MIGRATION OF NATURAL RADIONUCLIDES IN THE SYSTEM «HYDROCRYOGENIC COMPONENTS – WATER – PORE WATER OF BOTTOM SEDIMENTS» IN URBAN WATER BODIES

Abstract

The relevance of the research is caused by the necessity of obtaining information on the behavior of natural radionuclides under urban landscape conditions during contemporary sedimentation. In particular, there are no complete data on the following issues: influence of physical and chemical properties of urban environmental components on the transfer of radionuclides in the system « catchment – water body», accumulation of natural radionuclides during sediment runoff from the catchment of urbanized environment into the bottom sediments during the long-term period, patterns and geochemical features of natural radionuclides behavior in the system «hydrocryogenic components – water of water bodies – pore solutions of bottom sediments». The main aim of the research is to identify the migration patterns of natural radionuclides in the system « catchment-watershed» in the urban area during the formation of sediment runoff. Objects: waterbody, catchment, natural waters, snow, ice, snow-dirt sludge, chemical composition of environmental objects, uranium and thorium content. Methods: water chemistry analyzed by means of a set of methods: potentiometric titration, spectrophotometry, flame photometry and mass spectrometry (ICP-MS). The mineral composition of the rocks was determined using a powder X-ray diffraction (XRD). Results. Data on the hydrochemical characteristics of selected water bodies of the urban environment and their catchments were obtained. The waters of water bodies are enriched with U and Th in orders of magnitudes in comparison with water fraction surface runoff and precipitations. Dominant forms of migration of natural radionuclides in the studied components of the urban landscape were determined. Uranium forms are represented in the form of uranyl carbonate complexes of different composition, thorium – by carbonate-hydroxyl complexes. Relationships between physico-chemical and hydrochemical indicators of environmental components in the system «cutoff basin – undrained reservoir» were revealed. Trends and mechanisms that may affect the formation of the geochemical situation of water bodies, pollution of water and bottom sediments were identified. Pore solutions of bottom sediments contain uranium and thorium in higher concentrations than in water bodies. Such minerals of bottom sediments as pyrite, montmorillonite and calcite along with organic matter determine the behavior of natural radionuclides and their mobilization in the bottom sediments of urban water bodies in Ekaterinburg. © 2023 Tomsk Polytechnic University, Publishing House. All rights reserved.