The results of investigation of the bottom sediments sampled in the Balaklava Bay in February and June, 2015 are represented. The grain-size distribution, and the organic carbon (Corg) and calcium carbonate (CaCO3) content have been studied. Noticeable change in the fractions' content that took place in course of the last 10 years is revealed. To a greater extent it is referred to the sand or gravel material, its quantitative characteristics and the features of its spatial distribution. As for the silt material in the Balaklava Bay sediments, its content, according to all the samples, grew, on the whole, from 58 to 66 %. The changes in the organic carbon abundance that took place in the bottom sediments in 2005-2015 were comparatively analyzed both for the Balaklava Bay and other water areas of the Heraklion Peninsula. A general tendency of the organic matter abundance to decrease in the bottom sediments of the bay was noted; it is treated as a result of some alteration in the anthropogenic pressure. The organic carbon mean concentration in the Balaklava Bay bottom sediments is two to three times lower than that in the other bays of the region which were subjected to permanent anthropogenic pressure. However, pollution of the Balaklava Bay with the untreated municipal, storm and industrial sewages leads to formation of the local bottom zones where the sediments are saturated with organic matter (Corg> 2.5 %). Such phenomena can exert a negative impact on the state of the marine environment ecology including, in particular, structural deviations in the macrozoobenthos community. Further decrease of the organic matter abundance is possible only in case the pollution basic sources are either completely removed or, at least, their influence is reduced. Such a condition is indispensable due to its extreme importance for implementing the state plan to turn the Balaklava Bay into a recreational area and a yacht marina.
The purpose of the paper consists in studying the pollution level, and the character of spatial distribution of microelements and trace metals, the chlorophorm-extractable substances and petroleum hydrocarbons and in evaluating the features of their accumulation in the upper layer of bottom sediments in the Balaklava Bay depending on the natural and anthropogenic sources of pollutants. Methods and Results. The samples were taken from the bottom sediments upper layer (0-5 cm) in the Balaklava Bay by the Peterson grabber in February, 2015. Location of the sampling stations was chosen proceeding from the features of the bay morphometry, hydrological and hydrochemical water structure, pollution sources and the character of the sedimentation processes. The samples were selected, preprocessed and analyzed by the standard methods according to the regulatory documents. Some changes in relation between the clay fractions and the gravel material composition were revealed. The correlation dependence between the contents of chlorophorm-extractable substances and petroleum hydrocarbons was calculated. The features of spatial distribution of the metals' content depending on the natural geochemical processes in the bottom sediments are revealed. The regions subjected to the most intensive anthropogenic load within the region under study are distinguished. Conclusions. The content of clay material in all the samples taken in the Balaklava Bay on the average increased from 58.2 to 65.9 % and its maximum values are still concentrated in the western and northwestern parts of the water area under study. During last ten years, growth of the portion of a fine-grained material in the bottom fractions has been noted; at that the places where it accumulats are located in the areas of intense anthropogenic activity. The chlorophorm-extractable substances concentration in the Balaklava Bay bottom sediments varied within a wide range. On the whole, in course of the investigated period their content decreased, whereas the petroleum hydrocarbons concentration remained unchanged. It is found that pollution of the bottom sediments by metals is of a polyelemental nature and is characterized primarily by such metals as Pb, Cr, Zn, Cu and Sr. The increased microelements concentrations are observed in the northeastern and central parts of the water area, whereas the decreased metal concentrationsin its northwestern and eastern parts.
The physicochemical characteristics of the sediments of Balaklava bay: granulometric composition and fractional composition content of organic and inorganic carbon are considered. The spatial distribution of the main factions of particle size distribution and content of organic carbon (TOC) and calcium carbonate (CaCO 3 ) are investigated. The relationship between the organic and inorganic carbon and particle size distribution of sediments are analyzed. The main formation factors of the sediments from Balaklava bay are hightlighted. The results of the performed investigations have shown that the bottom deposits in the Balaklava Bay are represented mainly by silts and in some areas the gravel and sandy materials are interspersed. On average, for all the stations the fine-dispersed fraction content makes up 61%. The coarse-dispersed material is concentrated near the coast, and at the bay exit; the increased content of the sand fraction is typical for the central part of the water area. The calcium carbonate content in the Balaklava Bay varies within 18.32-82.95 %; its average value constitutes 40.06%. Its maximum concentrations are in the coastal parts of the bay. The highest correlation between the inorganic carbon content and the granulometric composition in the samples is observed in the coarse-dispersed material (fraction 2-1 mm). As for the fine-dispersed material, the sandy and alevrite-pelite silts are characterized by the inverse relation: from 0.4 -for the fraction 0.25-0.1 mm up to 0.6 for the fraction lower than 0.05 mm. The organic carbon content varies from 0.66 to 4.74%; the average value is 2.37 %. The presence of the increased values in the central part of the bay can be explained by "weak" water exchange formed by minimum wind and wave effect and insignificant eddy formations. Introduction. Coastal areas have always been an object of active human activity. It has contributed to formation of specific ecosystems which now constitute a part of the total ecosystem of the Black Sea. Study of sediments, their physical and chemical features, as well as the processes taking place in the water -suspended matter -sediments system is an important part of the total system of the coastal waters monitoring.A distinctive feature of the bottom sediments of the Black Sea coastal area is a high rate of sedimentation. In contrast to the deep-sea part where the sedimentation rate is 0.15 -0.35 mm/year [1], this process in the coastal areas increases. According to [2] in the Crimea coastal regions where the determining factor is the abrasion processes, the sedimentation rate is 0.35 mm/year, in the Sevastopol Bay -2.4 mm/year and in the Danube estuarine zone -11.5 mm/year [3].
Purpose. Based on the mathematical modeling methods, influence of the wind waves on redistribution of the sand fractions in the semi-closed estuary-type water area is estimated using the Balaklava Bay as an example. Methods and Results. A two-dimensional version of the XBeach model with a constant grid spacing 10 m was used. The characteristics of wind waves were preset using the JONSWAP spectrum. The calculations were carried out for a storm event lasting about 12 hours once a year. The in-situ data on the particle size distribution in the bottom sediments resulted from the monitoring observations in the Balaklava Bay region was used in the numerical experiments. Conclusions. The results of modeling showed that the basic determining factors regulating the sediments movement were the depth and the bottom slope. It is noted that changing of the bottom inclination angle between the isobaths 6–7 and 7–8 m leads to deposition of the large and medium fractions, and in the area between the isobaths 9–10 and 10–12 m – to accumulation of fine sand. It was revealed that in the Balaklava Bay water area, the main redistribution of sand material caused by the storm waves took place within the southern basin, as well as at the bay exit in the coastal zone of the Megalo-Yalo Gulf. This is primarily determined by the features of the Balaklava Bay coast orography, namely, the knee-shaped narrowness separating the northern and southern basins. Nevertheless, in the isolated northern part of the Balaklava Bay being affected by the storm waves, insignificant dynamics of sand material was observed. The fractions of bottom sediments are redistributed from the western coast to the central part of the basin and to the eastern coast of the bay.
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