Correlations between fatty acid composition of seston and zooplankton and effects of environmental parameters in a eutrophic Siberian reservoir     

Michail I. Gladyshev  Nadezhda N. Sushchik  Olesia N. Makhutova  Olga P. Dubovskaya  Elena S. Kravchuk  Galina S. Kalachova  Elena B. Khromechek 《Limnologica》2010,40(4):343-357

During two sampling seasons we analyzed on weekly basis fatty acid (FA) composition of seston fraction <130 μm and zooplankton fraction >130 μm, and compared them using a multivariate canonical correlation analysis (CCA). Besides, we evaluated a possible impact of water temperature and inorganic nutrients on FA composition of the seston and the zooplankton.In spite of significant differences in percentages of several individual FAs, we found very strong canonical correlation (cross-correlation, 1-week lag) between FA composition of the seston and the zooplankton. The most important factor, providing the overall canonical cross-correlation between FA profiles of the seston and the zooplankton fractions was eicosapentaenoic acid (20:5ω3, EPA). FA composition of the zooplankton fraction had comparatively poor correlations with taxonomic composition of the zooplankton. Thus, seasonal variations of FA composition of the zooplankton were determined primarily by seasonal changes in FA composition of the seston, rather than by taxonomic differences of FA profiles between rotifers, cyclopoids and cladocerans. FA composition of the seston was strongly affected by its taxonomic composition, namely by that of phytoplankton. According to CCA, the highest factor loadings pertained to diatoms interacting with their marker acids, including EPA, and cyanobacteria and greens, interacting with their marker acids. Ciliates and small rotifers composed considerable and sometimes major part of the seston biomass, but according to CCA their contributions to seasonal variations of the total FA profile of the seston were insignificant. This finding indirectly support the conclusion of the other authors, that the main source of FAs presented in ciliates and rotifers must be sought in algae and that they do not modify FA composition of food consumed, apart from repackaging it.Water temperature was the principal environmental parameter which drove the overall variations of FA composition. Factor loadings for the inorganic nutrients were comparatively negligible. The main contribution in the seasonal variation of FA composition of the seston was given by negative interaction between water temperature and percentage of EPA in the seston.  相似文献   

Winter distribution of euphausiids (Euphausiacea) in the Barents Sea (2000–2005)     

Natalia G. Zhukova  Valentina N. Nesterova  Irina P. Prokopchuk  Galina B. Rudneva 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(21-22):1959

The purpose of the study is to analyze the state of the Barents Sea euphausiids populations in the warm period (2000–2005) based on the study of their structure dynamics and distribution under the influence of abiotic and biotic factors. For estimation of their aggregations in the bottom layer, the traditional method was used with the help of the modified egg net (0.2 m² opening area, 564 μm mesh size). The net is used for collecting euphausiids in the autumn–winter period when their activity is reduced, which results in high-catch efficiency. The findings confirmed the major formation patterns of the euphausiids species composition associated with climate change in the Arctic basin. As before, in the warm years, one can see a clear-cut differentiation of space distribution of the dominant euphausiids Thysanoessa genus with localization of the more thermophilic Thysanoessa inermis in the north-west Barents Sea and Thysanoessa raschii in the east. The major euphausiids aggregations are formed of these species. In 2004, the first data of euphausiids distribution in the northern Barents Sea (77–79°N) were obtained, and demonstrated extremely high concentrations of T. inermis in this area, with the biomass as high as 1.7–2.4 g m⁻² in terms of dry weight. These data have improved our knowledge of the distribution and euphausiids abundance during periods of elevated sea-water temperatures in the Barents Sea. The oceanic Atlantic species were found to increase in abundance due to elevated advection to the Barents Sea during the study period. Thus, after nearly a 30-year-long absence of the moderate subtropical Nematoscelis megalops in the Barents Sea, they were found again in 2003–2005. However in comparison with 1960, the north-east border of its distribution considerably shifted to 73°50′N 50°22′E. The portion of Meganyctiphanes norvegica also varied considerably—from 10% to 20% of the total euphausiids population in the warm 1950s–1960s almost to complete disappearing in 1970–1990s. The peak of this species’ occurrence (18–26%) took place in the beginning of warm period (1999–2000) after a succession of cold years. The subsequent reduction of the relative abundance of M. norvegica to 7% might have been mostly caused by fish predation during a period of low population densities of capelin. This high predation pressure may therefore have been mediated both by other pelagic fishes (i.e. herring, blue whiting, polar cod) but also by demersal fishes such as cod and haddock. Similar sharp fluctuations in the capelin stock (the major consumer of euphausiids) created marked perturbations in the food web in the Barents Sea in the middle 1980s and the early 1990s.  相似文献   

