Posts Tagged 'Black sea'

Influence of hydro-hydrochemical factors on the biodiversity of phytoplankton in the coastal aquatoria Black Sea with enhanced anthropogenous pollution (in Russian)

The distribution of most phytoplankton representatives is significantly influenced by various hydrological and hydrochemical environmental factors. Degree of development of phytoplankton communities and their species composition can determine the level of pollution of sea water by various nutrients.

A survey was made of the coastal waters of the Black Sea, with in-creased anthropogenic pollution at 15 stations in winter period. At these stations, temperature, pH, and DOM concentration were registered and the composition of microalgae and phytoplankton cyanobacteria was studied.

The results obtained in the analysis of hydrological, hydrochemical and algological data make it possible to speak about the pronounced discreteness of abiotic environmental factors and the distribution of various phytoplankton representatives at 15 stations studied. The thermohaline structure in the water area was characterized by a pronounced temperature inversion in the cutaway part. The pH on the sea surface everywhere corresponded to its natural rate. A high degree of pollution of the waters of the entire investigated area by dissolved organic matter was noted. Using the methods of laboratory cultivation of samples, it was possible to identify the cyanobacteria component in the phytoplankton. The active development of cyanobacteria was revealed precisely at that point in the water area (station No. 8), where the local maximum of DOM content was observed. The presence in two samples (No. 13 and No. 16) of alkaliphilic cyanobacteria of the genus Rhabdodermain probably indicates a tendency for alkalization of water due to eutrophication. At stations No. 7 and No. 9, favorable conditions were established for the development of diatom algae, and at station No. 18, for unicellular green forms. In the remaining areas, the poor composition of phytoplankton largely corresponded to the data we obtained in the water area for the previous two years.

Continue reading ‘Influence of hydro-hydrochemical factors on the biodiversity of phytoplankton in the coastal aquatoria Black Sea with enhanced anthropogenous pollution (in Russian)’

Features of the regional balance of inorganic carbon of marine ecosystems under anthropogenic pressure (in Russian)

The global changes in the biogeochemical structure of the oceans, which are most pronounced on a regional scale, caused by an increase in the flow of carbon into aquatic ecosystems as a result of increased releases from the atmosphere, coastal sources, primary production and destruction processes in the marine environment, make the issues of sharing the influence of the natural climatic and anthropogenic factors. For a quantitative assessment and analysis of the degree of influence of factors leading to the transformation of the natural carbon cycle, it is necessary to restore its budget, which is determined by the intake and removal of carbon, as well as the processes that result in its redistribution between different forms. The paper estimates the carbon budget for the ecosystem of the Sevastopol Bay (Black Sea), as well as analyzes the contribution of the anthropogenic component according to many years of research (2007–2018) of hydrochemical and geochemical characteristics. The results of studying the carbonate system of bottom sediments are presented: the vertical profile of the total dissolved inorganic carbon, alkalinity and pH, as well as the ratio between dissolved inorganic carbon and alkalinity. It has been established that the oxidation of organic matter occurs predominantly under anaerobic conditions. The values ​​of the flux of total dissolved inorganic carbon ( J TCO2 ) at the water-bottom boundary are directed from the bottom sediments to the bottom layer of water and are J T CO2 = 0.42 … 0.61 mol / (m 2 ∙ year). An analysis of the various components of the inorganic carbon budget showed that the largest role is played by anthropogenic sources, whose contribution is at least 75% of the total inorganic carbon supply. By the value of the total stock of dissolved inorganic carbon and its removal to the open sea, it was suggested that the time for the complete renewal of the waters of the Sevastopol Bay is 2 years 4 months.

Continue reading ‘Features of the regional balance of inorganic carbon of marine ecosystems under anthropogenic pressure (in Russian)’

The spatiotemporal variability of pH in waters of the Black Sea

Based on archival data of the Institute of Natural and Technical Systems for the period from 1956 to 2010, the large-scale structure, seasonal variability, and long-term trends of pH variations in the upper 150-m layer of the deep-water part of the Black Sea were analyzed. The spatial climatic inhomogeneities of pH in the surface layer of the open part of the Black Sea are about 0.06 pH units; the magnitude of the average seasonal cycle is 0.05 pH units. In the deep-water part of the sea, low values of pH are observed in the vicinity of the centers of cyclonic gyres, where more acidic waters move upward. A long-term increase in the acidity of waters of the surface layer is observed. Thetrend of pH in this layer is generally conditioned by the increase in the CO2 content in the lower troposphere and absorption of part of the excess CO2 by sea water. The increase in the acidity manifests itself in the decrease in pH (at a level of –0.06 pH units per 50 years) in waters of the surface layer. This is close to the estimations for other regions of the World Ocean. However, the intermediate waters are characterized by a negative pH trend, the absolute value of which exceeds more than fivefold the pH trend on the surface. A likely reason for the intense decrease in pH here is the intensification long-term vertical circulation in the intermediate layer of the Black Sea waters, resulting in the ascension of more acidic waters with a typical velocity of ~1 m per year. This can lead to more intense acidification of surface waters in the sea over the next 10 years.

