Indirect Solar Wind Measurements Using Archival Cometary Tail Observations     

Nadezhda Zolotova  Yuriy Sizonenko  Mikhail Vokhmyanin  Igor Veselovsky 《Solar physics》2018,293(5):85

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A Deep Extragalactic Survey with the ART-XC Telescope of the Spectrum-RG Observatory: Simulations and Expected Results     

I.?A.?MereminskiyEmail author  E.?V.?Filippova  R.?A.?Burenin  S.?Yu.?Sazonov  M.?N.?Pavlinsky  A.?Yu.?Tkachenko  I.?Yu.?Lapshov  A.?E.?Shtykovskiy  R.?A.?Krivonos 《Astronomy Letters》2018,44(2):67-80

To choose the best strategy for conducting a deep extragalactic survey with the ART-XC X-ray telescope onboard the Spectrum–Röntgen–Gamma (SRG) observatory and to estimate the expected results, we have simulated the observations of a 1.1° × 1.1° field in the 5–11 and 8–24 keV energy bands. For this purpose, we have constructed a model of the active galactic nuclei (AGN) population that reflects the properties of the X-ray emission from such objects. The photons that “arrived” from these sources were passed through a numerical model of the telescope, while the resulting data were processed with the standard ART-XC data processing pipeline. We show that several hundred AGNs at redshifts up to z ≈ 3 will be detected in such a survey over 1.2 Ms of observations with the expected charged particle background levels. Among them there will be heavily obscured AGNs, which will allow a more accurate estimate of the fraction of such objects in the total population to be made. Source confusion is expected at fluxes below 2 × 10^?14 erg s^?1 cm^?2 (5–11 keV). Since this value can exceed the source detection threshold in a deep survey at low particle background levels, it may turn out to be more interesting to conduct a survey of larger area (several square degrees) but smaller depth, obtaining a sample of approximately four hundred bright AGNs as a result.  相似文献   

Optical Identification of Candidates for Active Galactic Nuclei Detected by the Mikhail Pavlinsky ART-XC Telescope Onboard the SRG Observatory during an All-Sky X-ray Survey     

Zaznobin  I. A.  Uskov  G. S.  Sazonov  S. Yu.  Burenin  R. A.  Medvedev  P. S.  Khorunzhev  G. A.  Lyapin  A. R.  Krivonos  R. A.  Filippova  E. V.  Gilfanov  M. R.  Sunyaev  R. A.  Eselevich  M. V.  Bikmaev  I. F.  Irtuganov  E. N.  Nikolaeva  E. A. 《Astronomy Letters》2021,47(2):71-87

Astronomy Letters - We present the results of our identification of eight objects from the preliminary catalogue of X-ray sources detected in the 4–12 keV energy band by the Mikhail Pavlinsky...  相似文献   

Effect of temperature on contents of essential highly unsaturated fatty acids in freshwater zooplankton     

Michail I. Gladyshev  Vitaliy P. Semenchenko  Olga P. Dubovskaya  Elena B. Fefilova  Olesia N. Makhutova  Zhanna F. Buseva  Nadezhda N. Sushchik  Vladimir I. Razlutskij  Ekaterina V. Lepskaya  Mariya A. Baturina  Galina S. Kalachova  Olga N. Kononova 《Limnologica》2011,41(4):339-347

In 11 lakes from cold and warm regions we studied the content of highly unsaturated fatty acids (HUFA) in seston (<130 μm) and crustacean zooplankton using gas chromatography–mass spectrometry. An increase of temperature correlated with a decrease of HUFA content in zooplankton. A multivariate canonical correlation analyses revealed, that the decrease of HUFA content was related with a decrease of per cent of copepods in zooplankton communities, which are known to have higher HUFA levels in their biomass, than cladocerans. This means that temperature primarily affected the HUFA levels indirectly, via changing of taxonomic structure of zooplankton community, while the homeoviscous adaptation of zooplankton individuals had comparatively lower importance. As found, water temperature was better predictor of HUFA contents of zooplankton, than the fatty acid composition of seston. Thus, it can be predicted, that a probable climate warming will decrease the content of the essential HUFA in freshwater zooplankton with possible negative consequences for animals of higher trophic levels.  相似文献   

Mineralogy, geochemistry and stratigraphy of the Maslovsky Pt–Cu–Ni sulfide deposit, Noril’sk Region, Russia     

Nadezhda Alexandrovna Krivolutskaya  Alexandr Vladimirovich Sobolev  Sergey Grigor’evich Snisar  Bronislav Iosiphovich Gongalskiy  Dmitry Vladimirovich Kuzmin  Folkmar Hauff  Irina Nikolaevna Tushentsova  Natalya Mikhailovna Svirskaya  Natalya Nikolaevna Kononkova  Tatyana B. Schlychkova 《Mineralium Deposita》2012,47(1-2):69-88

