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2023 | Buch

Complex Investigation of the World Ocean (CIWO-2023)

Proceedings of the VII International Conference of Young Scientists


Über dieses Buch

The book presents the most relevant research of the participants of the VII International Conference of Young Scientists "Complex Investigation of the World Ocean" (CIWO-2023). This conference was held at Saint Petersburg State University in May 15-19, 2023 (Saint Petersburg, Russia). It covers a wide range of fundamental and applied marine and limnology studies combined in eight sections: Ocean Physics, Ocean Biology, Ocean Chemistry, Marine Geology, Marine Geophysics, Marine Ecology and Environmental Management, Physical and Biological interactions (interdisciplinary section), Oceanological Technology and Instrumentation. The aim of this book is to show the relevance of the marine research due to the crucial role of the World Ocean in determining climate change on Earth, huge resources (fish resources, oil, gas and ore deposits, etc.) and intensive development of infrastructure in coastal and offshore zones. All these topics were marked within the framework of realization of the United Nations Decade of Ocean Science for Sustainable Development (2021-2030).

The studies presented in the book covers the wide spectrum of different the most important marine and limnology issues: thermohaline structure of water body and interactions between ocean and atmosphere, dynamic of the ocean, marine ice in polar regions, biodiversity of the marine ecosystems, adaptation of marine life to climate changes, geological and geophysical investigations in oil and gas regions, sedimentation, paleooceanology and biostratigraphy, hydrochemistry of estuary regions and carbon fluxes, microplastic pollution of the ocean, eutrophication and etc.



Ocean Physics

Climate assessment of water, heat and salt fluxes in the Pechora Sea

The Pechora Sea is a Barents Sea part located in the southeast. The natural conditions of the Pechora Sea are very different from the Barents Sea water area. There are various types of water masses and many dynamic processes. The purpose of the study is to assess the components of the water, heat and salt balances of the Pechora Sea. Based on the monthly average data of the CMEMS GLORYS12V1 and ERA5 reanalyses for the period 1993–2018, the water, heat and salt transport at the boundaries of the Pechora Sea (in longitude 50 E on the west, latitude 71 N on the north and in the Kara Strait) and the characteristics of the sea surface-atmosphere interaction are calculated. The average long-term resulting water transport on the Pechora Sea boundaries coming from the west (0.36 Sv) and from the north (0.04 Sv), leave the Pechora Sea through the Kara Gates (0.40 Sv). It is shown that in the region there is heat excess coming due to advection, which is compensated by sea-atmosphere interaction. All transports during the study period have a significant positive trend, which characterizes the growth of the transit of North Atlantic water through the Pechora Sea.

D. V. Deshova, S. M. Gordeeva
Assessment of Seasonal and Multi-year Variations in Ice Age Composition of Greenland Sea and Barents Sea

We present the first winter estimates of the Greenland and Barents Seas ice age composition using the ice charts for the period from 1997 to 2022 compiled by the Arctic and Antarctic Research Institute (AARI). The interannual variations in the ice amount of different age categories in it relative fractions in the Greenland Sea and the Barents Sea do not show significant linear trends. When comparing the estimates, obtained in this study, with previous studies on this subject, we may state that quantitative changes in the Greenland and Barents Seas ice age composition began earlier than 1997. Only on the basis of data on the ice age composition over a 25-year long period of observations analyzed in this study, it is impossible to draw a clear conclusion about a decrease in its thickness in the Greenland and Barents Seas.

E. S. Egorova, Ye. U. Mironov
Laboratory Investigations of the Evolution of Baroclinic Eddies in a Two-Layer Rotating Fluid

In this work, by means of laboratory modeling, the patterns of evolution of baroclinic eddies in a rotating two-layer fluid. Using the original application of the “cylinder method”, single axisymmetric cyclonic and anticyclonic eddies were produced in the upper layer, and their evolution was traced over 100 or more platform rotation periods.

D. N. Elkin, A. G. Zatsepin
Analysis of Hydrophysical and Energy Fields in the Northern Part of the Black Sea on the Basis of the Numerical Model With the Assimilation of the Hydrological Data in 2016

Three experiments were performed to reconstruct the fields of currents during the periods of hydrological cruises at the R/V “Professor Vodyanitsky” in 2016: June - July (summer season), September - October (autumn season) and November - December (autumn-winter season) on the basis of the z-coordinate hydrodynamic model of the Black sea and a procedure of assimilation of contact measurements of temperature and salinity. The components, that made the most significant contribution in the equations of dencity of kinetic and potential energy, were analyzed in order to study the possible mechanisms of formation of the reconstructed features of water dynamics.

N. A. Evstigneeva, S. G. Demyshev
Water Structure and Dynamics in the Transform Fracture Zones of the Tropical Atlantic According to Instrumental Measurements

The structure and dynamics of different water masses in the Tropical Atlantic is investigated using the results of instrumental measurements. The main attention is focused on the Vema fracture zone and the northern part of the WOCE A15 section. In the Vema Fracture zone an intradiurnal variability of hydrological parameters was observed. We also assess the long-term variability of hydrological parameters along the WOCE A15 section.

F. N. Gippius, A. N. Demidov, K. V. Artamonova, S. B. Krasheninnikova
The Spatio-Temporal Variability of the Ocean-Atmosphere Heat Exchange and the Sea-Ice Cover in the Nordic Seas

Turbulent heat flux in the Nordic Seas were decomposed into characteristic modes of variability using Empirical Orthogonal Functions (EOF). The first EOF describes the general warming trend in the Arctic Basin. The region of the highest fluctuations is consistent with the area of the sea-ice reduction by more than 20% between 1959–1980 and 2004–2021. In these areas the air temperature increases is a result of an increasing ocean heat release to the atmosphere. The ocean-atmosphere heat exchange over the ice-free ocean is a result of a change in atmospheric wind pattern.

A. S. Kaledina, I. L. Bashmachnikov
“1.5D” Vertical Turbulent Exchange Model Verification Based on Microstructural Probe Data on Cruise 122 of the R/V Professor Vodyanitsky

From June 7 to July 2, 2022, for the first time, information on the fluctuation characteristics of the flow in the stratified layers of the Black Sea was obtained with data on the vertical distribution of oxygen, chlorophyll A and turbidity at depths up to more than 900 m on cruise 122 of the R/V Professor Vodyanitsky. Studies in this region included obtaining the dependences of the vertical turbulent diffusion coefficient K on the buoyancy frequency N and on the depth z according to the pulsation characteristics of the flow. Calculation results were compared with the results of a 1.5D vertical turbulent exchange model, as well as the hydrophysical features general analysis of the region under study. Data analysis showed the presence of several layers with different characteristic features of mixing in them. The obtained power-law approximations of the dependences K ≌ A · Nα in these layers showed good convergence with the model ones in the power part.

