Hydrological changes in the White Sea during the historical period inferred from analysis of dinocysts

According to available historical evidence, colonization of the White Sea region began in the 9th–8th centuries B.C. [2]. This unique region with ancient residence sites experiences progressively increasing anthropogenic load against the background of natural climatic changes. The intense economic development of the region requires complex ecological and paleogeographic studies aimed at detailed reconstruction of past sedimentation settings. The analysis of dinocysts, which makes it possible to reconstruct various parameters of water masses washing the Arctic shelf, has become a promising method in paleohydrological studies, widely used in recent years [10, 11]. Dinoflagellates, which represent one of the main phytoplankton groups in the Arctic Seas, the White Sea included, form cysts with biopolymer envelopes, which are preserved in sediments. Thus, information on glacial–hydrological conditions is recorded in marine sediments. In the White Sea, this method was first used for the study of bottom sediments only in 2003 [3, 15]. In this communication, we present the first results obtained during the thorough study of dinocysts in bottom sediment cores from the White Sea, which cover the last 250 years. The study of this microfossil group made it possible to reconstruct in detail changes in glacial–hydrological settings in the sea and reveal their relations with known climatic–hydrological events that occurred in neighboring regions during the historical period

Dinoflagellate cysts in the surface sediments of the White Sea

Dinoflagellate cysts were studied in 42 samples from the surface sediments of the White Sea. The total concentration of dinocysts varies from single cysts to 25 000 cyst/g of dry sediments, which reflects the biological productivity in the White Sea waters and the regional particular features of the sedimentation processes. The highest concentrations are observed in silts; they are related to the regions of propagation of the highly productive Barents Sea waters in the White Sea. Generally, the spatial distribution of dinocysts species in the surface sediments corresponds to the distribution of the major types of water masses in the White Sea. The cysts of the relatively warm-water species (Operculodinium centrocarpum, Spiniferites sp.) of North Atlantic origin that dominate in the sediments indicate an intensive intrusion of the Barents Sea water masses to the White Sea along with hydrological dwelling conditions in the White Sea favorable for the development of these species during their vegetation period. The cold-water dinocyst assemblage (Islandinium minutum, Polykrikos sp.) is rather strictly confined to the inner parts of shallow-water bays, firstly, those adjacent to the Onega and Severnaya Dvina river mouths

High-resolultion reconstruction of Lena River discharge during the Late Holocene inferred from microalgae assemblages

On the basis of a detailed study of the diatom and aquatic palynomorph assemblages and a detailed radiocarbon chronology of sediment cores obtained from the south-eastern inner Laptev Sea shelf adjacent to the Lena Delta the spatial and temporal variability in the Lena River discharge during the last 6 cal. ka were reconstructed. It was shown that in the area adjacent to the Lena Delta variations in surface water salinities, reconstructed using freshwater diatoms as a proxy, were mainly caused by changes in the volume of the Lena River runoff through the major riverine channels Trofimovskaya, Bykovskaya and Tumatskaya. Several paleohydrological phases are recognized: (i) establishment of modern-like conditions within the eastern Lena River Valley occurred from 6-4.2 cal. ka; (ii) Lena River outflow increased in north-eastward direction via the Trofimovskaya or Bykovskaya channels from 4.2-2.7 cal. ka, coeval with a reduction of runoff toward the north via the Tumatskaya Channel; (iii) generally stable hydrological conditions northward of the Tumatskaya Channel and variations in riverine discharge north-eastward of the Trofimovskaya and Bykovskaya channels prevail since 2.7 cal. ka. Using indicator species of dinocysts as principle marine proxy, an influence of Atlantic water to the southeast inner Laptev Sea shelf could be inferred, possibly along the Eastern Lena paleovalley, brought into this area by winddriven reversed bottom currents. Zusammenfassung: Untersuchungen von Diatomeen- und aquatischen Palynomorphen-Vergesellschaftungen wurden an Radiokohlenstoff datierten Sedimentkernen aus der inneren südöstlichen Laptevsee nahe des Lenadeltas durchgeführt. Anhand dieser Daten wurde die zeitliche und räumliche Veränderlichkeit des Flusswasserausstromes der Lena für die letzten 6 ka (Kalenderjahre) rekonstruiert. Zeitliche Veränderungen in den Häufigkeiten von Süßwasserdiatomeen sind begründet durch Wechsel in der Menge des Lenaausflusses durch die drei großen Haupkanäle im Delta: Trofimovskaja, Bykovskja, sowie Tumatskaja. Darauf basierend konnten prinzipiell drei große paläohydrologische Phasen unterschieden werden: (1) heutigen Verhältnissen vergleichbare Bedingungen wurden östlich des Lenadeltas zwischen 6 und 4.2 ka etabliert; (2) Erhöhung des Flusswasseraustrags in nordöstliche Richtung über die Kanäle Trofimovskaja und/oder Bykovskaja zwischen 4.2 und 2.7 ka bei gleichzeitiger Reduzierung Richtung Norden via Tumatskaja; (3) Ausbildung relativ stabiler Bedingungen nördlich des Deltas sowie Auftreten wechselhafter Flusswasserausträgen in östliche Richtung nach 2.7 ka. Das Auftreten von marinen Dinocysten in den Sedimenkernen belegt den Einfluss von Wassermassen mit vermutlich atlantischem Ursprung. Es ist zu vermuten, dass diese durch windgetriebene Bodenströmungen entlang der alten versunkenen Flusstäler auf den östlichen inneren Schelf verfrachtet werden

