Северный (Арктический) федеральный университет имени М.В.Ломоносова

The respective environments in two ancient rivers were studied using geochemical methods with paleogeographic reconstructions of fossil material represented by shells of freshwater bivalve mollusks. The studied outcrops are located in the basins of the Dniester and Prut rivers. Materials were collected from two Pliocene (Brînza, Giurgiuleşti) outcrops and the ages of the second group of localities (Sucleia, Slobozia Mare, Gura Bîcului) are from Middle to Late Pleistocene. The determination of the taxonomic position was carried out using standard malacological methods. Geochemical data were used for the environmental reconstruction and included stable isotope ratio and trace element compositions in subfossil freshwater bivalve shell (Bivalvia: Unionoida). Key indicators of paleoenvironments show changes in water temperature. Changes in the taxonomic composition of bivalve mollusk assemblages also occurred. In the present study, increasing the water temperature caused a change of stenobiont species of bivalve mollusks to eurybiont species. Eutrophication of watercourses, caused by anthropogenic pollution and climate change in the direction of warming, has led to the replacement of pearl mussels of the family Margaritiferidae by more eurybiont species of the family Unionidae in the benthic communities of European oligotrophic rivers. These processes are similar to those deduced for the Neogene-Quaternary watercourses of the Prut and Dniester basins, but they proceed at a much faster pace. They are processes of eutrophication of watercourses – the main factor leading to the catastrophically rapid modern reduction of the ranges of pearl mussel.

This work has been carried out using methods of numerical modeling to detect weakened zones in the basement of the region in regard to the construction and economic human activities. For this purpose, we have constructed quantitative models of the stressed-deformed state of the Earth’s crust in the region considering its evolution. Determined for the first time are the structures that accumulated a tectonic-magmatic activity and produced mobile-permeable zones in the Precambrian mainly. For the first time, we have found an interrelation between localities of deep fractures (activation areas) and the stressed-deformed state of the Earth’s crust caused by the impact of regional tangential stresses. Most of mineral deposits are located within the identified weakened zones of the geological basement. Economic activity of the population is concentrated there, which affects the ecological situation in the region. In addition, most of the territory where the mobile- permeable areas are detected in the basement is overlapped by known seismogenic zones of the region. Consequently, seismic events with an increased level of magnitude are more often generated in these areas due to the detente of interblock stresses in the geological environment. The provided research indicates the necessity of studying the general geological structure of the region and identifying setting areas of ancient deep deformation structures in design and construction of the major industrial, road, hydraulic engineering and other objects.

The respective environments in two ancient rivers were studied using geochemical methods with paleogeographic reconstructions of fossil material represented by shells of freshwater bivalve mollusks. The studied outcrops are located in the basins of the Dniester and Prut rivers. Materials were collected from two Pliocene (Brînza, Giurgiuleşti) outcrops and the ages of the second group of localities (Sucleia, Slobozia Mare, Gura Bîcului) are from Middle to Late Pleistocene. The determination of the taxonomic position was carried out using standard malacological methods. Geochemical data were used for the environmental reconstruction and included stable isotope ratio and trace element compositions in subfossil freshwater bivalve shell (Bivalvia: Unionoida). Key indicators of paleoenvironments show changes in water temperature. Changes in the taxonomic composition of bivalve mollusk assemblages also occurred. In the present study, increasing the water temperature caused a change of stenobiont species of bivalve mollusks to eurybiont species. Eutrophication of watercourses, caused by anthropogenic pollution and climate change in the direction of warming, has led to the replacement of pearl mussels of the family Margaritiferidae by more eurybiont species of the family Unionidae in the benthic communities of European oligotrophic rivers. These processes are similar to those deduced for the Neogene-Quaternary watercourses of the Prut and Dniester basins, but they proceed at a much faster pace. They are processes of eutrophication of watercourses – the main factor leading to the catastrophically rapid modern reduction of the ranges of pearl mussel. Citation: Lyubas AA, Kabakov MB, Kriauciunas VV, Obada TF, Nicoara IN, Tomilova AA (2019) Freshwater mollusks from Neogene-Quaternary Dniester and Prut riverine deposits as indicator paleoenvironments: chemical composition of shells and its palaeoecological interpretation. Arctic Environmental Research 19(1): 35–42. https://doi.org/10.3897/issn2541-8416.2019.19.1.35