D. A. Kazakov, M. I. Pavlov, A. M. Chukharev
Seasonality of Pacific Water Distribution in the Sea of Okhotsk Revealed by Lagrangian Approach

The eastern Sea of Okhotsk is commercially important ecosystem with substantial documented changes in physical setup and fish stocks. The productivity of this area is at least partly related to the water of Pacific origin which is rich in nutrients. However, the variability of Pacific-origin water distribution within this area is still purely studied. Thus the main objective of this study is to illustrate temporal variability of Pacific-origin water distribution. Another specific objective is to evaluate the degree of seasonal variability of this water distribution. Lagrangian approach related to the analysis of life history of water particles was used as the main instrument. The results revealed substantial inter-annual variability of Pacific-origin water distribution. The area of Pacific-origin water of particular residence time was suggested as an index of Pacific influence on the studied region. Area of Pacific-origin water with residence time from 61–180 days was chosen for further analysis. Seasonal component of this area index was distinguished with complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) method. The parameters of variability of this component were investigated. The analysis revealed substantial inter-annual variability of amplitude and period of seasonality.

K. K. Kivva, M. V. Budyansky, M. Yu. Uleysky, S. V. Prants
Turbulence Influence on the Thickness of the Mixed Layer in the Coastal Zone of the Black Sea

Significant problem in present climate theory is the consideration of rapidly changing wind-dependent parameters when modeling the dynamics of the MBL depth. Perceptible errors in the simulation of the mixed layer are due to Langmuir and turbulent mixing. The paper presents a way to modernize the one-dimensional model of the mixed layer by Niiler-Kraus using a multiscale turbulence model, which takes into account three parameters of turbulence generation from wind: current velocity shear, surface wave nonlinearity and wave breaking. The verification of the model is presented by field data collected in the coastal zone of the Black Sea on a stationary oceanographic platform of the Marine Hydrophysical Institute of the Russian Academy of Sciences. The model working is evaluated with different variability of wind speed and direction.

V. A. Korzhuev
Heat Fluxes in a Multilayer Atmosphere-Snow-Ice-Water Environment Using the Gulf of Finland as an Example

This publication outlines and summarises the results of ice research in the eastern Baltic Sea conducted in February 2021 by oceanology students of the Russian State Hydrometeorological University and in February 2023. Namely, the vertical profile of the actual temperature, vertical distribution of hourly average temperatures in each layer was studied while setting up experiments with a thermometric streamer, and the purpose of the research was to calculate heat fluxes in a multilayer medium. Ice accretion from the ice surface through snow was calculated from the obtained fluxes. Currently there are not many scientific papers on the chosen topic and this is the relevance of this work, which can serve as a basis for more extensive directions in the future.

K. V. Kravtsova, N. A. Podrezova
Spatial Trend Analysis of Significant Wave Heights in the Caspian Sea

The paper presents the analysis of a number of storms and the trends for average annual and maximum annual of significant wave height based on the results of wave model WAVEWATCH III and the Peak Over Threshold method. The mean, maximum and 95th percentile SWH were analyzed for the Caspian Sea. Significant positive trends were found for the number of storms with SWH > 3–4 m. A significant positive trend was found in total storm duration: every 10 years, the number of stormy days with SWH > 2 m increases by 4 days. Trends were calculated for the average annual and maximum annual SWH at each point of the Caspian Sea. The maximum significant positive trends—0.03 m/10 years, the minimum trend value −0.03 m/10 years. For the average and maximum annual SWH values, negative trends observed for the area of the border between the Middle and South Caspian. The maximum values of trends are observed in the western part of Middle Caspian Sea.

E. E. Kruglova, S. A. Myslenkov
An Influence of Meridional Oceanic and Atmospheric Heat Fluxes to the Atlantic Sector of the Arctic on Arctic Amplification

One of the triggers of the Arctic amplification is the poleward heat transport; however, the relative contribution of its oceanic and atmospheric components remains poorly understood. In this study, we investigate the role of the Atlantic meridional oceanic and atmospheric heat fluxes to the Arctic for the emergence of the Arctic amplification. The meridional heat fluxes were computed using ORAS4 and ERA5 reanalyses for the Atlantic Water layer and over the lower troposphere. The horizontal and vertical boundaries of the sections in the ocean and atmosphere were selected to include only the areas, where the time mean heat transport is directed into the Arctic. It is found that the meridional heat fluxes and the regional Arctic amplification in the Eurasian Arctic are strongly coupled on the decadal time scales (10–15 years). We argue that the low-frequency variability of the Arctic amplification is regulated via a feedback, which elements include the oceanic heat transport, atmospheric heat transport and Arctic amplification. An increase (decrease) in the oceanic heat transport leads to a decrease (increase) in the atmospheric heat transport and to a decrease (increase) in the Arctic amplification. The atmospheric response to the ocean forcing occurs with a delay of three years and is attributed to the Bjerknes compensation mechanism. In turn, the atmospheric heat and moisture transport directly affects the magnitude of the Arctic amplification, with the latter lagging by one year. Thus, the variability of the oceanic heat transport at the southern boundary of the Nordic Seas might be a predictor of the magnitude of the Arctic amplification over the Eurasian Basin of the Arctic Ocean with a lead time of four years.

M. M. Latonin, I. L. Bashmachnikov, L. P. Bobylev
Lagrangian Method for Studying Agulhas Leakage in the Water Mixing Area

This article is motivated by a vital component of the ocean circulation called the Agulhas leakage. The aim of the study is to examine the impact of the South Atlantic Gyre, Benguela Current, and Benguela upwelling on the thermohaline properties of mesoscale eddies generated in the Cape Basin. The research explored statistics by Eddy Detection Algorithm, Lagrangian analysis, and vertical thermohaline cross-sections. The findings of the research illustrate how the process of mixing the waters of the Agulhas Current with the waters of the South Atlantic Gyre, including the Benguela Current, occurs. The impact of the South Atlantic Gyre on the Cape Basin eddies is significant. The findings support the unique eddy structure illustrated by alternative studies.

