Hydrothermal Mineral Assemblages at 71° N of the Mid-Atlantic Ridge (First Results)     

Kravchishina  M. D.  Lein  A. Yu.  Boev  A. G.  Prokofiev  V. Yu.  Starodymova  D. P.  Dara  O. M.  Novigatsky  A. N.  Lisitzin  A. P. 《Oceanology》2019,59(6):941-959

Oceanology - The article discusses the preliminary results of plume and bottom sediment studies of the Trollveggen hydrothermal vent field based on data from cruise 68 of the R/V Akademik Mstislav...  相似文献   

Distribution and Feeding of Herbivorous Zooplankton in the Laptev Sea     

E. G. Arashkevich  A. V. Drits  A. F. Pasternak  M. V. Flint  A. B. Demidov  A. B. Amelina  M. D. Kravchishina  I. N. Sukhanova  S. A. Shchuka 《Oceanology》2018,58(3):381-395

Sampling was conducted along the quasi meridional transect at 130° E from the Lena River estuary to northern deep-sea regions of the Laptev Sea in September 2015. The latitudinal zonality and the impact of river runoff are manifested in the temperature and salinity distribution, concentration of particulate organic matter, and the structure of plankton communities. The differences in the chl a concentration and primary production along the transect are insignificant. The feeding rate of mesozooplankton herbivores was assessed by a fluorescence technique. The total consumption of phytoplankton biomass and primary production are estimated based on the feeding rate, abundance of zooplankton species, and their diel migrations. The daily grazing impact of zooplankton on phytoplankton biomass increases from 2% on the inner shelf to 3% on the mid-shelf, 5% on the outer shelf, and 10% in the deep-sea part of the basin. The consumption of primary production also increases: 1, 4.5, 5.7, and 13.9%, respectively. In the fall, the consumption of phytoplankton does not compensate the energy demands for respiration. The latitudinal zonality of the Laptev Sea appears not only in the hydrophysical water parameters and the structure of plankton communities, but also in their functional characteristics.  相似文献   

Stable Isotopic Composition of Particulate Organic Carbon in the Caspian Sea     

M. D. Kravchishina  A. A. Klyuvitkin  L. A. Pautova  N. V. Politova  A. Yu. Lein 《Oceanology》2018,58(1):45-56

The data on the isotopic composition of particulate organic carbon (δ¹³C_POC) in the Caspian Sea water in summer–autumn 2008, 2010, 2012, and 2013 are discussed in the paper. These data allowed as to reveal the predominant genesis of organic carbon in suspended particulate matter of the active seawater layer (from 0 to 40 m). The δ¹³C_POC =–27‰ (PDB) and δ¹³C_POC =–20.5‰ (PDB) values were taken as the reference data for terrigenous and planktonogenic organic matter, respectively. Seasonal (early summer, late summer, and autumn) variations in the composition of suspended particulate matter in the active sea layer were revealed. A shift of δ¹³C_POC towards greater values was seen in autumn (with a slight outburst in the development (bloom) of phytoplankton) in comparison with summer (with large accumulations and an extraordinary phytoplankton bloom confined to the thermocline area). The seasonal dynamics of autochthonous and allochthonous components in the suspended particulate matter of the Middle and Southern Caspian Sea was studied with the use of data on the concentration of particulate matter and chlorophyll a, the phytoplankton biomass and the POC content.  相似文献   

Comprehensive studies of the Caspian Sea system during cruise 35 of the R/V <Emphasis Type="Italic">Rift</Emphasis>     

A. K. Ambrosimov  V. N. Lukashin  N. V. Libina  A. O. Korzh  A. D. Mutovkin  A. N. Novigatskiy  M. D. Kravchishina  I. I. Rusanov  Yu. A. Goldin 《Oceanology》2012,52(1):141-146

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Authigenic Mg-calcite at a cold methane seep site in the Laptev Sea     

M. D. Kravchishina  A. Yu. Lein  A. S. Savvichev  L. E. Reykhard  O. M. Dara  M. V. Flint 《Oceanology》2017,57(1):174-191

Authigenic minerals were studied in Holocene shelf sediments of the Laptev Sea (cold methane seep site, water depth 71 m). The study presents the first finds of large hard carbonate concretions with Mg-calcite cement in recent sediments of the Arctic shelf seas. These concretions differ from previously reported glendonites and concretions from bottom sediments of the White Sea, Kara Sea, Sea of Okhotsk, etc. A study of the morphology, microstructure, and composition of these newly reported concretions revealed the multistage formation of carbonates (structural varieties of Mg-calcite and aragonite). It was shown that organic matter played an important role in the formation of authigenic carbonates, i.e., in the formation of sedimentary–diagenetic Mg-calcite. The role of methane as a possible source for authigenic carbonate formation was estimated. It was found that methane-derived Mg-calcite accounts for 17–35% of concretion materials. Mg-calcite had δ¹³С-С_carb values between–24 and–23‰ and δ¹³С-С_org values between–44.5 and–88.5‰.  相似文献   

