Speaker
Description
Radon is a natural radioactive gas released from the soil as the result of 226Ra decay. Although, together with its short-lived decay products, it is monitored mainly in a purpose of radiation protection, in research can apply as a potential tracer of various natural processes. Carbon dioxide, on the other hand is a stable gas, but classified as a greenhouse gas with a key role in a climate changes issue. Roughly 2000 PgC is stored in the soil with a total flux with the atmosphere around 2.6 PgC/y [1] which makes the soil the most important source of CO2 on earth.
While the production of 222Rn as such is constant and its concentrations in the soil with its exhalation depend only on the meteorological conditions, the storage – releasing process of CO2 in the soil is influenced by the activity of vegetation which changes during a year even a day. As the result, the direct measurement of CO2 exhalation can be distorted and burdened with a high uncertainty with no representative value for a given area.
Just a radon can be used as a tool to determine CO2 exhalations from the soil by the method “Radon Tracer Method“ though it requires to know the concentrations of 222Rn and CO2 in the soil and also the exhalation rate of 222Rn [2,3]. For this reason, it is important to understand the variations of these gases in the soil, their mutual correlations as well as their dependence on meteorological conditions. For this purpose, we have focused on a comprehensive analysis of the concentrations of 222Rn and CO2 and their exhalations from the soil measured on the area of the campus of FMPH CU in Bratislava. These measurements took place continuously in the period from October 2020 to March 2024 during which we monitored the concentrations of these gases at a depth of 80 cm and their exhalation rate using an accumulation method, along with monitoring of meteorological parameters such a moisture, temperature, rainfall, etc. These long-term measurements provide us a comprehensive picture of the behaviour of 222Rn and CO2 in the soil, unaffected by soil characteristics (e.g. soil texture) and eliminating random fluctuations or possible abnormalities, while the results show interesting albeit complicated dependences.
This work was supported by the Scientific Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic and the Slovak Academy of Sciences (VEGA project No. 1/0019/22 and No. 1/0086/22) and the Slovak Research and Development Agency (project No. APVV-21-0356).
Ref.
[1] CIAIS, P. et al. Carbon and Other Biogeochemical Cycles. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2013. Radon A., Thoron B. : Radon in Environment, N.Y.Edition (1990), pp. 452–459.
[2] HOLÝ K. MÜLLEROVÁ M., PALUŠOVÁ V., BULKO M.: Comparison of various approaches to determining CO2 fluxes from the soil by 222Rn calibrated method. Radiat. Prot. Dosim. (2017), 177 (1-2), pp. 144–148.
[3] ARSTENS U., SCHWINGSHACKL C., SCHMITHHÜSEN D., LEVIN I.: A process-based 222radon flux map for Europe and its comparison to long-term observations. Atmos. Chem. Phys. (2015), 15, pp. 12845–12865.