Modeling of the marine environmental pollution by petroleum hydrocarbons and their biotransformation in Tatar Strait waters

A hydroecological model is used for simultaneous studying water pollution processes by petroleum hydrocarbons and their decay under the oceanographic conditions of Tatar Strait. The model calculations were based on long-term averaged observational data on interannual variations of water temperature, light intensity, and transparency. Some oceanographic characteristics of the strait were reconstructed with the help of GIS “Sakhalin Shelf.” The strait’s water area was divided into three regions, and water exchange between them and the neighboring regions of the Sea of Japan was estimated by a hydrodynamic model. The results of the study made it possible to assess interannual variations in the concentrations and inner fluxes of petroleum hydrocarbons, oil-oxidizing bacteria biomasses, and the characteristics of their oxidation activity.     

Transformations of biogenic substances in Tatar Strait water (the Sea of Japan): Analysis of mathematical modeling results

The state of the marine environment (the temperature, light intensity, transparency, biogenic load) in Tatar Strait was assessed based on mean annual data from literary sources and with the use of GIS “Sakhalin Shelf.” The entire strait was divided into three regions (northern, southwestern, and southeastern), and water exchange between them for each month was estimated by using Bergen Oceanic Model. The information about the state of the marine environment and water exchange characteristics was used as input data for a hydroecological model, which enabled the assessment of annual variations of biogenic substance concentrations and biomasses of microorganisms (heterotrophic bacteria, three groups of phytoplankton, and two groups of zooplankton) in the strait regions chosen. The development conditions of microorganism biomasses within the year can be characterized by their activity indices (specific growth rates), the values of internal fluxes of biogenic substances, and calculated bioproductivity values. The calculated biogenic substance concentrations and phytoplankton bioproductivity values showed good agreement with the estimates for the Sea of Japan and Tatar Strait available from the literature.     

Practical Use of Computationally Frugal Model Analysis Methods

Three challenges compromise the utility of mathematical models of groundwater and other environmental systems: (1) a dizzying array of model analysis methods and metrics make it difficult to compare evaluations of model adequacy, sensitivity, and uncertainty; (2) the high computational demands of many popular model analysis methods (requiring 1000's, 10,000 s, or more model runs) make them difficult to apply to complex models; and (3) many models are plagued by unrealistic nonlinearities arising from the numerical model formulation and implementation. This study proposes a strategy to address these challenges through a careful combination of model analysis and implementation methods. In this strategy, computationally frugal model analysis methods (often requiring a few dozen parallelizable model runs) play a major role, and computationally demanding methods are used for problems where (relatively) inexpensive diagnostics suggest the frugal methods are unreliable. We also argue in favor of detecting and, where possible, eliminating unrealistic model nonlinearities—this increases the realism of the model itself and facilitates the application of frugal methods. Literature examples are used to demonstrate the use of frugal methods and associated diagnostics. We suggest that the strategy proposed in this paper would allow the environmental sciences community to achieve greater transparency and falsifiability of environmental models, and obtain greater scientific insight from ongoing and future modeling efforts.     

Reconstruction of the annual variations of thermohaline characteristics and water circulation on the northeastern Sakhalin Shelf

Methods of statistical analysis and GIS Sakhalin Shelf have been used to reconstruct the annual variations of water temperature, salinity, and density from the surface to the bed at 60 standard oceanographic stations on northeastern Sakhalin shelf (with the total duration of observations of ～40 years). Numerical simulation using Bergen University oceanic model has been applied to calculate the spatial fields of water temperature and salinity at standard horizons in nodes of a regular grid. The analysis of calculation results revealed new features of the hydrological regime and gave previously unknown thermohaline fields with maximal detail for full annual cycle. The obtained data were used to evaluate the mean monthly three-dimensional water circulation.     

