The paper presents data on geochemical features of the water-rock system of the Skalinskoye radon water manifestation. The waters of the Skalinskoye manifestation by chemical composition belong to the SO4-HCO3 Na-Mg-Ca type with a total mineralization value of 279–787 mg/dm3. The geochemical parameters of the medium correspond to the oxidizing environment with Eh +84,6…+187,0 mV, pH 6.9–8.8 and O2dissolved concentrations of 3.75–9.93 mg/dm3. Radon activity is up to 572 Bq/dm3. The water-bearing rocks are represented by biotite granites of normal and moderately alkaline series, which are permeated by quartz and sericite-quartz veins. With an increase in the total mineralization of radon waters, the prevailing forms of migration are calcium, magnesium, nickel and strontium bicarbonates, nickel carbonate and magnesium sulfate. Uranium migrates mainly in the form of dissolved hydroxide U(OH)4(aq). According to saturation indices, all waters are saturated in relation to calcite, uraninite and amorphous uranium oxide.

Relevance. The need to dentify the characteristics of the distribution of radioactive elements in the groundwater of Northern Kazakhstan. Aim. Generalization of available data on the geochemistry of groundwater and uranium and radon distribution in them using the example of the northern regions of the Republic of Kazakhstan. Methods. Generalization of long-term hydrogeochemical research and compilation of an electronic data bank on the territory of Northern Kazakhstan. A laboratory study of the chemical composition of groundwater was carried out at the Research Laboratory of Hydrogeochemistry of the School of Natural Resources Engineering of Tomsk Polytechnic University. Measurements of 222Rn contents in waters were carried out using the Alfarad Plus complex in the Laboratory of Hydrogeology of Sedimentary Basins of Siberia, Institute of Geology and Geography, Siberian Branch, Russian Academy of Sciences. Results. The groundwater of aquifers of different ages, distributed in the territory of Northern Kazakhstan (North Kazakhstan uranium province), was studied. Two geochemical sets of groundwater were identified. The first is characterized by the dominance of HCO3– and Mg2+ in the water composition, and the second by Cl– and Na+. A change in composition and an increase in the value of total mineralization from 0,1 to 49 g/dm3, in the direction from north to south, indicate the development of continental salinization. In natural waters of the first group, uranium content varies from 0.065 to 16000 μg/dm3 and radon activity from 4 to 3885 Bq/dm3. For sodium chloride waters of the second set, concentrations can reach 32500 μg/dm3, and radon activity is 6–59 Bq/dm3, since the emanating reservoir (granitoids) is located to the north – at a distance of 80–100 km. Naturally, granitoid massifs of the studied region are sources of uranium. Their drainage by the river network leads to its removal and concentration on geochemical barriers in the groundwater of the Neogene-Quaternary aquifer. This distribution of radioactive elements is associated with the high migration ability of uranium in solution in the form of uranyl ion in oxidizing geochemical conditions.

The paper presents data on the mineralogical, petrographic and geochemical features of granitoids of the Ob-Zaisan folded region. Two complexes such as Priobsky and Barlaksky are considered. The first one is represented by medium and acidic rocks of the moderately alkali-type. The rocks are enriched with light REE to the greatest extent, and are also characterized by generally low uranium content (mainly 1–3 g/t), the thorium content is mainly 1–16 g/t. The U/Th ratio in these rocks mainly varies in a narrow range from 0.1 to 0.5 and does not exceed 1. The second one is composed of granites of normal and moderately alkali-type. The Barlaksky complex rocks have comparable values of light and heavy REE contents. The rocks are characterized by a sharply increased content of uranium (10–30 g/t) and thorium (up to 35–40 g/t). The ratio of uranium to thorium is mainly 0.1–0.7.

