Nutrients Dynamics in the Surface Waters of the Black Sea

Purpose. One of the key characteristics of water quality and marine ecosystems’ sustainability is nutrients supply, which are the main factors of phytoplankton bloom. Since the mid 20th century, in the northwestern Black Sea and on its western shelf, significant changes in nutrients concentrations took place, which were manifested in increase of the inorganic nitrogen and phosphorus concentrations, and decrease of the dissolved silicon content, that in its turn, led to a strong anthropogenic eutrophication of the above-mentioned regions. The aim of the work is to assess the current state of the Black Sea based on the data on the nutrients distribution and dynamics in the surface water layer. Methods and Results. The data obtained in the cruises of R/V “Professor Vodyanitsky” in 2016–2019 were analyzed. The main regions under study included the deep part of the Black Sea, as well as the Crimean and Caucasian sectors of the economic zone of Russia. The data obtained showed significant variability in the nutrients concentration both in the coastal and open areas. Conclusions. A decrease of nutrients concentration in 2016–2019 as compared to that in 2009–2014 was noted, that can indicate a decrease in the eutrophication degree and an improvement of the Black Sea waters quality. Intra-annual variability of the nutrients concentration in the sea surface layer is observed. No pronounced features in spatial variability of the nutrients concentration in this layer were revealed. It is assumed that in the central deep part of the sea, their concentrations are conditioned mainly by the physical processes of water transfer. In addition to physical transport, the increased nutrients concentrations in the coastal areas are, probably, also related to influence of the anthropogenic factor, namely inflow of nutrients from the coastal sources or their formation resulting from the biogeochemical processes which include organic matter.

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Upward and regeneration fluxes of inorganic nitrogen and phosphorus in deep-water areas of the Black Sea

Biology Bulletin Reviews ◽

10.1134/s2079086415030044 ◽

2015 ◽

Vol 5 (5) ◽

pp. 512-525 ◽

Cited By ~ 2

Author(s):

O. V. Krivenko ◽

A. V. Parkhomenko

Keyword(s):

Black Sea ◽

Deep Water ◽

Inorganic Nitrogen ◽

The Black Sea ◽

Nitrogen And Phosphorus

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Studying the Fluxes of the Marine Ecosystem Components from the Northwestern Shelf to the Deep Part of the Black Sea

Physical Oceanography ◽

10.22449/1573-160x-2020-5-460-471 ◽

2020 ◽

Vol 27 (5) ◽

Author(s):

V. L. Dorofeyev ◽

L. I. Sukhikh ◽

◽

Keyword(s):

Black Sea ◽

Wind Stress ◽

Inorganic Nitrogen ◽

Marine Ecosystem ◽

Shelf Zone ◽

The Black Sea ◽

Shelf Edge ◽

Deep Part ◽

Narrow Strip ◽

Northwestern Shelf

Purpose. The study represents analysis of the features of the Black Sea ecosystem components transfer from the northwestern shelf to the deep-sea part and its dependence on circulation in the sea upper layer. Methods and Results. The fluxes of water mass, nutrients and bioproduction from the shelf zone to the deep part of the sea were calculated using the current fields and biogeochemical ones resulted from the reanalysis, which, in its turn, was carried out due to the Black Sea ecosystem model including assimilation of remote sensing data both in the numerical circulation model and in the biogeochemical block. Numerical modeling permitted to calculate the fluxes through three sections that bound the shelf zone (by the capes Kaliakra and Chersonesus, and along the 200 m isobath). Behavior of the RIM Current jet and, consequently, direction and magnitude of the flows through the boundaries of the northwestern shelf depend on the wind stress vorticity over the western part of the Black Sea. The type of circulation with the intense RIM Current jet pressed to the shelf edge, is characterized by the pattern of distribution of the inorganic nitrogen and phytoplankton surface concentration as a narrow strip of its high values along the Black Sea western and partially southern coasts. When the RIM Current jet is weak or moves from the shelf edge (that corresponds to the low values of the wind stress vorticity) the increased concentration values are located on the northwestern shelf. Conclusions. Direction, magnitude and character of horizontal distribution of the nutrient and bioproduction fluxes are determined mainly by circulation in the sea upper layer. The magnitude of these flows is significantly affected by difference between the nutrient and bioproduction concentrations in the shelf zone and in the deep part of the Black Sea.