We report new data on the stratigraphy, mineralogy and geochemistry of the rocks and ores of the Maslovsky Pt–Cu–Ni sulfide deposit which is thought to be the southwestern extension of the Noril’sk 1 intrusion. Variations in the Ta/Nb ratio of the gabbro-dolerites hosting the sulfide mineralization and the compositions of their pyroxene and olivine indicate that these rocks were produced by two discrete magmatic pulses, which gave rise to the Northern and Southern Maslovsky intrusions that together host the Maslovsky deposit. The Northern intrusion is located inside the Tungusska sandstones and basalt of the Ivakinsky Formation. The Southern intrusion cuts through all of the lower units of the Siberian Trap tuff-lavas, including the Lower Nadezhdinsky Formation; demonstrating that the ore-bearing intrusions of the Noril’sk Complex post-date that unit. Rocks in both intrusions have low TiO₂ and elevated MgO contents (average mean TiO₂ <1 and MgO?=?12?wt.%) that are more primitive than the lavas of the Upper Formations of the Siberian Traps which suggests that the ore-bearing intrusions result from a separate magmatic event. Unusually high concentrations of both HREE (Dy+Yb+Er+Lu) and Y (up to 1.2 and 2.1?ppm, respectively) occur in olivines (Fo_79.5 and 0.25% NiO) from picritic and taxitic gabbro-dolerites with disseminated sulfide mineralization. Thus accumulation of HREE, Y and Ni in the melts is correlated with the mineral potential of the intrusions. The TiO₂ concentration in pyroxene has a strong negative correlation with the Mg# of both host mineral and Mg# of host rock. Sulfides from the Northern Maslovsky intrusion are predominantly chalcopyrite–pyrrhotite–pentlandite with subordinate and minor amounts of cubanite, bornite and millerite and a diverse assemblage of rare precious metal minerals including native metals (Au, Ag and Pd), Sn–Pd–Pt–Bi–Pb compounds and Fe–Pt alloys. Sulfides from the Southern Maslovsky intrusion have δ ³⁴S?=?5–6‰ up to 10.8‰ in two samples whereas the country rock basalt have δ ³⁴S?=?3–4‰, implying there was no in situ assimilation of surrounding rocks by magmas.  相似文献   

Arsenic mobility in two mine tailings drainage systems and its removal from solution by natural geochemical barriers     

Nataliya V. Yurkevich  Olga P. Saeva  Nadezhda A. Pal’chik 《Applied Geochemistry》2012

Sulfide-mineral-bearing mill wastes are sources of high concentrations of acid, soluble metals, and As. These are serious problems for ore mining areas such as the Kemerovo and Cheljabinsk regions in Russia. This study evaluated the distribution of the mill wastes, the mobility of As from the wastes, and the potential of natural materials to attenuate As dispersion in the broader environment. Arsenic contents in wastes of the Belovo Zn-processing (Kemerovo) and the Karabash Cu-smelting plants (Cheljabinsk) are 2–3 orders of magnitude higher than the content of continental crust. Main mineral forms of As in these wastes are arsenopyrite (FeAsS) and scorodite (FeAsO₄·2H₂O). High dissolved As concentrations are found in water draining the wastes and in rivers adjacent to the mill sites. The water concentrations commonly exceed drinking water standards. High As concentrations in bottom sediments of the affected rivers extend a 100 m downstream of the waste drainage input. These sediments are also a source of river water contamination. Experiments were conducted to evaluate the ability of natural water to mobilize As from the wastes. The Belovo tailings released 86% of their contained As to the infiltrating water, whereas the less reactive Karabash tailings released only 22% of total As. The experimental leachates were used as influent to columns that tested the ability of limestone and natural clay to reduce the concentration of dissolved As and associated metals. Some dissolved As was precipitated with Fe, Pb and Sb initially in the limestone column. The decrease in dissolved As is consistent with the accumulation of As in yellow ferriferous sediments in the Belovo settling pond. In the pond and wetland sediments, As mobility is also decreased by the formation of sulfides and arsenides. Cubanite (CuFe₂S₃), klaprothite (Cu₃BiS₃)_, rammelsbergite (NiAs₂), maucherite (Ni₁₁As₈), semseyite (Cu₉Sb₈S₂₁), and skutterudite (CoAs₃) were found in the chemically reducing lower sediments of the Belovo settling pond.  相似文献   

Characteristics of extreme precipitation events within the Amur river basin in summer 2013     