--We present the first results of comprehensive isotope-geochemical studies of mineral radon waters of the Tulinskoe field (Novosibirsk), aimed at identifying their stages of interaction with the host rocks. By geochemical coefficients Ca/Na, Ca/Mg, Ca/Si, Mg/Si, Na/Si, Si/Na, rNa/rCl, and SO4/Cl, the studied waters are assigned to fracture-vein waters of granitoids. The indices of carbonate mineral saturation of the radon waters show their oversaturation with aragonite, calcite, and dolomite. The waters are also saturated with diaspore, ferrohydrite, gibbsite, and kaolinite, which leads to the deposition of these minerals as secondary phases. In the thermodynamic diagrams, the points of the activities of the radon water components are localized mainly in the stability fields of clay minerals (kaolinite and Na-, Ca-, and Mg-montmorillonites), layered silicates (talc), and zeolites (laumontite). A few points fall in the stability field of silicates (Mg-chlorite). The studied waters of the Tulinskoe field are neutral fresh, with Si = 6.41-9.02 mg/dm3. According to the results of thermodynamic calculations, the radon waters of the Tulinskoe field are in equilibrium with carbonate minerals and hydromicas. Following the classification by S.L. Shvartsev, they are assigned to the Si-Na geochemical type.

The results of integrated isotope-geochemical and microbiological studies of reservoir waters from oilfields under development in the southern part of the West Siberian petroleum province are reported for the first time. The waters have mainly Cl Na chemistry, with salinity 13–72 g/L TDS, pH between 6.9 and 8.5, and reductive geochemical environment with Eh ranging from − 166.3 to − 90.1 mV. Salinity variations are due to the injection of waters from the Aptian–Albian–Cenomanian aquifer to maintain the reservoir pressure early during the development, and subsequent use of closed-cycle produced water, at increased water cutting of the production well stock. The presence of two main genetic types of groundwaters in the hydrogeological section is revealed: the ancient waters of infiltration genesis, and the waters of sediment genesis. In most of the sampled waters, the δD–δ 18 O pair indicates climate-induced 4–5‰ 16 O depletion prior to burial, combined with later 2–3‰ 18 O enrichment during prolonged water–rock interaction. In some water samples, dissolved inorganic carbon is of bacterial origin, as suggested by its isotope composition (δ 13 C DIC ). The waters hotter than 90°Cshow an evident positive δ 13 C DIC shift to a range of − 8 to + 4‰ VPDB, which is common to thermal water values. The analyzed waters are characterized by lower 87 Sr/ 86 Sr ratios than those in the present-day seawater. A substantial Sr input from mantle sources is assumed, manifested up to different degrees in the waters of the studied oilfields. Microorganisms involved in the nitrogen, sulfur, iron, and carbon cycles are detected in the studied water samples. The products of the vital activities of nitrifying, thionic, and sulfate-reducing bacteria are nitric and sulfuric acids, and hydrogen sulfide. The joint action of these microbial groups poses large-scale corrosion risks to the oilfield facilities.

The paper presents the first results of studying the radioactivity of water-bearing rocks in a wide stratigraphic range within the Ob-Zaisan folded region. It was found that contents of uranium and thorium in igneous rocks (from the Devonian to the Triassic), on average amount to 9.6 and 17.7 g/t, and 2.5 and 4.6 g/t, respectively in sedimentary rocks (from the Lower Cambrian to the Middle Jurassic). It was determined that igneous complexes of the Kolyvan granitoid massif are most enriched in uranium (up to 65.1 g/t) and thorium (up to 108.8 g/t).