A. A. Malysheva, T. V. Belonenko, M. V. Budyansky
Wind Profile Evaluation by Using Result of Wave Forecast Model

The paper presents method of using wind wave spectrum for evaluation of wind profile in the wave boundary layer. Result of experiments performed by the wave boundary layer model with the method are shown.

D. D. Romashchenko, K. Yu. Bulgakov
Features of the Ice Extent Dynamics in the Western Sector of the Arctic on the Example of the Archipelagos of Svalbard and Franz Josef Land

The article is devoted to the analysis of interannual and seasonal variability of sea ice extent in the waters of the Svalbard and Franz Josef Land archipelagos for the period of 1979–2020. Quantitative results are based on the analysis of trends in surface air temperature, sea surface temperature and sea ice extent in the water areas of both archipelagos are obtained, indicating the current climate warming. In the course of the study, global warming trends were confirmed and evaluated, which are expressed in the reduction of ice cover, increase in surface air temperature and surface sea temperature in the investigated region.

N. O. Rudenko, B. V. Ivanov
Estimation of Ice Age Categories Composition in the East Siberian Sea at the End of Winter Period

The article is dedicate to the study of ice age categories composition in the East Siberian Sea. The calculation results showed that thick first-year ice (over 120 cm) prevails in drifting ice and fast ice in the sea by the end of the winter period (May). The transition of ice from one age gradation to an older one in fast ice occurs earlier than in drifting ice, by ten-day period 2–4. In the western part, thick first-year ice forms on average a month earlier than in the eastern part. The amount of drifting thick first-year ice in the East Siberian Sea in May was about 50%.

M. V. Sharatunova, V. V. Ivanov
Surface Manifestations of Short-Period Internal Waves in the Sea of Okhotsk and the Kuril-Kamchatka Region of the Pacific Ocean

The paper considers the characteristics of surface manifestations of short-period internal waves in the Sea of Okhotsk based on the analysis of Sentinel-1 radar images for the summer period of 2019. The features of the field of wave manifestations in the Sea of Okhotsk and the Kuril-Kamchatka region of the Pacific Ocean are also compared. It was found that in the Sea of Okhotsk, thrice fewer wave manifestations are recorded than in the Kuril-Kamchatka region, while the differences in the characteristics of the manifestations are insignificant. The manifestations of the Sea of Okhotsk are characterized by the formation of isolated clusters, while in the Kuril-Kamchatka region, manifestations are recorded everywhere. The position of the wave manifestations partially coincides with the potential generation sites of diurnal internal tidal waves, which may indicate the generation of short-period waves under the influence of the disintegration of the diurnal internal tide.

E. I. Svergun, A. V. Zimin, K. V. Kulik, N. S. Frolova
Topographic Waves of the Aleutian Trench

Based on the mesoscale eddy trajectory data, the propagation of topographic Rossby waves south of the Aleutian Ridge in various areas of topography is described. It is noted that anticyclonic eddies propagate along the shelf zone at depths of 1–2 km in the form of shelf waves, and cyclonic eddies drift westward along the trench with depths of 5–7 km in the form of trench waves. Using the example of the trajectories of individual long-lived anticyclonic eddies, it is shown that the separation of eddies from isobaths occurs under the action of a current. The amount of the mesoscale eddies and the number of mesoscale eddies generation are analyzed. It was found that more anticyclonic eddies are formed in the area of the Aleutian Ridge than cyclonic ones, and the maximum number of anticyclonic eddies per cell 0.25° in latitude by 0.5° in longitude is observed south of the Near and Rat islands. The mechanisms influencing the propagation of mesoscale eddies of the region are compared: the β-effect, the meridional gradient of the zonal velocity shear, the topographic factor and the combined action of the flow and topography. The places of eddy “separation” from the flow and topography are determined. Anticyclonic eddies stop following isobaths approximately between 171–176° E.

S. P. Khudyakova, V. S. Travkin, T. V. Belonenko
Probability Distributions for Finite Ensembles of Irregular Waves

The data of wind waves in the area of Cape Svobodny in the Sea of Okhotsk have been obtained and processed. For comparison, numerical simulation of waves with similar parameters was carried out, and probability distribution functions for the appearance of waves of a certain magnitude were constructed. Particular attention was paid to the anomalously large waves that arise in experiments, the so-called “freak waves”.

A. S. Tregubov, E. G. Didenkulova, A. V. Kokorina
Model of the Schooner “Saint Anna” Drift with the Usage of NOAA-CIRES-DOE 20CR and ERA-20C Reanalises

“Saint Anna” disappeared in the Arctic Ocean in the middle of spring 1914 after two years drift with drifting ice. During this period the air pressure, daily mean air temperature, wind direction and velocity were measured, and now correlation analyze between schooner’s data and data from 20th century reanalysis were made. Based on its results model of “Saint Anna’s” movements after April, 1914 was suggested.

S. V. Tsedrik
The Spatial and Temporal Distribution Patterns of Icebergs in the Barents Sea Based on Satellite Radar Data

In northern latitudes, icebergs frequently cross shipping routes and impair marine operations. To estimate the distribution of icebergs in the Barents Sea, this work explores the capabilities of an algorithm that detects and identifies icebergs based on sentinel-1 mission radar data. Synthetic Aperture Radar (SAR) is one of the main tools for studying the Arctic ice cover: it not dependent on daylight and largely independent of weather conditions. The applied algorithm uses the «Blob detection» method, based on searching for local bright areas of the image with subsequent classification using a Variable Selection Networks (VSN). The algorithm has shown its effectiveness in detecting icebergs on open water. Based on the obtained data, maps of iceberg density distribution in the Barents Sea for the ice-free period of 2021 were produced.

T. S. Ustinova
Small Eddies Observed in Ladoga and Onega Lakes Using SAR Data

This article presents the results of analysis of observations of spatial and temporal variability of small eddy structures from May to October 2021–2022 in Ladoga and Onega lakes. As input data 626 high resolution Sentinel - 1A/B images were processed. There were 279 surface appearances of eddy structures of which 235 in Lake Ladoga and 44 in Lake Onega. In both lakes the cyclonic type of eddies were more common. The average diameter of the eddy structures in Lake Ladoga was 1.5 km, in Lake Onega 4.8 km. In Onega Lake the eddies are concentrated in the central and western parts of the basin. In Lake Ladoga - in the northern and central parts. More than 80% of the registered structures belong to the submesoscale range of variability.

