Dynamics of radon and thoron concentrations in the surface air layer at the “Fonovaya" observatory
V.V. Antonovich, P.N. Antokhin, V.G. Arshinova, M.Yu. Arshinov, B.D. Belan, S.B. Belan, D.K. Davydov, N.V. Dudorova, G.A. Ivlev, A.V. Kozlov, G.A. Kolotkov, T.M. Rasskazchikova, D.E. Savkin, D.V. Simonenkov, T.K. Sklyadneva, G.N. Tolmachev, A.V. Fofonov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: atmosphere, air, gas, concentration, radon, composition, thoron
Abstract
Studies of the content of radioactive gases in the atmosphere are important for assessing their danger to public health and as an auxiliary characteristic of gas exchange between soil and atmosphere. There are very few measurements of radon and thoron concentrations in Russia. Therefore, this paper summarizes the results of their monitoring in the background region near Tomsk over 2020-2024. It has been shown that annual average radon concentrations are in the range 10.7-14.3 Bq/m3; the annual average maximal values can reach 81 Bq/m3. Thoron is characterized by a weaker variability of the average content (8.9-11.8 Bq/m3) and a lower maximal concentration (65 Bq/m3). It is found that radon has a well-defined daily cycle, while thoron does not. There are also significant differences in the annual variations in the concentrations of these gases. Although the main maxima of their concentrations are recorded in July, 222Rn has a secondary maximum in the cold season. A slow increase in the concentrations of both radon and thoron from 2020 to 2024 was found. The content of 222Rn increases at a rate of 0.5 Bq/m3 per year, and of 220Rn, with a rate of 0.2 Bq/m3 per year. The concentration of 222Rn is higher than 220Rn on daily, annual, and long-term scales. The data presented in this paper will be useful in choosing the range and uncertainty of new devices or protection against radiation and assessment of the probability of occurrence of a particular phenomenon.
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