Анализ данных химического состава подземных вод водозабора на территории Новосибирского научного центра за длительный период эксплуатации (1958-2023 гг.), в том числе полученных лабораторией гидрогеологии осадочных бассейнов Сибири Института нефтегазовой геологии и геофизики СО РАН, свидетельствует о стабильности макрокомпонентного состава подземных вод. В работе представлены результаты многолетнего гидрогеохимического мониторинга подземных вод участка “Береговой-1”, который снабжает бóльшую часть верхней зоны Академгородка, и участка “Зырянка”, поставляющего воду в коттеджную зону Академгородка, включая улицы Академическая, Золотодолинская, поселки Кирова и Геологов. Дана оценка качества воды на основе действующих в России санитарных правил и норм, государственных стандартов и критериев, которые применяются в настоящее время за рубежом. Воды этих участков гидрокарбонатные магниево-кальциевые с минерализацией в диапазоне значений 200-400 мг/дм3, общей жесткостью от 3.8 до 7.7 мг-экв/дм3. Характерной особенностью вод инфильтрационного водозабора участка “Береговой-1” является высокое содержание железа (0.11-7.14 мг/дм3), что больше предельно допустимой концентрации (ПДК) в 5-20 раз, а также концентрация марганца (0.12-0.61 мг/дм3), превосходящая ПДК в отдельные годы до 8 раз. Практически постоянно отмечается незначительное превышение концентрации мышьяка, в отдельные годы фиксировались значения в два и более раз выше ПДК. Такой состав вод участка “Береговой-1” предопределяет обязательную водоподготовку перед подачей населению. Воды участка “Зырянка” соответствуют санитарным нормам по качеству, за исключением показателя по радону, концентрация которого может достигать 130 Бк/дм3. Analysis of data on the chemical composition of groundwater from the water intake of the Novosibirsk Scientific Centre over a long period of operation (1958-2023), including the results obtained at the Laboratory of Hydrogeology of Sedimentary Basins of Siberia, Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, indicates the stability of the macrocomponent composition of groundwater. The results of many years’ hydrogeochemical monitoring of groundwaters from the Beregovoy-1 site, supplying water to most of the buildings in the higher district of Akademgorodok, and from the Zyryanka site from which water is supplied to the cottage area including Akademicheskaya and Zolotodolinskaya streets, as well as Kirov and Geologov settlements, are presented in the work. Water quality is assessed on the basis of actual sanitary rules and norms adopted in the Russian Federation, State Standards and the criteria currently applied abroad. The waters from these sites have hydrocarbonate magnesium-calcium composition with total salt content within the range of 200-400 mg/dm3, total hardness from 3.8 to 7.7 mg-equiv/dm3. A characteristic feature of water from the infiltration water intake of the Beregovoy-1 site is a high iron content (0.11-7.14 mg/dm3), which is 5-20 times higher than the maximum permissible concentration (MPC), and manganese concentration (0.12-0.61 mg/dm3), which exceeds the MPC by a factor of 8 during some years. Arsenic concentration is almost always slightly above the permissible level, and in particular years it exceeded the MPC by a factor of 2 and more. These features predetermine obligatory water treatment before supplying to the population. The waters of the Zyryanka site meet sanitary quality standards, with the exception of radon level, which can reach 130 Bq/dm3.

The first integrated isotope and chemical data on radon-rich waters of the Tulinka aquifers (Novosibirsk, West Siberia) are presented. The Tulinka radon waters are fresh, with neutral to moderately alkaline pH (7.3-7.7), SO4-HCO3 Na-Mg-Ca major-ion chemistry. The amount of total dissolved solids is 720-910 mg/L, Si content 6.41-9.02 mg/L. Eh is within +169.1 - +250.0 mV, corresponding to oxidized conditions. The concentration of dissolved oxygen is 2.86-7.37 mg/L. Radon activity (222Rn) varies from 173 to 276 Bq/L. The concentrations of U, Th, and Ra isotopes are 0.015-0.017 mg/L238U, 9.59 center dot 10-7 to 1.58 center dot 10- 5 232Th, and up to 4.93 center dot 10- 10 226Ra; the 232Th/238U ratio is in the range 5.81 center dot 10- 5 to 9.42 center dot 10-4. Total alpha activity is not higher than 891 mBq/L, and beta activity is 80 mBq/L. The compositions of stable isotopes are-15.4 to - 15.1%0 delta 18O,-114.2 to -112.8%0 delta D, and-13.9 to - 9.9%0 delta 13C. The isotope signatures and recharge patterns of the Tulinka waters are insensitive to seasonal effects, which suggests the slow water exchange. Substantial seasonal variations of the content of dissolved inorganic carbon (DIC) are detected. The range of delta 13CDIC in the analyzed samples (from-14.3 to-9.0%0) corresponds to a mixed CO2 origin: diffusion of soil CO2 approaching the atmospheric delta 13CCO2 values, and biogenic CO2 released by decaying plant residues. The measured isotope characteristics provide evidence that the waters recharge by infiltration from meteoric sources. The approximate radiocarbon age of DIC in the Tulinka waters, determined for the first time, is 2663 +/- 144 years. However, this age may be underestimated due to groundwater mixing with the present-day surface waters.

