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Sevastopol, Ukraine

Polonsky A.,Marine Hydrophysical Institute
Turkish Journal of Fisheries and Aquatic Sciences | Year: 2012

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. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey. Source

Kukushkin A.S.,Marine Hydrophysical Institute
Oceanology | Year: 2014

The peculiarities of the distribution of the components of the suspended organic matter (SOM) and their interannual and seasonal variability have been analysed in the surface water layer and photic water layer of the Black Sea (the deep-sea areas) for the period of 1978–1995. The statistical assessment of the seasonal and monthly dynamics of the SOM components and their ratios was performed. The seasonal dynamics of the concentration of particulate organic carbon have been calculated based on the data on the Chlorophyll “a” (Chl “a”) concentration in the surface water layer based on the regression relationship between these two parameters measured in situ simultaneously. Taking these relationships into account, the interannual dynamics of the Chl “a” concentration have been analysed for the period of 1978–2010. It was found that the concentrations of the SOM components increased significantly in the 1980’s and early 1990’s with the maximum reached in the summer of 1992. It was also found that the seasonal interannual dynamics of the components of the SOM were mainly preconditioned by the interannual dynamics of the phytoplankton biomass, which, in turn, depended on the climatic conditions. © 2014, Pleiades Publishing, Inc. Source

Min'kovskaya R.Y.,Marine Hydrophysical Institute
Russian Meteorology and Hydrology | Year: 2015

Considered is the possibility of using water salinity and its variation coefficient as criteria for separating the boundaries of marine river estuaries and for their zoning. Used are the data on the long-term observations over the variations of marine estuaries of the Danube, Dnieper, Southern Bug, Chernaya, and Bel’bek rivers (the northern Black Sea region). © 2015, Allerton Press, Inc. Source

Yucel M.,University of Delaware | Konovalov S.K.,Marine Hydrophysical Institute | Moore T.S.,University of Delaware | Janzen C.P.,Susquehanna University | Luther III G.W.,University of Delaware
Chemical Geology | Year: 2010

We report solid phase sulfur speciation of six cores from sediments underlying oxic, suboxic and anoxic-sulfidic waters of the Black Sea. Our dataset includes the five sulfur species [pyrite-sulfur, acid volatile sulfides (AVS), zerovalent sulfur (S(0)), organic polysulfides (RS x), humic sulfur] together with reactive iron and manganese, as quantified by dithionite extraction, and total organic carbon. Pyrite - sulfur was the major phase in all cores [200-400 μmol (g dry wt) - 1] except for the suboxic core. However, zerovalent sulfur and humic sulfur also reached very significant levels: up to about 109 and 80 μmol (g dry wt) - 1, respectively. Humic sulfur enrichment was observed in the surface fluff layers of the eastern central basin sediments where Unit-1 type depositional conditions prevail. Elemental sulfur accumulated as a result of porewater sulfide oxidation by reactive iron oxides in turbidities from the anoxic basin margin and western central basin sediments. The accumulation of elemental sulfur to a level close to that of pyrite-S in any part of central Black Sea sediments has never been reported before and our finding indicates deep basin turbidites prevent the build-up of dissolved sulfide in the sediment. This process also contributes to diagenetic pyrite formation whereas in the non-turbiditic parts of the deep basin water column formed (syngenetic) pyrite dominates the sulfur inventory. In slope sediments under suboxic waters, organic sulfur (humic sulfur + organic polysulfides) account for 33-42% of total solid phase S, indicating that the suboxic conditions favor organosulfur formation. Our study shows that the interactions between depositional patterns (Unit 1 vs. turbidite), redox state of overlying waters (oxic-suboxic-sulfidic) and organic matter content determine sulfur speciation and enable the accumulation of elemental sulfur and organic sulfur species close to a level of pyrite-S. © 2009 Elsevier B.V. All rights reserved. Source

Leckler F.,Service Hydrographique et Oceanographique de la Marine | Ardhuin F.,CNRS Physics Laboratory | Peureux C.,CNRS Physics Laboratory | Benetazzo A.,CNR Marine Science Institute | And 2 more authors.
Journal of Physical Oceanography | Year: 2015

The energy level and its directional distribution are key observations for understanding the energy balance in the wind-wave spectrum between wind-wave generation, nonlinear interactions, and dissipation. Here, properties of gravity waves are investigated from a fixed platform in the Black Sea, equipped with a stereo video system that resolves waves with frequency f up to 1.4Hz and wavelengths from 0.6 to 11m. One representative record is analyzed, corresponding to young wind waves with a peak frequency fp = 0.33Hz and a wind speed of 13ms21. These measurements allow for a separation of the linear waves from the bound second-order harmonics. These harmonics are negligible for frequencies f up to 3 times fp but account formost of the energy at higher frequencies. The full spectrum is well described by a combination of linear components and the second-order spectrum. In the range 2fp to 4fp, the full frequency spectrum decays like f-5, which means a steeper decay of the linear spectrum. The directional spectrum exhibits a very pronounced bimodal distribution, with two peaks on either side of the wind direction, separated by 150° at 4fp. This large separation is associated with a significant amount of energy traveling in opposite directions and thus sources of underwater acoustic and seismic noise. The magnitude of these sources can be quantified by the overlap integral I( f ), which is found to increase sharply from less than 0.01 at f= 2fp to 0.11 at f = 4fp and possibly up to 0.2 at f = 5fp, close to the 0.5π value proposed in previous studies. © 2015 American Meteorological Society. Source

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