Chapter 10: Movement of Solutes in Soil: Computer-Simulated and Laboratory Results

Genuchten, Martinus Th. van; Cleary, Robert W.

doi:10.1016/s0166-2481(08)70665-2

Cited by 98 publications

(33 citation statements)

References 51 publications

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“…the transformation of former QD and river sediments into agricultural land. The radionuclide activity concentration along Path 2 is estimated by an advection-dispersion model [4] assuming constant moisture content and one-dimensional flow:…”

Section: Transport Models For Path 2 Andmentioning

confidence: 99%

Prediction of concentration and model validation

Dverstorp

Wörman

2009

Radioprotection

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Abstract. In this paper we examine some critical aspects concerning the justification of simplified radioecological models used in safety assessments for geological repositories. We propose a modelling approach for regulatory review of dose and risk calculations for a nuclear waste repository. The SSI modelling tools are applied to explore uncertainties in the size of the contaminant area due to leakage of radionuclides from a damaged nuclear waste canister. We demonstrate that an improved representation of geosphere transport processes will also enhance our understanding of radionuclide migration in the biosphere and provide a better basis for evaluating radiological consequences in the safety assessment.

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Section: Transport Models For Path 2 Andmentioning

confidence: 99%

Prediction of concentration and model validation

Dverstorp

Wörman

2009

Radioprotection

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“…If local equilibrium and constant values for v w and D w are assumed, the total concentration C t (x,t) of the radionuclide in the soil (mobile and sorbed) with respect to the concentration C o t of the radionuclide deposited as a single pulse at time t=0 to the soil surface (x=0) is given [1,2,3] as: (2) Here λ is the decay constant of the radionuclide, erfc(ξ)= 1-erf(ξ), where erf(ξ) is the error function. Also, one usually defines (3) where K d is the distribution coefficient of the radionuclide in the soil, ρ the bulk density, and ε the water filled porosity of the soil.…”

Section: Convection-dispersion Modelmentioning

confidence: 99%

“…The convection-dispersion model (e.g. [1,2,3,4,5]) is frequently applied where the radionuclide transport is characterised by the parameters D w (dispersion coefficient), v w (average pore water velocity) and K d (distribution coefficient, characterising the sorption of the radionuclide in the soil). Compartment models (e.g.…”

Section: Introductionmentioning

confidence: 99%

Migration of fallout-radionuclides in the soil: effect of non-uniformity of the sorption properties on the activity-depth profiles

Bunzl¹

2001

Radiation and Environmental Biophysics

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Experimentally observed activity-depth profiles of fallout radionuclides in the soil frequently exhibit a comparatively fast moving tail in soil layers below the peak concentration (tailing). Monte Carlo calculations on the basis of the convection-dispersion model show that this phenomenon can be explained by assuming that either the hydraulic properties of the soil (characterised by the diffusion/dispersion coefficient and pore water velocity) or the sorption properties of the soil (characterised by the distribution coefficient Kd), or both, exhibit a horizontal variability according to a log-normal distribution. Modifications of the activity-depth profile due to a Kd value which decreases linearly with depth were examined by using a random walk approach, based also on the convection-dispersion model. In this case, however, a pronounced tailing effect of the activity-depth profile did not result. Interpretation and realistic modelling of an experimentally observed activity-depth profile which exhibits a tailing effect is thus not unambiguously possible without any additional information on the spatial variability of the hydraulic parameters and, independently, also for the sorption properties.

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“…In this one-dimensional convective-dispersive, local equilibrium, mass transport model the total concentration C t (x, t) of the radionuclide in the soil (mobile and sorbed) at time t and distance x with respect to the concentration C o t of the radionuclide deposited as a single pulse at time t=0 to the soil surface (x=0) is given [7,8,9] as: (1) Here λ is the decay constant of 137 Cs, erfc(ξ)=1-erf(ξ), where erf(ξ) is the error function, (2) where K d is the distribution coefficient of 137 Cs in the soil, ρ the bulk density and ε the porosity of the soil. D and v w are the dispersion coefficient and the mean pore water velocity, respectively.…”

Section: Convection-dispersion Modelmentioning

confidence: 99%

Spatial variability of the vertical migration of fallout 137 Cs in the soil of a pasture, and consequences for long-term predictions

Bunzl

Schimmack

Zelles

et al. 2000

Radiation and Environmental Biophysics

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Various transport models are presently used to predict the long-term migration behaviour of fallout radiocesium on the soil. To examine to what extent the uncertainty of these predictions is influenced by the spatial variability of the migration rates, we determined the depth profiles of Chernobyl-derived 137Cs at 100 plots in a 100 m x 100 m pasture. These data were used to obtain the frequency distributions of the characteristic transport parameters of three widely used transport models (e.g. dispersion-convection model, residence time model, and back-flow model). The results show that these transport parameters are generally log-normally distributed with a coefficient of variation of about 80%. Finally, each transport model was employed to predict the resulting frequency distribution of the 137Cs inventory in the main root layer (0-7 cm) of the pasture, 20, 50, and 100 years after the deposition. If only the spatial variability of the transport parameters is taken into account, this analysis revealed that the dispersion-convection model and the back-flow model always predicted rather similar, but significantly higher median inventories than those obtained with the residence time model. If, in addition, the spatial variability of the amount of 137Cs deposited is also taken into account, the frequency distributions of the 137Cs inventories in the root layer become so wide that differences in the median inventories predicted by the three models become statistically significant only after 100 years. Several statistically significant correlations between the transport parameters of the three models were also detected.

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Chapter 10: Movement of Solutes in Soil: Computer-Simulated and Laboratory Results

Cited by 98 publications

References 51 publications

Prediction of concentration and model validation

Prediction of concentration and model validation

Migration of fallout-radionuclides in the soil: effect of non-uniformity of the sorption properties on the activity-depth profiles

Spatial variability of the vertical migration of fallout 137 Cs in the soil of a pasture, and consequences for long-term predictions

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