A. V. Zimin, E. A. Blagodatskikh, O. A. Atadzhanova
Antarctic Bottom Water in the Vema Channel

Based on complex data obtained in two IO RAS cruises, the distribution of the Antarctic Bottom Water flow at the exit of Vema Channel was studied. The distribution paths of two flow jets were confirmed and a third one was found. For the first time, synchronized measurements of hydrochemical and hydrophysical parameters were made, which allowed us to see small-scale changes inside the channel. Long-term measurements of bottom temperature at the main sill of the channel were continued.

O. A. Zuev, A. M. Seliverstova

Ocean Biology

Trophic Ecology of Chaetognaths in the Barents Sea Revealed by Nitrogen Stable Isotope Analysis (δ15N)

Stable isotope analysis of nitrogen (δ15N) was applied to investigate the trophic ecology of the three chaetognath species inhabiting the Barents Sea (Parasagitta elegans, Eukrohnia hamata and Pseudosagitta maxima). For the first time, we provide detailed information on the inter- and intra-specific variability of their isotopic composition and trophic levels. Different size-related and depth-related trends were found among the studied species, which indicated differences in their feeding strategies.

G. M. Artemev, D. V. Zakharov, G. A. Batalin, B. I. Gareev, G. Z. Mingazov, R. M. Sabirov, A. V. Golikov
Vertical Distribution of Viral Particles in the Deep Part of the Black Sea

The study was carried out in the deep-water part of the Black Sea in October 2022. Using flow cytometry and epifluorescence microscopy, the first data for the Black Sea on the abundance and vertical distribution of virioplankton were obtained, as well as the abundance of bacterioplankton and the viruses-to-bacteria ratio (VBR) were estimated. The number of viruses varied in the range from 0,4 to 9,4 × 106 cells ml−1 with maxima in the aerobic zone. A decrease in the number of viral particles from the oxycline to the suboxic layer by more than an order of magnitude was revealed. Within the hydrogen sulfide zone, the number of viruses was found to increase insignificantly with increasing depth.

M. A. Ufimtseva, V. S. Mukhanov
MtDNA Polymorphism of Macrohectopus branickii Dybowsky, 1974 (Amphipoda) – An Endemic Pelagic Key Species of Lake Baikal

Macrohectopus branickii is species endemic to Lake Baikal. The number of amphipod species in Lake Baikal is over 350, but M. branickii is the only species with an exclusively pelagic lifestyle. This work we are study of the population structure M. branickii based on the molecular genetic data. In our study, we used the COI marker - fragment of the cytochrome oxidase subunit 1 of mitochondrial DNA (mtDNA). Based on these sequences, we constructed a haplotype tree using the Network software as well as a phylogenetic tree using the BEAST software packages and molecular clock calibrations. The network showed the presence of separate haplotype groups in the population structure. The dates in the nodes of the phylogenetic tree of M. branickii were near with those of other Baikal endemic amphipod Gmelinoides fasciatus Stebbing, 1899. This may indicate a commonality of events that influenced their population structure in the past, such as the influence of past geological and climatic changes.

I. Y. Zaidykov, E. Y. Naumova, L. V. Sukhanova

Ocean Chemistry

Marine Carbonate System Parameters of the West Spitsbergen Fjords in Late Summer 2022

The focus of research was to assess the current state of carbonate system parameters and CO2 air-sea flux also. We used the data from expeditions to the Isfjorden and Grønfjorden, West Spitsbergen, in September 2022. We carried out an investigation of surface distribution of total alkalinity, pH, salinity, temperature and meteorological observations of CO2 air concentration and wind speed. The obtained data were applied for carbonate parameters calculation. Our observations identify a minor change of distribution of carbonate system parameters. The results showed that both fjords are characterized by carbon dioxide invasion and sufficiently saturated with aragonite and calcite.

N. K. Alekseeva, A. L. Nikulina, I. V. Ryzhov, A. E. Novikhin, R. V. Kornilova, N. A. Smirnov, A. A. Fedorova
The Hydrochemical Composition of the Watercourses of the Bay Oga, Tzivolki, Sedova (The Coast of the Kara Sea, Novaya Zemlya)

Hydrochemical studies of watercourses and the water area of Tzivolki, Oga, Sedova bays (Novaya Zemlya, Arctic, Russia) were carried out. The concentrations of nutrients in rivers and streams are higher than the concentrations in the water area. It is shown that the concentration of silicon in constantly flowing rivers is 1–13 μM, the concentration of NO3− 0.5–8, for watercourses flowing directly from the glacier these values are in the range of 7–10 μM Si, 3 μM NO3−. The influence of streams and rivers flowing into the Bays on the water area of the bay is local and extends to 1–5 km from the mouth, and does not influence on Kara Sea nutrient content.

G. V. Borisenko, A. A. Polukhin, D. V. Sharmar
Characteristics of Bottom Sediments of the North-Eastern Part of the Black Sea Coastal Zone

The features of the spatial distribution of geochemical characteristics and the chemical profile of the pore waters of bottom sediments of the north-eastern coastal zone of Black Sea are studied. It has been established that the surface (0–5 cm) sediment layer is formed mainly by silty material, the proportion of which increases with increasing sampling depth, as well as in the areas where large rivers of the Caucasus flow in. The results of the analysis of the chemical composition of pore water showed that in most of the studied areas, oxic conditions prevail in the upper layer of sediments and an oxygen fluxes are formed at the boundary with the bottom water layer. The oxygen flux values are determined by the oxygen concentration gradient between the surface layer of sediments and the bottom layer of water, as well as the granulometric composition of the sediment.

Y. S. Gurova, K. I. Gurov, N. A. Orekhova
Marine-Freshwater Ratio by Hydrochemical Proxies in the Surface Desalinated Layer of the Kara Sea

Freshwater in the Arctic seas is an important factor in the circulation of water masses and the functioning of the marine ecosystem. The Kara Sea is a unique object of interaction between sea waters and freshwaters of different genesis. The paper presents the results of calculating the percentage contribution of freshwater of different origin to the surface desalinated layer using hydrochemical parameters. The structure of the surface desalinated layer in different seasons is considered. The predominance of meltwater and river waters of the Ob’ and Yenisei was noted, depending on the observation period. The variability of the structure of the surface layer and the redistribution of freshwater during the ice-free period are shown.

