977 resultados para Vladimir Mayakovsky
Resumo:
From July 4 to 18,1995 surface chlorophyll a concentrations (C_cs) and integral primary production (C_ps) were studied in the northeastern part of the Norwegian Sea (73°42'N; 13°16'E), over a test area where an accident of the nuclear submarine Komsomolets had taken place. It was found that during this interval C_cs decreased by factor of about 3.3 (from 0.78 to 0.24 mg/m**3); average chlorophyll concentration within the photo-synthetic layer (C_cl) decreased by factor of about 3.5 (from 0.97 to 0.28 mg/m**3). The value of C_ps in the water column varied slightly (from 445 to 539 mg C/m**2 per day), since decrease in C_cl was compensated both by 1.5-fold growth of the photosynthetic layer thickness (from 40 to 60 m) and by 2.1-fold increase in its average assimilation number (from 0.58 to 1.20 mg C/mg chl a per hour). Monthly averages of C_ps were obtained from published data on seasonal C_cs changes and on the level of incident solar irradiation. They were found to be less than 100 mg C/m**2 per day in March and October and 100-500 mg C/m**2 per day in April-June. Annual primary production calculated from above values was equal to 105 g C/m**2.
Resumo:
Combined geodetic, geophysical and glaciological in situ measurements are interpreted regarding surface height changes over subglacial Lake Vostok and the local mass balance of the ice sheet at Vostok station. Repeated GPS observations spanning 5 years and long-term surface accumulation data show that the height of the lake surface has not changed over the observation period. The application of the mass conservation equation to purely observational data yields an ice mass balance for Vostok station close to equilibrium.
Resumo:
This set provides 1779 CTD profiles of temperature and salinity measured with a russian "Zond-Bathometer" by the research vessels Yakov Gakkel and Vladimir Parshin, of the former Soviet Union, during 1987-1990. It is dedicated to the memory of Professor Ivan Ovchinnikov (1931-07-14 to 2000-06-10) who initiated the soviet program of research of the Mediterranean Sea and contributed significantly to the investigation of physical processes in the Mediterranean Sea.
Resumo:
Results of comprehensive geological, geophysical and geochemical studies carried out in the Cape Verde Fracture Zone (Central Atlantic) during Cruise 9 of R/V ''Antares'' (1990-1991) are published in the book. Detailed characterization of various bedrock complexes (ultrabasites, gabbroids, dolerites, basalts, metamorphic rocks) is given. Geological conditions of newly found hydrothermal mineralization in the area are described. Problems of ore melts are under consideration. New data on hydrochemical anomalies and heat flow are given. The book contains original materials on sedimentary formations of the area.
Resumo:
Mineralogy of suspended matter from surface and bottom waters has been studied at two sites in the Barents Sea. Along with terrigenous minerals, particulate matter samples contain authigenic mineral phases of iron and manganese oxyhydroxides. Mn-feroxyhite, Fe-vernadite, goethite, and proto-ferrihydrite have been identified in samples from the surface waters, whereas birnessite and non-ferruginous vernadite have been found in samples from the bottom waters. Formation of suspended manganese minerals in the bottom waters is explained by an additional Mn supply from underlying reduced sediments during their early diagenesis and oxygen depletion in the near-bottom nepheloid layer. Bacteria are supposed to take part in the authigenic mineral formation.
Resumo:
Isotopic compositions of uranium (234U and 238U) and thorium (230Th and 232Th) were measured in metalliferous sediments from the western flank of the East Pacific Rise at 21°-22°S, in the area of hydrothermal activity and massive sulfide accumulation at the axis of the EPR. Concentration of 232Th (on the carbonate-free base) is consistent with composition of mafic extrusive rocks; isotope ratios 232Th/238U and 234U/238U indicate that about 70% of uranium passes into sediments from sea water with hydrothermal iron hydroxide. Mean sedimentation rates are calculated for seven cores by the nonequilibrium 230Th method with use of the constant concentration model. Flux of 230Th to bottom sediments is calculated and its mean value is used to determine sedimentation rate in four other cores. The constant flux model is used to calculate change of sedimentation rate with depth for seven cores over time interval of 100-300 ky. Sedimentation rates varied not much (0.3-0.6 cm/ky). The greatest changes occurred in two cores: one located near massive sulfide structures, and another near the spreading axis. Determinations of mean rates by the radiocarbon method and the nonequilibrium thorium method are in good agreement.