Facies system of the Eastern Barents Sea since the last glaciation to present     

Ivar Murdmaa  Elena Ivanova  Jean-Claude Duplessy  Michael Levitan  Tatyana Khusid  Maria Bourtman  Galina Alekhina  Tatyana Alekseeva  Michael Belousov  Valentina Serova 《Marine Geology》2006,230(3-4):275-303

Twenty-two sediment cores raised from the central and eastern parts of the Barents Sea have been studied to reconstruct the evolution of the facies system since the Late Weichselian glaciation. Multiproxy records reveal four lithostratigraphic units, which reflect major development stages of paleoenvironments. Age control is provided by 23 AMS ¹⁴C dates for Holocene sections of four cores. Continental moraine deposits of the last glaciation are overlain by proximal glaciomarine facies of the initial deglaciation phase. During this phase, the Barents Sea ice sheet detached from the ground resulting in seawater penetration into troughs, iceberg calving, deposition of IRD and fine-grained glacier meltwater load in newly formed marine basins. The main deglaciation phase is characterized by pulsed sedimentation from various gravity flows resulting in accumulation of distal glaciomarine facies comprising laminated clay and sand sequences with minor IRD. Redistribution of fine-grained suspended matter by bottom currents and brine-induced nepheloid flows combined with biogenic processes and minor ice rafting caused facies diversity of the Holocene marine sediments. The Holocene facies of shelf depressions reflect rather high, but variable productivity responding to climate changes and variations of Atlantic water inflow into the Barents Sea.  相似文献   

Model intercomparison study to investigate a dense contaminant plume in a complex hydrogeologic system     

Mark D. Williams  Charles R. Cole  Michael G. Foley  Galina A. Zinina  Alexander I. Zinin  Nelly A. Vasil'kova  Lilia M. Samsonova 《Environmental Geology》2002,42(2-3):199-213

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The radioastronomical “time machine” effect can help the solution of the gamma ray bursts mystery     

Galina V. Lipunova  Ivan E. Panchenko  Vladimir M. Lipunov 《New Astronomy》1997,2(6):555-558

The possible low-frequency radio emission from the progenitors of gamma ray bursts can experience a delay from tens of seconds to hours on the way to the observer due to the dispersion in galactic and extragalactic plasma, and thus reach the observer as a radio afterglow of the burst. This opens a unique possibility (peculiar “time machine”) of seeing what happened at that place before the catastrophe.  相似文献   

Improving BeiDou real-time precise point positioning with numerical weather models   总被引：1，自引：1，他引：0  

Cuixian Lu  Xingxing Li  Florian Zus  Robert Heinkelmann  Galina Dick  Maorong Ge  Jens Wickert  Harald Schuh 《Journal of Geodesy》2017,91(9):1019-1029

