Experimental Study and Mathematical Modeling of Hg and Cu Transformations in the Water–Bottom Sediment System

The results of laboratory modeling of transformations of the ionic forms of Hg and Cu are discussed. The processes considered include the formation of organic and inorganic complexes, sorption on mineral suspension and bottom sediment. A peak in the concentration of organic complex of metals is found to exist. Published data are used to study the physicochemical mechanism of metal transformations in the water–bottom sediment system and to develop a mathematical model of these processes. An explanation is given to the metal concentration peak, which forms in water as a result of the competition between complex formation and sorption processes. Comparison of the experimental and model curves allowed the evaluation of the kinetic coefficients of the complex formation and sorption stages.     

Primary production and phytoplankton characteristics as eutrophication criteria of Kursiu Marios Lagoon, the Baltic Sea

The results of studies of phytoplankton production, biomass, and species composition conducted in Kursiu Marius Lagoon in 2001, 2002 are presented. A significant effect of blue-green alga blooming on the trophic status and processes in the coastal part of Kursiu Marius Lagoon is revealed. It is shown that the mass development of algae in combination with setup phenomena can cause alga accumulation in the coastal zone, oxygen deficiency, and fish kills.     

Lower precambrian metapelites of the Yenisei Range: REE systematics,provenances, paleogeodynamics

Doklady Earth Sciences -     

Numerical modelling of wavefields in three-dimensional inhomogeneous media

Summary. Numerical modelling is one of the most efficient methods for an investigation of the relationship between structural features and peculiarities of observed wavefields. It is practically the only method for 2-D and 3-D inhomogeneous media.
An algorithm based on ray theory has been developed for calculations of travel times and amplitudes of seismic waves in 3-D inhomogeneous media with curved interfaces. It was applied for numerical modelling of kinematic and dynamic characteristics of seismic waves propagating in laterally inhomogeneous media.
Travel-time and amplitude patterns were studied in the 2-D and 3-D models of a geosyncline, in which velocity distribution was given by an analytical function of the coordinates. For a more complicated model representing a subducting high-velocity lithospheric plate in a transition zone between oceanic and continental upper mantle, the velocity distribution was given by discrete values on a 2-D non-rectangular grid. It was shown that when a source was placed above the lithospheric plate, a shadow zone appeared along a strike of the structure, i.e. in the direction which is perpendicular to a strong lateral velocity gradient. Travel-time residuals were calculated along the seismological profile for a 3-D velocity distribution in the upper mantle beneath Central Asia, obtained as a result of inversion of travel times by the Backus-Gilbert method. They were found to be in a good agreement with the observed data.     

Seasonal and Inter-Annual Variability of Wind-Driven Upwelling near the East Coast of Sakhalin Island Based on QuikSCAT/SeaWinds Scatterometer Data

Izvestiya, Atmospheric and Oceanic Physics - In this paper, seasonal and interannual upwelling variability in the Sea of Okhotsk off the eastern coast of Sakhalin Island based on wind data obtained...     

Seasonal dynamics and Trophic interactions of phytoplankton and zooplankton in the Vistula Lagoon of the Baltic Sea

The trophic relationships of the phytoplankton and zooplankton in the Vistula Lagoon in 2008?C2010 were investigated. In the current period, the lagoon is an eutrophic water body with summer blooms of blue-green algae. The trophic level of the Vistula Lagoon influences both the composition and quantitative characteristics of the communities of phytoplankton and zooplankton and the trophic relationships between them. In the analyzed period, the consumption of phytoplankton by the zooplankton on the average in the growing season was 28%, which is 1.5 times higher than in the late 1970s. The high grazing pressure of the zooplankton on the phytoplankton reduces its biomass, production, and the intensity of the blooming by the blue-green algae in the Vistula Lagoon.     

Late Vendian postcollisional leucogranites of Yenisei Ridge

The Late Vendian (540–550 Ma) U–Pb zircon age of postcollisional granitoids in the Osinovka Massif was obtained for the first time. The Osinovka Massif is located in rocks of the island-arc complex of the Isakovka Terrane, in the northwestern part of the Sayany–Yenisei accretion belt. These events stand for the final stage of the Neoproterozoic history of the Yenisei Ridge, related to the completing accretion of the oceanic crust fragments and the beginning of the Caledonian orogenesis. The petrogeochemical composition and the Sm–Nd isotopic characteristics support the fact that the granitoid melt originated from a highly differentiated continental crust of the southwestern margin of the Siberian Craton. Hence, the granite-bearing Late Riphean island-arc complexes were thrust over the craton margin at a distance considerably exceeding the dimensions of the Osinovka Massif.     

Geochemistry of Riphean terrigenous rocks in the Southern Urals and Siberia and variations of the continental-crust maturity

We consider the general and specific features of the evolution of the composition of fine-grained terrigenous rocks in the Riphean sedimentary megasequences of the Southern Urals, Uchur-Maya region, and Yenisei Ridge. It has been established that the crust on the southwestern (in the modern frame of references) periphery of the Siberian craton was geochemically the most mature segment of the Riphean continental crust. For example, the fine-grained clastic rocks and metapelites of all Riphean lithostratigraphic units of the Yenisei Ridge have higher median contents of Th than the most mature Paleoproterozoic crust, and in median contents of Y and Cr/Th values they are the most similar to it. In the Southern Urals and Uchur-Maya region, some units of the Riphean sedimentary sequences show median contents of Y and Th and Cr/Th values close to those of primitive Archean crust. Analysis of Cr/Th variations in the fine-grained terrigenous rocks of all three megasequences shows that the minimum Cr/Th values, evidencing a predominance or the abundance of felsic rocks in provenances, are typical of the Riphean argillaceous shales and metapelites of the Yenisei Ridge. The distinct Cr/Th and Cr/Sc increase in the fine-grained clastic rocks of the Chingasan Group of the ridge reflects the large-scale destruction of continental crust during the formation of rift troughs as a result of the Rodinia breakup in the second half of the Late Riphean. The Cr/Th variations in the Lower and Middle Riphean argillaceous shales and mudstones of the Bashkirian mega-anticlinorium and Uchur-Maya region are in agreement, which evidences the subglobal occurrence of rifting in the early Middle Riphean (so-called “Mashak rifting”).