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General conclusions about the state of the rivers
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4.4. General conclusions about the state of the rivers
During the field study conducted in May-June, 2002 zoobenthos and phytoplankton species diversity and population numbers were examined at 15 stretches of the Dnipro tributaries flowing across the Russian Federation. The following indices and parameters were determined: the Vudivis biotic index, oligotrophic index, saprobiological index, species diversity indices for phytoplankton and zoobenthos and biomass of planktonic algae. The field study also produced an assessment of river water contamination by analyzing each of these parameters.
Table 4.39 summarizes the results obtained, which characterize the Dnipro River reach downstream of Smolensk as the most contaminated one (average water quality class WQCaver = 4 – “contaminated”). As “moderately contaminated” is characterized the Dnipro River upstream of Smolensk and the examined reaches of the Snov, Vorsklitsa, Vorskla and Iput rivers (WQCaver = 3). Of 42 water quality measurements made during the field study (excluding species diversity indices) 31% were assigned to the 3d water quality class, 29% were attributed to the 1st water quality class (“very pure”), 14% were categorized as belonging to the 4th class (“contaminated”) and only 2% were classified as “dirty” (5th water quality class) (See Fig. 4.9).
Table 4.39. Assessment of River Phytoplankton and Zoobenthos (May-June, 2001)
|
|
Dnipro, Bolshevo |
Dnipro, upstream of Smolensk |
Dnipro, downstream of Smolensk |
Dnipro, Krasnoye |
Sozh, Kliukino |
Oster, Dubovitsa |
Snov, Zabrama |
Snov, Zasnoviye |
Sudost, Sluchevsk |
Desna, Kamen |
Seim, Tiotkino |
Psiol, Gornal |
Vorsklitsa, Spodariushyno |
Vorskla, Graivoron |
Iput, Vyshkov |
|
WQC for BI |
1 |
2 |
3 |
1 |
2 |
3 |
2 |
2 |
2 |
2 |
2 |
2 |
4 |
4 |
2 |
|
WQC for OI |
1 |
3 |
5 |
1 |
1 |
1 |
3 |
1 |
1 |
1 |
1 |
1 |
2 |
1 |
3 |
|
WQC for Sph |
3 |
4 |
4 |
4 |
|
|
4 |
3 |
3 |
3 |
3 |
3 |
3 |
3 |
|
|
WQCaver |
1,7 |
3,0 |
4,0 |
2,0 |
|
|
3,0 |
2,0 |
2,0 |
2,0 |
2,0 |
2,0 |
3,0 |
2,7 |
2,5 |
|
Hzb |
5,43 |
3,04 |
2,62 |
4,61 |
4,42 |
3,03 |
3,49 |
3,90 |
3,41 |
2,85 |
3,81 |
4,08 |
3,38 |
3,41 |
3,03 |
|
Hph |
2,81 |
1,49 |
1,90 |
0,38 |
|
|
1,43 |
3,11 |
3,34 |
3,00 |
2,65 |
3,93 |
2,99 |
2,31 |
|
|
Вph, mg/L |
0,02 |
0,21 |
0,09 |
1,66 |
|
|
1,37 |
0,10 |
0,02 |
0,43 |
0,05 |
0,04 |
1,12 |
0,10 |
|
Note: WQC – water quality class, BI – Vudivis biotic index, OI – oligotrophic index, Sphp – saprobiological index for phytoplankton, WQCaver – average water quality class, Hzb – zoobenthos diversity index, Нph – phytoplankton diversity index, Вph – phytoplankton biomass;
The Table is colored in accordance with water quality classes.
Fig. 4.9. Distribution of Measurements by Water Quality Class
It is evident from Table 4.39. that different parameters characterize the state of the rivers differently and this is only natural since different organisms and biocenoses react to their environmental conditions in a different way. At the same time, we have revealed some consistency of assessments made using certain methods. Thus, there is a plausible correlation between some parameters such as oligotrophic index and zoobenthos species diversity index, phytoplankton species diversity index and saprobiological index for phytoplankton, and oligotrophic index and saprobiological index for phytoplankton.
Given low biomass values for algae (up to 1.66 mg/L) we cannot talk about eutrophication developing in our rivers. The species diversity of the examined biocenoses is quite wide. Low species diversity indices which might give us concern were only reported in several cases (for example, in the Dnipro River near the village of Krasnoye Нph = 0,38).
At the same time, when analyzing the results one should take into account that living organisms (biocenoses) react to a wide variety of physical, chemical and biotic conditions in water bodies and that observed changes in biocenoses may have been caused not only by anthropogenic pressures (contamination) but also by natural changes in hydrological and hydrochemical parameters of rivers throughout the year. The river ecosystem is a very complicated and little-studied subject. Methods of hydrobiological analysis need to be improved.
It is difficult to make any final conclusions based on the results of only one field study. Thus, the research into the environmental state of the rivers in question should be continued.