Precise positioning with the current Chinese BeiDou Navigation Satellite System is proven to be of comparable accuracy to the Global Positioning System, which is at centimeter level for the horizontal components and sub-decimeter level for the vertical component. But the BeiDou precise point positioning (PPP) shows its limitation in requiring a relatively long convergence time. In this study, we develop a numerical weather model (NWM) augmented PPP processing algorithm to improve BeiDou precise positioning. Tropospheric delay parameters, i.e., zenith delays, mapping functions, and horizontal delay gradients, derived from short-range forecasts from the Global Forecast System of the National Centers for Environmental Prediction (NCEP) are applied into BeiDou real-time PPP. Observational data from stations that are capable of tracking the BeiDou constellation from the International GNSS Service (IGS) Multi-GNSS Experiments network are processed, with the introduced NWM-augmented PPP and the standard PPP processing. The accuracy of tropospheric delays derived from NCEP is assessed against with the IGS final tropospheric delay products. The positioning results show that an improvement in convergence time up to 60.0 and 66.7% for the east and vertical components, respectively, can be achieved with the NWM-augmented PPP solution compared to the standard PPP solutions, while only slight improvement in the solution convergence can be found for the north component. A positioning accuracy of 5.7 and 5.9 cm for the east component is achieved with the standard PPP that estimates gradients and the one that estimates no gradients, respectively, in comparison to 3.5 cm of the NWM-augmented PPP, showing an improvement of 38.6 and 40.1%. Compared to the accuracy of 3.7 and 4.1 cm for the north component derived from the two standard PPP solutions, the one of the NWM-augmented PPP solution is improved to 2.0 cm, by about 45.9 and 51.2%. The positioning accuracy for the up component improves from 11.4 and 13.2 cm with the two standard PPP solutions to 8.0 cm with the NWM-augmented PPP solution, an improvement of 29.8 and 39.4%, respectively.  相似文献   

Carbon dioxide on planetary bodies: Theoretical and experimental studies of molecular complexes     

Galina M. Chaban 《Icarus》2007,187(2):592-599

An absorption band at ∼4.26 μm wavelength attributed to the asymmetric stretching mode of CO in CO₂ has been found on two satellites of Jupiter and several satellites of Saturn. The wavelength of pure CO₂ ice determined in the laboratory is 4.2675 μm, indicating that the CO₂ on the satellites occurs either trapped in a host material, or in a chemical or physical complex with other materials, resulting in a blue shift of the wavelength of the band. In frequency units, the shifts in the satellite spectra range from 3.7 to 11.3 cm⁻¹. We have performed ab initio quantum chemical calculations of CO₂ molecules chemically complexed with one, two, and more H₂O molecules and molecules of CH₃OH to explore the possibility that the blue shift of the band is caused by chemical complexing of CO₂ with other volatile materials. Our computations of the harmonic and anharmonic vibrational frequencies using high levels of theory show a frequency shift to the blue by 5 cm⁻¹ from pure CO₂ to CO-H₂O, and an additional 5 cm⁻¹ from CO₂-H₂O to CO₂-2H₂O. Complexing with more than two H₂O molecules does not increase the blue shift. Complexes of CO₂ with one molecule of CH₃OH and with one CH₃OH plus one H₂O molecule produce smaller shifts than the CO₂-2H₂O complex. Laboratory studies of CO₂:H₂O in a solid N₂ matrix also show a blue shift of the asymmetric stretching mode.  相似文献   

Global change: Some concepts and problems of geographical research (a few results of the Soviet-American project)     

John R. Mather Dr.  Galina V. Sdasyuk Dr. 《GeoJournal》1990,20(2):85-94

About twenty geographers from the Soviet Union and the United States of America have joined in a review of selected geographical approaches to the study of global change. Taking account of the new effort sponsored by the International Council of Scientific Unions under its International Geosphere-Biosphere Programme to investigate major alterations in the world environment, they examine relevant geographical experience. Rather than assembling a collection of papers by individual authors, the project encouraged the preparation of a joint set of findings and observations.A joint USSR-USA project Global Change: Geographical Approaches under the scientific leadership of Vladimir M. Kotlyakov and Gilbert F. White; John R. Mather and Galina V. Sdasyuk are the editors of a monograph to be published in 1990 by Progress Publishers, Moscow, in Russian and by the University of Arizona Press, Tucson, USA, in English.

