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The article presents the results of detailed organic geochemistry studies being part of a comprehensive (lithological, geochemical, petrophysical) study of the Bazhenov Formation in the Tomsk Region using the IPGG SBRAS methodology for organic matter-rich source rock. As the thermal maturity increases from PK₃ to MK₂, the content of 'free micro oil' in source rock's pore spaces has been observed to increase. In the same time, there are modifications to the composition of bitumoids (chloroform source rock extracts) from open and closed pores at both the group and molecular levels. Even 'immature' organic matter has been establish to show a difference in bitumoids composition from open and closed pores, which increases as it enters the main phase of oil formation.

The practical feasibility of high-precision measurements of magnetic fields from remote radio transmitters in motion, including on unmanned aerial vehicles, has been demonstrated. The method is based on measuring the Euclidean norm of the full complex magnetic field vector, which makes the results independent of the sensor system's orientation. To compensate for instabilities in the primary field, normalization is performed using a synchronized signal from a stationary base station. Additional accuracy is ensured through pre-flight sensor calibration and post-processing with spatial smoothing filters. Field tests confirmed good reproducibility, with discrepancies between repeated passes below 0.5% of the signal level. In addition, magnetic field maps obtained at different altitudes show strong internal consistency and correlate well with archived ground-based inductive electromagnetic survey data.

Intra-annual climate variations and their effects on radial growth of trees have received increasing attention in recent decades. Tracheidograms have been widely used for the analysis of the xylem cell parameters varying over the course of a year. This paper describes the steps for creating tracheidograms based on high-resolution images using boundary identification methods through artificial neural networks (ANNs), computer vision library (OpenCV) and tracheidogram libraries (RAPTOR, tracheideR). The aim was to identify climate-related features of intra-annual xylem growth of Scots pine Pinus sylvestris L. on Sredny Island, Keret Archipelago, White Sea. To achieve the objective, parameters of 43,754 xylem cells were identified for 7 trees, of which 23,091 cells were grouped into radial profiles for the period from 2009 to 2018. The results indicate a relationship between precipitation from May to August and xylem cell parameters (lumen diameter along the radial axis, lumen perimeter, cell wall thickness, lumen area, lumen diameter to cell wall thickness ratio, lumen area to lumen perimeter ratio). Areas under tracheidogram curves were calculated as an integral metric of annual ring structure. Pearson′s correlation coefficient was estimated between these metrics and average temperature and precipitation from May to August. The strongest relationships identified were as follows: an inverse relationship between the amount of precipitation and the cell wall thickness, a direct relationship between temperature and the cell wall thickness, and a negative relationship between temperature and the lumen size.

The biochemical parameters (albumin content, levels of oxidized proteins (OP) and lipid peroxidation (LPO), antioxidant enzyme activities (superoxide dismutase (SOD) and catalase), aminotransferases and cholinesterase activities were analyzed in the liver of round goby Neogobius melanostomus from the Sea of Azov areas (central (CP), southern (SP) and southeastern (SEP)) with different anthropogenic impacts. Intensification of LPO and protein oxidation processes, as well as protein metabolism reorganization towards gluconeogenesis and detoxification reactions found in the liver of gobies from SEP have been established. This may indicate a more environmentally unfavorable condition of SEP as compared to SP and CP. The analysis of biochemical parameters in the liver of fish from SP and CP allowed characterizing these zones as similar by the level of mixed pollution, however more obvious changes in the biochemical parameters (inhibition of SOD activity, increase in the level of protein oxidation) were observed in the liver of gobies from SP. The obtained results permitted to rank the investigated areas according to the increase the level of mixed pollution as follows: CP → SP → SEP. Suggested reasons for the identified changes were discussed.

To assess the influence of the trophic factor on the survival and abundance of shrews in the conditions of the Far North, an analysis of the relationships between their population dynamics and the abundance of ground invertebrates was performed. The studies were conducted in typical (larch forest in the lower part of a mountain slope) and intrazonal (floodplain Chosenia forest) habitats on the northern Sea of Okhotsk coast. The relative biomass of invertebrates (according to pitfall trap counts) at the end of the summer period showed an inverse relationship with the number of shrews, which may indicate a significant impact of these insectivores on food resources in years of their high abundance. The number of overwintered shrews in a typical forest habitat positively correlated with the relative biomass of invertebrates at the end of the previous summer. In the intrazonal floodplain habitat, no significant relationship was found between the number of overwintered animals and the previous biomass of invertebrates, but due to floods and aufeis ice, the Chosenia forest is unsuitable for small mammals in the cold season. The results of the study suggest a fairly high interdependence between the dynamics of the abundance of shrews and their food items in relatively unproductive northern ecosystems.

The distribution of Viscum album L. in the Bryansk region has been studied. The distribution assessment was performed on a grid basis. In the 20th century, mistletoe was noted in 8 cells, and at present the species has been registered in 95 cells out of 378 squares of grid mapping. Recently, the species range in the region has significantly expanded in the north-eastern direction. Most often, mistletoe was noted in the central, southern and south-eastern regions of the Bryansk region, in the south-western regions on the border with Belarus in the 21st century the species was not found; finds north of Bryansk in the region have not been found. In the Bryansk region, mistletoe has been noted on 29 species of woody plants, most often in natural habitats it is recorded on Betula pendula. Within the boundaries of populated areas, V. album is most often found on Betula pendula, Sorbus aucuparia, Acer platanoides, Populus tremula, Pyrus communis, Prunus domestica and Malus domestica. V. album has been occasionally found on Pinus sylvestris and Picea abies. V. album attacks young plants with unformed bark, weakened old-growth trees with soft wood, confined to forest belts along highways, river valleys, old manor parks, and urban plantings. In parkland, V. album is found mainly on isolated trees that are well lit by the sun. The main distributor of mistletoe in the region is Bombycilla garrulus. The features of V. album dispersal in a model settlement - Dobrun village, Bryansk district, are considered, where the species has spread over the plantings of the entire village territory in 20 years. Pregenerative and young generative plants predominate in the studied population.

