Assessment of geogenic radon potential with activation of advective soil air flow

Prediction of radon potential and justification of measures for reducing radon concentration in buildings necessitate the study of soil radon transport. The article presents an approach to estimating the geogenic radon potential of a site based on the study of the dependence of the radon flux from the soil on the pressure gradient. The efficacy of the method of radon flux density measurement with artificial activation of controlled advective air flow from the soil into the accumulation chamber was evaluated at an experimental site. The measuring installation consisted of a large-volume accumulation chamber (200 l), a system of pumps, flow meters, and a differential manometer. The results of measurements at 12 points on the experimental site yielded a number of values, including advective radon flux density as a function of pressure difference between the accumulation chamber and the atmosphere (in the range 4–20 Pa), radon concentration in soil air, and resistance to air flow in the soil-chamber system. The results demonstrate that at the investigated site, the potential advective radon flux density significantly exceeds the diffusive radon flux density: the corresponding radon flux density ranges are 23–870 mBq/(m² s) and 5.5–7.0 mBq/(m² s), respectively. The air flow resistance in the system of the soil measurement chamber varies depending on the meteorological conditions, with a range from 93 to 2400 kPa/(m³·s^-1). On average, under dry conditions, the resistance to airflow is 4.8 times lower than in rain. The radon concentration in the soil varies from 0.6 to 3.2 kBq/m³, with an arithmetic mean of 1.4 kBq/m³. The dependence of the advective radon flux density, normalized to a pressure difference of 1 Pa, on the air flow resistance follows the Darcy’s law. This dependence, taking into account the soil radon concentration, characterizes the geogenic radon potential at the site. The advantages and disadvantages of the method of geogenic radon potential estimation based on the artificial activation of the pressure gradient in the measurement system are discussed.

1. Neznal M, Neznal M, Matolín M, Barnet I, Mikšová J. The new method for assessing the radon risk of building sites. Czech Geological Survey Special Papers 16. Prague: Czech Geological Survey; 2004. 48 p. Available from: http://www.radon-vos.cz/pdf/metodika.pdf [Accessed 10 June 2024].

2. Bossew P, Cinelli G, Ciotoli G, Crowley QG, De Cort M, Elío Medina J, et al. Development of a Geogenic Radon Hazard Index—Concept, History, Experiences. International Journal of Environmental Research and Public Health. 2020; 17: 4134. DOI: 10.3390/ijerph17114134.

3. Miklyaev PS, Petrova TB, Shchitov DV, Sidyakin PA, Murzabekov MA, Tsebro D et al. Radon transport in permeable geological environments. Science of The Total Environment. 2022;852: 158382. DOI: 10.1016/j.scitotenv.2022.158382.

4. Marenyi AM, Tsapalov AA, Miklyaev PS, Petrova TB. Regularities of radon field formation in the geological environment. Moscow: Pero Publishing House; 2016. 364 p. (In Russian).

5. Petermann E, Meyer H, Nussbaum M, Bossew P. Mapping the geogenic radon potential for Germany by machine learning. Science of the Total Environment. 2021;754: 142291. DOI: 10.1016/j.scitotenv.2020.142291.

6. Zhukovsky MV, Yarmoshenko IV. Radon: measurement, doses, risk assessment. Ekaterinburg: Ural Branch of the Russian Academy of Sciences; 1997. 231 p. (In Russian)

7. Kiselev SM, Zhukovsky MV, Stamat IP, Yarmoshenko IV. Radon. From fundamental research to the regulatory practice. Publishing of the GNC FMBC after A.I. Burnazyan: Moscow; 2016, 450 p. (In Russian).

8. Matolin M, Neznal M. Experience from radon in soil gas comparison measurements held in Czech Republic and in other countries, 1992–2022. Journal of the European Radon Association. 2024; 5. DOI: 10.35815/radon.v5.9545.

9. Neznal M, Neznal M, Šmarda J. Assessment of radon potential of soils —a five year experience. Environment International. 1996;22: 819–828. DOI: 10.1016/S0160-4120(96)00189-4.

10. Kemski , Klingel R, Siehl A, Valdivia-Manchego M. From radon hazard to risk prediction-based on geological maps, soil gas and indoor measurements in Germany. Environmental Geology. 2008;56: 1269–1279. DOI: 10.1007/s00254-008-1226-z.