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Cenozoic history of the Bering Sea and its northwestern margin     

Vadim Chekhovich  Dmitry Kovalenko  & Galina Ledneva 《Island Arc》1999,8(2):168-180

Tectonic reconstructions based on the geodynamic analysis of geologic, paleomagnetic, structural and kinematic data of Cenozoic age from the western Bering Sea region are proposed in the present paper. The most active tectonic and magmatic processes took place in the Komandorsky segment of the Bering Sea, exemplified by the Late Cretaceous–Early Eocene Olutorsky Arc and Eocene–Oligocene Govena–Karaginsky Arc, which was built on the structures of the Olutorsky Arc. A model of the complex collision of these two arcs with the paleocontinental margin, which considers rotations of the geological blocks from the various structural zones of the western margin of the Bering Sea in the horizontal plane (paleomagnetic data), was proposed by the authors. According to this model the collision of the flanks of the Olutorsky and Govena–Karaginsky arcs took place in the Eocene, before the collision of the central parts in the Miocene.  相似文献   

Experimental study of arsenic speciation in vapor phase to 500°C: implications for As transport and fractionation in low-density crustal fluids and volcanic gases     

Gleb S PokrovskiDenis Testemale  Jean-Louis HazemannAndrew Y.u Bychkov  Galina V Golikova 《Geochimica et cosmochimica acta》2002,66(19):3453-3480

The stoichiometry and stability of arsenic gaseous complexes were determined in the system As-H₂O ± NaCl ± HCl ± H₂S at temperatures up to 500°C and pressures up to 600 bar, from both measurements of As^(III) and As^(V) vapor-liquid and vapor-solid partitioning, and X-ray absorption fine structure (XAFS) spectroscopic study of As^(III)-bearing aqueous fluids. Vapor-aqueous solution partitioning for As^(III) was measured from 250 to 450°C at the saturated vapor pressure of the system (P_sat) with a special titanium reactor that allows in situ sampling of the vapor phase. The values of partition coefficients for arsenious acid (H₃AsO₃) between an aqueous solution (pure H₂O) and its saturated vapor (K = mAs_vapor /mAs_liquid) were found to be independent of As^(III) solution concentrations (up to ∼1 to 2 mol As/kg) and equal to 0.012 ± 0.003, 0.063 ± 0.023, and 0.145 ± 0.020 at 250, 300, and 350°C, respectively. These results are interpreted by the formation, in the vapor phase, of As(OH)₃(gas), similar to the aqueous As hydroxide complex dominant in the liquid phase. Arsenic chloride or sulfide gaseous complexes were found to be negligible in the presence of HCl or H₂S (up to ∼0.5 mol/kg of vapor). XAFS spectroscopic measurements carried out on As^(III)-H₂O (±NaCl) solutions up to 500°C demonstrate that the As(OH)₃ complex dominates As speciation both in dense H₂O-NaCl fluids and low-density supercritical vapor. Vapor-liquid partition coefficients for As^(III) measured in the H₂O-NaCl system up to 450°C are consistent with the As speciation derived from these spectroscopic measurements and can be described by a simple relationship as a function of the vapor-to-liquid density ratio and temperature. Arsenic^(III) partitioning between vapor and As-concentrated solutions (>2 mol As/kg) or As₂O₃ solid is consistent with the formation, in the vapor phase, of both As₄O₆ and As(OH)₃. Arsenic^(V) (arsenic acid, H₃AsO₄) vapor-liquid partitioning at 350°C for dilute aqueous solution was interpreted by the formation of AsO(OH)₃ in the vapor phase.The results obtained were combined with the corresponding properties for the aqueous As(III) hydroxide species to generate As(OH)₃(gas) thermodynamic parameters. Equilibrium calculations carried out by using these data indicate that As(OH)₃(gas) is by far the most dominant As complex in both volcanic gases and boiling hydrothermal systems. This species is likely to be responsible for the preferential partition of arsenic into the vapor phase as observed in fluid inclusions from high-temperature (400 to 700°C) Au-Cu (-Sn, -W) magmatic-hydrothermal ore deposits. The results of this study imply that hydrolysis and hydration could be also important for other metals and metalloids in the H₂O-vapor phase. These processes should be taken into account to accurately model element fractionation and chemical equilibria during magma degassing and fluid boiling.  相似文献