U. A. Kazakova, A. A. Polukhin
Evidence of Atlantic-Origin Water Shoaling in the Western Chukchi Sea

In August 2019, VNIRO Transarctic expedition aboard the R/V Professor Levanidov accomplished hydrological and hydrochemical studies in the western part of the Chukchi Sea. We observed transformed Atlantic water (AW) at depth of 117–137 m, which is not typical for this water mass. Salinity values within transformed AW were in range from 34.2 to 35.7. This water had unusually high content of dissolved Si (93–97 μM) and low apparent oxygen utilization (240–270 μM). Similar situations (but with lower Si concentration) have already been observed in approximately the same region by scientists from Japan, Sweden, and Korea. Combination of our results and previously published data allow to conclude that, at least since 2004, there is a tendency towards increase of mineral Si concentration and decrease of dissolved oxygen concentration in the waters of the upper halocline in the study area.

K. V. Kodryan, K. K. Kivva
Carbonate System and CO2 Fluxes in the Partizanskaya River Estuary
(Nakhodka Bay, Sea of Japan)

Coastal waters connect land, oceans, atmosphere, biota, and sedimentary deposits. Although estuarine areas represent only a small fraction of the total ocean surface area, they play a significant role in the transport of carbon and biogenic elements from continents to the open sea. In this study, a biogeochemical investigation was conducted, focusing on the carbonate system and Carbon dioxide (CO2) fluxes in the estuary of the Partizanskaya River (Nakhodka Bay, Sea of Japan). The vertical variability of temperature, salinity, and chlorophyll-a was presented based on CTD (Conductivity-Temperature-Depth) profiler data. The main parameters of the carbonate system, including pH, pCO2 (partial pressure of CO2), DIC (dissolved inorganic carbon), and TA (total alkalinity), were described for the four seasons of the year. The CO2 flux (FCO2) at the water-air interface was calculated. The need for further hydrochemical research in coastal areas to identify the drivers of changes in the directionality of one of the major greenhouse gases’ fluxes was justified. Intensive bloom of photosynthetic algae was detected during the winter period, with chlorophyll-a concentrations reaching 49,3 mg/l under the ice cover. In samples collected at stations located in the downstream part of the river and in the open section of the river estuary, pCO2 varied significantly, exceeding equilibrium values (taken as 390 μatm) in some cases (ranging from 1000 to more than 2000 μatm), while being lower in others. Overall, during the autumn-winter period, the Partizanskaya River estuary acted as a source of CO2 to the atmosphere due to high organic matter decomposition rates, as evidenced by the positive values of FCO2, with an average value of 83.05 mmol·m-2 $$\cdot$$ · day-1. In the spring-summer period, the fluxes changed direction at some sampling points, ranging from −74.01 mmol·m-2 $$\cdot$$ · day-1 (gas influx) to 198.41 mmol $$\cdot$$ · m-2·day-1 (gas efflux). In conclusion, the carbonate system explains the processes related to organic matter production and decomposition in river estuaries, providing a better understanding of the intensity and directionality of carbon flux fluctuations in coastal areas, enabling the control of eutrophication even in oligotrophic water bodies, and overall buffering capacity of ecosystems.Consequently, the relevance of conducting hydrochemical studies of both small and large rivers around the world is increasing regularly.

K. A. Kryzhova, P. Yu. Semkin
Results of the Carbonate System Features Study of the South-Eastern Part of the Baltic Sea in 2022

Measurements of total alkalinity and pH were carried out in two expeditions in autumn-winter season of year 2022 in the Russian exclusive economic zone in the south-eastern part of the Baltic Sea. The main distribution patterns of the total alkalinity and pH in were described, and the contribution of the sulphide component to the distribution of these parameters was also noted.

A. A. Muratova, E. S. Bubnova, A. A. Polukhin
Joint Analysis of the Variability of Dissolved Organic and Inorganic Carbon Concentrations as Markers of Biogeochemical Processes in Kara Sea

The purpose of the work is to use a joint analysis of the dependences of DOC and DIC on salinity as an indicator of hydrochemical and biological processes. The work is based on data obtained during expeditions of the IO RAS to the Kara Sea from 2007 to 2021. The study covered the entire water area of the sea, including the runoff zone of the Ob and Yenisei. The paper analyzes the dependence of dissolved organic and inorganic types of carbon in the surface layer of the sea on salinity. It is shown that the joint analysis of DOC and ROC can reflect the process of ice melting and intrusion of river waters. The limits of interseasonal variability for DOC and DIC have been determined.

Y. V. Murzakova, N. A. Belyaev, A. V. Kostyleva, V. Y. Fedulov, A. A. Polukhin
Distribution of Hydrochemical Parameters in the Surface Water Layer of the Zone of Mixing River and Sea Waters of the Amazon River Basin During the 52nd Voyage of the R/V “Academik Boris Petrov”

The article is written based on the results of 52 voyage on the R/V “Akademik Boris Petrov” from 22.11.2022 to 28.11.2022. During this period the work was carried out in the zone of mixing of river and sea waters in the estuary of the Amazon River. Hydrophysical and hydrochemical studies were carried out. According to the results of the work, it can be stated that these measurements were carried out during the “low” water season. River waters are well distinguished in terms of dissolved silicate distribution, total alkalinity and pH. Amazon River waters carry a lot of dissolved silicate, and very little phosphorus and nitrogen. The high oxygen saturation of the waters suggests an active photosynthesis process. The influence of the river plume was minimal.

A. M. Seliverstova, O. A. Zuev, A. L. Chultsova

Marine Geology

Features of the Behavior of Oil Hydrocarbons in the Barents Sea in 2019–2020

The results of studies of the distribution and composition of aliphatic hydrocarbons (AHCs) in the suspended particulate matter and bottom sediments of the Barents Sea are presented based on the data of expeditions in 2019 and 2020. R/V Akademik Mstislav Keldysh. An increase in HC concentrations in suspended matter in surface waters has been established up to 20–23 µg/l climate change. In bottom sediments, the distribution of HCs depends not only on the conditions of sedimentation and their particle size distribution, but also on the variability of redox conditions and endogenous fluxes from the sedimentary sequence.

