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FORMS OF MIGRATION OF CHEMICAL ELEMENTS IN RADON WATERS IN THE SOUTH OF SIBERIA

A. N. Nikitenkov 1,2,3, D. A. Novikov 1,2, T. V. Korneeva 1,2

1 Novosibirsk State University, Novosibirsk, Russia; 2 A.A.Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia; 3 National Research Tomsk Polytechnic University , Tomsk, Russia

The paper presents the first results of thermodynamic modeling of the chemical elements migration forms in radon waters of southern Siberia. It was determined that Ca, Mg, Na, K, Mn, as well as, Fe (at nearneutral pH) migrates in the form of free ions, the proportion of which in most cases is more than 90%. Among the complex forms of migration of trace elements, as well as U and Th, associates prevail with a participation of dominant anions HCO3 –, CO3 2–, compounds with Cl– ions are less common. Hydroxide and oxide coordination compounds play a significant role in the migration of Al, as well as Si, U and Th (reaching tens of % of gross content). In oxidizing environment, uranium migrates predominantly in the form of carbonate compounds, in a reducing environment – in the form of oxides and hydroxide ions. The proportion of samples with hydroxide forms decreases with an increase in pH value by more than 8.5, and the proportion of oxide forms increases. Thorium in the studied radon waters migrates mainly in the form of carbonate compounds, namely in the form of (ThCO3(OH)3)–, which accounts for more than 90% in most samples. Its decrease to values of about 60% is typical for slightly acidic waters with a pH of less than 6.5.

Keywords: forms of migration, hydrogeochemistry, radon waters, uranium, thorium, thermodynamic modeling, Siberia.

DOI 10.20403/2078-0575-2023-2-81-90

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