Reproductive toxicity of carbon nanostructured material - a promising carrier of drugs in laboratory mice

At the same time, the purpose of this study was to evaluate the reaction of the reproductive system on the carbon nanostructured material "Taunit (multi-walled carbon nanotubes), that was injected to laboratory miceyesBelgorod State Universit

The influence of the microstructure morphology of two phase Ti-6Al-4V alloy on the mechanical properties of diffusion bonded joints

The influence of ultra fine grained (UFG) and coarse grained (CG) microstructure of the titanium alloy Ti-6Al-4V on the strength of a diffusion bonded (DB) joint was studied using a laboratory DB fixture and a new shear test rig. The DB process was carried out at 725°C and 825°C during 2 and 4 hours in a vacuum furnace. Coarsening of grain structure resulting from different DB cycles was quantified. The chain pores were observed at 725°C for both microstructure conditions bonded during 2 hours. The increase of bonding time up to 4 hours leads to subsequent elimination of the pores. The UFG samples bonded at 725°C showed a higher level of the shear strength than CG samples for both bonding times. The CG material demonstrated the highest shear strength after 4 hours of DB bonding at 825°C. The increase of the creep deformation of UFG samples when compared to the CG condition was observed as a result of DB at of 725° C during 4 hours

Evolution of the barrier beaches in the Pechora Sea

The article discusses the main results of the complex investigations of barrier beaches in the Pechora Sea including coastal dynamics and accompanying exogenous processes (eolian transportation), lithological and micropaleontological studies of the sediment sequence and radiocarbon dating. We were the first to reconstruct sedimentation conditions and evolution of these big accumulative forms in the Pechora Sea. Stationary observations on coastal dynamics and the rate of eolian sedimentation allowed estimating the rate of barrier retreat. The mechanism of formation and evolution of dune belts on these barriers is described. Composition of diatom associations and lithological data provide evidence for facial-genetic conditions of sedimentation during accumulation of barriers. Radiocarbon datings corroborate the "young" age of the modern avandune ridges of the barrier beaches

Review of International Research on Ethical and Psychological Barriers to Reproductive Donation

