Vol 52, No 3 (2025)

Intense wind surges redistribute the waters of the Pregolya River mouth and impede the operation of the water intake for the needs of Kaliningrad. The inability to withdraw water during long-term (more than 10-20 days) brackish water penetration can create problems with water supply. Data (2020–2024) on water supply shutdowns at the water supply station (reflected the intensity of brackish water wedge penetration upriver) showed an interannual increase in the number and duration of such cases. A comparison was made of the salinity measurements at a control point in the middle of the river mouth section with the chlorine data at the water intake. The considered examples of water supply shutdowns for 7–20 days in August and October 2023 made it possible to assess the conditions (wind exposure, water level rise and the initial position of the salinity wedge), which all facilitating the movement of wedge up to the water intake point. A regression relationship is proposed between the values of chlorinity at the water intake and salinity in the middle of the estuary of the Pregolya River, which, as a first approximation, can be used to estimate the values of chlorinity at the water intake in the case of penetration of brackish water.

The article presents the results of determining the volumes of biological accumulation of microelements (V, Pb, Cr, Co, Mo, Cu, Zn, Ni, Fe, Sr, Mn) in eight species and rare earth elements (REE) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in two species of higher aquatic and coastal-aquatic plants of three overgrown bays of the dam part of the Ivan’kovo Reservoir – Novoselsky, Fedorovsky and Korovinsky. The floral composition of the plant communities of the bays has been studied, the, phytomasses of the dominant associations of overgrown areas, products and areas occupied by higher aquatic vegetation have been determined. A comparison of the data for 1977 with the data for 2005 showed that there was a significant increase in the total annual production due to the increase in the production of two ecological groups of macrophytes of the Ivan’kovo reservoir – air-water (gelophytes) and hydrophytes of free-floating and rooting with the change of species-edifiers and the increasing leading role of air-water (gelophyte) vegetation species in the formation of overgrowth zones. In the period from 1990 to 2005, the overgrowing process stabilized and the productivity of all ecological and biological vegetation groups remained at the same level. In total, 4657.8 kg of heavy metals accumulate in the dry biomass of macrophytes in Novoselsky, Fedorovsky and Korovinsky bays during the period of maximum development (July–August): 2.58 V, 1.98 Pb, 9.75 Cr, 0.78 Co, 0.82 Mo, 16.76 Cu, 45 Zn, 6.1 Ni, 1977 Fe, 171 Sr, 2426 kg Mn. The dry biomass of Glyceria maxima Holmb. and Potamogeton perfoliatus L. from three bays contains 0.33 kg of rare earth elements. The largest mass of heavy metals accumulates in the vegetation of the Korovinsky and Fedorovsky bays. In the Korovinsky Bay, where the proportion of submerged rooting species in the total phytomass is significantly increasing, the highest bioaccumulation values of heavy metals and rare earth elements have been obtained. The main accumulator species are the Stratiotes aloides L., Glyceria maxima Holmb., Potamogeton lucens L. It is shown that the process of overgrowing of bays, accompanied by a change in plant communities, an increasing area dominance and an increase in the annual production of airborne and aquatic species, contributes to the growth of biological accumulation of heavy metals.

The relationship between abiotic and biotic components in the water and soil is analyzed using the catchment area of the small urban river. Water quality was assessed as “polluted” based on a set of indicators. Similarity in the biogeochemical characteristics of bottom sediments (BS) and soils was revealed. The average organic carbon (C_org) content was 5.9 in BS and 6.8% in soil. The excess of the background level of hydrocarbons in BS (100 mg/kg) was no higher than 1.6 times, in the soil it was 1.2–1.7 times. The share of HC in the organic matter content in BS did not exceed 0.4 and 0.21% in the catchment soil. The total content of phytopigments in BS and soil did not differ significantly – 34.89 and 29.31 μg/g, respectively. The contribution of primary production, estimated by the chl a into the total content of C_org in BS averaged 1.53, in soil 0.61%. Carotenoids dominated in the composition of phytopigments in BS and soil. Studying the molecular composition of n-alkanes shown that the predominant type of organic matter in both soil and BS is terrigenous matter, genetically associated with higher vegetation, found in the studied objects in the form of transformed hydrocarbons.

