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Koronkevich N. I. Barabanova E. A. Georgiadi A. G. Dolgov S. V. Zaitseva I. S. 《Water Resources》2021,48(4):502-511
Water Resources - Different types of transboundary water exchange in Russia are considered, including through state, administrative, and natural boundaries. The presented characteristics refer to... 相似文献
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Space and time analysis of the formation of spring overland runoff in forest-steppe and steppe regions of the Russian Plain has been carried out. It has been shown that, in addition to zonal climate conditions, its distribution over the area is largely determined by the agricultural load on river catchment areas, primarily, the structure of agricultural lands—the proportions of areas under winter tillage and consolidated tillage. The character of overland runoff response to present-day climate changes and agricultural activity has been identified, and quantitative estimates have been given to the manifold hydrological role of these factors. 相似文献
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Natalia A. Yaragina Andrey V. Dolgov 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(21-22):2141
Abundance and biomass of the most important fish species inhabited the Barents and Norwegian Sea ecosystems have shown considerable fluctuations over the last decades. These fluctuations connected with fishing pressure resulted in the trophic structure alterations of the ecosystems. Resilience and other theoretical concepts (top-down, wasp-waste and bottom-up control, trophic cascades) were viewed to examine different response of the Norwegian and Barents Sea ecosystems on disturbing forces. Differences in the trophic structure and functioning of Barents and Norwegian Sea ecosystems as well as factors that might influence the resilience of the marine ecosystems, including climatic fluctuation, variations in prey and predator species abundance, alterations in their regular migrations, and fishing exploitation were also considered. The trophic chain lengths in the deep Norwegian Sea are shorter, and energy transfer occurs mainly through the pelagic fish/invertebrates communities. The shallow Barents Sea is characterized by longer trophic chains, providing more energy flow into their benthic assemblages. The trophic mechanisms observed in the Norwegian Sea food webs dominated by the top-down control, i.e. the past removal of Norwegian Spring spawning followed by zooplankton development and intrusion of blue whiting and mackerel into the area. The wasp-waist response is shown to be the most pronounced effect in the Barents Sea, related to the position of capelin in the ecosystem; large fluctuations in the capelin abundance have been strengthened by intensive fishery. Closer links between ecological and fisheries sciences are needed to elaborate and test various food webs and multispecies models available. 相似文献
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Trophic structure of the Barents Sea fish assemblage with special reference to the cod stock recoverability 总被引：1，自引：0，他引：1
The species composition and trophic structure of the Barents Sea fish assemblage is analysed based on data from research survey trawls and diet analyses of various species. Atlantic cod was the dominant fish species encountered, accounting for more than 55% by abundance or biomass. Only five fish species (long rough dab, thorny skate, Greenland halibut, deepwater redfish and saithe) were sufficiently abundant to be considered as possible food competitors with cod in the Barents Sea. However, possible trophic competition is not high, due to low spatial and temporal overlap between cod and these other species. Analyses of fish assemblages and trophic structures of the Barents Sea and other areas (North Sea, Western Greenland, Newfoundland-Labrador shelf) suggest that Barents Sea cod is the only cod stock for which the ability to recover may not be restricted by trophic relations among fishes, due to a lack of other abundant predatory species and low potential for competition caused by spatial-temporal changes. 相似文献
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A. D. Dolgov 《Astronomy Reports》2017,61(4):275-280
Astronomical observations of last few years have presented a surprising evidence that the Universe at redshift of order 10 is densely populated by supermassive black holes (quasars), supernovae, and contains very large amount of dust. All these data are in conflict with the canonical theory of quasar and supernova formation. A model is discussed which in a simple and natural way solves all these problem. In addition it explains an existence of supermassive black holes in each large galaxy and even in small ones. An inverted picture of galaxy formation is suggested when primordial black holes serve as seeds of galaxy formation. Simultaneously the origin and properties of black hole binaries, sources of gravitational waves registered by LIGO are explained. As a by-product the model may lead to abundant cosmological antimatter even in the Galaxy. 相似文献
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Emma L. Orlova Andrey V. Dolgov Galina B. Rudneva Ivan A. Oganin Ludmila L. Konstantinova 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(21-22):2054
The purpose of the study is to assess the role of trophic relations of the dominant pelagic fishes capelin and polar cod in the Barents Sea with regard to distribution and accessibility as prey for the Atlantic cod in warm years (2004–2005). Unlike in the previous period, during these warm years a dramatic increase of the polar cod population resulted in a northwards expansion of the feeding grounds where overlapping of polar cod and capelin concentrations was observed. This caused an increased competition for copepods, which are the main food item for young fish. In the areas dominated by polar cod the shortage of copepods forced immature capelin to switch to the chaetognath Sagitta, which affected their fatness negatively.During the warm years the feeding grounds of Atlantic cod also expanded, to a large degree caused by the shortage of their main food, the capelin. In 2004–2005 the cod formed feeding concentrations in the north and northeast Barents Sea where they fed on the capelin. In this area the consumption of polar cod by cod increased, and in some local areas the polar cod practically replaced the capelin in the diet of cod. In general polar cod in the diet of Atlantic cod were more important in the northern than in the southern part of the Barents Sea. The fatness of cod was extremely low during the whole spring–summer period (until August), and after the feeding period the fatness index of the Atlantic cod became lower than the average long-term autumn value. 相似文献
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G. A. Shchelkanova S. I. Blinnikov A. S. Saburova A. D. Dolgov 《Astronomy Letters》2013,39(10):665-675
The observed rotation curves of four low-surface-brightness galaxies are compared with the predictions of three models of the dark matter distribution with various degrees of singularity at the center or without it. Contrary to the assertions in the literature, the results of fitting the rotation curves by the least-squares method using a chi-square distribution with optimal parameters (dark matter halo, bulge, and disk) do not yet allow any one of the models to be uniquely preferred. The NFW and Burkert models have the highest significance levels for two of the four galaxies and for the other two, respectively. At the same time, using the NFW model in the latter two cases leads to an estimate of the disk surface density close to the photometric one, which may suggest that these models are more realistic. The surface density estimates for the galactic disks based the criterion of their marginal gravitational stability have also been used. The disks of the galaxies under consideration may be overheated, because the modeling using these estimates gives larger deviations of the model rotation curves from the observed ones than in the case where the surface density is assumed to be a free parameter. Using the disk surface density estimates based on the criterion of marginal gravitational stability does not change the preference in choosing the shape of the dark matter density profile in the galaxies under consideration compared to the case with a “free disk.” 相似文献
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A scheme of water balance differentiation of a territory is proposed. The vertical and space-time structure of water balance are considered. A procedure for regional space-time analysis of water balance was developed and tested, allowing one to evaluate its different characteristics and relationships, to simulate the series of their mean annual values in points where no observations are available, and to carry out computeraided mapping of the obtained results. Electronic maps were constructed to characterize the distribution of river runoff and its surface and subsurface components over the European Russia, the correlation and conjunction between them, the distribution of annual precipitation, and the precipitation of the warm and cold periods over the territory. Statistical relationships, reflecting different aspects of space-time variations in the major water balance elements, are given. 相似文献
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Astronomy Reports - Bulk of various astronomical observations of black holes suggest that virtually all observed black holes can be of primordial origin. A modified mechanism of the primordial... 相似文献