Analysis of radon and radium content in springs of the city of Ekaterinburg and its outskirts

Despite development of central water supply systems, springs still remain to be important sources of drinking water. In this work, the study of water quality in springs of Yekaterinburg city and its settlements was performed with the attention to radiological factor. Activity concentrations of radium-226 were determined in water of 20 springs. Methods. Determination of the radon-222 activities of was performed using gamma-spectrometry vis the equilibrium bismuth-214 gamma line. To determine radium-226, 5-liter water samples were taken, the radium was preconcentrated on a T-5 sorbent; then radium was separated on a thinlayer MnO2-PE sorbent followed by measurement on an alpha spectrometer. Results. In the vast majority of cases, activity concentrations of radium-226 were lower than the detection limit (0.3 Bq/L); the maximal activity concentration of 1.03 ± 0.27 was found that corresponded to the internal dose of 0.21 ± 0.05 μSv/y due to daily consumption of this water. No correlations were found between content of radium-226 and concentrations of radon-222, uranium-238 and alkaline earth ions. At the period of 09.2020 – 06.2021, monitoring of radon activity was performed in seven springs with previously found high radon content. Significant seasonal variations of radon activity were found; for some springs the difference between the minimal and the maximal activity reached 3. In the most cases, increase of radon activity occurred in water during winter that can be explained by both an increase of radon solubility in cold water and a decrease of flowrate.