The hydrochemical characterization of small lakes typical for different landscapes of the Republic of Karelia was compiled on the basis of statistical assessments. The test sample to be studied was formed on the basis of hydrochemical data on 223 most studied small lakes of Karelia, divided into groups based on their belonging to one or another landscape. The possibility of identifying atypical (anomalous) lakes for a certain territory, including unique lakes, has been assessed by applying statistical criteria for identifying outliers in the analysis of hydrochemical data. The search for anomalous values was carried out by classical methods of statistical analysis, among which the graphical method of box diagram and the statistical criteria for finding outliers Chauvenet and Roscher (Thompson). The effectiveness of these methods in detecting anomalies was evaluated. An expert analysis of the obtained sample of lakes with anomalous values of hydrochemical parameters was performed in order to identify the nature and causes of anomalies, as well as the uniqueness of lakes. The ways of further research on the possibility of using mathematical statistics methods to search for anomalies, as well as the development of criteria for the hydrochemical uniqueness of lakes are outlined.

The growing production of plastic products, the majority (about 54%) of which are single-use goods, and the lack of effective plastic waste management have led to the global problem of environmental contamination by polymers. Micro- (< 5 mm) and nano-sized (< 100 nm) plastic particles (MP and NP, respectively) are found in all environments and even in living organisms. The majority of researches are focused on microplastics in surface waters, but MP and NP particles have been detected also in groundwater. The article summarizes the results of current research focused on the analysis of groundwater contamination by microplastic particles. The results of testing the sample from the Podolsko-Myachkov aquifer for the presence of microplastics in the Zvenigorodskaya biostation are presented. Visual characterization was carried out using an Olympus BX53M light microscope, the chemical composition of the polymers was determined using an EnSpectr 532 Raman spectrometer. Identification showed the presence of various polymers: polyethylene, polyurethane, polycarbonate, polyimide. Phenol-formaldehyde and polyterpene resins and various copolymers were also detected. Analysis of the chemical composition of particles revealed among the potential polymers a significant part of natural polymers being cellulose and biodegradable polymer zein. Microplastics are represented by fragments, microfibers and films, which indicate groundwater contamination by secondary microplastics. The abundance of identified particles was 2 item/L.

Based on the results of research conducted in 2022–2023, the radioecological state of the aquatic ecosystem of the North Crimean Canal (NCC) was assessed in relation to long-lived artificial (⁹⁰Sr, ¹³⁷Cs) and natural (⁴⁰K, ²³⁸U, ²³²Th) radionuclides. The role of Dnieper water, which was re-supplied to Crimea in 2022 via the NCC, in the transfer of artificial and natural radionuclides to irrigated agricultural land in this region was also studied. Standard methods of radiochemical processing of samples, as well as beta and gamma spectrometry, accepted in world practice, were used. It was found that 37 years after the Chernobyl accident, Dnieper water remains a source of secondary supply of ⁹⁰Sr (up to 427.2 Bq/m³ in dissolved form) and ¹³⁷Cs (up to 521.9 Bq/kg of suspended solids) through the NCC to the territory of Crimea. The completed forecast showed that, at least for 10 years after the arrival of the Dnieper water with the same levels of activity concentration of ⁹⁰Sr and ¹³⁷Cs, which were determined in 2022–2023, the development of irrigated agriculture in the Crimea will be radiation-safe.

The species composition and quantitative abundance of diatom microperiphyton in the water intake tunnel of Vladivostok Thermal Power Plant-2 (VTPP-2) were studied for the first time as part of an experiment on studying biota in marine technoecosystems. Based on modern methods of algal flora analysis, including scanning electron microscopy (SEM), 49 species of microalgae from the class Bacillariophyceae were identified. A relatively high quantitative abundance of microperiphyton was noted on the surface of the macrofouling of the water intake tunnel (maximum density 17.4 ± 2.5 ‧ 10⁶ cells ‧ cm^–2, biomass 56.3 ± 9.8 mg ‧ cm^–1). The dominant position was occupied mainly by benthic diatoms adapted to mixotrophic metabolism. The quantitative abundance of diatom microperiphyton in different sections of the water intake tunnel varied quite significantly (by 3–6 times) and was determined by local hydrodynamic conditions.

Approaches to the formation of optimal compromise dispatching schedules for water resources management of the Irkutsk reservoir (Lake Baikal) based on multicriteria optimization methods are considered. Many alternative solutions have been formed in accordance with the list of different options for the hierarchy of priorities of water users. A set of solutions that are non-dominant according to the criteria used has been identified.