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Studying the Fluxes of the Marine Ecosystem Components from the Northwestern Shelf to the Deep Part of the Black Sea

Morskoy gidrofizicheskiy zhurnal ◽

10.22449/0233-7584-2020-5-501-513 ◽

2020 ◽

Vol 36 (5) ◽

Author(s):

V. L. Dorofeyev ◽

L. I. Sukhikh ◽

◽

Keyword(s):

Black Sea ◽

Wind Stress ◽

Inorganic Nitrogen ◽

Marine Ecosystem ◽

Shelf Zone ◽

The Black Sea ◽

Shelf Edge ◽

Deep Part ◽

Narrow Strip ◽

Northwestern Shelf

Purpose. The study represents analysis of the features of the Black Sea ecosystem components transfer from the northwestern shelf to the deep-sea part and its dependence on circulation in the sea upper layer. Methods and Results. The fluxes of water mass, nutrients and bioproduction from the shelf zone to the deep part of the sea were calculated using the current fields and biogeochemical ones resulted from the reanalysis, which, in its turn, was carried out due to the Black Sea ecosystem model including assimilation of remote sensing data both in the numerical circulation model and in the biogeochemical block. Numerical modeling permitted to calculate the fluxes through three sections that bound the shelf zone (by the capes Kaliakra and Chersonesos, and along the 200 m isobath). Behavior of the RIM Current jet and, consequently, direction and magnitude of the flows through the boundaries of the northwestern shelf depend on the wind stress vorticity over the western part of the Black Sea. The type of circulation with the intense RIM Current jet pressed to the shelf edge, is characterized by the pattern of distribution of the inorganic nitrogen and phytoplankton surface concentration as a narrow strip of its high values along the Black Sea western and partially southern coasts. When the RIM Current jet is weak or moves from the shelf edge (that corresponds to the low values of the wind stress vorticity) the increased concentration values are located on the northwestern shelf. Conclusions. Direction, magnitude and character of horizontal distribution of the nutrient and bioproduction fluxes are determined mainly by circulation in the sea upper layer. The magnitude of these flows is significantly affected by difference between the nutrient and bioproduction concentrations in the shelf zone and in the deep part of the Black Sea

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Impact of Winter Cooling on Water Vertical Entrainment and Intensity of Phytoplankton Bloom in the Black Sea

Morskoy gidrofizicheskiy zhurnal ◽

10.22449/0233-7584-2018-3-206-222 ◽

2018 ◽

Author(s):

E. A. Kubryakova ◽

A. A. Kubryakov ◽

S. V. Stanichny ◽

◽

...

Keyword(s):

Black Sea ◽

Phytoplankton Bloom ◽

The Black Sea ◽

Winter Cooling

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On the possible presence of oxygen in the upper sediment layer of the hydrogen sulfide zone in the Black Sea

Океанология ◽

10.31857/s0030-1574591166-169 ◽

2019 ◽

Vol 59 (1) ◽

pp. 166-169

Author(s):

P. A. Stunzhas ◽

M. B. Gulin ◽

A. G. Zatsepin ◽

E. A. Ivanova

Keyword(s):

Black Sea ◽

Benthic Fauna ◽

Water Layer ◽

Bottom Layer ◽

The Black Sea ◽

Depth Range ◽

Sediment Layer ◽

Bottom Water Layer ◽

Long Time ◽

Eukaryotic Organisms

In the northeastern Black Sea the search was performed for living eukaryotic organisms (micro- and meiobenthos) in hypoxic and anoxic conditions as well as measurement of O2 in the bottom water layer and in the upper layer of sediments. The results have shown the presence of a deep maximum abundance of zoobenthos in a depth range of 215–244 m. This aggregation of benthic fauna occupies a layer of 30 m along the vertical. In general, the proportion of active meiobenthos was no greater than 1.5% of the total number of organisms recorded from the sample.The presence of aerobic benthos near the upper boundary of the H2S zone can be explained by: sliding down of sediments from a higher depth; quasi-periodic O2 supply due to fluctuations in the position of the isopycna and/or sinking of waters downslope in the bottom Ekman layer. Also, in the case of physical entry of oxygen into the bottom layer, it can remain for a relatively long time in the upper part of the H2S zone due to the lack of deep Mn+2 flux and reaction with it.

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