Volume 63, Nº 5 (2023)

This study identified a process of water supply due to discrete transport by anticyclonic eddies towards the formation region of the intermediate water in the northwestern Japan Sea in the summer season. The structures and dynamics of three anticyclonic mesoscale eddies were studied by means of the Aqualog moored profiler observational survey at the continental slope in the Primorsky Current region east of Peter the Great Bay in June–July 2015. It was shown that the eddy cores were of ellipsoidal shape with an elongated lower part. The anticyclones as isolated dynamic structures carried water enriched with dissolved oxygen in the west-southwest direction. In terms of the thermohaline characteristics the water transported was similar to the Japan Sea intermediate water at its formation region south of Peter the Great Bay.

In the frameworks of the program “Ecosystems of the Siberian Arctic seas”, carried out by Shirshov Institute of Oceanology RAS since 2007, studies of the structure of waters, spatial variability of the carbonate system parameters have been performed, and the intensity and direction of the carbon dioxide flux over the continental slope of the Laptev Sea and in the Vilkitsky Strait in September 2018 have been calculated. The presence of several main water masses that determine the structure of waters in the study area is shown. A strong spatial variability of the parameters of the carbonate system of sea waters, determined by the complexes of physical and chemical-biological processes, has been revealed. The intensity and direction of the carbon dioxide flux at the water–atmosphere boundary were calculated, ranging from –12 to +4 mmol m^–2 day^–1. It was revealed that the investigated area of the outer shelf of the sea and the continental slope of the Laptev Sea is an emitter of carbon dioxide into the atmosphere as of September 2018. The area of the Vilkitsky Strait, on the contrary, is an area of absorption of CO₂.

Benthic foraminiferal assemblages were studied in twenty surface sediment samples collected in the western part of the East Siberian Sea in the framework of the expedition of the R/V “Ivan Kireev” in 2004. Rose Bengal treatment allows us to separate “living” and “dead” individuals. Taxonomic analyses reveal that “living” calcareous foraminifers dominate in the study region with the exception of the New Siberian Islands area and area to the northeast from the Indigirka river mouth where agglutinated tests constitute up to a half of the assemblage. Little amount of dead individuals points to a rapid dissolution of calcareous tests immediately after death of organism. Taxonomic composition of the studied assemblages is similar to river-proximal benthic foraminiferal assemblage previously determined for the Kara Sea. In the East Siberian Sea, the most commonly occurred species are E-lphidium clavatum, Elphidiella groenlandica, Haynesina orbiculare, E. incertum и Lagenammina atlantica. Less abundant species are Gordiospira arctica, Buccella frigida, E. bartletti, Reophax curtus, R. scorpiurus and polymorphinids. As a result of statistical treatment, four areas with specific BF assemblages have been distinguished: area of the Indigirka River mouth, zone affected by Siberian Coastal Current, area located to the north of the Siberian Coastal Current and zone situated close to the New Siberian Island archipelago together with an area located to the northeast from the Indigirka river mouth. Such a distribution of BF assemblages in the study area seems to be related to the distance of the river discharge area, type of sediments and fresh organic matter content.

A hypothesis is proposed for the functioning of the diatom population under conditions of water column stratification. It is assumed that cells in the upper illuminated water layer accumulate biomass due to photosynthesis. In the lower layer, rich in minerals, the cells replenish their intracellular reserves. Moving from one layer to another allows to cells to compensate for the lack of resources. Sinking occurs as a result of sedimentation, and lifting occurs due to the release of carbon dioxide microbubbles in the process of respiration. On the basis of this hypothesis, an agent model of the population is constructed. The calculations have shown that vertical movements ensure the existence of the population. Various surface illumination make it possible to obtain various distributions of cell numbers in the upper and lower water layers, which is consistent with the data of expeditionary observations.

The paper presents the results of studying the bottom sediments of the lake Trekhtsvetnoe, which is situated at the meromictic stage of separation from the White Sea (Kandalaksha Bay). The geochemical parameters of the process of bacterial sulfate reduction are considered – the formation and accumulation of various forms of reduced sulfur in relation to the content of organic matter and reactive iron in sediments. A significant level of content of reduced sulfur compounds (up to 1.467%) and their distribution in the sediments of the lake. Tricolor, due to a fairly active process of sulfate reduction. The activity of the recovery processes is ensured by the entry of labile organic matter into the sediments, which is formed due to intensively developing microbial communities in the chemocline zone and in the lake water column.

This research provides classification and analysis of the spatial distribution of the Holocene aeolian landforms within the White Sea Coast. We identified 5 types of secondary dunes based on the interpretation of detailed satellite images, topographic charts and analysis of literary sources: foredune plains and beach ridges plains, cliff-top dunes, blowouts and parabolic dunes, transgressive dunefields, sand sheets. The dunes were formed mainly from the Middle-Late Holocene. They gravitate towards sandy shores, where post-glacial uplift rates didn’t exceed ~3 mm/year during the Middle-Late Holocene. The coastal dunes were formed in connection with sediments, which entered the coastal zone with solid river flow and from selective erosion of glacial deposits. The rhythms of aeolian processes activation in different parts of the White Sea Coast were non-synchronous.

The use of towed underwater uninhabited vehicles equipped with photo, video, and sonar systems has proven its effectiveness in studies of the bottom surface within the framework of integrated studies of the World Ocean. This class of devices solves a wide range of tasks, including biological studies of benthic fauna and surveys of underwater technogenic objects. The towed vehicle “Videomodule” was developed at the Shirshov Institute of Oceanology of the Russian Academy of Sciences and successfully used for several years to conduct such surveys. This article discusses the technical features and application issues of working with the “Videomodule” device.

Comprehensive geological and geophysical, geomorphological and hydrophysical studies carried out on the R/V Akademik Boris Petrov in the eastern part of the Barents Sea and the western part of the Kara Sea in the fall of 2022. The research included multibeam echo sounding and seismic profiling, hydrological sounding, as well as sampling of water and sediments in the areas of oil and gas fields’ development and along the Northern Sea Route. The expedition studied the structure of the seabed relief and the upper sedimentary strata on the polygons of detailed investigations. The areas of distribution of various glacial landforms and modern geohazards specified during the expedition.