Water Quality Estimation Based on Histological Investigations of Fish: Case Study of Kenozero Lake

Specific hydrological and hydrochemical conditions in Kenozero Lake have led to changes in the morphology of fishes at a cellular level. The abnormalities in the function of the respiratory, digestive, and excretory systems were recorded. The degree of pathology depended on the ecological features of the fish. The pathological changes were most pronounced in the gills of the fish species (orfe, perch, and roach) characterized by active mode of life and sensible to oxygen deficiency. The changes in the epithelium of gill filaments had a compensatory significance and were aimed at increasing the area of the functional surface of the gills under the conditions of hypoxia.     

Formation of the fast ice from the seasonal ice and its destruction

Considered is the theoretical mechanism of the formation of immovable ice cover along the coast (the fast ice) from the seasonal ice and the mechanism of its destruction. It is demonstrated that the process of formation and spread of the winter stable fast ice is determined by simultaneous impact of several factors: the morphometry of the coast and bottom, the width of the close ice, dynamic effects that shear stress forces of the flow and wind make on the ice, the duration of maintaining the condition of immobility and freezing (adhesion) of the ice, the thickness of adhered ice, and the intensity of thermal growth of ice from below. It is revealed that the permanent factor is the morphometry of coasts and the bottom while the other factors have temporal variability of various scales.     

Influence of strong sudden stratospheric warmings on ozone in the middle stratosphere according to millimeter wave observations

This paper reports the study data on variations in the ozone content in the middle stratosphere over Moscow based on millimeter wavelength observations during a range of midwinter sudden stratospheric warmings that occurred in the past two decades. The relation of ozone with planetary waves and the intensity of the polar stratospheric vortex has been established. The ozone vertical distribution has been monitored with a highly sensitive spectrometer with a two-millimeter wave band. The discovered phenomena of a relatively long-term lower ozone content in December in the considered cold half-year periods are related to the higher amplitude of the planetary wave with n = 1. Such phenomena preceded the development of strong midwinter stratospheric warmings, which, in turn, were accompanied by a significant increase in the ozone content in January. This ozone enrichment was related to the lower amplitude of the wave with n = 1 and higher amplitude of the wave with n = 2 and was accompanied by geopotential H _c.v. growth in the polar vortex center. Specific features of variations in the ozone content under the influence of the major atmospheric processes are observed not only in certain cold half-year periods but are also well seen in the general averaged pattern for winters with strong stratospheric warmings.     

Satellite Monitoring of the Northern Territories Disturbed by Oil Production

The results of satellite monitoring of the state of northern territories disturbed by oil production are presented by the example of the Usinsk oil field in the Komi Republic. The sets of vegetation indices formed by the results of processing long-term series of multispectral satellite images for the period from 1988 to 2014 are analyzed. They are used to assess long-term environmental changes, to reveal the most disturbed zones, and to estimate the dynamics of changes in the vegetation cover area caused by the extraction and transportation of hydrocarbons.     

Polychlorinated biphenyls and hydrocarbons in bottom sediments of Pechora Basin Rivers

The quantitative concentrations of 21 congeners of polychlorinated biphenyls and 16 priority polycyclic aromatic hydrocarbons were studied in bottom sediments of the Usa River, the largest Pechora’s tributary, and its tributaries located in the central part of Timan-Pechora petroleum province. In accordance with the classification of the regional and international standards, the pollution degree of bottom sediments by organic compounds of those classes was evaluated. Pollution profiles were examined and the character of the dominating source of polychlorinated biphenyls and polycyclic aromatic hydrocarbons for bottom sediments in the region under study was identified. Key words: bottom sediments, polychlorinated biphenyls, profiles of polycyclic aromatic hydrocarbons, petrogenic, pyrogenic pollution source.     

Population Structure of White Sea Harp Seals (<Emphasis Type="Italic">Pagophilus groenlandicus</Emphasis>) as an Adaptation to Habitat Conditions

The spatiotemporal distribution of harp seal pups around breeding grounds in the White Sea is considered. It is shown that spatial localization of groups of females with different terms of mass pup birth takes place. This somewhat confirms the data on the gregarious structure of White Sea harp seal population. It is possible to explain the structure of this adaptation of the seal population to different living conditions in different feeding areas.     

Changes in integral and aerosol atmospheric turbidity in Trans-Baikal and Central Siberia

The analysis of time series of the Linke turbidity factors is performed for the atmosphere mass m = 2 (T ₂) and atmospheric aerosol optical thickness for the wavelength λ₀ = 0.55 μm (AOT) from the data of 14 actinometrical stations of Central Siberia and Trans-Baikal territory. It is shown that over the period from 1976 to 2006, the increased atmospheric transparency is observed in the region. Quantitative estimates of changes in multiyear mean annual variations of T ₂ and AOT at different periods of averaging and for different time periods are derived.     

Fossil gas-seepage marks in coal-bearing sequences of the Lviv-Volyn basin

The work discusses morphology, vertical and lateral distribution, and genesis of gas-seepage marks first established in the Carboniferous coal-bearing sequence of the Lvov-Volyn Basin. The abundance of gasseepage marks inPosidonia horizons confined to the basal part of the upper coal-bearing subformation is noted. The unique character of established gas-seepage marks and the necessity of their further study for the resolution of many scientific and applied problems are emphasized.