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 agro-climatic conditions on the yield of sunflower in the Belgorod region

The research showed that natural conditions and agro-climatic resources of the Belgorod region potentially are rather favorable for the cultivation of sun-flower. However, due to considerable variability of the agro-meteorological conditions in time and space, the sunflower yield will experience substantial var-iability by years and by the administrative districts of the regio

Design of a socio-economic processes monitoring system based on network analysis and big data

Socio-economic policy should satisfy the interests of the society as much as possible and contribute to improving the quality of life. This actualizes the role of developing the theoretical and methodological foundations for building an innovative information system for monitoring the socio-economic situation and population responses. The study built and tested an algorithm for supporting management decisions based on the collection of large data sets of socio-economic information based on the principles of the digital economy and processing them through network analysis. The algorithm is focused on building a monitoring system that presupposes a synergy of the authorities and the society, not only in its pensionary part, but also among the masses, which are diverse in their representativeness. The result of the study was the formation of a theoretical and methodological framework for creating a system for making management decisions and assessing the effectiveness of the activities of government bodies, based on the principles of reflection of the final beneficiaries of economic policy.peer-reviewe

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