Mathematical modeling of marine environment pollution processes by petroleum hydrocarbons and their degradation in Caspian Sea ecosystem

The available observational data on the pollution of tributaries and areas of the Caspian Sea by petroleum hydrocarbons and products are examined. The possible petroleum input from sources in the sea is assessed using up-to-date data of satellite observations of sea surface pollution by oil films. The hydroecological CNPSi-model is applied to studying water pollution processes by petroleum hydrocarbons in ten areas chosen in the Caspian Sea and the subsequent biodegradation of those pollutants. The model calculations of the within-year dynamics of petroleum hydrocarbon concentrations use mean annual observational data on within-year variations in water mediium characteristics (water temperature, light intensity, and transparency), as well as the morphometric parameters of sea areas (the area, mean depth, and water volumes). The characteristics of water exchange between the areas were evaluated using a hydrodynamic model. The model calculations were used to characterize the within-year variations in petroleum hydrocarbon concentrations, the biomasses of petroleum-oxidizing bacteria, the characteristics of their oxidation activity and bioproduction, and the internal fluxes of petroleum hydrocarbons (their input from various sources, horizontal and vertical transport, and biotransformation) in different sea areas. Calculation results were used to compile annual balances for the processes of input and consumption of petroleum hydrocarbons in the chosen and aggregated sea areas.     

Sulfate reduction in natural water bodies: 2. Empirical models for process rate assessment

Empirical models that are used to assess sulfate reduction rates in the aquatic environment and bottom sediments of water bodies are discussed. Such models, with different detail, take into account the effect of the major habitat factors (the concentrations of organic matter, its components, and sulfates; ambient temperature; the numbers and activity of sulfate-reducing bacteria) on matter oxidation transformation during the sulfate reduction process. Improvements in the empirical models are proposed with the aim to more adequately account for the effect of environmental factors on the sulfate reduction rate distribution in water bodies. Validation of such models and the assessment of their parameters are demonstrated against available observational data collected at appropriate water bodies.     

Gravitationally Injective Mixtites: A New Type of Mass Transport Deposits

Doklady Earth Sciences - An analog experiment simulating the dynamics of density gravitational flows and the mechanism of their burial in the sedimentary cover section was conducted. As a result, a...     

The Deformation Mechanisms of Tien Shan Basement Rocks in Alpine Tectogenesis

Geotectonics - The article describes the main mechanisms of deformation of rock masses of the Paleozoic basement of the Tien Shan complementary to plicative bending of its surface in the process of...     

Formation of the orogen-foredeep system: A geodynamic model and comparison with the data of the northern Forecaucasus

The disturbance of mechanical and thermal equilibria in the upper shell of the Earth as a result of mantle or local within-plate processes related to periodic tectonic activity gives rise to the formation of convective flows in the low-viscosity asthenosphere. These flows affect the lithosphere and create domains of subsidence and uplift, which can continue to develop long after the cessation of active periods. If the density of the lithosphere does not decrease with depth, then small-scale flows increase uplift in zones of compression of the continental lithosphere and create domains of extension at their margins. In our opinion, small-scale convection is the main geodynamic factor that forms foredeeps. The results of detailed numerical modeling of foredeep formation at the margins of adjoining orogens are presented in the current paper. In order to set the initial conditions for the stage of continental collision, the precollision stages of the foldbelt evolution are considered, including the stage of trough formation on the thinned continental crust or on the oceanic lithosphere and the stage of sedimentary basin formation; depending on the degree of extension, this can be an inner sea or a passive continental margin. Such initial conditions were used in modeling of the compression stage (continental collision), when the orogen-foredeep system is formed. The parameters of the model and the tectonic processes are chosen so as to bring the results of numerical computation in line with the data on the Greater Caucasus and northern Forecaucasus, including the thickness of the crustal layers and sedimentary cover, structure of the foredeeps, rate of tectonic subsidence, heat flow, etc. Comparison of the numerical modeling results with the formation history of the Caucasus foredeeps confirms that the first stage of regional compression of the Greater Caucasus took place before the deposition of the Maikop sediments. At least three compression stages followed: 16.6–15.8 Ma (Tarchanian), 14.3–12.3 Ma (Konkian-early Sarmatian), and 7.0–5.2 Ma (Pontian). The next stage of regional compression is apparently occurring at present.     

Structural-kinematic parageneses of the basement and cover at the southeastern margin of the Baltic Shield

Through, long-lived structural-kinematic parageneses were established in the southeastern marginal part of the Baltic Shield on the basis of structural studies. These parageneses were formed and periodically rejuvenated from at least the Paleoproterozoic until the neotectonic stage of the evolution of this territory. A series of consecutive tectonic events related to the vertical and horizontal mobility of rocks of the crystalline basement and sedimentary cover had important implications for the formation of present-day structure of the southeastern margin of the Baltic Shield. These tectonic displacements developed for an extremely long time with retention of the main kinematic tendencies. At the end of the Paleoproterozoic, the volcanic and sedimentary rocks of the Vetreny Belt underwent tectonic stacking as a result of the countermotion of the crystalline masses of the Vodlozero Massif and the Belomorian-Lapland Belt. The clockwise rotation and lateral displacement of the Vodlozero Massif to the northeast provided the left-lateral transpression of the Vetreny Belt. Under these conditions, the Paleoproterozoic sequences experienced squeezing in the southeastern direction. This kinematic tendency was retained at the subsequent evolutional stages and eventually was recorded in the structure of the present-day boundary between the Baltic Shield and the Russian Platform.     

Petroleum hydrocarbons in the waters of major tributaries of the White Sea and its water areas: A review of available information

The White Sea is a natural analogue of arctic seas. The pollution of the sea by petroleum hydrocarbons is not high now. However, the load on sea ecosystem can increase in the nearest future because of the anticipated industrial development in its watershed, including an increase in oil, coal, and diamond production. The specific features of the nature of arctic marine systems (hydrological, ice, hydrobiological, hydrochemical, and radiation regimes), and the poor knowledge of the conditions of dispersion, transformation, and utilization of petroleum hydrocarbons in such seas make their ecological studies especially important. Petroleum hydrocarbon concentrations in the waters of tributaries and water areas of the White Sea (for 1980–2006 and 1989–2006, respectively) were evaluated using literary and authors’ data. Analysis of the collected materials shows that the majority of petroleum hydrocarbons enter the sea’s water areas with river runoff. Petroleum hydrocarbon concentrations were evaluated in major tributaries of the sea, including the rivers of Northern Dvina, Onega, Mezen, Niva, Kem, and Keret, delivering petroleum hydrocarbons into the bays of Dvina, Onega, Mezen, and Kandalaksha, water area near the Solovetskie Islands, and Chupa Bay, respectively (Bay — Gulf). Model calculations should yield within-year variations in petroleum hydrocarbon concentrations in different part of the sea (under a correctly specified load) and the conditions of their biotransformation and horizontal transport through the boundaries between areas within the sea.