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1.
Water Resources - The article gives the results of integrated studies of bottom sediments in four watercourses in the central St. Petersburg: the rivers of Ekateringofka, Okhta, Fontanka, and...  相似文献   
2.
This study attempts to assess the influence of changing land-use patterns on the groundwater quality of the hard rock aquifer system in the Maheshwaram watershed, near Hyderabad, India. The study area is a rapidly urbanizing region with land development progressing at a fast pace. To study the impact of this rapid urbanization and overall land-use transition, a groundwater quality index (GQI) was prepared within a geographical information system (GIS). The GQI integrates the different water quality parameters to give a final index value that can be used for spatio-temporal comparisons. The land-use transitions were closely monitored from 2003 to 2008 using multispectral satellite images. The land-use pattern has changed drastically with an increase in the built-up area at the expense of other land uses. The analysis reveals a rapid deterioration of groundwater quality related mainly to the increase in built-up land with unsewered sanitation and poultry farms. Seasonal variability of the groundwater quality was also assessed. Mean GQI decreased from 84.16 to 83.26 over a period of 5 years from 2003 to 2008, while seasonal variability of water quality increased. GQI and Seasonal Variability of water quality were integrated in GIS to yield a groundwater sustainability map, in terms of water quality. Zones of sustainable and unsustainable groundwater use were demarcated for better decision making related to municipal land allotment in this rapidly urbanizing region.  相似文献   
3.
In this study, the hydrodynamics of lower Ganges basin in India has been monitored using radar altimetry data from environmental satellite (ENVISAT) mission and microgravity data from the Gravity Recovery and Climate Experiment (GRACE) mission. River stage time series have been constructed for different virtual stations on the lower Ganges. Time series for the integrated water volume changes from microgravity measurements have also been constructed to characterize the seasonal and interannual fluctuation patterns in water storage and flux. The ENVISAT dataset indicates an average seasonal river stage fluctuation of 8 m in the lower Ganges River. The GRACE dataset reveals a seasonal fluctuation ranging from 0.18 to 0.40 m in the vertically integrated total water storage in the lower Ganges basin. The two independent datasets show broad similarity in the lower Ganges basin and outline the importance of space-based techniques for monitoring continental water resources.  相似文献   
4.
We have analyzed the physical status of the pre-cataclysmic variables SDSSJ172406+562003 and RE J2013+4002, which have evolved after their common-envelope stage a time t = 106?107 years. Spectroscopy and photometry of these systems were performed with the 6-m and 1-m telescopes of the Special Astrophysical Observatory. We demonstrate that emission lines in the spectra were formed solely by the reflection of radiation emitted by the white dwarfs on the surfaces of their cool companions, under conditions close to local thermodynamic equilibrium. These effects are also responsible for most of the objects?? photometric variability amplitude. However, comparing the light curves of SDSS 172406 from different epochs, we find aperiodic brightness variations, probably due to spottedness of the surface of the secondary. Jointly analyzing the spectra, radial-velocity curves, and light curves of the pre-cataclysmic variables and modeling the reflection effects, we have derived their fundamental parameters. We demonstrate that the secondaries in these systems are consistent with evolutionary models for main-sequence stars and do not have the luminosity excesses characteristic of cool stars in young pre-cataclysmic variables.  相似文献   
5.
