Asymmetry of Sunspot Distribution in Solar Cycles 12–24 and the Gnevyshev–Ohl Rule

Geomagnetism and Aeronomy - The nonaxisymmetric component of the sunspot distribution (longitudinal asymmetry) is considered based on the Greenwich–USAF/NOAA data for 1874–2016. Vector...     

Conflagration fires in taiga landscapes of Central Siberia

We examine the issues relating to the origin of conflagration fires, and the conditions for their emergence and occurrence in taiga landscapes of Central Siberia. We carry out an analysis of the natural-pyrological conditions of landscape where conflagration fires occur.     

Mineralized lakes of the Transbaikalia and Northeastern Mongolia: Specific features of occurrence and ore-generating potential

The paper presents a review of shallow lakes on two neighboring territories, Transbaikalia in Russia and Northeastern Mongolia. Five systems of shallow lakes are distinguished in the regions under study: Barguzin, Eravna-Gusinoozersk, Ingoda, Onon-Borzya, and Eastern-Mongolian systems. The shallow lakes are sub-grouped according to common chemical compositions and geochemical evolution types. Characteristics of ground- and surface waters feeding the lakes are considered. Based on results of trace element analyses of water samples from about 200 lakes and more than 100 springs, wells and boreholes, elements that manifest higher concentrations, resulting from evaporation of lacustrine waters, are determined. Prospects of assessment of ore-generating potential of the shallow lakes as ‘liquid ore’ sources in view of commercial extraction of Li, U, REE, and others metals are discussed.     

Iodine and selenium speciation in natural waters and their concentrating at landscape-geochemical barriers

Drinkable waters in Bryansk oblast are generally poor in I and Se. Possible I and Se speciation in the drinkable waters and their means of migration and concentration in soils at geochemically contrasting conditions are analyzed, and the possible reason for the high mobility of I is demonstrated to be predetermined not only by its occurrence in the form of iodide and organic complexes but also by solute mineral species (CaI⁺ and MgI⁺), with the former and the latter types of the complexes spread more widely in the polessky and opolny landscape types, respectively. Iodine complexation with alkali-earth cations under reduced neutral-weakly alkaline conditions facilitates, on the one hand, vertical iodine migration and, on the other hand, its precipitation on the carbonate barrier. The predominant solute species of Se in these environments is hydroselenide, which can form FeSe in the presence of significant Fe concentrations and be precipitated on the reduced barrier in soils of hydromorphic landscapes. The generally low total I and Se concentrations in the drinkable waters and the migration of solute compounds of radioactive I in the form of organic and inorganic complexes could likely result in a higher thyroid morbidity rate over the whole territory of Bryansk oblast, including areas contaminated with radioactive I isotopes after the accident at the Chernobyl nuclear power plant.     

Transversal small-scale MHD perturbations in space plasma with magnetic surfaces

This paper analyzes transversal small-scale perturbations in arbitrary three-dimensional (3D) spatially nonuniform space plasma systems with magnetic surfaces and deduces a system of equations for these perturbations. It shows that a dipole magnetic field can have perturbations of two different polarizations. Within dipole geometry, it derives equations for MHD-eigenmodes and investigates stability of the perturbations.     

Epigenetic Graphitization in the Basement of the Siberian Craton as Evidence of the Migration of Hydrocarbon-enriched Fluids in the Paleoproterozoic

Doklady Earth Sciences - This paper reports on diagnostic and structural studies that were first carried out for carbonaceous material of quartz–muscovite dynamoschists from the schistosity...     

Concentrations of heavy metals in bottom sediments of Lake Dautkul as an indicator of anthropogenic impact in the area south of the Aral Sea

Data on the microelement composition of bottom sediment and water samples from Lake Dautkul for recent years are presented. Concentrations of more than 30 chemical elements are determined using instrumental neutron-activation analysis. This allowed the authors to reveal the regularities in the distribution and accumulation of chemical elements in water and bottom sediments. It is shown that bottom sediments exhibit a cumulative effect and prolonged activity, which adversely affect the aquatic medium and can serve an indicator of anthropogenic impact on the area under consideration.