Specificities of predicting metal distribution between aqueous phase and bottom sediments (by the example of strontium and cesium radionuclides)

Summary

The basic provisions of the developed methodological approach to predicting the coefficient of K_d radionuclide distribution on the material of bottom sediments and suspended substances in water bodies are presented. As a tool for predicting K_d coefficient of metals under the conditions of the changing chemical composition of water the use of geochemical modelling was suggested. The basic approaches, models and results of predicting the values of K_d coefficient of metals in a reference water body (a surface water reservoir – radioactive waste storage) characterized by high pollution with ⁹⁰Sr strontium and ¹³⁷Cs radionuclides as well as by the intensive decrease of water mineralization are laid out. During the research the specific features of hydrochemical and hydrodynamic behavior of metals in the water body system as well as the methods of geochemical modeling were studied in detail. The geochemical thermodynamic model of metal sorption (by the example of ⁹⁰Sr and ¹³⁷Сs) by the suspended matter and bottom sediment layer in the model water reservoir was developed that could be considered as a basis for modeling different scenarios of the evolution of real polluted water reservoirs. The values of K_d coefficient for ⁹⁰Sr and ¹³⁷Сs at decreasing water mineralization were calculated. It was determined that K_d value is increasing while water mineralization is decreasing. The model can be used for predicting the rate of metal elimination from polluted water bodies in the process of self-purification.