The structure of phytoplankton communities in the eastern part of the Laptev Sea     

I. N. Sukhanova  M. V. Flint  E. Ju. Georgieva  E. K. Lange  M. D. Kravchishina  A. B. Demidov  A. A. Nedospasov  A. A. Polukhin 《Oceanology》2017,57(1):75-90

Studies have been performed on a transect along 130°30′ E from the Lena River delta (71°60′ N) to the continental slope and adjacent deepwater area (78°22′ N) of the Laptev Sea in September 2015. The structure of phytoplankton communities has distinct latitudinal zoning. The southern part of the shelf (southward of 73°10′ N), the most desalinated by riverine discharge, houses a phytoplankton community with a biomass of 175–840 mg/m², domination of freshwater Aulacoseira diatoms, and significant contribution of green algae (both in abundance and biomass). The northern border for the distribution range of the southern complex of phytoplankton species lies between the 8 and 18 psu isohalines (~73°10′ N). The continental slope and deepwater areas of the Laptev Sea (north of 77°30′ N), with a salinity of >27 psu in the upper mixed layer, are populated by the community prevalently composed of Chaetoceros and Rhizosolenia diatoms, very abundant in the Arctic, and dinoflagellates. The phytoplankton number in this area fall in the range of 430–1100 × 10⁶ cell/m², and the biomass, in the range of 3600 mg/m². A moderate desalinating impact of the Lena River discharge is observed in the outer shelf area between 73°20′ and 77°30′ N; the salinity in the upper mixed layer is 18–24 psu. The phytocenosis in this area has a mosaic spatial structure with between-station variation in the shares of different alga groups in the community, cell number of 117–1200 × 10⁶ cells/m², and a biomass of 1600–3600 mg/m². As is shown, local inflow of “fresh” nutrients to the euphotic layer in the fall season leads to mass growth of diatoms.  相似文献   

Occurrence forms of trace metals in recent bottom sediments from the White and Barents Seas     

D. F. Budko  L. L. Demina  A. P. Lisitzin  M. D. Kravchishina  N. V. Politova 《Doklady Earth Sciences》2017,474(1):552-556

For the first time based on determination of the geochemical occurrence forms of trace metals the main processes that control the accumulation of elements (Al, Mn, Fe, Mo, Cr, Ni, Co, Cu, Pb, Cd, and As) in the recent sediment cores from the White Sea and Barents Sea were quantified. A high-resolution study of the bottom sediment cores allowed us to estimate the short-term variations (periodicity of 10–15 years) in the accumulation of metals to reveal the periods of maximum Fe and Mn contents in the amorphous hydroxides fraction, which serve as effective adsorbents of the trace elements majority, including heavy metals. The Mn/Fe ratio in the amorphous hydroxides phase can be considered as geochemical indicators of early diagenesis.  相似文献   

Vertical Fluxes of Suspended Sedimentary Matter in Arctic Sedimentogenesis of Intracontinental Seas     

Novigatsky  A. N.  Lisitzin  A. P.  Klyuvitkin  A. A.  Shevchenko  V. P.  Kravchishina  M. D.  Politova  N. V. 《Doklady Earth Sciences》2018,479(1):384-389

Doklady Earth Sciences - Based on long-term studies of a small sea in the Arctic Ocean, new regularities in the sedimentary process under the conditions of Arctic sedimentogenesis were established....  相似文献   

Pelagic Ecosystem of the Nansen Basin under the Influence of Variable Atlantic Water Inflow: The Mechanism Forming Diatom Bloom in the Marginal Ice Zone     

Pautova  L. A.  Silkin  V. A.  Kravchishina  M. D.  Yakubenko  V. G.  Kudryavtseva  E. A.  Klyuvitkin  A. A.  Lobkovsky  L. I. 《Doklady Earth Sciences》2021,499(1):590-594

Doklady Earth Sciences - Unique data were obtained on the abnormally high level of phytoplankton biomass (30 g m–3) in the marginal ice zone of the deep-water High Arctic (the Nansen Basin,...  相似文献   

Early diagenesis in recent bottom sediments of the Dvina Bay (White Sea)     

N. V. Politova  A. A. Klyuvitkin  A. N. Novigatskii  N. V. Ul’yanova  A. L. Chul’tsova  M. D. Kravchishina  G. A. Pavlova  A. Yu. Lein 《Oceanology》2016,56(5):702-713

Investigations in the water column and bottom sediments including entrapped water were carried out on expeditions of the P.P. Shirshov Institute of Oceanology in the Dvina Bay, the White Sea. We studied the transformation of particulate organic matter at the biogeochemical barrier between the water and bottom and in the underlying Holocene sediments. Low rates of the early diagenesis of sediments caused by low values of primary production in the conditions of high fluxes of terrigenous organic matter were established. The low temperatures of microorganisms habitat play the secondary role.  相似文献