0.01 M) were placed onto the filter to remove inorganic carbonates. The C SOM and
N SOM concentrations were measured on a CHN–1 analyzer (Czech Republic). The
accuracy of the method was 1% for C SOM and 0.3% for N SOM relative to the
analyzed sample mass (Burlakova et al. 1988, 1997). The C Chl concentration was
analyzed by fluorometric methods (Yunev and Berseneva 1986).
The SOM destruction was assessed by the atomic ratio of C SOM /N SOM (from
here on, C/N), the ratio between the detritus (dead) and phytoplankton (live)
organic fraction in SOM was calculated as C SOM /C Chl (from here on, C/Chl)
(Hobson et al. 1973), where C SOM [μM] Â 12 (atomic mass of C) ¼ C SOM [mgC/m
3 ], C Chl [mg/m
3 ]. The average values of these ratios were calculated additionally
using the C SOM and chlorophyll a concentrations measured simultaneously.
10.2.1 The Spatial Structure of the Hydro-Biological
and Bio-Optical Parameters
Features of the distributions of components of SOM war and bio-optical parameters
and their variability are considered for areas NWBS different level of impact on
these areas of the runoff waters and the open sea (Fig. 10.1a), and coastal western
part of the sea (Fig. 10.1b). The size of the zone of influence of transformed river
waters in these areas were limited to isohalines 17 PSU (Fig. 10.2), adopted for the
border of their distribution (Bol’shakov 1970). Distribution of seasonal concentrations of these parameters in the surface layer shown in Figs. 10.3, 10.4 and 10.5.
10.2.1.1 The Northwestern Part of the Sea
The western and northern areas NWBS were located in the area of transformation
of river waters. Here, the highest SOM concentrations were found in every season
in comparison the other areas of the NWBS. During the winter, when riverine
discharge was low and the width of the water transformation zone was relatively
small (Bol’shakov 1970; Kukushkin et al. 2004), the concentrations of SOM
components in the surface water layer in the preestuarine areas of the Danube
River and Dnieper–Bug estuary were nearly equal and relatively low, according to
several observations (Figs. 10.3a,b and 10.4a; Table 10.1). The average C SOM
concentrations were 10.0–12.8 μM; of N SOM , 1.63–1.70 μM. The average C Chl
concentration in these areas varied as 1.83–2.01 mg/m
3 , according to numerous
observations performed in 1984–1988. The average C/Chl ratio was 99–140; of
C/N, 7.6–8.4. This may be evidence of phytoplankton and detritus as the main SOM
components; the detritus was represented by particles at different stages of biochemical transformation.
The weighted averages of the SOM components in the photosynthetic water
layer (0–20 m) were less by a factor of 1.3–1.5 compared to those observed in the
156
A.S. Kukushkin
N SOM concentrations were measured on a CHN–1 analyzer (Czech Republic). The
accuracy of the method was 1% for C SOM and 0.3% for N SOM relative to the
analyzed sample mass (Burlakova et al. 1988, 1997). The C Chl concentration was
analyzed by fluorometric methods (Yunev and Berseneva 1986).
The SOM destruction was assessed by the atomic ratio of C SOM /N SOM (from
here on, C/N), the ratio between the detritus (dead) and phytoplankton (live)
organic fraction in SOM was calculated as C SOM /C Chl (from here on, C/Chl)
(Hobson et al. 1973), where C SOM [μM] Â 12 (atomic mass of C) ¼ C SOM [mgC/m
3 ], C Chl [mg/m
3 ]. The average values of these ratios were calculated additionally
using the C SOM and chlorophyll a concentrations measured simultaneously.
10.2.1 The Spatial Structure of the Hydro-Biological
and Bio-Optical Parameters
Features of the distributions of components of SOM war and bio-optical parameters
and their variability are considered for areas NWBS different level of impact on
these areas of the runoff waters and the open sea (Fig. 10.1a), and coastal western
part of the sea (Fig. 10.1b). The size of the zone of influence of transformed river
waters in these areas were limited to isohalines 17 PSU (Fig. 10.2), adopted for the
border of their distribution (Bol’shakov 1970). Distribution of seasonal concentrations of these parameters in the surface layer shown in Figs. 10.3, 10.4 and 10.5.
10.2.1.1 The Northwestern Part of the Sea
The western and northern areas NWBS were located in the area of transformation
of river waters. Here, the highest SOM concentrations were found in every season
in comparison the other areas of the NWBS. During the winter, when riverine
discharge was low and the width of the water transformation zone was relatively
small (Bol’shakov 1970; Kukushkin et al. 2004), the concentrations of SOM
components in the surface water layer in the preestuarine areas of the Danube
River and Dnieper–Bug estuary were nearly equal and relatively low, according to
several observations (Figs. 10.3a,b and 10.4a; Table 10.1). The average C SOM
concentrations were 10.0–12.8 μM; of N SOM , 1.63–1.70 μM. The average C Chl
concentration in these areas varied as 1.83–2.01 mg/m
3 , according to numerous
observations performed in 1984–1988. The average C/Chl ratio was 99–140; of
C/N, 7.6–8.4. This may be evidence of phytoplankton and detritus as the main SOM
components; the detritus was represented by particles at different stages of biochemical transformation.
The weighted averages of the SOM components in the photosynthetic water
layer (0–20 m) were less by a factor of 1.3–1.5 compared to those observed in the
156
A.S. Kukushkin