Ra in the Black Sea and Sea of Marmara

Water column distributions of²²⁶Ra were determined at stations in the Sea of Marmara and the Black Sea as part of the 1988 Joint U.S.—Turkish Black Sea Expedition. Black Sea surface water²²⁶Ra concentrations were a factor of three to four lower than measurements made 20 years earlier. The most likely cause is increased removal of²²⁶Ra and Ba [35] due to increased surface biological activity; a secondary effect is decreased fluvial discharge and related dimunition of inputs by desorption from fluvial suspended sediments. The amount of²²⁶Ra missing from the surface waters of the Black Sea over this period is accounted for in the high-porosity surficial “fluff” sediment layer.

Throughout the Black Sea, depth profiles of²²⁶Ra exhibited pronounced maxima of approximately 25 dpm/100 L at aboutσ_θ = 16.2–16.3, in the vicinity of a bacterial maximum, but slightly shallower than the total dissolved Mn and Fe maxima (σ_θ = 16.4–16.5) reported by Lewis and Landing [38]. While the²²⁶Ra maximum may, in part, be linked to the cycling of Mn and Fe oxyhydroxides near theO₂H₂S interface, its distribution appears to be more plausibly explained as a result of the microbial breakdown of particulate organic matter and the subsequent release and partial dissolution of associated barite in this region.

A simple steady-state two-☐ model has been used to obtain a semiquantitative understanding of the behavior of²²⁶Ra in the Black Sea. By incorporating reasonable estimates for the input and removal of²²⁶Ra in the Black Sea, an excellent agreement between predicted and observed (1988)²²⁶Ra concentrations was achieved. The model suggests that the dominant variables controlling the distribution of²²⁶Ra in the Black Sea are riverine input and cycling with Ba.     

Paleohydrology of the Black Sea Pleistocene Basins

The history of the Black Sea Pleistocene basins, whose paleohydrologic and faunistic characteristics markedly differ, is discussed. A distinct hierarchy of rhythms is established in the variations in the levels of the water bodies.     

Persistent organochlorine residues in sediments from the Black Sea

The extent of contamination of the Black Sea by selected organochlorine compounds has been assessed through the analysis of surficial sediments taken from throughout the region. Concentrations of HCHs at sites influenced by the Danube delta are among the highest recorded on a global basis (up to 40 ng g(-1) dry wt). The ratio between the alpha- and gamma-isomers was relatively low indicating contamination through the use of lindane. Concentrations of DDTs (0.06-72 ng g(-1) dry wt) and PCBs (0.06-72 ng g(-1) dry wt) were not especially high in comparison to levels reported from throughout the world. The DDE/DDT ratio was, however, low indicating fresh inputs and hence current usage of DDT within the Black Sea region.     

Hydrodynamic modelling of mesoscale eddies in the Black Sea

A three dimensional structure of mesoscale circulation in the Black Sea is simulated using the Proudman Oceanographic Laboratory Coastal Ocean Modelling System. A number of sensitivity tests reveal the response of the model to changes in the horizontal resolution, time steps, and diffusion coefficients. Three numerical grids are examined with x-fine (3.2 km), fine (6.7 km) and coarse (25 km) resolution. It is found that the coarse grid significantly overestimates the energy of the currents and is not adequate even for the study of basin-scale circulation. The x-fine grid, on the other hand, does not give significant advantages compared to the fine grid, and the latter is used for the bulk of simulations. The most adequate parameters are chosen from the sensitivity study and used to model both the basin-scale circulation and day-to-day variability of mesoscale currents for the months of May and June of 2000. The model is forced with actual wind data every 6 h and monthly climatic data for evaporation, precipitation, heat fluxes and river run-off. The results of the fine grid model are compared favourably against the satellite imagery. The model adequately reproduces the general circulation and many mesoscale features including cyclonic and anticyclonic eddies, jets and filaments in different parts of the Black Sea. The model gives a realistic geographical distribution and parameters of mesoscale currents, such as size, shape and evolution of the eddies.     

Petroleum and PAH contamination of the Black Sea

Concern has been expressed regarding the extent of contamination of the Black Sea. Analyses of coastal sediments taken from throughout the region indicate, however, that levels of petroleum hydrocarbons (2-300 microg g(-1) dry wt total hydrocarbons) are generally comparable to those encountered in the Mediterranean and are lower than concentrations reported for highly contaminated areas such as the Gulf, Hong Kong, Taiwan and New York Bight. Highest concentrations of total hydrocarbons (>100 microg g(-1) dry wt) were associated with discharges from Odessa, Sochi and the River Danube. Chronic/degraded petroleum was the major contributor at these sites. Samples from the Ukrainian coastline were comparatively clean (<10 microg g(-1) dry wt total hydrocarbons). Major contributions of fresh oil (as indicated by sigma n-C14-34) occur through the River Danube. Concerning total PAH, concentrations (7-638 ng g(-1) dry wt) compare to relatively unpolluted locations in the Mediterranean and are much lower than levels reported for polluted UK estuaries (e.g. Mersey, Tyne, Thames). Both pyrolytic and petrogenic PAH are present in most samples, although petroleum derived PAH are dominant at Sochi and pyrolytic sources are prevalent in the Bosphorus region. The absence of a correlation between total hydrocarbons and PAH (R2 = 0.04) indicates different primary sources for the two.     