11. Font L, Baixeras C, Moreno V, Bach J. Soil radon levels across the Amer fault. Radiation Measurements. 2008;43: S319–S323. DOI: 10.1016/j.radmeas.2008.04.072.

12. Bossew P. Mapping the Geogenic Radon Potential and Estimation of Radon Prone Areas in Germany. Radiation Emergency Medicine. 2015;4: 13–20.

13. Cinelli G, Tollefsen T, Bossew P, Gruber V, Bogucarskis K, De Felice L, et al. Digital version of the European Atlas of natural radiation. Journal of Environmental Radioactivity. 2019;196: 240–252. DOI: 10.1016/j.jenvrad.2018.02.008.

14. Pavlov IV. Mathematical model of the process of radon exhalation from the ground surface and criteria for assessing the potential radon hazard of the territory of the building. ANRI = ANRI. 1997;5(11): 15-26. (In Russian).

15. Lei B, Zhao L, Girault F, Cai Z, Luo C, Thapa S, et al. Overview and large-scale representative estimate of radon-222 flux data in China. Environmental Advances. 2023;11: 100312. DOI: 10.1016/j.envadv.2022.100312.

16. Gavriliev S, Petrova T, Miklyaev P, Karfidova E. Predicting radon flux density from soil surface using machine learning and GIS data. Science of The Total Environment. 2023;903: 166348. DOI: 10.1016/j.scitotenv.2023.166348

17. IAEA. Measurement and calculation of radon releases from NORM residues. Technical reports series, no. 474. STI/DOC/010/474. International Atomic Energy Agency; 2013.

18. Zhukovskiy MV, Dontsov GI, Shorikov AO, Rogatko AA. Modification of the accumulation chamber method for measuring the radon flux density from the soil surface. ANRI= ANRI. 1999;3(18): 9-20. (In Russian).

19. Tsapalov A, Kovler K, Miklyaev P. Open charcoal chamber method for mass measurements of radon exhalation rate from soil surface. Journal of Environmental Radioactivity. 2016;160: 28–35. DOI: 10.1016/j.jenvrad.2016.04.016

20. Ryzhakova NK, Stavitskaya KO, Plastun SA. The problems of assessing radon hazard of development sites in the Russian Federation and the Czech Republic. Radiation Measurements. 2022;150: 106681. DOI: 10.1016/j.radmeas.2021.106681.

21. Demoury C, Ielsch G, Hemon D, Laurent O, Laurier D, Clavel J, et al. A statistical evaluation of the influence of housing characteristics and geogenic radon potential on indoor radon concentrations in France. Journal of Environmental Radioactivity. 2013;126: 216–225. DOI: 10.1016/j.jenvrad.2013.08.006.

22. Petermann E, Bossew P, Hoffmann B. Radon hazard vs. radon risk – On the effectiveness of radon priority areas. Journal of Environmental Radioactivity. 2022; 244–245: 106833. DOI: 10.1016/j.jenvrad.2022.106833.

23. Zhukovsky M, Yarmoshenko I, Kiselev S. Combination of geological data and radon survey results for radon mapping. Journal of Environmental Radioactivity. 2012;112: 1–3. DOI: 10.1016/j.jenvrad.2012.02.013.

24. Yarmoshenko I, Malinovsky G, Vasilyev A. Comments to special issue geogenic radiation and its potential use for developing the geogenic radon map. Journal of Environmental Radioactivity. 2017;172: 143–144. DOI: 10.1016/j.jenvrad.2017.03.023.

25. Yarmoshenko I, Malinovsky G, Vasilyev A, Zhukovsky M. Method for measuring radon flux density from soil activated by a pressure gradient. Radiation Measurements. 2018;119: 150–154. DOI: 10.1016/j.radmeas.2018.10.011.

26. Yarmoshenko IV, Malinovsky GP, Vasilyev AV, Zhukovsky MV. Method for measuring the radon flux density from the pressure gradient-activated soil. ANRI=ANRI. 2018;2(93): 48-55. (In Russian).

27. Yarmoshenko I, Malinovsky G, Vasilyev A, Zhukovsky M. Reconstruction of national distribution of indoor radon concentration in Russia using results of regional indoor radon measurement programs. Journal of Environmental Radioactivity. 2015; 150: 99-103. DOI: 10.1016/j.jenvrad.2015.08.007.