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The barite deposits that emerge as veins and lodes within or along the contact zones of recrystallized limestone and dolomite units of Cambrian Degirmentas Formation are of epigenetic character. Depositional styles, paragenesis, host rock alteration styles, and high SrO contents of the barites suggest a hydrothermal origin for their formation. However, considering their rare earth element compositions, barite samples surround the field for seawaters when plotted on Ce _N / Yb _N -Yb _N and Ce _N /Sm _N -Ce _N /Yb _N diagrams. Fluid inclusion data obtained from the barites indicated a formation from a fluid with low salinity (0.9-1.6 wt.% NaCl eq.) at homogenization temperatures between 78 and 190°C. Sulfur isotopic compositions of barites vary between +32.2 and +36.3‰, and their ⁸⁷Sr/⁸⁶Sr values range between 0.709885 and 0.749652. Depositional styles, parageneses, trace element compositions, fluid inclusion data as well as δ³⁴S and ⁸⁷Sr/⁸⁶Sr isotopic data indicate a model in which hydrothermal fluids were possibly derived from a buried intrusion mixed with meteoric and marine waters, further interacting with the Precambrian - Phanerozoic metaclastic and Cambrian carbonate rocks to form barite deposits.

Neutron tomography is considered as an alternative to X-ray tomography in the study of paleontologic and geologic objects. Based on experimental data, a contrast scale of minerals and rocks, including those present in paleontologic objects, has been constructed for neutron tomography. Examples of application of neutron tomography of geologic objects are given, and the potentialities of the above methods are compared.

A new algorithm is proposed to compute magnetotelluric (MT) curves for a horizontally layered earth with laterally inhomogeneous conductivity. It is fast and ensures correction of induced eddy currents and galvanic distortions of MT curves produced by 3D inhomogeneities. The computation time is short (~1 min) due to the use of the perturbation method for solving Maxwell’s equations. The suggested algorithm has a better performance than the more costly classical Trefftz method but has an applicability limitation.

The influence of small cylindrical bluntness of the leading edge of a flat plate on the formation of spatial structures in a nominally two-dimensional supersonic flow in a compression corner at the Mach number M_∞ ≈ 8 and a laminar state of the undisturbed boundary layer is studied by the method of temperature-sensitive paints. Streamwise vortices are found in the region of reattachment of the separated flow in a wide range of Reynolds numbers (0.15 × 10⁶ – 2.55 × 10⁶) for various angles of flow deflection and plate lengths. It is demonstrated that the existence of these vortices induces transverse oscillations of the heat transfer coefficient; the amplitude of these oscillations may reach 30%. The maximum Stanton numbers reaching 80% are observed in the case with significant roughness of the leading edge of the flat plate. Both the maximum Stanton numbers in the reattachment region and the amplitude of transverse oscillations of the Stanton number induced by streamwise vortices are found to decrease significantly in the case of small bluntness of the leading edge. Solutions of three-dimensional Navier-Stokes equations are derived for some test conditions. The computed results are in good agreement with experimental data, which testifies to a significant stabilizing effect of small bluntness on the intensity of streamwise vortices.

For the first time polymorphisms in Kodar snow sheep, KOD ( Ovis nivicola kodarensis ) nuclear DNA were studied. KOD is a representative of small isolated population of Asian snow sheep ( Ovis nivicola Eschscholtz, 1829) inhabiting the Kodar Ridge (Irkutsk Oblast, Transbaikal Krai). We compared KOD with its geographically closest Yakut subspecies ( Ovis nivicola lydekkeri ). Genome-wide study of single-nucleotide polymorphisms (SNPs) was performed using the Illumina OvineSNP50 BeadChip (Illumina Inc., San Diego, CA, USA). The final set of markers for analysis included 1030 SNPs. We found that Kodar snow sheep had almost 10 times lower level of genetic diversity evaluated by multilocus heterozygosity - MLH (0.027 for KOD - 0.215-0.270 for individuals of Yakut subspecies) and standardized MLH - stMLH (0.116 against 0.910-01.147). The results of multidimensional scaling (MDS), Nei distances calculations ( DN ) and STRUCTURE analysis showed a clear genetic differentiation of Kodar snow sheep from Yakut subspecies. Our data represent the first step to understanding of the demographic history of the original Kodar population of snow sheep.