We present the spectral analysis of the physical state and evolution of the WZSge-type cataclysmic variable GSC02197-00886. The spectra of the system, covering the total orbital period at the time of the outburst on May 8, 2010, at the late relaxation stage, and in the quiescent state, were obtained at the SAO RAS 6-m BTA telescope in 2010–2012. From the absorption and emission HI, He I, and Fe II lines, we have determined the radial velocities for all the nights of observations and constructed the maps of Doppler tomography for the quiescent state. It was found that during the outburst the spectra of the object were formed in an optically thick accretion disk with an effective temperature of T eff ≈ 45 000 K and in a hotter boundary layer. During the relaxation of the system, the accretion disk gradually became optically thinner in the continuum and in the emission lines. In the quiescent state (July 2012), the continuous spectrum was dominated by the radiation of the cooling white dwarf with T eff = 18 000 K. The emission lines are formed on the surface of the cool star by the X-ray irradiation of the 1RXSJ213807.1+261958 source. We propose a method for determining the parameters of the white dwarf, based on the numerical modeling of the system spectra in the quiescent state and their comparison with the observed spectra. It is shown that the effective temperature of white dwarf has decreased by ΔT eff = 6000 K during the relaxation from August 2010 to July 2012. We have obtained a set of parameters for GSC02197-00886 and shown their good agreement with the average parameters of the W Z Sge-type systems, presented in the literature.  相似文献   
6.
Analysis of photometric and spectroscopic observations of GSC 02197-00886 at the outburst maximum (on May 8, 2010) and at the stage of relaxation towards the quiescent (on August 4, 2010) was performed. Radiation of an optically thick accretion disc with a hot boundary layer dominates the spectra, which are consistent with the spectra of a WZ Sge-type dwarf novae. In the relaxation phase, an optically thin accretion disc with radiation in the HI and HeI emission lines is observed against the background of the absorption spectrum of a white dwarf. The parameters of GSC 02197-00886, which were determined by combining the radial velocities of the components with the assumption that the secondary component is close to mainsequence stars, differ significantly from the parameters that characterize other WZ Sge-type systems. We hypothesize that the secondary component was excited in the course of the outburst and experienced long-lasting relaxation towards the main-sequence state.  相似文献   
7.
This paper analyzes the possible impact of lunar phases on the dynamics of acute cardiovascular diseases: acute myocardial infarctions (MIs) and acute brain strokes (BSs) at different levels of heliogeomagnetic activity. The superposed epoch analysis (SEA) has been applied with dates of the new moon and full moon used as reference days. A statistical analysis of a 14-year-long (1992 to 2005) series of everyday medical data from the Central Clinical Hospital no. 1 of Russian Railways (Moscow) and the parameters of heliogeomagnetic activity was carried out. It was found that daily occurrences of MIs and BSs vary with the phase of the moon. These variations are significant; they continue at different levels of heliogeomagnetic activity and are not related to the variations in geomagnetic activity identified by the same method. The effect of lunar phases on MIs and BSs is quite different. New moons and full moons have qualitatively the same effect on MIs; however, there are significant differences in the incidence of BSs during new moons and full moons.  相似文献   
8.
The analysis of diatom, palynofloral, and benthic foraminiferal assemblages made it possible to substantiate the age of Cenozoic sections recovered by wells on the northern and northeastern Sakhalin shelf. Biostratigraphic materials, lithological properties of stratigraphic units, and standard logs served as the basis for developing the first stratigraphic correlation scale of Cenozoic sequences on the Sakhalin shelf.  相似文献   
9.
An analysis of IZNIRAN magnetic observatory data indicated that geomagnetic storms with sudden and gradual commencements form two independent populations with respect to the disturbance occurrence time and character because the solar sources of these disturbances are different. Storms with sudden and gradual commencements are caused by coronal mass ejections and high-speed solar wind streams from coronal holes, respectively.  相似文献   
10.
The results of studying biological aerosols (pollen spectra) in precipitation registered in the south of Western Siberia in the winter of 2014/15 are presented. Pollen grains of birch (Betula sp.), willow (Salix sp.), pine (Pinus sp.), and poplar (Populus sp.) were identified in the three of 28 analyzed precipitation samples. The comprehensive analysis of synoptic conditions during precipitation, back trajectories of air masses calculated with the HYSPLIT model as well as the analysis of the Northern Hemisphere snow cover dynamics and the area of distribution of the identified taxa were carried out. The results allowed determining the Euro-Scandinavian region as the main source of pollen grains inflow with precipitation to the south of Western Siberia in March 2015.  相似文献   
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