Vol 64, No 5 (2024)

Measurements of oceanographic characteristics, currents, and tides in the Fram Strait and the Greenland Sea are analyzed using historical measurement data. Measurements on moorings across the Fram Strait made it possible to estimate the speeds of the East Greenland and West Spitsbergen currents. It is shown that the speeds of these currents are low (within 10 cm/s) and the amplitudes of the speed of tidal currents are two or more times greater. Tidal currents are intensifying on the shelf of Greenland and Spitsbergen. Direct measurements are compared with the University of Oregon barotropic tide model.

For the first time, the isotopic composition and concentration of dissolved inorganic carbon in the waters of the western part of the Bering Sea (at the Koryak shelf and Chukotka continental slope, and Commander Islands, depth interval 10–4100 m) have been analyzed. [DIC] values vary from 1900 μmol/kg in the summer waters of the Koryak shelf to 2510 μmol/kg in the deep waters of the Commander Islands area. The value of δ¹³С(DIC) in productive summer waters exceeds +1‰, and reach +3.08‰ in the Koryak shelf surface waters. The depth of the carbon isotope minimum (–0.7‰) is ≈500 m. The model calculations were made taking into account physical processes (isotopic exchange with atmospheric CO₂ and conservative mixing). The calculations show that in the main water column δ¹³С(DIC) and [DIC] values are controlled by the oxidation of organic substances. The predominance of primary production occurs only in the surface (<20 m) waters of the Bering Sea. Concentrations of DIC increase to depths of ≈1000 m and remain approximately constant (2430 ± 30 μmol/kg), exceeding [DIC] levels in deep Pacific waters. A “physical carbon pump” model in which the main role in the accumulation and redistribution of DIC within the water column is assigned to the winter waters of the Bering Sea is proposed.

In the NE of the Gorlo Strait of the White Sea interpretation of satellite images, geomorphological and ground penetrating radar profiling, aerial photography and topographic survey of coastal terraces and dunes, diatom analysis and ¹⁴C dating of sediments were carried out. The patterns of morphodynamics of coastal and aeolian relief have been established. At the mouth of the Maida River were reconstructed relative sea level changes and the sequence of relief evolution over ~3.7 cal ka BP. Сliff-top dunes are formed on the erosive coasts of the Strait, and on the mouth spit of the Maida River is a foredune plaine. The source of sediment supply for coastal dunes is an extensive sediment flow from NE to SW. Sediment input mainly from the scarp erosion (0.5–3.7 m/year) and from the shoreface, and the role of alluvial runoff is insignificant. At the mouth of the Maida River spit and foredunes have been evolve since the end of the Holocene transgression (~3.7–2.3 cal ka BP). The sea level at mean high water at this time was slightly higher (up to ~2.5 m a. s. l.), and coastal processes were significantly more intense than modern ones. Then, against the background of a decrease in sea level and weakening sediment flows, the growth of the spit slowed down. The ancient foredunes were stabilized by vegetation. Aeolian processes have been activated ~2.1 and after ~0.8–0.7 cal ka BP.

This paper provides information on the integrated geological and geophysical investigations in the transform faults valleys of the tropical Atlantic (cruise 65 of the R/V Akademik Ioffe), geomagnetic survey and passing observations on waves and quantitative distribution of cetaceans, birds and flying fish in the North Atlantic (cruises 64 and 65 of the R/V Akademik Ioffe) in October–December 2023. The preliminary scientific results are discussed.

The environmental monitoring of the Russian sectors of the Baltic Sea was continued through three expeditions t in 2023: the 55^th cruise of the P/V “Akademik Sergei Vavilov” (April), the 54^th and 55^th cruises of the R/V “Akademik Boris Petrov” (November and December, respectively). Seasonal quantitative estimates of hydrological-hydrochemical and hydrobiological parameters, carbon dioxide fluxes at the water-air interface were obtained, and the geological and geomorphological conditions of the study areas were clarified. Influence of the Neva River to the eastern part of the Gulf of Finland was stable in all seasons and could be traced at a distance of up to 30 nautical miles from the Neva Bay. The South-Eastern Baltic bottom layer experienced extensive hypoxia and mosaic euxunia. Significant aeration of bottom waters occurred in December due to the combined influence of seasonal convection and downwelling resulting from a series of storms. In both study areas, high values of integral primary production were obtained in April, which were two orders of magnitude higher than the December values. The concentration of chlorophyll “a”, accordingly, differed by an order of one magnitude. The Gulf of Finland was an emitter of carbon dioxide into the atmosphere, especially in April, while the South-Eastern Baltic absorbed carbon dioxide in April and was an area of weak emissions in November and December.

Integrated marine investigations were carried out by researchers at the Murmansk Marine Biological Institute of the Russian Academy of Sciences during a cruise in August 2023 on r/v “Dalnie Zelentsy” within the national project called “Science and Universities”. The investigations included CTD sampling, hydrologic, hydrochemic, hydrobiologic, ichthyologic, and radioecologic studies, and observations of marine birds and mammals. The outcome of the cruise was new data on the reference state of the ecosystem of the eastern Barents Sea.

During the cruise No. 65 of the R/V “Akademik Oparin”, which was carried out from November 26 to December 29, 2022, research was continued in the area of the Avachinskiy Bay of Kamchatka to study the possible factors that caused the mass moratlity of marine organisms in the Fall of 2020, and complex hydrographic and hydrochemical surveys on the northeastern shelf of Sakhalin Island to monitor the environmental situation in areas of oil and gas production and in the southern part of the Sea of Okhotsk. According to data from two autonomous moorings deployed in the coastal zone of Avachinskiy Bay with an exposure of 169 days, relatively calm water dynamics in the bay were noted throughout the entire Summer-Fall season of 2022, which contributed to the enrichment of waters with nutrients necessary for the development of plankton. No noticeable decrease in oxygen content was recorded. A survey of the southern part of the East Kamchatka Current was carried out, the evolution and the structure of the anticyclonic eddy of the Avachinskiy Bay at the moment of its splitting were traced. Hydrochemical characteristics of coastal bays and rivers during the freeze-up period were studied. Samples of plankton and bottom sediments were taken for special analyzes in the laboratories of the Pacific Institute of Bioorganic Chemistry and the National Center for Marine Biology of Far Eastern Branch of the Russian Academy of Sciences.