Physical Oceanography, Vol. 19, No. 2, 2009
SPECIFIC FEATURES OF THE VERTICAL DISTRIBUTION OF ELEMENTS OF
THE MAIN BIOGENIC CYCLES IN WATERS OF THE NORTHWEST
SHELF OF THE BLACK SEA
S. I. Kondrat’ev
We study specific features of the vertical distribution of elements of the main biogenic cycle in
the upper layers of waters on the northwest shelf of the Black Sea in spring and autumn and the
correlation between the specific features of the vertical distributions of hydrochemical and hy-
drological characteristics. It is shown that the location of the halocline always specifies the loca-
tion of the chemocline, whereas the effect of the thermocline on the distribution of hydrochemi-
cal characteristics is ambiguous. The vertical distribution of the hydrochemical parameters can
be homogeneous in the presence of the seasonal thermocline. At the same time, in its absence,
one may observe significant vertical gradients in the distributions of hydrochemical characteris-
tics inside the upper mixed layer.
In analyzing the vertical distributions of elements of the main biogenic cycle in the upper layers of the
Black Sea, main attention of the researchers is traditionally focused on the behavior of concentrations in the
course of transformation of the aerobic zone into the anaerobic zone. A detailed description of the biochemical
processes running in this case between the isopycnic surfaces with σ
= 14.2 and σ
= 16.5 can be found in
Much less attention is given to the specific features of the vertical distribution of biogenic elements in shelf
waters, although the problem of expected changes in the concentrations of biogenic elements in the course of
motion from the surface to the cold intermediate layer is actually of the same level of complexity as the analysis
of specific features of the vertical distributions of hydrochemical characteristics in the suboxic and hydrogen-
sulfide zones. The field studies carried out in the shelf zone are, as a rule, restricted to taking samples on the
surface and in the bottom layer.. However, by using this methodical approach, it is impossible to study specific
features of the vertical distribution of stratified shelf waters containing the upper mixed layer (UML), the layer
of seasonal thermocline, the upper boundary of the cold intermediate layer with σ
= 14.1–14.3, and the core of
the cold intermediate layer with σ
= 14.5–14.6. The specific features of the vertical distributions of elements of
the main biogenic cycle under the isopycnic surface σ
= 15.0 on the northwest shelf (NWS) in May 2004 and
May 2007 are studied in [7, 8].
In the present work, we study the distributions of biogenic elements in the spring and autumn seasons in the
layer of waters with high vertical resolution in the regions of the northwest shelf not subjected to
the influence of river discharge and analyze the correlations between the specific features of the distributions of
chemical and hydrological characteristics.
Materials and Methods
For the analysis of the vertical profiles of concentrations of biogenic elements, we use the data of three ex-
peditions of the Marine Hydrophysical Institute of the Ukrainian Academy of Sciences for the last twelve years.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
37–51, March–April, 2009. Original article submitted November 21,
2007; revision submitted February 13, 2008.
96 0928-5105/09/1902–0096 © 2009 Springer Science+Business Media, Inc.