Исследовано распределение загрязняющих веществ 1 класса опасности и микрокомпонентов в природных водах Новосибирской городской агломерации, где немаловажную роль в загрязнении вод играет не только большое количество транспортных средств, но и промышленных предприятий. Показано, что природные воды в основном гидрокарбонатного кальциевого и кальциево-магниевого состава с величиной общей минерализации от 127 до 910 мг/дм3 и концентрацией кремния 0.14-11.61 мг/дм3. Геохимическая обстановка изменяется от восстановительной (Eh -164.3 мВ) до окислительной (Eh 442.1 мВ), pH 6.9-8.8 с содержанием O2(раств.) 0.48-20.28 мг/дм3. В черте города Новосибирска выявлены превышения фоновых значений по 33 химическим элементам, содержания загрязняющих веществ 1 класса опасности составляют, мг/дм3: для Be (6.4·10-6)-(1.4·10-4), As 0.0003-0.26, Hg (8.33·10-7)-(2.3·10-4), Tl (6.2·10-7)-(8.2·10-5), U (1.3·10-5)-0.21. Активность радона, установленная в природных водах города Новосибирска, изменяется от 1 до 1570 Бк/дм3. Определено, что активному антропогенному воздействию подвержены в основном речные воды Ини, 2-й Ельцовки, Плющихи, Ельцовки, Камышенки и Оби. В подземных водах выявлены большие несоответствия действующим нормативным документам и превышения предельно допустимых концентраций в скважине пос. Кирова (Mn - в 14 раз, Fe - в 10 раз, As - в 5 раз) и в СНТ "Тополь" (Mn - в 59 раз, Fe - в 94 раза, As - в 27 раз). The distribution of the 1st hazard class substances and trace elements in the natural waters of the Novosibirsk urban agglomeration is investigated. A substantial role in water pollution is played in the study area not only by a large number of vehicles but also industrial enterprises. The composition of natural waters is determined as mainly hydrocarbonate calcium and hydrocarbonate calcium-magnesium, with total dissolved solids varying from 127 to 910 mg/dm3, and silicon concentration 0.14-11.61 mg/dm3. The geochemical setting changes from reducing (Eh -164.3 mV) to oxidizing (Eh 442.1 mV), pH 6.9-8.8 with O2(sol.) content 0.48-20.28 mg/dm3. Within the city of Novosibirsk, excesses of background values for 33 elements were revealed; the concentrations of the first hazard class substances are, mg/dm3: Be (6.4·10-6)-(1.4·10-4), As 0.0003-0.26, Hg (8.33·10-7)-(2.3·10-4), Tl (6.2·10-7)-(8.2·10-5), U (1.3·10-5)-0.21. The activity of radon, established in the natural waters of the city of Novosibirsk, varies from 1 to 1570 Bq/dm3. The waters under active anthropogenic load are mainly the river waters of the Inya, the Eltsovka the 2nd, the Plyushchikha, the Eltsovka, the Kamyshenka, and the Ob. In groundwater samples, excesses over the actual normative documents and maximum permissible levels were revealed in the well in Kirov settlement (Mn - by a factor of 14, Fe - 10, As - 5), and in the Topol Gardeners Non-Commercial Partnership (Mn - by a factor of 59, Fe - 94, and As - 27).

