The first integrated isotope and chemistry results have been obtained for radon-rich thermal waters from the Belokurikha field which are used at a large spa resort in Altai, Russia. The waters reside in an unconfined aquifer composed of Quaternary soft sediments and in a confined (artesian) aquifer of monolithic to weathered Upper Paleozoic granites. The waters belong to three geochemical groups: low-radon nitrogen-silicic interstitial waters in weathered Paleozoic granites; groundwaters of REE-enriched and background compositions; surface waters of the Belokurikha River. The interstitial waters in granites have HCO3-SO4 Na and SO4-HCO3 Na major-ion chemistry, total salinity from 198 to 257 mg/L, pH = 8.6–9.6, silica contents of 19.8 to 24.6 mg/L, and 222Rn activity from 160 to 360 Bq/L (290 Bq/L on average). Judging by their oxygen and hydrogen (deuterium) isotope compositions (−17.5 to −14.2 ‰ and −126.9 to −102.7 ‰, respectively), the Belokurikha aquifers recharge with infiltrating meteoric water, especially the winter precipitation. The carbon isotope composition of dissolved inorganic carbon (−9.7 to −25.6 ‰ δ13СDIC) corresponds to biogenic origin. Comparison of radon-rich mineral waters from different areas of southern Siberia shows that the change from oxidized to reduced environments leads to 232Th/238U increase from 4.20∙10−5–7.39∙10−2 to 0.0022–26, respectively, with an intermediate range of 2.63∙10−5–0.20 in transitional conditions.
- Belokurikha spa
- Stable isotopes
- Thermal water
- 1.05 EARTH AND RELATED ENVIRONMENTAL SCIENCES