Dynamics of oil product distributions in water and bottom sediments of the sea of Azov and the Black Sea after ship accidents in the Kerch Strait

The dynamics of concentrations of oil products spilled into the aquatic ecosystem as a result of accidents in the Kerch Strait is discussed. Provision is made for the analysis of the results of long-term monitoring and for the revealing of differences in concentrations and distribution of oil hydrocarbons in the Sea of Azov and in the Black Sea after emergency spills. The available information was used to outline the course of events that led to such redistribution of spilled mazut in marine ecosystems.     

Spatial-temporal variations in organic matter of the Sea of Azov

The spatial-temporal variations in the amount and biochemical composition of organic matter and the rates of its transformations in the ecosystems of the Russian part of the Sea of Azov are analyzed. Maximum OM concentrations are typical for Taganrog Bay. A characteristic feature of the Sea of Azov is a large proportion of particulate organic matter, which in summer in Taganrog Bay exceeded 35%. It is shown that not only the concentration of organic matter changes from season to season, but also its elementary (C_org, N_org, and P_org) and biochemical composition (proteins, carbohydrates, and lipids). The major biochemical compound of dissolved organic matter is shown to be carbohydrates (13–28%), and that of particulate matter is protein (44–51%). The hydrolytic (phosphatase and protease) and oxidation-reduction enzymes of electron-transport system demonstrate a high activity in summer. The estimated short turnover times of phosphates and protein suggest the rapid and complete utilization of organic matter in the Sea of Azov.     

Climatic changes in zoobenthos of the Sea of Azov under anthropogenic impact

The relationship between many-year variations in zoobentbos of the Sea of Azov and the largescale variations in atmospheric circulation (G.Ya. Vangengeim typification) from the mid-XX to the early XXI century has been considered. It has been shown that the western form facilitates an increase in zoobentbos biomass of the Sea of Azov and the eastern form, its growth. The effect of the northern type of macroprocesses is controversial. The change from eastern to western form in the mid-1980s caused a freshening in the Sea of Azov and reduced the total zoobentbos biomass, especially mollusk. The farther predominance of the western form will facilitate the preservation of the present-day structure of benthic communities up to the end of the first quarter of the XXI century.     

Legal Aspects of Natural Resources Management in the Basin of the Sea of Azov

Legal aspects of natural resources management in the basin of the Sea of Azov are investigated. The available legal documents and agreements are carefully analyzed. Measures to be taken both to eliminate the uncertainty of the Sea of Azov legal status and to promote cooperation in the natural conservation zone between Russia and Ukraine at the international level are suggested. The experience of Mediterranean countries succeeding in marine environment protection is analyzed.     

Oil components in the mouth area of the Don R. and in the Sea of Azov: Results of many-year studies

The data given are the results of many-year studying the distribution of the concentrations of main oil components (hydrocarbons, surfactants, and asphaltene-tarry substances) in the water mass, vertically settling particulate matter, and bottom sediment cores taken from the section Lower Don-The Gulf of Taganrog-Russian sector of the Sea of Azov in summer and autumn periods in 2006–2011. Spatial and seasonal regularities in the distributions of the total concentration of oil components and the values of their ratios in water, as well as the spatial and annual features of their accumulation in bottom sediments have been established. Radiological methods have been used for layer-by-layer dating of bottom sediment cores and determine the thickness of the layer that had formed under the maximal anthropogenic impact on ecosystems. The presence of considerable amounts of hydrocarbons of modern biological origin has been revealed in all components of examined aquatic complexes.     

Probabilistic Regularities in Setup Variations in the Level of a Large Inland Water Body: Case Study of the Caspian Sea

The results of probabilistic analysis of data on setup level variations collected during long-term observations at all gages along the Caspian Sea coast are discussed. A procedure for evaluating low-probability sea level extremes is proposed. Estimates are given for the probabilities of outstanding setups in the Caspian Sea and the Sea of Azov.     

Long-Term Water Level Variations in the Eastern Sea of Azov and in the Mouth Reach of the Don River

Studies of long-term water level variations at marine hydrometeorological stations in the eastern Sea of Azov established a rise in the sea level which accelerated in the past 40 years. Allowance for the tectonic component permitted assessing the average rate of eustatic rise in the level. Oppositely directed long-term level variations were established in the mouth area of the Don River. Water level was found to rise at the downstream gages because of the backwater effect caused by the Sea of Azov level rise and delta deposits subsidence and to drop at the upstream gages mainly because of bed erosion owing to a reduction in sediment runoff after the construction of the Tsimlyanskoe Reservoir.     

Nutrient Loading of the Don and Kuban on the Ecosystem of the Sea of Azov

Hydrochemical data collected in field studies in the near-mouth area and delta of the Don R. (Aksay T.—the mouths of Don delta branches) in 2006–2015 are analyzed. The seasonal dynamics is demonstrated, and the average annual concentrations were evaluated for mineral, total dissolved, and total forms of nitrogen, phosphorus, silica; dissolved and particulate organic carbon; and total suspended solids in river water. The export of dissolved and particulate organic carbon and nutrients by the Don River into the Sea of Azov in the low-water period of 2007–2015 is evaluated. Retrospective analysis of nutrient export into the Sea of Azov with river runoff in the XX–early XXI century is given.     

Present-Day Estimates of the Hydrological Conditions for the Formation of Biological Production in the Sea of Azov

The main feature of the present-day hydrological conditions governing the formation of biological production in the Sea of Azov is shown to be the appreciable freshening of seawater, which is due, first of all, to climate changes. It is established that the freshening of seawater can benefit most for the reproduction of fish resources in the Sea of Azov only if the river runoff withdrawals are reduced step by step down to 5 km³/year (14% of the norm), the annual runoff is maintained at 35–36 km³, and the spring runoff is restored to 18.5 km³.     

