The isotopic composition of copper is of great interest for researchers in various fields of science, geochemistry and hydrology in particular, wherein the consideration is being given to the variations in the isotopic composition of the Earth’s crust, extraterrestrial matter, and water basins, as well as to the origin and transfer of matter. Zn isotopes appear to be promising for identifying the sources and pathways of the environmental pollution. The aim of this study involves the refinement and validation of the zinc and copper isotopic ratio determination methodology covering the whole process from sample digestion to MC ICP-MS measurements. For this reason, as well as to assess the suitability of the methodology for the analysis of environmental samples, Zn and Cu isotopic analysis of the BHVO-2, BCR-2 and AGV-2 USGS certified reference materials has been performed. The method for determination of Cu and Zn stable isotope ratios by multi-collector inductively coupled plasma mass spectrometry in environmental samples is developed. The application of the AG MP-1 resin with optimized layer parameters (resin bed height 3.5 cm, diameter 1 cm) provides the high-purity Cu and Zn fractions. The method is characterized by high throughput and adequate analytical figures of merit when using the standard-sample bracketing technique for mass bias correction. The procedural blanks related to chemical dissolution and ion exchange procedures are lower than 1 and 3 ng for Cu and Zn, respectively, assuring no blank effect on the isotopic composition of samples. The accuracy and precision obtained for Cu and Zn isotope measurements in the BHVO-2, BCR-2 and AGV-2 geological certified reference materials demonstrate good agreement with the reference values published.

87Sr/86Sr isotopic ratios are widely used to identify strontium sources and study strontium behaviour in(bio)geochemical cycles. 87Sr/86Sr in surface waters can reflect the average composition of bioavailable (i.e. available forfurther absorption by plants and animals) strontium in the catchment specific area. Based on those 87Sr/86Sr ratios, theregional maps of the bioavailable strontium distribution (strontium isoscapes) can be compiled. A complex block structurecharacterizes the Ural mountain system. Individual parts (blocks) are composed of rocks of various ages, genesis andgeochemical characteristics, which can radically change at a distance of several tens of kilometres. Such variability wouldbe reflected in strontium isotopic ratios, thus making it possible to determine the local isotopic signatures of bioavailablestrontium.This work aimed to study 87Sr/86Sr in the water in the rivers of the Southern Urals. We determined the contents andisotopic ratios of strontium in river water samples collected from the territories of the Orenburg and Chelyabinsk regionsand the Republic of Bashkortostan in 2019–2020.For the first time in the surface water of the rivers in the Southern Urals (Ural, Belaya, Tobol, Karagaily-Ayat, Sim, andothers), the 87Sr/86Sr isotopic ratios have been determined, and their variations have been analyzed. 87Sr/86Sr values varyin the range 0.70666–0.71063 (average 0.70908) for the rivers of the Urals basin, 0.70749–0.71058 (average 0.70924)for the Kama-Volga basin, 0.70946–0.71176 (average 0.71071) for the Tobol basin. Such features of the strontium isotopiccomposition may be due to the influence of underlying rocks of the catchment area drained by river water. The dataobtained can be used to identify the sources of strontium input into the water system during hydrological and environmentalstudies; to confirm the authenticity of food products of plant and animal origin; to carry out comparisons in thestudies of the migration of ancient people and animals, as well as to determine the raw material areas for the productionof vegetable and woollen textiles and wooden products in antiquity.

87Sr/86Sr isotopic ratios are widely used to identify strontium sources and study strontium behaviour in(bio)geochemical cycles. 87Sr/86Sr in surface waters can reflect the average composition of bioavailable (i.e. available forfurther absorption by plants and animals) strontium in the catchment specific area. Based on those 87Sr/86Sr ratios, theregional maps of the bioavailable strontium distribution (strontium isoscapes) can be compiled. A complex block structurecharacterizes the Ural mountain system. Individual parts (blocks) are composed of rocks of various ages, genesis andgeochemical characteristics, which can radically change at a distance of several tens of kilometres. Such variability wouldbe reflected in strontium isotopic ratios, thus making it possible to determine the local isotopic signatures of bioavailablestrontium.This work aimed to study 87Sr/86Sr in the water in the rivers of the Southern Urals. We determined the contents andisotopic ratios of strontium in river water samples collected from the territories of the Orenburg and Chelyabinsk regionsand the Republic of Bashkortostan in 2019–2020.For the first time in the surface water of the rivers in the Southern Urals (Ural, Belaya, Tobol, Karagaily-Ayat, Sim, andothers), the 87Sr/86Sr isotopic ratios have been determined, and their variations have been analyzed. 87Sr/86Sr values varyin the range 0.70666–0.71063 (average 0.70908) for the rivers of the Urals basin, 0.70749–0.71058 (average 0.70924)for the Kama-Volga basin, 0.70946–0.71176 (average 0.71071) for the Tobol basin. Such features of the strontium isotopiccomposition may be due to the influence of underlying rocks of the catchment area drained by river water. The dataobtained can be used to identify the sources of strontium input into the water system during hydrological and environmentalstudies; to confirm the authenticity of food products of plant and animal origin; to carry out comparisons in thestudies of the migration of ancient people and animals, as well as to determine the raw material areas for the productionof vegetable and woollen textiles and wooden products in antiquity.

Subject. The aim of the work is to study the mechanism and sources of water formation, as well as the peculiarities of carbonate mineralization in the aquifer of the Kyndyg thermal water deposit. Materials and methods. The samples of water (8) and deposited carbonates (15), collected at different seasons at three sites, characterized by different temperatures and distances from the source, were investigated. pH, Eh, and electrical conductivity were determined by an electrochemical method. For the determination of HCO3 – , Cl– , SO4 2–, titrimetric, mercurymetric and turbidimetric methods were used. Trace element composition was determined by ICP-MS (NexION 300S); strontium isotopic composition – by MC-ICP-MS (Neptune Plus) using the bracketing technique after Sr chromatographic separation. Results. The chloride-calcium hydrochemical type prevails in the studied waters. A number of trace elements in water exceeds the clarke concentrations for groundwater in the supergene zone of mountain landscapes. 87Sr/86Sr isotope ratios (0.7065–0.7072) in thermal waters suggest that their composition is determined rather by the isotopic characteristics of the rocks through which water drains than by the influence of sea water. Among the newly formed carbonates, aragonite prevails. In contrast to thermal water, the concentrations of most metals in carbonates are below the clarke values; only Sr and Se are increased, which content is significantly increased in water as well. Deposited carbonates are characterized by 87Sr/86Sr values (0.7028–0.7074), which are lower than in the source thermal waters. Conclusions. On the basis of hydrogeological, hydrochemical and geochemical data, it can be assumed that the waters of this aquifer complex are formed mainly due to fresh fractured karst waters of lower Cretaceous limestones with submerged monocline dipping into the zone of slow circulation and mixing with sedimentogenic sodium chloride waters. The geochemical data and the presence of scandium anomaly suggest that the underlying Jurassic volcanogenic rocks also participate in water exchange.

Polymeric derivatives of sterically hindered phenols and polyvinyl alcohol have been prepared. Conditions have been found for preparing polymers with various solubilities in water. Certain kinetic parameters have been determined for acetalization of polyvinyl alcohol and hydrolysis of resulting polymers.