggregates and clods

Flow, Transport, and Reaction in Porous Media: Percolation Scaling, Critical‐Path Analysis, and Effective Medium Approximation

Effectiveness of best management practices that have application to forest roads: a literature synthesis

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