This work has been carried out using methods of numerical modeling to detect weakened zones in the basement of the region in regard to the construction and economic human activities. For this purpose, we have constructed quantitative models of the stressed-deformed state of the Earth’s crust in the region considering its evolution. Determined for the first time are the structures that accumulated a tectonic-magmatic activity and produced mobile-permeable zones in the Precambrian mainly. For the first time, we have found an interrelation between localities of deep fractures (activation areas) and the stressed-deformed state of the Earth’s crust caused by the impact of regional tangential stresses. Most of mineral deposits are located within the identified weakened zones of the geological basement. Economic activity of the population is concentrated there, which affects the ecological situation in the region. In addition, most of the territory where the mobile- permeable areas are detected in the basement is overlapped by known seismogenic zones of the region. Consequently, seismic events with an increased level of magnitude are more often generated in these areas due to the detente of interblock stresses in the geological environment. The provided research indicates the necessity of studying the general geological structure of the region and identifying setting areas of ancient deep deformation structures in design and construction of the major industrial, road, hydraulic engineering and other objects. Citation: Filatova VT (2019) Formation of defused stress areas in the Earth's crust of the Kola region and associated environmental risks in capital construction. Arctic Environmental Research 19(1): 20–34. https://doi.org/10.3897/issn2541-8416.2019.19.1.20

The results of the study of certain biochemical parameters of blood in grey seals (Halichoerus grypus Fabricius, 1791) from birth to weaning are presented. In the blood plasma, 20 indices describing the state of the metabolism of proteins, carbohydrates, lipids, minerals (total protein, urea, creatinine, glucose, lactic acid, total lipids, triglycerides, cholesterol, calcium, phosphorus, sodium, potassium, magnesium, iron, aspartate aminotransferase, alanine aminotransferase, γ-glutamyltransferase, creatine kinase, alkaline phosphatase, lactate dehydrogenase) are studied. It has been established that metabolic changes in the early period of postnatal development of grey seals occur in mammals in general, but the expression level of individual reactions may be considered a feature of pinnipeds. By the ratio of transaminase activity, the predominance of catabolism over anabolism was established in animals in the studied period of development. The most significant changes in the metabolism of grey seals were noted during weaning and the transition to self-feeding. The adsorption- transport function of erythrocytes was evaluated by washout on the erythrocyte membranes using 3% sodium chloride solution. It was established that all detected components of blood plasma are found in erythrocyte washings. The level of adsorption, expressed as a percentage of the content of a certain metabolite in the blood plasma, is not the same for different compounds. Enzymes, urea, creatinine, lipids are adsorbed most on the erythrocyte membranes (in some cases more than 100%), and glucose, lactic acid, cholesterol, iron, calcium are adsorbed in a smaller quantity (<50%). The data obtained indicate that the transfer of organic compounds on erythrocytes is more variable and demonstrative than shifts in the corresponding blood plasma parameters, and erythrocytes can participate in maintaining a range of concentrations of a number of substances in the blood plasma.

Ensuring stability of subgrade soil under engineering structures is a critical task at oil field development projects in the Arctic. It is largely determined by the state of the permafrost influenced by natural and man-induced changes to the temperature regime. The issue of permafrost stability forecasting is still underexplored, this entailing a number of challenges for construction and trouble-free operation of facilities in the Far North. The Ardalin Oil and Gas Field (AOGF) is the only project in the Nenets Autonomous District (NAD) where results of extensive temperature measurements carried out in special thermometric wells have been accumulated over a lengthy period of over 20 years. This article contains the findings of thermometric monitoring of the top layer of soil with an average depth interval of 20 metres. Changes in the permafrost temperature regime, in both the presence and absence of sand (soil) filling, over the study period are described in the article. Natural physical and climatic disturbances that rule out the possibility of maintaining a continuous permafrost temperature are identified. In addition, the key sources of man-induced impact on the top layer of permafrost at the location of the AOGF production infrastructure facilities are analysed. This analysis resulted in recommendations that might be of help during design and construction of engineering works in the European North of Russia and serve to minimise thermal impact on frozen ground. Preserving the permafrost layer in its original natural state will help ensure stability of the subgrade of buildings and structures, thereby reducing the chances of any accidents.

The Barents Sea is a highly productive shelf region. Zooplankton assemblages are a key component of the carbon cycle in Arctic marine ecosystems; they transfer energy from lower trophic levels to higher levels, including larval and young commercial fish. The winter state of the zooplankton community in the Central Through and their slopes (Barents Sea) was investigated in late November 2010. Vertical structure of water layer was characterised by pycnocline located below 80 m. The upper strata were occupied by transformed Atlantic Water, while winter Barents Sea Water with negative temperatures was in the bottom strata. Total zooplankton abundance varied from 162 to 1214 individuals/m3. Biomass ranged from 88 to 799 mg wet mass/m3. Copepods dominated in terms of total zooplankton abundance (average 99%) and biomass (92%). Maximum densities of Calanus finmarchicus and Calanus glacialis were registered in the frontal zone separating warm and cold water masses. Abundances of Metridia longa and O. similis were highest in cold waters. Three groups of stations differing in terms of the common copepod composition were delineated with cluster analysis. The age structure of Calanus finmarchicus and Metridia longa was characterised by a prevalence of copepodites IV–V. Total zooplankton abundance and biomass were correlated to water temperature and salinity, suggesting that hydrological conditions were the key driver of spatial variations of the zooplankton communities. High biomass of large copepods suggests potential significance of the investigated region for feeding of young and adult fish.