Continue reading ‘The spatiotemporal variability of pH in waters of the Black Sea’

Variation in the carbon cycle of the Sevastopol Bay (Black Sea)

Continuous increase in CO2 inventory in the ocean results in dramatic changes in marine biogeochemistry, e.g. acidification. That is why temporal and spatial variabilities in atmospheric pCO2 and dissolved inorganic carbon, including CO2, pH and alkalinity in water, as well as organic and inorganic carbon in bottom sediments have to be studied together making possible to resolve the key features of the carbon cycle transformation. A 30% increase of pCO2 in the Sevastopol Bay for 2008 – 2016 evidences changes in the DIC components ratios and a significant decrease in the ability to absorb atmospheric CO2 by surface waters. High organic carbon content in the bottom sediments and predominance of organic carbon production in the biological pump at inner parts of the bay reveal ongoing transformation of the carbon cycle. This has negative consequences for recreation, social and economic potentials of the Sevastopol region.

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Total alkalinity and pH in the Black Sea waters in 2010 – 2011

Based on the data of the expeditionary researches of Marine Hydrophysical Institute in 2010-2011, the total alkalinity TA and pH distributions in the Black Sea waters including the Danube estuary region and the changes in the TA vertical distribution since 1988 are analyzed. It is shown that the coastal and deep-sea water TA is strongly influenced by the river flow. In the Black Sea aerobic zone, TA does not change virtually with depth and does not depend on pH. In the anaerobic zone, it weakly depends on pH, but its dependence on the hydrogen sulfide concentration is of a linear character. Comparison with the data obtained in 1988 shows that in course of the last 20 years no noticeable changes in the TA values in the Black Sea aerobic and anaerobic zones took place, whereas on the sulfide zone upper boundary the total alkalinity increased by 0.04 mg-eq*l-1.

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Cumulative human impacts on Mediterranean and Black Sea marine ecosystems: assessing current pressures and opportunities

Management of marine ecosystems requires spatial information on current impacts. In several marine regions, including the Mediterranean and Black Sea, legal mandates and agreements to implement ecosystem-based management and spatial plans provide new opportunities to balance uses and protection of marine ecosystems. Analyses of the intensity and distribution of cumulative impacts of human activities directly connected to the ecological goals of these policy efforts are critically needed. Quantification and mapping of the cumulative impact of 22 drivers to 17 marine ecosystems reveals that 20% of the entire basin and 60–99% of the territorial waters of EU member states are heavily impacted, with high human impact occurring in all ecoregions and territorial waters. Less than 1% of these regions are relatively unaffected. This high impact results from multiple drivers, rather than one individual use or stressor, with climatic drivers (increasing temperature and UV, and acidification), demersal fishing, ship traffic, and, in coastal areas, pollution from land accounting for a majority of cumulative impacts. These results show that coordinated management of key areas and activities could significantly improve the condition of these marine ecosystems.

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Had been observing the acidification of the Black Sea upper layer in XX. century?

The article’s goal is to assess the rate of acidification of the Black sea upper layer in XX century using historical data since 1924. It is shown that statistically significant century-scale acidification cannot be extracted, while decadal-scale reduction of pH has been really observing in 1960’s and between 1980 and 2000 in spite of high noise level and intense interannual pH variability. The rate of acidification for these periods reached 0.4 (0.2) pH units per decade at the surface (10 m depth). Such high level of acidification of the Black sea upper layer is mostly due not to the rise of carbon dioxide concentration in the atmosphere, but to natural quasi-periodical decadal-scale intensification of upward motions in the subsurface layer of the Black sea transporting the water with low-pH to the surface. Rough assessment of recent century-scale rate of acidification of the surface Black sea layer shows that its likely magnitude lies in the range -0.1 to -0.5 pH units per 100 years.

Continue reading ‘Had been observing the acidification of the Black Sea upper layer in XX. century?’

Ocean acidification issues in the Mediterranean and Black Seas: present status and future perspectives

The semi-enclosed Mediterranean and Black Seas have many unique oceanographic and biogeographical features which could either serve to exacerbate or reduce future effects of increased pCO2 and ocean acidification (OA). Despite the fact that these seas have been the intense focus of marine research activities for decades, few studies on the effects of OA have been carried out in the region and specific OA studies with Mediterranean species and communities are only in their infancy. The existing literature relevant to this region is reviewed, specific gaps in knowledge are identified and types of OA studies needed in the future are emphasized. Owing to the overall lack of specific OA research in the Black Sea, a marine area under severe anthropogenic and environmental stress, targeted studies on future impacts of OA on its fragile marine ecosystem are urgently needed.

Continue reading ‘Ocean acidification issues in the Mediterranean and Black Seas: present status and future perspectives’

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Ocean acidification in the IPCC AR5 WG II

OUP book