Environmental Engineering Reference
In-Depth Information
Figure 3.
Combined depth distributions of dissolved hydrogen sulphide in the Black Sea
water column from data collected in the period from 1999 to 2002 in the north-eastern Black
Sea (stations are shown in Fig. 2).
other chemical parameters in the Black Sea water column are also density
dependent [59, 76, 95, 105; Murray and Yakushev, this volume]. On average,
the upper sulphide boundary corresponds to a density surface of about 16.2
kg m
−
3
independent of geographical position and season. This density surface
corresponds to the lower pycnocline and was used as an independent estimate
for the location of the sulphide onset in many studies. Our studies have shown
that the upper sulphide boundary shoaled from σ
θ
=16.2 kg m
−
3
to σ
θ
= 16.09-
16.15 kg m
−
3
in 1999-2002 (see also Murray and Yakushev, this volume). The
observed tendency is a result of several warm winters during this period, which
led to a weakening of winter convection process in the upper water column and
increased temperature in the core of Cold Intermediate Layer and decreased
dissolved oxygen content. The reverse trend has been observed after 2002
[74].
