Influence of Biogenous Elements on Components of the Lake Baikal Plankton Community

Fertilization experiments in mesocosms of 1 … 2,000 1 containing up to 0.32 mg/l P and 1.7 mg/l N in summer and in winter did not show any significant changes of the hydrochemical conditions and in the bacterio-plankton. CO₂-assimilation (14-C method) is reduced by circa 10= by nutrient doses, whereas the chlorophyll concentration increases significantly due to addition of P and N at the same time in summer, a decrease taking place in winter. The different courses of development are connected with different reactions of individual species of phytoplankton.     

Impact of Natural Extreme Events on Geophysical Fields in the Environment

Izvestiya, Physics of the Solid Earth - Abstract—The effects of the strong natural events on the acoustic fields in the atmosphere, geomagnetic field, and electrical characteristics of...     

Acoustic Effects of Strong Earthquakes

Izvestiya, Physics of the Solid Earth - Absrtact—The results of instrumental observations of acoustic effects from a number of strong earthquakes in Albania, Greece, Iran, and Turkey with...     

Near-surface geophysics: Complex investigations of the lithosphere-atmosphere interactions

The key trends and problems in the study of interactions between the geospheres in the near-surface areas of the continental crust of the Earth which are of most interest for the formation of living environment are formulated. The main periodicities in the variations of geophysical fields determining the natural environmental rhythms are determined. The interactions and transformations of geophysical fields (electric field in the ground and in the atmosphere, radon emanation field, and the field of microseismic vibrations) are considered. It is noted that the tectonic discontinuities and weak disturbances in the solid Earth such as lunar-solar tides and variations in the atmospheric pressure play an important role in the formation of the regimes of geophysical fields at the boundary of the Earth’s crust and the atmosphere. The synchronous instrumental observations reveal a mutual influence and significant correlation between the amplitude variations of geophysical fields of different nature.     

Tidal effects in geomagnetic variations

Doklady Earth Sciences - This paper reports the results of processing and analysis of geomagnetic variations, estimates of their spectra, and the first identified waves of lunar–solar tides...     

The specific features of geophysical fields in the fault zones

Instrumental measurements of geophysical fields in several regions of the Earth’s crust with a complex structure and tectonics are analyzed. The observed geophysical fields include the electric field in the boundary layer of the atmosphere and in the subsurface crust, the ground magnetic field, and the fields formed by microseismic vibrations and natural radon emanation. It is shown that the fault zones are characterized by noticeably higher (compared to the middle segments of crustal blocks) variations in the geophysical fields, a stronger response to the faint external impacts in the form of lunisolar tides, and baric variations in the atmosphere, as well as by higher intensity relaxation processes. Energy transformations between the geophysical fields of different origins are observed predominantly in the fault regions.     

Paragenetic relations of diamond with silicate and carbonate minerals in the carbonatite-diamond system: Experiments at 8.5 GPa

Phase relations of diamond and syngenetic minerals were experimentally investigated in the multicomponent system natural carbonatite-diamond at a pressure of 8.5 GPa and temperatures of 1300–1800°C (within the thermodynamic stability field of diamond). Under such conditions, the natural carbonatite of the Chagatai complex (Uzbekistan) acquires the mineralogy of Ca-rich eclogites (grospydites). The melting phase diagram of this system (syngenesis diagram) was constructed; an important element of this diagram is the diamond solubility curve in completely miscible carbonate-silicate melts (solubility values are 15–18 wt % C). The diamond solubility curve divides the phase diagram into two fields corresponding to (1) phase relations involving diamond-undersaturated melts-solutions of carbon with garnet as a liquidus phase (region of diamond dissolution) and (2) phase relations with diamond-saturated melts-solutions with diamond as a liquidus phase (region of diamond crystallization). During a temperature decrease in the region of diamond crystallization from carbonate-silicate melts, the crystallization of diamond is accompanied by the sequential formation of the following phase assemblages: diamond + garnet + melt, diamond + garnet + clinopyroxene + melt, and diamond + garnet + clinopyroxene + carbonate + melt, and the subsolidus assemblage diamond + garnet + clinopyroxene + carbonate is eventually formed. This is indicative of the paragenetic nature of silicate and carbonate minerals co-crystallizing with diamond and corresponding primary inclusions trapped by the growing diamond. A physicochemical mechanism was proposed for the formation of diamond in carbonate-silicate melts. The obtained results were used to analyze the physicochemical behavior of a natural diamond-forming magma chamber.     

Population Structure of the SW Atlantic Estuarine Crab Neohelice granulata Throughout Its Range: a Genetic and Morphometric Study

Phylogeographic patterns of the SW Atlantic estuarine crab Neohelice granulata were examined using mitochondrial DNA cytochrome oxidase I sequences and analyzed together with morphometric data. Specimens were sampled during a 4-year period (2001?C2004) from 11 localities encompassing the full distributional range of this species along the SW Atlantic (22°57?? S to 42°25?? S). DNA sequences were obtained from 69 individuals belonging to seven localities, and morphometric variation in 12 continuous characters was analyzed for 646 crabs from ten localities. Strong genetic differentiation, consistent with a pattern of isolation-by-distance, was detected among all localities indicating that gene flow occurs mainly between neighboring populations. Analyses of molecular variance showed genetic subdivision between the southern (Argentina) and the northern (Brazil) sites, suggesting restricted gene flow at a regional scale. The genetic structure of this species could be divided into two distinct groups due to a limited gene flow between southern and northern regions as a consequence of larval dispersal patterns. Coastal currents in the vicinity of the Rio de la Plata likely act as a barrier to dispersal within the species range. Moreover, genetic data indicate that populations of N. granulata might have undergone a northward demographic expansion since the late Pleistocene. The morphometric analysis showed no geographical pattern of morphological differentiation, although there were differences among sampling sites.