The paper is aimed at the research practice on identifying the features of interaction in the water-rockcarbon dioxide system in relation to terrigenous reservoirs, widely occurring in hydrogeological basins in the territory of the Russian Federation and potentially suitable for the placement of carbon dioxide. As the CO2 solution is saturated, along with an increase in total dissolved solids there is a naturally-determined increment in the volume of transition of ions into their complex forms. The main macro components (Ca2+, Mg2+, Na+, K+, (SO4)2–, Cl– ) migrate mainly in the form of their own ions, with a decrease in their fraction by an order of 1–3 % with an increase in mineralization. Ions such as Fe, Al3+, Mn3+, (NO3)–, (HCO3)–, SiO2, (NH4)+, (NO2)– are prone to transition into the form of complex compounds, the fraction of which in the total volume increases with the amount of saturation of solution with carbon dioxide. When CO2 is injected into the terrigenous reservoir, there is a natural decrease in the solution pH, absence of precipitation of carbonates and minimal changes in the rock porosity. The observed process of dissolution of primary aluminosilicate minerals (albite, anorthite, potassium feldspar) is characteristic of most of the considered mineralogical varieties of reservoirs, when they are saturated with CO2. This process is accompanied by deposition of secondary mineral phases in the form of montmorillonites, illites, chlorites, etc. Taking into account the low rates of these reactions, no significant changes in reservoir properties are noticed.

Аннотация.В настоящей работе приведены данные о распределении элементов первого класса опасности, урана и тория в подземных водах Обь-Зайсанской складчатой области.Лабораторное изучение химического состава проводилось методами титриметрии, ионной хроматографии, масс-спектрометрии с индуктивно связанной плазмой в Проблемной научно-исследовательской лаборатории гидрогеохимии Инженерной школы природных ресурсов Томского политехнического университета.С использованием действующих нормативных документов: СанПиН 2.1.3684-21,ГОСТ Р 58573-2019, и рекомендаций Всемирной организации по здравоохранению была проведена оценка токсикологических особенностей вод.Изученные воды HCO3 Mg-Ca и HCO3 Na-Mg-Ca состава с величиной общей минерализации, варьирующей от 203 до 1568 мг/дм 3 .Геохимические параметры среды как восстановительные, так и окислительные с Eh -331,6 -+438,5 мВ, pH 6,6 -8,3 с содержанием О2раств.0,29 -10,72 мг/дм 3 .Выявлены относительно высокие концентрации Ti до 0,04 мг/дм 3 , V до 0,03 мг/дм 3 , Fe до 93,9 мг/дм 3 , Zn до 0,38 мг/дм 3 , As до 0,27 мг/дм 3 , Zr до 0,018 мг/дм 3 , Sb до 0,016 мг/дм 3 , Ba до 0,51 мг/дм 3 , W до 0,005 мг/дм 3 , Hg до 0,0002 мг/дм 3 , Pb до 0,057 мг/дм 3 , U до 0,34 мг/дм 3 , что, может быть, связано как с автомобильным транспортом, промышленными предприятиями, так и с водовмещающими породами.В работе были изучены элементы первого класса опасности, а также уран и торий.Установлено, что по бериллию 20% изученных проб находятся выше фонового значения, а также по таллию и мышьяку, по торию -26%, по урану -19%.

The geochemical features of 22 deposits and manifestations of radon waters in the south of Siberia (some of them for the first time) are considered. The studied waters are very diverse in terms of gas and chemical composition, total mineralization, geochemical parameters of the environment, and temperature. Three groups of radon waters have been established according to the Eh value: oxidizing conditions, transitional and reducing. Due to the wide variety of waters in terms of chemical composition, some of the studied objects belong to several groups at once, for example, the Choigan natural complex, the Skalinsky, Novobibeevskoye, and Sedova Zaimka manifestations. The concentrations of natural radionuclides are (mg/dm): U (3.68∙10 - 1.40), Th (4.04∙10 - 2.16∙10). The activity of dissolved radon (Rn) varies from 4 to 2257 Bq/dm. The Th/U ratio varies from 2.63∙10 to 26, and its maximal values were detected in ultrafresh, thermal, alkaline waters with reductive geochemical medium in which thorium possesses increased migration capacity. Quite contrary, uranium migrates in the oxidative geochemical setting.