E. V. Koltovskaya, I. A. Nemirovskaya
Features of the Distribution of Dispersed Sedimentary Matter Composition in the Nordic Seas

Two geodynamic sedimentary settings were studied in the sedimentary system of the Norwegian Sea – in the Lofoten Basin and in the zone of the junction of the Mohns and Knipovich ridges. Dispersed sediment samples were collected from different horizons of the water column, including the subsurface and benthic layers. Elemental and constituent compositions were studied, and the fluxes of matter were analyzed. The vertical and seasonal variability of individual components of the sedimentation system was also assessed. The distribution of the main sediment components in the two sedimentary settings differs insignificantly, several general patterns were identified. The presence of authigenic barite of different morphology in the subsurface horizon of the Lofoten Basin water column was noted.

I. A. Migdisova, D. P. Starodymova, A. A. Klyuvitkin, A. N. Novigatsky, A. V. Bulokhov
New Data on the Age of the Khvalynian Strait

The Early Khvalynian transgression developed in the Caspian Sea at the end of MIS 2. Waters of the transgression were discharged through the Manych Depression into the Azov-Black Sea basin. Deposits of the Early Khvalynian strait are poorly studied, and the time of the strait functioning is determined on the basis of scattered radiocarbon dates. We studied the coastal outcrop of the Chogray reservoir (riv. Vostochny Manych), where the deposits of the ancient strait are exposed, and we obtained a series of AMS dates on mollusc fauna.

D. V. Semikolennykh, A. V. Panin
A CSM-Based Python Bot for Estimating the Stability Zone of Gas Hydrates

This text describes a study and its findings that utilized the “GHSZ_VNIIO” robot program to determine the thickness of the Gas Hydrate Stability Zone (GHSZ) in the Sea of Okhotsk. The program was developed using the Python language and offers automated calculation and visualization of gas hydrate distribution data. The results of the calculations revealed the presence of an extensive GHSZ in the Sea of Okhotsk, with a thickness of up to 720 m. A correlation analysis between the calculated and actual data, based on the position of the Bottom Simulating Reflector (BSR), demonstrated a high level of agreement (94%) between the predicted and observed data. This robot program enables researchers to obtain preliminary assessments of gas hydrate distribution in marine areas and possesses versatility for application in any oceanic region.

Yu.Yu. Smirnov, T. V. Matveeva, N. A. Shchur, A. A. Shchur, A. V. Bochkarev
Study of Background and Focused Hydrocarbon Discharge, NE Kara Sea

The work in the TTR-21 expedition was aimed at searching for areas of focused fluid discharge and the identifying of background and abnormal concentrations of fluids and organic matter in near-surface sediments. Seismoacoustic research methods have made it possible to identify places that are characterized by a high probability of the presence of fluid-saturated deposits. Their testing showed both increased concentrations of methane and the presence of homologues, and an increased content of organic matter, including light bitumen, indicating a possible migration flow of hydrocarbons from deep intervals of the sedimentary section.

A. K. Yumasheva, E. D. Basova, E. N. Poludetkina, M. Y. Tokarev, A. Y. Rybalko, A. O. Kil

Marine Geophysics

Features of Multiple Waves Suppression in the Seismoacoustic Data Processing Obtained During Near Surface Geophysical Surveys in the Northern Part of the Kara Sea

At present, high resolution seismic survey methods are widely used for engineering surveys in the offshore area. At the same time, there are specific features such as multiple waves and ghosts that reduce the data quality. Therefore, the purpose of this work was to select the optimal procedures and parameters for the primary processing of data obtained in expeditions with a certain observation system. For this purpose, modeling of seismic data with the same observation system was performed. After that, the processing procedures were tested on these data. The selection of accurate values was carried out after fine-tuning on real data. While analyzing the results, it can be concluded that the methods of adaptive subtraction of interference waves from the free surface can effectively improve the quality of primary processing.

I. O. Paltsev, V. V. Polovkov, A. A. Kudinov, A. E. Rybalko
Joint Processing Technology of MCS Data (600 m Streamer) and Wide-Angle Reflection/refraction Seismic Sonobuoy Soundings Acquired in Ice Conditions During Expedition “ARCTIKA-2014”

The regional seismic data – 2D MCS (multichannel seismic) with a short streamer of 600 m and wide-angle reflection/refraction seismic sonobuoy soundings were obtained in the Arctic Ocean in 2014. The subject of study is the eastern part of the profile AR1407 (expedition “ARCTIKA-2014”). This study is related to the joint reprocessing of two types of data. The processing of this data was made in 2014–2015. The reprocessing started in 2023 and it will have been completed by the end of 2023 year. Now it is in progress.

S. N. Tabyrtsa, A. S. Zholondz, V. V. Polovkov

Marine Ecology and Environmental Management

Persistent Organic Pollutants in Rhinoceros Auklet (Cerorhinca Monocerata) from the Sea of Japan

The study presents the levels of organochlorine pesticides and polychlorinated biphenyls in the organs of the rhinoceros auklet (Cerorhinca monocerata) from the coast of Boysman Bay (Sea of Japan). A priority group of toxic chemical compounds for this species and in the region has been identified.

M. A. Belanov, M. Yu. Shchelkanov, D. V. Pankratov, M. M. Donets, V. Yu. Tsygankov
Ichthyofauna of the Karkinitsky Gulf (Black Sea) and Its Changes Under the Anthropogenic Impact

The ichthyofauna of the Karkinitsky Gulf includes 99 species of fish belonging to 42 families, 16 orders and 2 classes. The basis of taxonomic diversity is formed by representatives of the families Gobiidae (16 species), Cyprinidae (8 species), Syngnatidae (7 species), Labridae and Blenniidae (6 species each), Clupeidae (5 species), Mugilidae and (4 species each). In the eastern part of the Karkinitsky Gulf, changes in the composition of the ichthyofauna are determined by the restructuring of the hydrochemical characteristics of the water area associated with the functioning of the North-Crimean Channal, as a result of which the fluctuations in water salinity ranged from 0.55 to 26.80 ‰. Changes in the taxonomic composition, the nature of dominance and localization of fish from different ecological groups affected mainly fish of the freshwater complex and Ponto-Caspian endemics. At present, a fundamental restructuring of historically established ecosystems is taking place in the Karkinitsky Gulf and the process of formation of specific ichthyocenes is underway; species composition and its ecological structure are unstable and mainly depend on human activities. The starting of the Channel in 2022, obviously, will cause a new round of transformations in the ecosystem of the eastern part of the Karkinitsky Gulf.

