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Radiation and Environmental Biophysics

, Volume 40, Issue 3, pp 237–241 | Cite as

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

  • K. Bunzl
Short Communication

Abstract 

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 K d ), or both, exhibit a horizontal variability according to a log-normal distribution. Modifications of the activity–depth profile due to a K d 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.

Keywords

Peak Concentration Soil Layer Random Walk Pore Water Spatial Variability 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2001

Authors and Affiliations

  • K. Bunzl
    • 1
  1. 1.GSF–National Research Centre for Environment and Health, Institute of Radiation Protection, 85764 Neuherberg, Germany e-mail: bunzl@gsf.de Tel.: +49-89-31872203, Fax: +49-89-31873323DE

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