The paper considers approaches to the analysis of physicochemical interactions in the water-rock-carbon dioxide system, solved by mathematical modeling and aimed at analyzing the behavior of this system during CO burial in the Cretaceous aquifers of the Arctic sector of Western Siberia. The problem was solved using the HydroGeo software package, which makes it possible to analyze the change in the chemical composition of solutions, the forms of migration of the main components of groundwater, as well as mineral equilibria both at the time of carbon dioxide invasion and when the solution reaches equilibrium.

Results of a geochemical study of brines and oil occurrences in the Udachnaya kimberlite pipe are presented. Like other intrusions in the Daldyn-Alakit diamondiferous region, this diamond deposit is a unique cryohydrogeologic microstructure differing from the host sedimentary rocks and other diamond pipes of the Yakutian diamond-bearing province. Two waterlogged zones distinguished in the section of orebodies at the explored depths of the deposit correspond to the upper and middle Cambrian aquifers. Predominantly acidic (average pH = 5.5) Cl-Ca and Cl-Ca-Na brines with TDS from 94.3 to 391.3 g/dm(3) are widespread within the orebodies and host rocks. The brine mineralization and contents of major salt-forming components increase with depth, to the horizon at the -365 m elevation, where TDS reaches 391 g/dm(3), while below, at the -650 m level with noted hydrogeochemical-field inversion, TDS is 253 g/dm(3). The mineral-ization of Cl-Ca, Cl-Ca-Na, Cl-Ca-Mg, and Cl-Ca-Mg-Na brines in the upper Cambrian rocks varies from 102.9 to 192.9 g/dm(3), and the pH values, from 4.9 to 6.2, averaging 5.6. Among the microcomponents, the highest average concentrations (mg/dm3) are found for Br-1292.8 > S-875.7 > Sr-453.7 > Fe-79.7 > Li-53.4 > B-32.7 > I-13.3 > Si-10.8 > Mn-6.4 > Se-3.6 > Rb-2.3. The values of genetic coefficients vary widely: The rNa/rCl coefficient ranges from 0.18 to 0.31; rCa/rMg, from 1.03 to 3.60; Ca/Cl, from 0.2 to 0.3; and the integrated metamorphism index S (according to S.L. Shvartsev) varies from 193 to 277. The middle Cambrian rock complex, containing more saline brines, has been ex-amined in much more detail. It hosts Cl-Ca, Cl-Ca-Na, Cl-Ca-Mg, and Cl-Na-Mg brines with TDS from 94.3 to 391.3 g/dm(3) and high average concentrations (mg/dm3) of microcomponents: Br-2224.9 > Sr-1024.9 >S-500.1 > B-202.9 > Li-147.1 > Fe-97.0 > I-33.2 > Rb-11.4 > Si-9.6 > Se-9.5 > Mn-3.6 > Ni-1.7. As compared with brines in the overlying rocks, the middle Cambrian brines show a wider variation in element ratios: rNa/ rCl from 0.14 to 0.34, rCa/rMg from 0.66 to 9.71, and Ca/Cl from 0.03 to 0.45. These brines are also characterized by a significantly higher metamorphism grade, which is indicated not only by the rNa/rCl and rCa/rMg ratios but also by the S index varying from 278 to 316. The composition of stable isotopes (delta D and delta O-18) and dissolved inorganic carbon (delta C-13) of the brines was investigated. The studied waters are assumed to be of sedimentary-metamorphic origin. Their isotopic composition reflects the climatic conditions existing at the time of their burial, which were probably aggravated by the contribution of the oxygen isotope exchange with water-bearing rocks. The delta C-13 values of carbon dioxide dissolved in water allow an inference about its biogenic origin. The biogenic carbon isotope exchange is governed by the relationship between methanogenic and SMT processes. Analysis of the Rb-87/Sr-86 and Sr-87/Sr-86 isotope ratios of the studied brines has revealed affinity between the isotopic compositions of waters in the Cambrian deposits and in ancient seawaters. The mass chromatograms of saturated-hydrocarbon (HC) fractions show at least two individual types of oils and malthas (naphthides). The third variety resulted from their mixing at different stages of migration. The fourth is from the contact zone; it changed during the explosion of kimberlites. The first, most common, type of naphthides ("postexplosive") is similar in all geochemical parameters to oils from the Nepa-Botuobiya anteclise, in particular, to those from the Mirnyi arch. Oils of the second (pre-explosive) type are found only in the Udachnaya Formation, within the depth range 1130-1430 m.