R. E. Belogurova, E. P. Karpova
Comparative Analysis of Contamination with Microplastic Particles of Ice in the Curonian Lagoon (Baltic Sea) and Novik Bay (Sea of Japan)

In this work, ice cores from the Novik Bay (Sea of Japan) and the Curonian Lagoon (Baltic Sea, Kaliningrad region) are examined for contamination with microplastics (0.3–5 mm). The method of sampling and processing samples in a similar. The average concentration of MP particles (0.3–5 mm) in the ice of Novik Bay was 204.3 items/L of meltwater, and in the Curonian Lagoon – 60.3 items/L of meltwater. The number of fibers, fragments, and films somewhat increased with decreasing particle size.

I. Yu. Bocherikova, O. I. Lobchuk, I. P. Chubarenko
Chlorinated Organic Compounds in Mytilidae Mollusks from Nakhodka Bay (the Sea of Japan)

Persistent organic pollutants (POPs) are considered to be one of the most hazardous and underinvestigated organic compound class in the context of environmental and human health effects. POPs characteristics incorporate high toxicity, ability to bioaccumulate and convey through food chains. Due to transferring within air and water masses, POPs are able to relocate and deposit accumulating in aquatic and terrestrial ecosystems outermost the source of the pollution. Despite the Stockholm Convention signing in 2001 by a number of countries, some states still retain the right to use DDT for the purposes of sanitary and epidemiological control. This study presents the current levels of POPs content in the soft tissues of bivalves from Nakhodka Bay (the Sea of Japan).

A. D. Borovkova, V. Yu. Tsygankov
Individual Components of Microbiological Community in Water Northeast Part of the Kara Sea

The paper presents the results of microbiological studies of the coastal waters of the northeast Kara Sea in summer under low temperature conditions. In the surface water layer, the abundance of bacteria using protein substrate as a single source of carbon and energy varied from 1 to 106 cell/mL (from 102 to 105 cell/mL in the bottom layer), that of bacteria using carbohydrates (glucose) varied from 10 to 104 cell/mL (from 103 to 105 cell/mL in the bottom layer), and that of bacteria using lipids ranged from 1 to 100 cell/mL in both layers. Hydrocarbon-oxidizing bacteria were found in 53% of samples collected in the surface layer and in 36% of samples collected in the bottom layer. Their counts were from 1 to 10 cell/mL in both the surface and bottom layers. An uneven distribution of the studied bacterial groups was observed. No significant correlations were found between the abundance of the observed groups of microorganisms and the mentioned physical and chemical parameters of the marine environment.

V. Yu. Budarova, E. A. Tikhonova, N. V. Burdiyan, Yu. V. Doroshenko
Influence of External Factors on the Seaweeds Productivity in the Coastal Zone of Crimea

Bottom seaweeds is the main source of oxygen and carbon in coastal zone of the Crimea. The productivity of macrophytes mainly depends on a number of environmental factors, such as water temperature, solar irradiance and nutrients (nonorganic nitrogen and phosphorus). We carried out a series of simulations with extreme environmental changes to track the response of six algae that are widespread in the Black Sea on these changes. It was found that the main factor, which affect alga productivity, is light. Furthermore, macroalgae growth rate in the Crimean coastal zone is limited by phosphorus concentration in water. Increasing of nitrogen compounds content in water mainly affects the growth of green alga. Simultaneous long-time increasing of both nutrients in water leads to multiple increasing of seaweeds biomass.

T. A. Filippova, E. F. Vasechkina
Microlitter Distribution on Sandy Beaches of the Neva Bay of the Gulf of Finland (Baltic Sea) in 2018–2022

The city of St. Petersburg plays a significant role in the environmental state of the Neva Bay, including its contamination with wastes and marine litter. The goal of this work is to assess the distribution of microlitter on the coasts of the open part of the Gulf of Finland and the Neva Bay (Baltic Sea) based on the data of field observations of PlasticLab RSHU for the period of 2018–2022. Structure of microlitter, variability of its concentrations on the coasts, and the main factors of its accumulation were studied. The largest amount of microlitter was found on the beaches confined to the central part of the city (Dekabristov Island (2019), Kanonersky Island (2022)), and the smallest amount was found in the open part of the Gulf of Finland behind the FPB (Kotlin (South) (2022), Zelenogorsk (2021), Solnechnoye (2019)). In general, there is a variety of types of materials found on the beaches, but microplastics is the dominant one. During the study period (2018–2022), on the one hand, there is a downward trend in the average amount of microlitters on the beaches. On the other hand, a significant scatter of concentrations indicates the insufficiency of single surveys during the year and the need for repeated observations during the entire ice-free period, taking into account storm events, i.e. conducting seasonal monitoring surveys.

E. A. Golubeva, A. A. Ershova
Data on the Microplastics Content in the Bottom Sediments of the Gulf of Finland and Southeastern Part of the Baltic Sea According to the Data of 39th Cruise of the R/v “Akademik Nikolai Strakhov”

The problem of microplastic (MPs) contamination is nowadays of concern to scientists over the world. MPs accumulation pattern in bottom sediments is shown to be rather chaotic and diverse. MPs content (0.3–5 mm) was analyzed in 19 samples of bottom sediments collected using the Van Veen grab in the Gulf of Finland and southeastern part of the Baltic Sea. A modified NOAA method was used for the extraction of MPs particles; zinc chloride was used for separation by density. As many as 10 421 suspected MPs particles were detected, more than 90% were fibers. The relationship between the content of MPs, the type of bottom sediments and sampling depth was not found. The results correlate well with previous research of MPs contamination in the Baltic Sea.

P. N. Krivoshlyk, I. P. Chubarenko
137Cs Latitudinal Distribution in the Surface Waters of the Atlantic Ocean: Results of Expeditionary Research in 2020

The latitudinal distribution of the anthropogenic radionuclide 137Cs in the Atlantic surface waters was studied according to the results of expeditionary research carried out during 79 cruise of the R/V «Akademik Mstislav Keldysh» (March-May 2020). Radiospectrometric analysis of the samples showed that the 137Cs activity concentration in the Atlantic Ocean water was in the range of 0.65 ± 0.10–1.44 ± 0.21 Bq/m3. It was found that the 137Cs activity peaks corresponded to the global fallout peaks in the middle latitudes of the Earth. Comparison of the data obtained in 2020 with the results of the 1988/1989, 1992/1993, 2002 expeditions revealed a tendency to smooth out the 137Cs activity peaks in the middle latitudes due to hydrodynamic processes in the World Ocean.

