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.
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Received: 5 January 2001 / Accepted: 1 May 2001
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Bunzl, K. Migration of fallout-radionuclides in the soil: effect of non-uniformity of the sorption properties on the activity–depth profiles. Radiat Environ Biophys 40, 237–241 (2001). https://doi.org/10.1007/s004110100102
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DOI: https://doi.org/10.1007/s004110100102