Spatial distribution of radon flux density from subsoil surface on the territory of Tyumen and its surroundings

   A special role among natural radionuclides is occupied by radon and its short-lived daughter decay products, which form from 50 to 90 % of the total radiation dose of the population. A danger to a person is represented by closed poorly ventilated rooms in which radon can accumulate in excess of the established hygienic standard. One of the factors for the accumulation of radon in buildings and structures is its emanation from rocks and subsoil. The method of measuring the radon flux density from the subsoil surface is used to assess the potential radon hazard of the land plot intended for the construction of buildings and structures.

   The purpose of the study is radiation and environmental assessment of the potential radon hazard of the territory of Tyumen and its surroundings.

   Materials and Methods: The studies were carried out from May to August 2025; the area covered was 697 km². The measurement of the radon flux density from the soil surface was performed using the AlphaRad Plus-R radiometer (Russia) at 513 control points. At the same time, meteorological parameters (air temperature and humidity, atmospheric pressure) were measured at the measurement sites; the physical properties of the soil (temperature, density, and field moisture) were also measured. The mapping data was created using the QGIS geoinformation system.

   Results and Discussion: The radon flux density from the soil surface ranges from 20 to 730 mBq/(s·m²). An increase in temperature and a decrease in air humidity intensify the natural erosion of the upper layers, causing cracks and changes in density, resulting in higher radon flux densities from the soil surface in these areas.

   Conclusion: The identified boundaries of anomalies with high values of radon flux density from the soil surface can be used: 1) in urban planning during the construction, repair, and reconstruction of buildings and structures in order to ensure radiation safety of the population; 2) in the field of engineering surveys and environmental monitoring by executive authorities and private firms.

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