Hydrogeochemical characteristics and radionuclide dynamics in the Kyndygsky-1 thermal spring system, Western Transcaucasia.

Abstract

Water from four thermal springs in the Western Transcaucasia territory was studied. The main chemical parameters of the water, its isotopic, and gas composition were determined. It has been demonstrated that groundwater in mountainous regions, located between 1300 and 1750 m above sea level, exhibits characteristics of a classical nitrogen-methane therm. These characteristics are primarily attributed to the infiltration of atmospheric precipitation. The results of the geomorphological mapping demonstrated not only the radiation and chemical impact of thermal sources on the environment but also changes in the terrain and the chemogenic morpholithogenesis. The distribution of radionuclides ^226,228Ra (and their decay products) and ¹³⁷Cs entering the river with thermal water was investigated in bottom sediments from a borehole located in close proximity to Kyndyg village and downstream of the Dabakuara River. It was determined that equilibrium between ²²⁶Ra and its daughter decay products is restored at a distance of approximately 300 m from the sources. Additionally, an elevated concentration of radon decay products was observed at a distance of approximately 100 m from the thermal source. The specific activity of radium and its decay products in bottom sediments exceed the intervention levels (the level of radiation factor above which certain protective measures should be taken) by a factor of 3.5 at the direct release site. However, radioactivity decreases very quickly due to sorption of nuclides on bottom sediment particles and the decay of radon progeny. The text continues with recommendations regarding the thermal waters safe use in a recreational context.