O. N. Miroshnichenko, I. G. Sidorov, A. A. Paraskiv
Qualitative and Quantitative Assessment of Hydrocarbons Composition in the Water of the Kara Sea Northeastern Part

As part of the voyage of the research vessel «Akademik Boris Petrov», studies were carried out on organic pollution of surface and bottom waters in the Kara Sea northeastern part. Determination of the qualitative and quantitative composition of aliphatic hydrocarbons (AHC) was carried out by gas chromatography on chromatograph «Kristall 5000.2» with a flame ionization detector. The total content and individual composition of AHC in the surface and bottom waters of the Kara Sea northeastern part was studied. The content of AHC in the surface waters of the Kara Sea averages 0.06 ± 0.04 mg/l, which slightly exceeds the maximum permissible concentration (MPC) for oil hydrocarbons –0.05 mg/l. And in the bottom waters, the average AHC concentration was 0.1 ± 0.12 mg/l, which exceeds the MPC by 2 times. In general, it can be concluded that the concentrations of hydrocarbons in the water are quite high, exceeding the maximum allowable concentration in 44% of samples in the surface water and in 40% of samples in the bottom water, however, in accordance with the calculated markers (CPI2, ACL, LWH/HWH, TAR and C31/C29) found that most of the hydrocarbons are of autochthonous nature and terrigenous origin.

Y. S. Tkachenko, E. A. Tikhonova

Physical and Biological Interactions

Results of Hydrooptical Field Studies in the Barents and Kara Seas in September 2022

The presented results were obtained during the 1st stage of the 89th cruise of the R/V «Akademik Mstislav Keldysh» in the Barents and Kara seas in September 2022. The spatiotemporal variability of the seawater bio-optical characteristics distributions was studied in order to identify climatic and interannual changes. An array of hydrooptical measurement data was obtained, including the results of measurements performed using a flow-through complex and a polarization lidar, as well as data on light fields and seawater bio-optical characteristics. In the Kara Sea two under-aircraft measurement sessions were performed together with the ‘Optik’ Tu-134 flying laboratory. This array will be used to validate regional satellite algorithms.

D. I. Glukhovets, E. A. Aglova, V. A. Artemiev, O. V. Glitko, V. A. Glukhov, D. N. Deryagin, S. K. Klimenko, M. A. Pavlova, I. V. Sahling
The Impact of Mesoscale Eddies on the Vertical Distribution of Oxygen in the Black Sea

The influence of mesoscale eddies of different signs on the seasonal variability and vertical distribution of dissolved oxygen in the Black Sea was investigated based on the method of eddy identification by altimetric measurements and a long-term array of hydrochemical measurements. It has been shown that in z-coordinates, at the depths of the oxycline, the maximum growth is observed in anticyclonic eddies (AE) during the summer season and a decrease in cyclonic eddies (CE). In the upper layers, the situation is opposite, with a decrease in AE and an increase in CE, especially pronounced during the period of spring phytoplankton bloom and associated with the influence of eddies on bioproductivity. At the same time, in isopycnic coordinates, eddies of both signs cause unidirectional changes: a significant increase in oxygen anomaly in the oxycline and a decrease in the sub-oxygen zone, apparently caused by an intensification of shear turbulence mixing in eddy formations.

A. A. Kubryakov, S. V. Svishchev, P. N. Lishaev, E. A. Kubryakova
Modeling Chlorophyll a Concentration for the European Arctic Corridor Based on Environmental Parameters

This study analyzes remotely sensed chlorophyll a (Chl a) concentration as an indicator of ocean productivity in the European Arctic Corridor (the Norwegian, Greenland, and Barents Seas), and its connection to physical environmental parameters: Photosynthetically Active Radiation (PAR), Sea Surface Temperature (SST), Mixed Layer Depth (MLD) and Sea Surface Salinity (SSS). Using the Random Forest Machine Learning algorithm in the Classifier modification we created models describing a correlation between Chl a and environmental parameters, and retrieved a total area of high-productivity zones (Chl a is more than 1 mg m−3) based on these correlations.

S. K. Kuzmina, P. V. Lobanova, S. S. Chepikova
Optical and Microphysical Characteristics of Tropospheric Aerosol over Kara Sea using Measurements Onboard TU-134 “Optic” Aircraft Laboratory in 2014, 2020, and 2022

We present the results from the study of the joint measurements of the aerosol optical and microphysical characteristics onboard TU-134 “Optik” aircraft laboratory and research vessel “Akademik Mstislav Keldysh”, carried out in the Kara Sea in September 2022. The mass concentrations of aerosol MA and absorbing substance MeBC in the near-surface and 9-km layers of the atmosphere were obtained. The results from aircraft sensing are compared with analogous data, obtained during aircraft expeditions in the Kara Sea in 2014 and 2020. Also, our estimates are compared with MERRA-2 reanalysis data.

P. N. Zenkova, B. D. Belan, D. G. Chernov, D. M. Kabanov, I. A. Kruglinsky

Oceanological Technology and Instrumentation

Application of Microwave Resonant Measuring Transducer for Express Assessment of Water Salinity

In this paper a precision water salinity sensor based on microwave resonator is proposed. The geometrical dimensions of the sensor aperture are optimised. Experimental verification of sensitivity is carried out and operational characteristics of the device are determined. The methodology of work with the development is proposed.

D. A. Poletaev, B. V. Sokolenko, V. I. Voytitsky
Investigation of Winter Plankton Ecology of Lake Baikal Using Complex Instrumental Methods

Continuous observations of changes in ecosystems are necessary due to global climate change, which affects the state of water bodies and has affected even the deepest lake of the planet - Lake Baikal. For the tasks of establishing continuous automated monitoring of Lake Baikal, daily observations of plankton behavior were carried out. Within the framework of the publication we give a brief description and the first results of the complex work on the evaluation of the efficiency of using the immersed holographic camera and hydroacoustic instruments for monitoring the amount of zooplankton in Lake Baikal.

T. P. Rzhepka, E. Y. Naumova
Complex Investigation of the World Ocean (CIWO-2023)
herausgegeben von
Tatiana Chaplina
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