Luminescence of Eu<Superscript>2+</Superscript> in feldspars from muscovite pegmatites

The data on photoluminescence (PL) that precisely detects Eu²⁺ centers and X-ray luminescence (XL) were compared for plagioclases and potassium feldspars in 21 samples from muscovite pegmatites of the Mama region. The Eu contents determined in 10 samples vary from 10^?4 to 10^?6 wt %. Europium occurs mainly as bivalent species that replaces Sr²⁺, Ca²⁺, and Ba²⁺. Eu is gained in the products of early crystallization, and its relative amounts decrease by an order of magnitude in the course of pegmatite formation down to complete disappearance in late generations of feldspars. It is shown that Eu²⁺ can be detected in XL spectra, and the Eu²⁺ content can be determined in qualitative terms, for instance, by the intensity of radiation band 400–420 nm in plagioclase.     

Problems in determining spatial inhomogeneity of <Superscript>137</Superscript>Cs fallout for estimating rates of erosion-accumulative processes

The issues of assessing variability of ¹³⁷Cs fallout of global and Chernobyl origin at reference sites are discussed with a purpose to use this isotope as a tracer for estimating the rates of erosion-accumulative processes. It is shown that local variability of soil contamination by ¹³⁷Cs at reference sites is within 7–20%, which makes it possible to use the isotope as a tracer. When studies are conducted within drainage basins, the available trend of the atmospheric ¹³⁷Cs fallout should be taken into account in assessing the soil and sedimentation redistribution.     

Late Vendian-Early Cambrian formations of the north-west Siberian Craton

The composition and structure of principal key-sections for the Tira (Late Vendian) and Danilovo (Late Vendian-Early Cambrian) Horizons were characterized on the basis of deep-drilling data and studies of natural outcrops along the peripheries of the Kureika syneclise. The typical sedimentary formations/associations were recognized, their vertical and lateral successions were distinguished, and their deposition environments were interpreted. A distribution pattern scheme of thicknesses and depositional environments of Upper Vendian-Lower Cambrian deposits was compiled at the 1: 1000000 scale. The reservoir characteristics of the formations are discussed and forecasted for poorly studied areas of the northwestern Siberian platform.     

Depositional environments of the lower Jurassic-Aalenian reservoir of the Vilyuy syneclise

Lithological analysis was used to study the structure, depositional environments, and gas potential of the Lower Jurassic-Aalenian terrigenous reservoir rocks within the Vilyuy syneclise. The results were used to predict the extent of permeable sand reservoirs and thickness distribution of regional seals.     

Trophic relationships in the community of a bivalve mollusk and a boring polychaete

The community of the Japanese scallop Mizuhopecten yessoensis with its dominant endobiont polychaete Polydora brevipalpa, which bores into the scallop’s shell, was studied. It was established that the bulk of the scallop’s food ration consists of diatom algae and, to a lesser extent, flagellates and small invertebrates. The polychaete species considered mainly assimilates diatom algae and, to a significant degree, bacteria. Thus, the elements of the community enter competitive food relations. In the process of feeding, the scallop excretes detritus with its pseudofeces and this way increases the concentration of food available for polychaetes. In the course of its motion and filtration, the scallop enhances the water flow around the polychaete, which also favors the feeding of the latter. Meanwhile, negative relations between the degree of the population of the scallop’s shell by polychaetes and the volume of its internal cavity were recognized; this indicates a decrease in the potential for water filtering and, correspondingly, for food procuring by the host mollusk. With the increase in the polychaete-related bioerosion of the shell, the linear sizes and weight parameters of the scallop fall together with the rate of its growth.     

Long-range radionuclide transport in the atmosphere and water bodies

A long-range atmosphere transfer of radionuclides from nuclear explosions and nuclear plant accidents is considered. Data on radionuclide transport in the Yenisey, Pripet, Sozh, Iput’, and Besed’ rivers are presented. The time of the radionuclide transport from the Irish Sea to the Baltic and Barents seas is defined using changes in the cesium 134/cesium 137 isotope ratio.     

Parameters of Electric Currents in Active Regions with Different Levels of Flare Productivity and Different Magnetomorphological Types

Geomagnetism and Aeronomy - In this paper, the magnetic-field and electric-current parameters are calculated for a sample of 73&nbsp;active regions (ARs) of solar activity cycle 24 based on...     

Social-demographic development of Vologda Oblast during the intercensal period 1970-79

"Demographic trends in Vologda Oblast are analyzed on the basis of 1979 census results as a case study of an oblast involved in the [development] program for the Nonchernozem Zone of the RSFSR. The trend in the 1970-79 intercensal period was for continuing growth of urban population, especially in the two major urban centers of Vologda and the iron and steel city of Cherepovets, and depopulation of rural areas. The age-sex structure is distinguished by a strong aging trend and sex imbalance, especially in rural areas. Despite the proclaimed aim of fostering abandonment of tiny rural places (with 25 residents or less), the number of places in that size class actually increased during the intercensal period (from 40% of all rural places in 1970 to 52 percent in 1979)."     

Effect of reducing groundwater on the retardation of redox-sensitive radionuclides

Laboratory batch sorption experiments were used to investigate variations in the retardation behavior of redox-sensitive radionuclides. Water-rock compositions were designed to simulate subsurface conditions at the Nevada Test Site (NTS), where a suite of radionuclides were deposited as a result of underground nuclear testing. Experimental redox conditions were controlled by varying the oxygen content inside an enclosed glove box and by adding reductants into the testing solutions.