The calculation of meteor motion parameters based on the single station TV observations

Recently, television observations of meteors have steadily replaced photographic observations. Television recording with short exposures is a close analog of a photographic survey with a rotary shutter in the form of a system of set time marks on the meteor track. Each meteoric event is a series of recordings of separate phases of the motion of a meteor. This allows for the use of the geometric method for the determination of the motion parameters of meteors. In this work, a critique is given regarding the concept proposed by K.P. Stanyukovich in 1932–1939, and a mathematical justification of the geometric method of the analysis of the television images of meteors is given.     

Detection of ammonia-oxidizing Bacteria and Archaea within coral reef cyanobacterial mats

Coral-reef filamentous cyanobacterial mats are complex communities of microbes. We used DGGE and eubacterial and archaeal 16S rRNA and amoA ammonium monooxygenase subunit A primer sets to explore the presence of genes mediating nitrogen conversion within cyanobacterial mats from Hawaii. DGGE band analysis revealed the presence of halophiles such as Halococcus salifodinae and of Nitrosopumilus-like organisms. Twenty seven out of 31 clone sequences exhibited a 95 % or greater 16S rRNA gene identity with known archaeal ammonia oxidizers such as Nitrosopumilus maritimus. The presence of Archaea within those mats, as well as the co-occurrence of both ammonia-oxidizing Archaea and ammonia-oxidizing Bacteria suggests importance of the former in the cyanobacterial mat community, and suggests greater than anticipated diversity of nitrogen conversion processes and organisms in those systems.     

Geological structure of central East Antarctica from geophysical data

Examination of the subglacial topography of central East Antarctica reveals the block structure of the Earth’s crust in this region. The intracontinental blocks of the subglacial Vostok Highlands (400 masl), Komsomol’sky Mountains (700 masl), Schmidt Basin (150 masl), and Aurora Basin (?300 masl) are distinguished. The geological nature of the Komsomol’sky Subglacial Mountains (KSM) and the Schmidt Subglacial Basin (SSB) is interpreted from gravity measurements and regional aerogeophysical routes. The basin of Vostok Subglacial Lake (VSL) is located in the conjugation zone of these blocks. The KSM are considered to be a block of the Proterozoic mobile belt disturbed by a system of normal and reverse faults. The SSB is a rigid cratonic block partly overlapped by platform cover. The localization of the VSL Graben in the zone of conjugation of heterogeneous blocks testifies to its formation in a deep fault zone characterized by intense normal and reverse dislocations.     

Pseudosecondary clastic rocks of the Dzuramtai massif (Southern Mongolia)

Specific rocks (tectonomixtites) developed in the framing of Mongolian granite massifs (Dzuramtai and some others) at the Mesozoic section bottom are studied. It is shown that the tectonomixtites are tectonic rocks rather than eluvial or sedimentary rocks, as was considered previously. They formed in the Cenozoic in the process of granite protrusion beneath a thick sedimentary cover owing to the crushing of granites and abrasion of granite fragments with the subsequent transformation of clastic rocks by groundwaters (suffosion). In this process, clastic rocks yielded fine products of the destruction of feldspars and quartz was concentrated. The rocks formed at relatively low temperatures (no more than 200–300°C) under stress strains.     

Crystalline Protrusion as the Typical Structural–Tectonic Model of Intragranite Hydrocarbon Accumulation

Geotectonics - The paper deals with issues related to the study questions on magmatic tectonics and intragranitic hydrocarbon accumulating formation: (i) post-magmatic structure of granitic massifs...     

Suspended and Dissolved Forms of Nutrients: Their Relationships and Interaction in the Major Tributaries of the Caspian Sea

Normal annual data are used to evaluate the within-year variations in the concentrations of biogenic substances (organic and mineral components of N and P, dissolved organic carbon, inorganic Si) in the major tributaries of the Caspian Sea. Variations in the concentrations of biogenic substances are analyzed, the relationships between their mass concentrations in individual months are evaluated, and correlation between the organic and mineral components of N and P and their aggregated fractions are established. The obtained high-significance correlation between the concentrations of N and P components suggests that the rates of biochemical processes of biogenic substance transformation taking place in the water of tributaries are commensurable.