Spatial variations of nutrients along the northwestward stream from Bering Sea to Chukchi Sea are considered for dissolved inorganic phosphorus (DIP) on the data of two surveys conducted in early September of 2010 and 2020. The waters of Bering Sea origin have higher DIP than the waters of Chukchi Sea, but in the upper layer gradually loose phosphorus because of both mixing with local waters and consumption for photosynthesis. In the subsurface layer, the DIP decreasing is prevented by its recycling from destructed organics. The fluxes of phosphorus are estimated separately using the balance model with TS-analysis, previously used in estuarine studies. Successive utilization of DIP along the stream is traced, that forms in the Chukchi Sea two zones of high productivity divided by wide low-productive zone. The nutrients from the upper layer are utilized within the southwestern Chukchi Sea providing primary production 0.1–0.2 gC/m3day, but the main stock of allochtonous nutrients from the subsurface layer is utilized further downstream (at Wrangel Is. or in the northern Chukchi Sea) and provides the production of 0.3–0.4 gC/m3day. Localization of the high-productive zones is determined by density stratification that possibly depends on the stream strength: the stronger advection through Bering Strait – the further from the strait both zones are located. Recent tendency of the stream strengthening tends to remove the zones of utilization the nutrients of Pacific origin out of the southwestern Chukchi Sea.
92d cruise of R/V “Akademik Mstislav Keldysh” was organized by Shirshov Institute of Oceanology in a frame of long-term Program “Marine Ecosystems of Siberian Arctic” and was held from 5 October to 7 November 2023. 76 scientists from the institutes of Russian Academy of Sciences, National Research Center Kurchatov Institute, Moscow State University, Moscow Institute of Physics and Technology, VNIRO and MES of Russia participated in the cruise. Coordinated hydrophysical, hydrochemical, biooceanological, geochemical research were carried out in the eastern part of the Kara Sea in the period of seasonal ice formation, as well as in the Ob river estuary and fjords of Novaya Zemlya archipelago. Conditions of largest disposals of radioactive waste in the Kara Sea were evaluated.
The ice-gouging topography of the southwestern part of the Kara Sea bed is a result of the impact of icebergs and sea ice. During 52 cruise of the R/V Akademik Nikolaj Strakhov using a multibeam echo sounder we collected a representative data of key parameters of ice scours (location, orientation, depth, width) for the first time, which allows us to draw conclusions on a regional scale. We revealed regularities in the distribution of the ice scours both in space and in depth and their density in different parts of the seabed. It was revealed that the maximum dimensions of the ice scours decrease with the distance from the sources of iceberg calving from NW to SE. The orientation of the ice scours correlates with the main drift directions of the icebergs. Most of the ice scours are located at depths up to 220 m and could have formed both at modern and at lower sea level (in post-glacial time). We identified a high degree of the seabed transformation by ice-gouging processes in the southwestern part of the Kara Sea.
Brief results of expedition investigations of the southeastern part of the Baltic Sea and the eastern part of the Gulf of Finland during the 53rd cruise of the R/V Akademik Boris Petrov (2023) are presented. The expedition was dedicated to continuation of longstanding oceanological researches conducted by the AB IO RAS. An integrated geological, geophysical, hydrological, hydrochemical, hydrobiological and geoecological investigations were carried out. New data on the state and dynamic of natural systems of the Baltic Sea were obtained.
This report is devoted to the analysis of original geological materials on the Magellan Seamounts in the Pacific Ocean, obtained by the authors in numerous voyages of R/V ʺGelendzhikʺ. This chain of guyouts does not have a common volcanic basement and apparently was formed in the second half of the Early Cretaceous on the oldest (middle-last Jurassic) fragment of the Pacific plate. The main points of view on the genesis of the Magellan Mountains are as follows: either they originated at the crossing of the transform fractures, or the Pacific plate moved them from the southern hemisphere to their present-day position. Because of their high degree of study, the Magellan Seamounts are one of the key sites for understanding the mechanism of the origin of linear chains in the ocean. A comprehensive analysis of new geological on the Magellan Seamounts has established the important role of magmatism and tectonics in the formation of the modern morphological shapes, sedimentation and influence on the paleooceangraphy. The periodic renewal of these processes from the Early Cretaceous to Late Cenozoic can be traced in the cyclicity of sedimentation, the permanent growth of ore crusts and the formation of secondary volcanic domes and cones.