Received 24 January 2020. Accepted 19 June 2020. Published online 9 July 2020.This review examines the international research literature discussing the barriers for those considering the possibility of becoming donating sperm, eggs, or embryos or becoming surrogate mothers. While there is a significant body of research on donors’ motivations, less attention is given to the reasons why potential donors decide not to donate or withdraw from donation procedures. Nevertheless, we have collected about 70 studies, including journal articles, book chapters and reports. Contemporary findings show that as much as there is no single motivation for reproductive donation, there is also no single barrier to it. The studies we considered deal with two salient themes. First, barriers to reproductive donation serve as a space for negotiation of a donor’s beliefs, fears and perceived consequences of donation to themselves, the recipients and resulting offspring. Second, these barriers are a complex web of intersecting factors, influenced by secondary factors. This review reveals the limited nature of our current knowledge of barriers to reproductive donation. Indeed, research on this problem needs to catch up with research on motivation because obstacles to reproductive donation are no less important than the stimuli

Отношение жителей мегаполиса к репродуктивному донорству (на примере Екатеринбурга)

Аbstract. The paper presents the findings of a population survey conducted in the city of Ekaterinburg in 2019 (1300 respondents). The study aimed at measuring the citizens' awareness about reproductive donation and their attitudes to different types of reproductive donation in general and in connection with the specificity of reproductive material. The data were analyzed in the context of Goffman's concept of social stigma and the results of similar works by other authors. The majority of the respondents are aware of reproductive donation and have a positive attitude towards it. The level of awareness, as well as the prevalence of positive attitudes, depends on the specificity of the reproductive material. The most wellknown and accepted technology is sperm donation, while the most controversial is embryonic donation. More than half of the respondents (52%) consider the embryo a human being, and 47% have a negative attitude towards embryo donation. Perceptions of embryo status are correlated with gender, family history, and religious beliefs. Most of the respondents say that they themselves are not ready to become donors of genetic material, and the main motive of those who become a reproductive donor is financial interest. The study reveals a clear gap between the general attitudes towards donation, when it is perceived in abstract, and situations of personal relatedness to the field of reproductive donation. In the latter case, the attitude towards reproductive donation becomes much more positive. The results of the study strongly suggest that the involvement of third parties in the parenting process is ethically and psychologically ambiguous, and it requires further study together with the position of the involved parties. Since Ekaterinburg, on the one hand, demonstrates trends inherent in capital cities, and on the other, has a clear regional specificity, this data may reflect the current attitude of the population of all large Russian cities towards reproductive donation. © 2021 Russian Public Opinion Research Center, VCIOM. All rights reserved

Temperature, composition and age of the Kara Sea Shelf sediments in the area of the Marre-Sale Geocryological Station

The paper presents results of the study of the uppermost 20 m-thick layer of the near-Yamal shelf bottom sediments, penetrated in May 2014 by two VSEGINGEO boreholes equipped with LРС loggers, with an aim of the temperature regime dynamics monitoring in the nearshore bottom sediments, both for the research purposes and in as much as the data add value to the forthcoming hydrocarbon resource development on the Russian continental shelf. On the basis of the temperature variation observations during three summer months of 2014, it has been established that marine silty clays and aleurites composing the bottom sediment section, represent relict frozen deposits subjected to cryogenic metamorphism in the subaerial exposure environment. Diatom assemblages occurring in aleurite and clayey deposits consist exclusively of the marine extinct species typical of the Early Eocene Pyxilla gracilis diatom zone. A modern marine sublittoral diatom assemblage is found inhabiting the sands of the upper part of the onshore borehole section

Diatom assemblages from Holocene sediments of the Kola Peninsula

The Kola Peninsula is one of the key areas for the study of postglacial development of northern Europe. The repeated formation of ice shields during the Pleistocene determined the peculiar features of the relief, structure of Quaternary sediments, and recent landscapes of the peninsula. The paleogeographic reconstructions available for the last 10–11 ka are based on results of the palynological analysis of lacustrine and boggy sediments [3–5, 9–11] and, to a lesser extent, on diatoms from the lacustrine sediments [7, 8]. In this communication, we present the first data on diatom assemblages from peat sections of the central Kola Peninsula and their detailed radiocarbon ages. The high sensitivity of lacustrine–boggy ecosystems to environmental changes made it possible to define several Holocene diatom assemblages and to correlate their succession with regional climatic events and variations in the local base level