Landscape mapping of the Russian Black Sea coast

The purpose of this investigation is to study structure, evolution and present ecological state of background and anthropogenically modified landscapes of the Abrau Peninsula. This region has been recommended as one of the main conservation sites on the Russian Black Sea coast due to its relatively low anthropogenic transformation and its historical importance. The ecological situation is aggravated today by the construction of a pipe-line and oil terminal near Novorossiysk and by an increase in unregulated recreation activity within the peninsula's narrow coastal zone. A special landscape-ecological map has been compiled for the model area. All ecosystems shown on the map can be grouped into four main categories based on changes of landscape structure resulting from direct impact of human activity and indirect impact mainly from chemical pollution. Ecosystems exhibiting a high degree of transformation are more typical for regions characterized by settlements, vineyards and the coastal recreation zone. Ecosystems with moderate changes also exist in the coastal area, including, for example, some unique ecosystems with pine-tree forests, pistachio-juniper and juniper open-lands. Nearly 50% of pine-tree (Pinus pithyusa) forests are in the fourth and fifth stages of recreation degradation. Some protection measures are suggested to maintain biodiversity and sustainable development of these coastal landscapes and to improve their current condition.     

Environmental effects of North Sea oil operations

To appreciate the impact of large-scale industrial operations on the marine environment requires a range of scientific studies which ideally should include physical, chemical and biological surveys of the various environmental compartments likely to be contaminated, linked with experiments designed to detect and quantify effects. More finely focused studies can then provide an evaluation of the impact. In relation to North Sea oil activities, this type of approach suggests that at present significant offshore contamination is found only in the sediments close to platforms using oil-based drilling muds.     

A Study of Oil Biodegradation in the Black Sea Water

A laboratory study was conducted to examine oil biodegradation in the presence of a fouling organism community. It is shown that the majority of fouling species exhibit relatively weak tolerance to oil. Oil degradation in seawater is shown to proceed quicker and more completely in the presence of the fouling organism community than it does without such organisms. The population of specific bacterial groups is shown first to grow and next decrease as a result of accumulation in water of toxic products of their vital activity. Oil biodegradation is found to cause substantial changes in the water hydrochemical characteristics in experimental vessels.     

Biomonitoring of the coastal waters of the Black Sea

Morpho-physiological and biochemical parameters were determined in Scorpion fish Scorpaena porcus L. from two bays in the area of Sevastopol, which experience a high anthropogenic load. The effect of natural and anthropogenic factors on the size, weight, and age composition, as well as on the sex ratio of the fish from both populations, was studied. The relationships between the concentrations of chlororganic substances in the water of the bays, their accumulation in the liver and gonads of the fish, the activity of antioxidant enzymes in the blood, and the fractional composition of serum proteins were determined. A possibility for the use of the Scorpion fish as a indicator species for the biomonitoring and assessment of the environmental conditions in the coastal waters of the Black Sea was considered.Translated from Vodnye Resursy, Vol. 32, No. 2, 2005, pp. 238–246.Original Russian Text Copyright © 2005 by Rudneva, Shevchenko, Zalevskaya, Zherko.     

Evaluating ecological quality in the north-eastern Black Sea coastal zone

Anthropogenic pressures have resulted in measurable impacts on the coastal ecosystems of the northern (Sevastopol Bay, Ukraine) and eastern (Batumi aquatoria, Georgia) Black Sea. Indices suggest that major impacts are relatively localized and are comparable to similar situations in the northern Atlantic. In contrast, biodiversity was appreciably lower than from comparable north Atlantic waters. The number of macrobenthic species was typically round 50, less than half the number that might be expected from similar exercises in US or European waters. Site-specific indices likewise indicated a somewhat lower diversity within communities, yielding metrics which would indicate a measure of stress in N. Atlantic situations. Microbial status was generally good, although regions close to urbanisation did not comply with standards laid down in the current EC Bathing Water Directive (76/EC/160). Likewise viruses were more commonly, although not exclusively, associated with urban locations, as were phages. Microbial investigation of the sediments confirmed the presence of heterotrophic and oil-oxidising bacteria. Abundance of the latter was closely correlated to the degree of oil contamination of the sediments, and to temperature, although for both, the results showed that the increase in bacterial abundance did level off beyond a certain point. Numbers of oil-oxidising bacteria in the water column displayed a classical response to temperature, with abundance doubling over a 10-degree C rise in temperature. Overall the results suggest that while indices in current use are useful in evaluating coastal quality in the Black Sea, some adjustments would be necessary especially in the establishment of baseline or reference values.     

