Выпуск: 12 , Том: 63 , Год издания: 2022

In August 2019, four descending (gravity) springs in the Inya River valley were sampled during the field works conducted within the study of low-radon waters of the Novosibirsk urban agglomeration in the area lying away from known granite massifs. Laboratory analyses have revealed enhanced radon activity concentrations (from 5 to 149 Bq/dm³). It has been established that these waters are fresh, of HCO₃ Mg-Ca chemical composition, and have a TDS value of 413 to 548 mg/dm³ and a silicon content of 4.1-8.6 mg/dm³. They are characterized by neutral to slightly alkaline pH (7.1-8.4) and oxidizing geochemical conditions with Eh from +205.3 to +231.8 mV and O_{2 dissolv.} = 6.24-12.26 mg/dm³. The revealed predominance of SO₄²- over Cl^-U concentrations in the waters of the study area was probably due to the presence of sulfides in the water-bearing sediments, in particular, pyrite in the surface sediments. More than tenfold proportional excess of Ca concentrations over Si in the Inskie spring waters indicates the predominantly carbonate composition of the water-bearing sediments. The gross α-activity of waters is 3-4 mBq/dm³, and gross β-activity is 11-15 mBq/dm³. Natural radionuclides are found in the spring waters within the following limits (mg/dm³): ²³⁸U, from 2.83 · 10^-3 to 4.13 · 10^-3; ²³²Th, from 2.39 · 10^-6 to 1.16 · 10^-5, and ²²⁶Ra, from 3.83 · 10^-10 to 4.93 · 10^-10. The value of the ²³²Th/²³⁸U ratio for the waters ranges from 5.79 · 10^-4 to 3.61 · 10^-3, as a result of the oxidative geochemi