Institute of Oceanology. PP Shirshov Russian Academy of Sciences
Recent publications
Using temperature and salinity profiles from the Argo repository, distributions of water volume on temperature‐salinity plane (so‐called volumetric T‐S diagrams or TSV plots) are compiled for the upper 2,000‐m layer of the Atlantic, Indian, and Pacific oceans. The study is focused on Central Waters (CWs) that originate at the surface in the Subtropical Convergence and occupy the permanent thermocline within subtropical gyres. The South and North Atlantic, South Indian, and western North Pacific CWs (SACW, NACW, SICW, and WNPCW, respectively) are shaped as steep‐sided ridges or narrow strips of elevated volume on the T‐S plane (tight T‐S relationship). In contrast, the western South Pacific, eastern South Pacific, and eastern North Pacific CWs (WSPCW, ESPCW, and ENPCW, respectively) do not have a tight T‐S relationship and appear as still elongated but relatively wide poorly structured low elevations on TSV plots. Central Waters with tight T‐S relationship are bordered from the poleward side by strong eastward baroclinic currents. The tight T‐S relationship is found only in a denser part of CWs that outcrops within the strong eastward baroclinic currents and at higher latitudes. We hypothesize that enhanced isopycnal stirring and further diapycnal mixing of thermohaline irregularities in the strong meandering eddy‐producing eastward currents substantially contribute to tightening the T‐S relationship in CWs. By searching for same T‐S characteristics in the main thermocline and at the surface, it was confirmed that CWs originate at the surface in the Subtropical Convergence in early spring and late winter.
Elemental sulfur is a common product of hydrogen sulfide oxidation in the photic zone of meromictic basins due to the anoxigenic oxidation of hydrogen sulfide by photosynthetic bacteria. The photic zone in the Black Sea is limited to 50–60 m, which is much higher than the upper limit of the hydrogen sulfide zone interface, which is at a depth of 90–100 m in the center of the sea. In peripheral areas of the Black Sea, the depth of the redox interface reaches 150–170 m, where, as expected, photoautotrophic bacteria are rare and in an inactive state. A study of the distribution of elemental sulfur in the Black Sea anoxic zone showed that waters from depths of 180–300 m are light sensitive. This leads to a sharp increase in sulfur concentrations up to 11.3 µmol/kg with background values of 0.15–0.18 µmol/kg under strictly anaerobic conditions. It was found that such a significant increase in elemental sulfur is associated with the activity of photoautotrophic bacteria. The conditions for the existence of photoautotrophic bacteria at depths of 180–300 m in the Black Sea in the absence of light remain unclear.
An Erratum to this paper has been published: https://doi.org/10.1134/S000143702406002X
Based on sedimentological, isotope-geochemical, and micropaleontological parameters of bottom sediments of the AMK-5188 core, differences in the natural environment of the last interglacial of the Late Pleistocene (marine oxygen isotope substage 5e) and the Holocene in the Lofoten Basin of the Norwegian Sea were revealed. The local thermal optimum of the last interglacial was shifted to the second half of substage 5e ~124–115 ka and consisted of two short intervals separated by strong cooling ~122–120 ka. In the Early–Middle Holocene ~10–3 ka, a long stable climate optimum was noted for the main identified parameters, and a short paleotemperature minimum occurred in the Late Holocene ~3–2 ka during the regional Neoglacial cooling.
Based on data obtained during seven Kara Sea expeditions (2017–2023), seasonal variation in the contribution of phytoplankton size groups to the total values of primary production (PP) and chlorophyll a (chl a ) are examined for the first time. Micro- and nanophytoplankton (MPh + NPh) (>3 µm) dominated in the community composition during the entire ice-free period (June–October). Its predominance was especially noticeable during the spring bloom immediately after first-year sea-ice retreat (up to 97% for PP and up to 93% for chl a ). The role of picophytoplankton (PPh) (<3 µm) increased in summer (July, August) (up to 50% for PP and up to 44% for chl a ) and decreased by the end of the growing season (September, October). Seasonal variation in the size composition of phytoplankton during the growing season was determined mainly by variability in water temperature and incoming solar radiation. The contribution of PPh to the total chl a increased (up to 51%) at depths of the deep chlorophyll maximum in July and August. The assimilation activity of PPh was higher than that of MPh + NPh in July–September, with an increase in its contribution to the total PP and chl a . For the first time, annual PP of Kara Sea phytoplankton size groups was assessed: 8 ТgС (65%) for MPh + NPh and 5 ТgС (35%) for PPh.
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428 members
Max Semenovich Barash
  • Department of Geology
Andrey N. Serebryany
  • Ocean acoustics
Vladimir Silkin
  • Southern Branch
Nadezda D. Romanova
  • Department of Biology
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Moscow, Russia
Head of institution
Alexey Sokov