The Influence of Temperature and Humidity on Greenhouse Gas Emission in Experiments on Imitation of the Full Vegetation Cycle of Tundra Ecosystems

Doklady Earth Sciences - Laboratory experiments were conducted in a hermetically sealed growth chamber with two soil samples obtained from the arctic tundra zone with different levels of moisture....     

On the amplitude of the radio response of the active region magnetosphere to long-period natural oscillations of sunspots

The following has been indicated for the cyclotron emission of microwave sources based on a simple modeling of a unipolar sunspot magnetosphere by the magnetic monopole, submerged in subphotospheric layers, and a temperature, changing with altitude as hyperbolic tangent. At insignificant changes in the sunspot magnetic field strength, originating as a result of oscillations of a sunspot as an integrated structure, the oscillation amplitude (in percent) of brightness temperatures of the Stokes I and V parameters at a wavelength of 1.76 cm (NoRH) is an order of magnitude as large as the magnetic field strength amplitude. This amplitude is of the same order of magnitude as the field oscillation amplitude at a wavelength of 5.2 cm (SSRT).     

Microwave emission from hot X-ray kernels in solar flares

Spectral and polarization characteristics of radio emission from hot X-ray kernels are considered. It is shown that the frequency spectrum of thermal cyclotron radio emission and bremsstrahlung from these regions may contain a set of lines at cyclotron harmonics and the maximum at plasma frequency. This makes possible the diagnostics of the X-ray kernel plasma and magnetic fields according to spectral and polarization observations of microwave radio emission in solar flares.     

Geoenvironmental problems of recreational use of the Ivankovo Reservoir

Methodical principles of recreational studies of reservoirs are discussed. The impact of main types of recreational water use on water quality is revealed using the Ivankovo Reservoir as an example.Translated from Vodnye Resursy, Vol. 32, No. 1, 2005, pp. 115–122.Original Russian Text Copyright © 2005 by Lantsova, Grigoreva, Tikhomirov.     

The “Upper Basalts” of the East Chukotka Segment of Okhotsk–Chukotka Belt: the Along Strike Migration of Volcanic Activity or the Overprint by Later Magmatic Event?

Doklady Earth Sciences - New U–Pb and 40Ar/39Ar isotopic dates on volcanic rocks of the East Chukotka segment of the Okhotsk–Chukotka Belt correspond to 76–71 Ma span, which is...     

Regional Retrospective Analysis of Water and Bottom Sediments in the Upper Volga

Water Resources - The dynamics of water quality in the Upper Volga was analyzed in the segment from the source to the Ivankovo Reservoir. It was found that the increase in anthropogenic stress in...     

Late Devonian and Triassic basalts from the southern continental margin of the East European Platform,tracers of a single heterogeneous lithospheric mantle source

In Late Devonian and Early-to-Late Triassic times, the southern continental margin of the Eastern European Platform was the site of a basaltic volcanism in the Donbas and Fore-Caucasus areas respectively. Both volcanic piles rest unconformably upon Paleoproterozoic and Late Paleozoic units respectively, and emplaced during continental rifting periods some 600 km away from expected locations of active oceanic subduction zones. This paper reports a comparative geochemical study of the basaltic rocks, and views them as the best tracers of the involved mantle below the Eastern European Platform. The Late Devonian alkaline basic rocks differ from the calc-alkaline Triassic basic rocks by their higher alkali-silica ratio, their higher TiO₂, K₂O, P₂O₅ and FeO contents, their higher trace element contents, a higher degree of fractionation between the most and the least incompatible elements and the absence of Ta-Nb negative anomalies. These general features, clearly distinct from those of partial melting and fractional crystallization, are due to mantle source effects. With similar Nd and Sr isotopic signatures indicating mantle-crust mixing, both suites would originate from the melting of a same but heterogeneous continental mantle lithosphere (refertilized depleted mantle). Accordingly the Nd model ages, the youngest major event associated with mantle metasomatism occurred during Early Neoproterozoic times (∼650Ma).     

The Okhotsk-Chukotka volcanic belt: Age of its northern part according to new Ar-Ar and U-Pb geochronological data

Current geochronological data on the Okhotsk-Chukotka volcanic belt (OCVB) and relevant problems are discussed. The belt evolution is suggested to be modeled based on ⁴⁰Ar/³⁹Ar and U-Pb dates more useful in several aspects than common K-Ar or Rb-Sr dates and methods of paleobotanical correlation. Based on new ⁴⁰Ar/³⁹Ar and U-Pb dates obtained for volcanic rocks in the OCVB northern part, the younger (Coniacian) age is established for lower stratigraphic units in the Central Chukotka segment of the belt, and the eastward migration of volcanic activity is shown for terminal stages of this structure evolution.     

Typification of oils in the Timan-Pechora province according to the composition of hydrocarbon biomarkers (steranes and terpanes)

Distinctive compositional features of cyclic saturated hydrocarbon biomarkers have been established in oils from the main petroliferous lithostratigraphic complexes of various structural zones in the Timan-Pechora petroliferous province (TPPP). Four geochemical families (types) of oils in TPPP are recognized based on the variations in the geochemical parameters of steranes and terpanes including sterane ratios C₂₇/C₂₉ and C₂₈/C₂₉, K¹ mat and K² mat, diasterane/regular sterane, pregnane (C_21–22)/sterane (C_21–22 + C_27–29), as well as terpane Ts/Tm parameters, adiantane C₂₉/hopane C₃₀, neoadiantane/adiantane, tryciclic terpane/pentacyclic terpane, hopane/sum of C₂₉ steranes, etc. The distribution of various types of oil in the sedimentary sequence of TPPP makes it possible to infer source rocks for each of the four selected types.