engleski

Transport of Radionuclides in the Environment. Nuclear Techniques in Study of Pollutant Transport in the Environment

Mechanisms governing the retardation of radionuclides in the geosphere are investigated by laboratory and fallout experiments. Solubility constraints, Sorption and long-term non-equilibrium processes are considered as the most important factors. The long-term non-equilibrium processes significantly affect the distribution of radionuclides between the solid and liquid phase. Dissolution of main clay constituents, precipitation of a secondary phase and variability in surface charge distribution are recognized as the most important mechanisms governing cesium sorption on montmorillonite over a long period of time. Studies of cesium distribution after the global contamination affected by Chernobyl accident, reveal that cesium is strongly sorbed in the upper soil layer and its migration downwards is limited. Cesium distribution through upper soil layer is described mathematically. Transport of radionuclides in groundwater is studied by a new type of models defined by the wave (telegraph) equations. Contrary to the classical diffusion equation, in these models a substance is transported with a finite velocity. A simpler subclass of models is applied to the description of tracer experiments in groundwater of Istria peninsula. Predictions from models are compared with the data and conclusions are derived for further research.

radionuclide; migration; environment

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