For the first time, a comparative analysis of soil, microbiological and botanical characteristics of biocenoses - habitats of rare endangered species of the Orchidaceae Juss. of the white-flowered Cypripedium guttatum Sw. f. albiflorum Aver. and the usual forms Cypripedium guttatum Sw. It was established that soil conditions are decisive in the distribution of cenopopulations of Cypripedium guttatum of the Orchidaceae Juss. within individual biocenoses in the cryoarid climate of Central Yakutia. Important factors influencing the development of this group of orchids are the granulometric composition of the soil, the content of humus in the upper layer, hydrothermal conditions, salinity and pH values. The differences between phytocenoses according to morphological features were the ecological conditions of existence of C. guttatum cenopopulations. The Cypripedium guttatum Sw. f. albiflorum growing on humus-carbonate soil of biocenosis-1 had larger leaf and bracts parameters than Cypripedium guttatum Sw. of the usual form on pale gray soil of biocenosis-2. The humus-carbonate soil of section 1ZH-21 of biocenosis-1 turned out to be the most optimal for the existence of soil microorganisms. In the microbial communities of forest cryogenic soils, soil microscopic fungi (micromycetes) prevailed, therefore, it can be assumed that they play an important role in the development of rare plant species of the Orchidaceae Juss.

The results of an 11 year study of the rare orchid Dactylorhiza traunsteineri (Saut. ex Rchb.) Soó population on the northeastern border of its range (the Komi Republic, north-east of the European part of Russia) are presented. Our research has shown that weather factors (air temperature and precipitation) influence various traits that determine the reproductive success of this species. Significant positive correlations were found between the temperature of August of the previous growing season and parameters such as the size of the inflorescence and the number of generative plants in the population. The fruit set is positively affected by precipitation during the flowering of the species (the third decade of June) and the overall moisture content of the territory in the current growing season. A negative correlation was found between fruit set and the size of the inflorescences of individual plants, while the height of the plants does not affect the effectiveness of pollination. The sizes of seeds and embryos of D. traunsteineri significantly differed in different years of research, but no reliable links between these traits and weather conditions were revealed. A negative correlation was found between seed volume and fruit set in individual plants. In the fruit of D. traunsteineri, from 3211 to 5172 seeds are formed in different years, the real seed productivity of an individual is 10696-44262 pcs. Tall plants produce more seeds per fruit. A positive relationship between real seed productivity and precipitation of the current growing season has been revealed. The final indicator of reproductive success at the population level is the number of young (juvenile) plants. They were present in the studied population during all the years of study, their proportion varied from 3.5 to 13.9 %. Positive reliable correlations between the number of juvenile individuals and the temperature of August, as well as the sum of the active temperatures of the entire previous growing season, were revealed.

Myricaria bracteata Royle and Myricaria longifolia (Willd.) Ehrenb. (Tamaricaceae) are herbal medicines in Mongolia, China and Russia (Siberia). M. bracteata was introduced into culture and it showed prospects for landscaping due to high winter hardiness, drought resistance and decorative properties. M. bracteata and M. longifolia leaves were reported to contain derivatives of 17 flavonoid aglycones, as well as ellagic acid and its derivatives. Principal component analysis of 10 populations of each of these species, based on 56 parameters of the phenolic composition of twigs, showed the high similarity between the species. The native populations of M. bracteata from Tajikistan and Khakassia, as well as native and cultivated populations of both species from Altai Republic exhibited the most significant differences from most samples in the composition of the analyzed components. Populations of M. longifolia of Altai origin were distinguished by the maximum content of the sum of phenolic compounds (up to 107.7 mg per 1 g of dry weight), hyperoside (18.1 mg/g) and quercitrin (2.8 mg/g). The composition of the exudative compounds of the twigs of the studied species was also characterized by a high similarity. Differences in the concentrations of compounds by year were revealed. The exudates exhibited higher antioxidant activity (IC₅₀ 34.2 и 42.2 μg/ml) compared to the extracts (IC₅₀ 110.7 and 172.2 μg/ml). Histochemical visualization showed the localization of phenolic compounds in the salt glands, vascular tissue and chlorenchyma in leaves and stems. The results uncover the high potential of native and cultured plants of the Siberian Myricaria species to be the sources of pharmacologically valuable compounds; in particular, in the phyllosphere of plants, which allows us to consider these species as elements of natural air purification and improvement of environmental air quality parameters.

Seabirds are able to occasionally ingest plastic waste in their feeding sites and excrete it as part of pellets and feces over new landscapes. In this study, the quantitative aspects of plastic transfer in pellets to the Salny island (Kola Bay, Barents Sea) by silver gulls Larus argentatus are estimated. The litter belonging to macro- and megaplastics size categories and classified as gull pellets are shown to be accumulated in the upper plateau of the Salny Island averaging the concentration of about 0.28 kg/ha. Adult birds are supposed to feed at municipal solid waste sites and carry plastic to the island during their nesting or transit stay. According to our observations, plastic ingestion is not accompanied by a decrease of the population: an increase of the nesting density on the island by 2-4 times over the observation period of 12-14 years is shown. For the first time the phenomenon of plastic waste transport by seabirds in the Russian part of the Barents Sea is described.