The paper proposes the concept of a regional assessment of the outlooks for implementation of CCUS (carbon capture, utilization and storage) projects at the territory of the Russian Federation. Three groups of criteria are considered: general hydrogeological, tectonic and environmental. For the first time, the categories of lands with high, medium, low prospects and unpromising ones are singled out. A map of the outlooks for the implementation of CCUS projects at the territory of the Russian Federation was compiled according to the criteria of the regional level on a scale of 1: 2500,000 in the form of an ArcGis project, including its interactive analogue with access via the Internet. The performed analysis of the hydrogeological features of the territory of the Russian Federation made it possible to identify 56 structures with high, 6 with medium and 29 with low prospects at the regional stage. The most promising areas are confined to three hydrogeological regions: the East European, East Siberian platforms and the West Siberian Plate.

This study is relevant for obtaining the first geochemical data (including information on radionuclides) on the drainage waters of developed and flooded quarries in the eastern areas of the Novosibirsk Region. The objective of the study was to identify the features of the chemical composition of drainage waters (a wide range of chemical elements from Li to U). The study was carried out by titrimetry, ion chromatography and mass spectrometry with inductively coupled plasma in a laboratory setting at the Hydrogeochemical Problem Research Laboratory (PNIL GGH) of the Engineering School of Natural Resources of Tomsk Polytechnic University (IShPR TPU). Measurements of 222 Rn in waters were carried out at the Alfarad Plus facility of the Laboratory of Siberian Sedimentary Basins Hydrogeology of the A. A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences (INGG SB RAS). The data were divided into homogeneous geochemical populations using the coefficients Ca / Na, Ca/ Mg, Ca / Si, Mg/ Si, Na / Si. The chemical composition of the studied objects was found to be highly diverse. The dominant waters have the chemical formula SO 4 -HCO 3 / Na-Mg-Ca with a TDS (total dissolved solids) of 400 to 700 mg/dm 3 . Three geochemical groups of waters were identified. The first is represented by drainage waters of the developed rubble stone quarries, the second includes facilities of the Gorlovka coal basin, and the third refers to abandoned flooded quarries. The first group is characterized by oxidizing conditions with Eh varying over a wide range from +84.6 to +261.0 mV, pH from 6.9 to 8.6, and O 2disso i ved from 3.43 to 14.39 mg/dm 3 . The radionuclide concentrations are (mg/dm 3 ): 238 U 9.30 • 10 -3 - 1,40; 232 Th 1,00 • 10 -6 - 2,16 • 10 -3 ; 222 Rn activity varies from 1 to 572.5 Bq/dm 3 . The 232 Th / 238 U ratio ranges from 4.20 • 10 -5 to 2.69 • 10 -3 with an average of 8.40 • 10 -4 . The second group has a smaller Eh variation range of +133.2 to +199.6 mV, pH from 7.5 to 8.5, and O 2dissolved from 6.81 to 10.43 mg/dm 3 . The radionuclide concentrations vary in the following ranges (mg/dm 3 ): 238 U 2.26 • 10 -3 - 2.90 • 10 -2 ; 232 Th 7.5 • 10 -6 - 5.57 • 10 -4 . The 232 Th / 238 U ratio ranges from 8.37 • 10 -4 to 4.80 • 10 -2 at an average of 9.54 • 10 -3 . The third group is also characterized by an oxidizingizing geochemical environment with Eh +131.3 - +250.0 mV, pH from 6.9 to 8.8 and O 2dissolved from 4.00 to 16.59 mg/dm 3 . The radionuclide concentrations are (mg/dm 3 ): 238 U 3.00 • 10 -4 - 2.74 • 10 -2 ; 232 Th 1.65 • 10 -6 - 1.15 • 10 -5 ; 222 Rn activity varies from 2 to 31 Bq/dm 3 . The 232 Th/ 238 U ratio ranges from 2.36 • 10 -4 to 1.02 • 10 -3 at an average of 6.25 • 10 -4 . Overall, the 232 Th / 238 U ratio of the studied waters indicates their uranium nature of radioactivity. The data obtained indicate a slight impact of the drainage water discharge from the abandoned quarries on the environment.