Many-year variations of the average salinity of the Sea of Azov

A brief review of studies of the hydrological regime of the Sea of Azov and approaches to assessing the average salinity—a key indicator of the state of its ecosystem is given. A database of salinity measurements at 47409 oceanographic stations over hundred years (from 1913 to 2014) were used to evaluate the sea-averaged mean annual salinity. The obtained values of the average salinity were found to differ from those published before because of the different approaches used to its calculation and different volumes of data involved. The difference was most significant for Taganrog Bay because of the high variability of its hydrological regime. Anomalies of the average salinity over period 1922–2014 were constructed, and the start of one more period of salinity increase in the Sea of Azov was recognized.     

Numerical Analysis of the Velocities of Currents Forming in the Kerch Strait at the Motion of Domains of Higher Atmospheric Pressure

Water Resources - A three-dimensional ocean general circulation model (Princeton Ocean Model) along with hydraulic calculations were used to evaluate the velocity of currents from the Sea of Azov...     

The environmental and biotic impact of the oil spill in Kerch Strait in November 2007

The effect of an emergency oil spill in Kerch Strait in November 2007 on the environment and biota in the southern Sea of Azov is analyzed based on the material of integrated expedition studies carried out by the Southern Scientific Center, RAS, before and after shipwrecks and during monitoring within a year after the emergency.     

Characteristic of oil pollution of the Sea of Azov and regularities in its dynamics

Oil pollution of water and bottom sediments (BS) of the Sea of Azov is characterized by using the results of studies carried out in different seasons of 1985–2005. Regularities in the dynamics of oil pollution are discussed and correlated with the stages in changes in the country’s economy.     

Current Desalination of the Sea of Azov and Its Correlation with Long-Term Variations in Atmospheric Circulation

Correlation is established between the long-term variations in the frequency of the atmospheric circulation forms, water balance elements, and the Sea of Azov water salinity. It is found that the river runoff into the sea and the sea freshwater balance increase and the sea salinity decreases in the periods, when northern and western forms of atmospheric processes develop; in the periods with a greater frequency of the eastern type of atmospheric macroprocesses, the situation is reverse. It is also found that the effect of atmospheric circulation on the sea salinity tends to strengthen, whereas the effect of the human-induced decrease in river runoff tends to diminish. The current desalination of the Sea of Azov down to 10.5 is shown to be mainly due to the development of western and northern forms of atmospheric circulation in the cold season of a year during the last 10–15 years.     

Characterization of the Azov Sea bottom sediments by the degree of present pollution with a complex of most hazardous toxicants

A great body of source data on the concentrations of oil products, organochlorine pesticides, and heavy metals in the Azov Sea bottom sediments in 1996–2005 is analyzed. An integral quantitative characteristicóan index of pollution of bottom sedimentsóis proposed and used for elaborating a five-level classification of sea floor regions. The causes and regularities of variations in concentrations of toxicants are established and the sites of their entry into the ecosystem are localized.     

A technique for evaluating flow parameters in water bodies with a highly heterogeneous depth

A method is proposed for calculating the hydrodynamic parameters of flows in water bodies with shallow and deep zones. Calculation of flow parameters in the Sea of Azov is given as an example.Translated from Vodnye Resursy, Vol. 32, No. 1, 2005, pp. 55–60.Original Russian Text Copyright © 2005 by Chikin.     

Formation of fish kills and anaerobic conditions in the Sea of Azov

Results of field observations and numerical modeling of hydrogen sulfide pollution of the Sea of Azov in 2001 are presented.Translated from Vodnye Resursy, Vol. 32, No. 2, 2005, pp. 171–183.Original Russian Text Copyright © 2005 by Debolskaya, Yakushev, Sukhinov.     

Influence of oil on nucleic acids of algae

While we have a fair amount of knowledge of the grosser effects of petroleum hydrocarbons on organisms, more subtle effects are still poorly known. This is particularly true of their influence on biologically active compounds. Studies on the effect of oil on DNA and RNA of some Black Sea algae suggests that it inhibits biosynthesis of these compounds and modifies the degree of polymerization of deoxyribonucleic acids.     

Carbon speciation and composition of natural microbial communities in polluted and pristine sediments of the Eastern Mediterranean Sea

Sediment samples collected from polluted (Augusta Bay) and pristine regions of the Eastern Mediterranean Sea (South Ionian Sea, Thracian Sea) were analyzed for black carbon, aliphatic hydrocarbons and phospholipid ester-linked fatty acids (PLFA). The aim of the study was to investigate the anthropogenic and biogenic inputs into the Eastern Mediterranean Sea and to evaluate the effects of refractory organic matter (e.g. black carbon) and the level of hydrocarbon contamination on benthic microbial community composition. Black carbon, generally considered to be chemically and biologically inert, comprised a significant but highly variable fraction of the sedimentary carbon pool in the analyzed sediments with a ratio to total organic carbon ranging from 0.02 to 0.66. Principal component analysis of the chemical characteristics of the sediments (organic carbon content, black carbon, bioavailable organic carbon, chlorophyll a, phaeopigments, aliphatic hydrocarbons) revealed clustering of samples along a gradient from the most productive and contaminated region of Augusta Bay to the carbon-poor and pristine sediments of the Thracian Sea. PLFA analysis revealed that gram-negative bacteria and microeukaryotes were most abundant in Augusta Bay and in the most impacted station of the Thracian Sea. The high levels of branched and odd-chain fatty acids recorded for these stations is probably linked to the elevated amounts of hydrocarbons at these stations; e.g. microbial communities may have developed the ability to degrade either naturally occurring aliphatic hydrocarbons or hydrocarbons derived from oil contamination.