We studied brown bear ( Ursus arctos ) land use using satellite collars deployed on four animals in Kamchatka in 2005-2006 and three animals on Sakhalin Island in 2011-2012. The annual home range sizes ranged from 6.09 to 27.58 km2 for females and was 153.12 km2 for male. The sizes of annual core area of home range did not exceed 1.68 km2. Seasonal home range sizes were the highest in August and September and the lowest in May. Home ranges of two females in Kamchatka significantly overlapped, while a lower degree of overlap was found for two females in Sakhalin. Habitat use by bears depends on the seasonal distribution of food, in particular salmon.

Ranges of three studied alien fish species (rotan Perccottus glenii , sunbleak Leucaspius delineaus , and bleak Alburnus alburnus ) in the Ob River basin, West Siberia, have expanded. Our data prove the expansion of rotan and sunbleak ranges to the north. In particular, for the first time populations of rotan have been reported from the lower section of the Ob. We also present new data on range expansion of the studied fish species southward. All three species have probably reached southern limits of their possible distribution in the Upper Ob system getting into potamon/rhithron transition zone because the species under study prefer lowland waters. Spatial-temporal dynamics of their expansion reveals the role of the Ob River as the main invasion corridor enhancing their distribution mostly in meridional direction. In the system of the Upper Ob, rotan and sunbleak were found by us in isolated ponds and lakes as well as in floodplain and river systems. This is in agreement with the concept of two invasion vectors: translocation of fish by humans between water bodies and self-distribution along the river courses.

In order to compare the impact of alien common carp ( Cyprinus carpio ) and native bream ( Abramis brama ) on water chemistry, phyto- and zooplankton, and macrozoobenthos, nine enclosures, 9 м² each, were placed in the littoral zone of Lake Obsterno (Republic of Belarus) at a distance of 60 m from the shore. Feeding behavior of carp, characterized by extensive burrowing in the sediment, led to the change in the phytoplankton community structure. But the significant differences in algae biomass between control and fish enclosures were received only for diatoms algae. Carp had a more pronounced effect on abundance of large-bodied species of zooplankton ( Diaphanosoma brachyurum ) than bream did. For both fish species an increase in abundance of small-bodied Bosminа longirostris was recorded. Decreased abundance and biomass of macrozoobenthos occurred at a much higher rate within the carp enclosures, with the strongest impact on ephemeropterans. There was no difference in the consumption of chironomids and oligochaetes regardless of fish species.

Based on materials collected in 1963, 1998 and from 2009 to 2016, the subzonal changes in the population of the small mammals of the Prealtai plain are described, its classification and spatial-typological structure are given, the strength of the connection between nonuniformity of communities depending on environmental factors are estimated. The results of the analysis of the spatial inhomogeneity of the population of the West Siberian and Prealtai plains and mountain provinces of the Altai are compared.

The results of the study of taxonomic, ecological and phytocenotic structure of plant communities formed in the initial stages of overgrowing the anthropogenic sandy outcrops within the forest-tundra zone and the subzone of the northern taiga forests of West Siberia are presented. At the pioneering stages of vegetative cover restoration, there are two to eleven species growing into sparse communities of the Loiseleurio-Vaccinietea, Artemisietea vulgaris and Koelerio-Corynephoretea classes. The participation in the recovery succession on the sandy outcrops of some meso-xerophitic forest-tundra, meadow-margin and weed herbaceous plant species and dwarf shrubs mostly with ruderal and stress-tolerant eco-phytocenotic strategies, as well as with secondary strategies - violent-ruderal and ruderal-stress-tolerant strategies are shown. The primary succession begins at the bottom and slopes of the quarry ditches, as well as on the surface of the sand dunes, and proceeds on an accelerated scenario. In the initial stages of succession participate hygro-, meso- and xerophilous species, predominantly oligo-mesotrophic rhizome and densely turf grass plants and shrubs of the native flora as well as ground lichens.