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/dm(3)). 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/dm(3) and a silicon content of 4.1-8.6 mg/dm(3). 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-2dissolv. = 6.24-12.26 mg/dm(3). The revealed predominance of SO42- over Cl- 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 alpha-activity of waters is 3-4 mBq/dm(3), and gross beta-activity is 11-15 mBq/dm(3). Natural radionuclides are found in the spring waters within the following limits (mg/dm3): U-238, from 2.83 center dot 10(-3) to 4.13 center dot 1(0-)3; Th-232, from 2.39 center dot 10(-6) to 1.16 center dot 10(-5), and Ra-226, from 3.83 center dot 10(-10) to 4.93 center dot 10(-10). The value of the Th-232/U-238 ratio for the waters ranges from 5.79 center dot 10(-4) to 3.61 center dot 10(-3), as a result of the oxidative geochemical migration-arresting capability of thorium. The uranium isotope ratio (gamma) U-234/U-238 varies from 2.6 to 3.2 for the waters, with the uranium isotope activity determined as 117-124 mBq/dm(3) for U-234 and 38-48 mBq/dm(3) for U-238. This indicates shallow circulation of the studied waters as compared with those of the Svyatoi spring in Verkh-Tula Village, for which gamma = 1.3; the U-234 activity, 147 mBq/dm(3); and the U-238 activity, 115 mBq/dm(3). By isotopic composition, the origin of the spring waters is assigned to the infiltration type, and they are characterized by relatively narrow distribution of delta O-18 (from -17.5 to -16.7 parts per thousand) and delta D (from -128.4 to -126.2 parts per thousand) values. The delta(CDIC)-C-13 values are from -10.3 and -10.9 parts per thousand in springs 3 and 2 and become lighter (-11.2 and -12.1 parts per thousand) in springs 1 and 4, respectively. This is due to significant participation of surface waters in the recharge mechanism of springs 1 and 4, which is also consistent with the delta O-18 and delta D data and C-14 dating. The estimated age of water-dissolved carbon is 1478 +/- 81 years for the waters of spring 3 (the oldest), while it is found to be only 651 +/- 53 years for spring 4 and is estimated as modern for spring 1. The reported decline in the age of water-dissolved carbon down to recent age is indicative of increased contribution of surface water to the spring recharge area. The C and O isotope compositions of calcite of the host aquifer rocks are characterized by close values for most of the samples: delta(13). varies within narrow limits (from -3.1 to -2.7 parts per thousand), and delta O-18 varies from 17.2 to 18.4 parts per thousand. The isotopic composition becoming lighter for carbon (up to -11.0 parts per thousand) and oxygen (up to 13.9 parts per thousand) was noted for weathered schist samples. Results of the carbon isotope analysis of rock samples, their organic component, and water indicate an active isotopic exchange in the water-rock-organic matter system.