Modelling the impact of Black Sea water inflow on the North Aegean Sea hydrodynamics

The impact of the Black Sea Water (BSW) inflow on the circulation and the water mass characteristics of the North Aegean Sea is investigated using a high-resolution 3D numerical model. Four climatological numerical experiments are performed exploring the effects of the exchange amplitude at the Dardanelles Straits in terms of the mean annual volume exchanged and the amplitude of its seasonal cycle. Larger inflow of low salinity BSW influences the water characteristics of the whole basin. The largest salinity reduction is encountered in the upper layers of the water column, and the most affected region is the northeastern part of the basin. The winter insulation character of the BSW layer (low-salinity layer) is reduced by the seasonal cycle of the inflow (minimum during winter). The maximum atmospheric cooling coincides with the minimum BSW inflow rate, weakening the vertical density gradients close to the surface and thus facilitating the vertical mixing. The inflow rate of BSW into the North Aegean Sea constitutes an essential factor for the circulation in the basin. Increased inflow rate results into considerably higher kinetic energy, stronger circulation and reinforcement of the mesoscale circulation features. Although the position of the front between BSW and waters of Levantine origin does not vary significantly with the intensity of the BSW inflow rate, the flow along the front becomes stronger and more unstable as the inflow rate increases, forming meanders and rings. The changes in the intensity of BSW inflow rate overpower the wind and thermohaline forcing and largely determine the general circulation of the North Aegean Sea.     

The Khvalynian transgression of the Caspian Sea and the New-Euxinian basin of the Black Sea

The Late Pleistocene history of the Caspian and Black seas is considered. It is suggested that the New-Euxinian basin was to a great degree due to the penetration of the Caspian water through the Manych depression into the Black Sea during the Caspian-Early Khvalynian transgression.     

Inundatios on the Black Sea coast of Krasnodar krai

Inundatios on the Black Sea coast of Krasnodar krai between 1945 and 2013 have been analyzed. The main genetic types of inundations on the coast have been identified. The specific features and regularities of inundation wave transformation along the rivers and over time have been studied. Seasonal and maximal runoff of Black Sea rivers has been analyzed over a long-term period. Regularities in the variations of the number of inundatios and their characteristics over the coastal area have been revealed both at the annual and long-term scales. Quantitative estimates are given to the hazard and damage to the population and economic activity due to inundations in the valleys of Black Sea rivers.     

Characteristics of the frequency spectra of wind-waves in Eastern Black Sea

Spectral information for wind-waves in the Black Sea is extremely limited. Knowledge on spectral characteristics of wind-waves would contribute to scientific, engineering, and operational coastal and marine activities in the Black Sea, and would allow a better understanding of the nature of the waves occurring in this enclosed basin. Frequency spectra obtained from the directional buoys deployed offshore Sinop and Hopa in Turkey, and Gelendzhik in Russia were utilized as the three sets of data to investigate characteristics of wind-waves frequency spectra for the Eastern Black Sea. Records were firstly analyzed to identify them as uni-modal or multi-modal spectra. Single-peaked spectra were then identified as belonging to fully arisen or developing sea states. Parameters of the JONSWAP and PM model spectra were estimated for the corresponding sea state by using a least square error method. Finally, the records of developing seas were further analyzed to select the ones belonging to stable wind conditions. ECMWF analysis wind fields were utilized as the wind information corresponding to the wave records. Fetch dependencies of non-dimensional spectral variables (variance and peak frequency) and α parameter of the JONSWAP model spectrum were investigated for this data sub-set.     

Global geoenvironmental problems: Black Sea basin

The issue of the geoenvironmental state of Black Sea basin, the final basin receiving the runoff of many large rivers of the European continent (Danube, Dnieper, Don, etc.) and considerable runoff from the nearby watersheds, including Turkish, is considered. The extent and geoenvironmental consequences of the large-scale changes in the hydrology, water balance, and hydrochemistry of the sea basin under the effect hydrotechnical interception and industrial pollution of river runoff are discussed. The genetic role of Black Sea rifting in one of the world’s largest oil-and-gas-bearing basins with its inherent thermal and geochemical processes, geoenvironmental conditions, and risks is emphasized. Improved information is given about the genesis of hydrogen sulfide dissolved in seawater and related to the processes of geochemical sulfate reduction of silt water sulfates under the effect of hydrocarbon gases, which mostly form in zones of deep catagenesis of sedimentary formations and lower crust rock metamorphism. It is emphasized that the ecological stability of a sea basin showing such complex and contradictory relationships with natural and technogenic objects and processes can be ensured only by joint and well coordinated efforts of the countries of the Black Sea and nearby regions aimed on rational nature and water management, including when laying pipelines on Black Sea bed and developing the power resources of the Black Sea oil-and-gas-bearing basin.