M. V. Bolgov  M. D. Trubetskova  I. A. Filippova  M. A. Kharlamov 《Geography and Natural Resources》2017,38(2):139-146

We investigated the precipitation characteristics for the summer period of 2013 on the basis of analyzing the daily precipitation amounts according to observational data from the Russian and Chinese meteostations on the territory of the Amur river basin. An analysis is made of the synchronism in the fluctuations of long-term series of precipitation amounts for two summer months (July and August) by using a modified algorithm for a classification of the fields of hydrometeorological characteristics, such as cluster analysis. The study revealed a poor correlation of precipitation amounts in different parts of the basin. We analyzed the interannual fluctuations in absolute maxima of the consecutive precipitation amounts for different periods of time (from 1 to 30 days). It is shown that precipitation over the summer period of 2013 that caused a disastrous flood in the lower reaches of the Amur were extreme primarily as regards the territory encompassed and the flood duration, which was due to a combination of synoptic processes of a different genesis. It was found that the precipitation amounts for periods shorter than 19 days in 2013 were not extreme in terms of intensity. A comparison was made with the year 1984 when there also occurred a flood on the Amur but not as violent. Parameters of the probability curves for 2013 and 1984 are presented for long-term series of maximum precipitation amounts for the summation period of 7 and 30 days. It is concluded that for calculating the maximum possible precipitation amounts which are necessary for assessing the maximum possible floods, it is appropriate to consider synoptic situations with long-lasting precipitation rather than separate short-lasting storm rains.  相似文献   

A Numerical–Analytical Approach to Modeling the Axial Rotation of the Earth     

Yu. G. Markov  V. V. Perepelkin  L. V. Rykhlova  A. S. Filippova 《Astronomy Reports》2018,62(4):299-308

A model for the non-uniform axial rotation of the Earth is studied using a celestial-mechanical approach and numerical simulations. The application of an approximate model containing a small number of parameters to predict variations of the axial rotation velocity of the Earth over short time intervals is justified. This approximate model is obtained by averaging variable parameters that are subject to small variations due to non-stationarity of the perturbing factors. The model is verified and compared with predictions over a long time interval published by the International Earth Rotation and Reference Systems Service (IERS).  相似文献   

Transpiration in Quercus suber trees under shallow water table conditions: the role of soil and groundwater          下载免费PDF全文

Clara A. Pinto  Nadezhda Nadezhdina  Jorge S. David  Cathy Kurz‐Besson  Maria C. Caldeira  Manuel O. Henriques  Fernando G. Monteiro  João S. Pereira  Teresa S. David 《水文研究》2014,28(25):6067-6079

Water is one of the major environmental factors limiting plant growth and survival in the Mediterranean region. Quercus suber L. woodlands occupy vast areas in the Iberian Peninsula, frequently under shallow water table conditions. The relative magnitude of soil and groundwater uptake to supply transpiration is not easy to evaluate under these circumstances. We recently developed a conceptual framework for the functioning of the root system in Q. suber that simulates well tree transpiration, based on two types of root behaviour: shallow connected and deep connected. Although this significantly improved knowledge on the functional traits of Mediterranean Q. suber, the approach has the limitation of requiring root sap flow data, which are seldom available. In this work, we present alternative methodologies to assess if trees are connected to groundwater and to estimate the soil and groundwater contributions to tree transpiration. We provide evidence on the tree unrestricted access to groundwater solely based on meteorological, stem sap flow and leaf water potential data. Using a soil mass balance approach, we estimated the yearly soil and groundwater contributions to tree transpiration: 69.7% and 30.3%, respectively. Groundwater uptake became dominant in the dry summer: 73.2% of tree transpiration. Results reproduce extremely well those derived from root modelling. Because of its simplicity both in formulation and data requirements, our approach is potentially liable to be adapted to other groundwater‐dependent Mediterranean oak sites, where interactions between land use and water resources may be relevant. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Results of long-term investigations on acid deposition in the area of South Baikal     

V. A. Obolkin  O. G. Netsvetaeva  L. P. Golobokova  V. L. Potemkin  E. A. Zimnik  U. G. Filippova  T. V. Khodzher 《Geography and Natural Resources》2013,34(2):151-157

We examine the acid deposition monitoring results (2000–2010) for the southern territory of East Siberia (the Irkutsk-Angarsk industrial center). It is established that acid deposition events are most frequently recorded in the area of South Baikal (70–100 km south-east of the Irkutsk-Angarsk industrial center), with the acidity of precipitation continuing to increase. Atmospheric precipitation acidity data are compared with long-term monitoring results for Europe.  相似文献