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The state and water quality of small rivers in Belarus: the case study of the Dnieper river basin
Vol. 6 No 1-4, 61-67 2006 Ecohydrology for Implementation of the European Water Framework Directive
The state and water quality of small rivers in Belarus: the case study of the Dnieper river basin
Vitaly Semenchenko1, Natallia Rybianets2 1
Institute of Zoology, National Academy of Sciences of Belarus, 27, Ul. Academycheskaia, Minsk-72, 220072, Belarus e-mail: [email protected] 2 Centre for Coordination of Cooperation with the UNESCO and Other International Organizations, National Academy of Sciences of Belarus, 66, Prospekt Nezavisimosti, Minsk -72, 220072, Belarus e-mail: [email protected]
Abstract For the assessment of ecological water quality in small rivers of the south-western part of the basin of the River Dnieper on the territory of Belarus the integrated approach was implemented based on hydrological, hydro-chemical and biological data. The rivers overflow has been determined as the main factor triggering the inflow of the water seeping from mires and also the pollution of the watershed that has led to decrease of the pH level, change in the color of the water, and also concentration of nitrogen and phosphorus in the water. The water quality was assessed on the basis of species diversity, the amount of sensitive macro-invertebrate community species as well as the biotic indices. In most of the cases, the water quality could be defined as "good" or "very good". The indicated river reference sites were selected on the basis of the integrated (common) analysis of abiotic and biotic characteristics. It is clear that the most credible information on water quality could be obtained only on the basis of an approach which includes abiotic and biotic components. Key words: hydrological and hydro-chemical factors, species richness, biotic indices.
1. Introduction The ecological situation in the river basin is assessed on the basis of integrated analysis of biotic and abiotic components (Zalewski 2004). The aim of the analysis is to determine a set of ecological indicators as the components for management of the water resources in the basin of the River Dnieper (Hunsaker, Levin 1995). The principal advantage of the indicators lies in simplification of the scientific data into
characteristics acceptable for the management. As a rule, the ecological indicators are based on the biotic component and include the species diversity, the community structure and the biotic indices. The main advantage of ecological indicators is their reflection of a cumulative effect of the chemical, physical and biological influences, thus ecological quality of the water resources being assessed with the help of these ecological indicators.
62
V. Semenchenko, N. Rybianets
The Dnieper basin is the biggest one in the territory of Belarus. Different parts of the basin have their own specific ecological situation. But there are typical factors predominantly influencing the water quality all around the basin. In most of the cases, these factors are common for both small and medium-size rivers alike. As different from the situation in the big rivers, the major problem for the small ones is caused by the lack of proper control of their condition. As a result, it leads to poor information on the condition of the river basins and, consequently, to difficulties in identification of reasons leading to changes in the water quality. The southern part of the Dnieper basin in the territory of Belarus has suffered a strong impact owing to the land-reclamation activities. In many cases, the land-reclamation works are the main reason for changes in the ecological and hydrological situation in the area. There are many soil-reclamation canals in this part of the basin that form a dense land-reclamation net. At places, the water courses of the rivers are either align or shaped by dams. All these factors cause modifications in the hydrological regimes, and, as a result overall changing of the ecological situation in the basins of the rivers. Under such circumstances, the rivers could not be classified as "natural" or undisturbed. For the research purposes, several control sites were selected on condition that they are located in the territories that had not undergone the land-reclamation.
Fig.1. Investigated part of Dnieper river basin
2. Materials and methods The part of the Dnieper basin under research is located in the south-eastern part of Belarus (Fig 1). All the data obtained was collected during the spring (May) of 2005 from the rivers differently ordered: the Rivers Vedernia, Ipa and Usa making the second order; the Rivers Besed', Sozh, Beresina and Iput' making the third order. Determination of potential reference sites and assessment of the ecological situation in this part of the river basin were the major purposes of the investigation. The characteristics under research were defined as components of two groups. The environmental characteristics: pH, dissolved oxygen content, water color index, conductivity, rate of flow, biogenic elements, and the biological characteristics: species richness of macroinvertebrate community, Ephemeroptera + Plecoptera + Trichoptera Taxa (EPT) as well as various biotic indices. These characteristics are the basic ones for the choice of the reference sites. The following equipments and methods were used in the research: - pH measurement - pH-meter (Hanna, CHECKER 1); - conductivity index - conduct-meter (Hanna, HI 8633); - dissolved oxygen level - Winkler' method; - water color - Cobalt Scale; - NH4+ - photometric, Nessler' method; - NO2- - photometric, Griss' method;
63
State of small rivers in Belarus: the Dnieper case study
- NO3- - photometric, with salicylic Na; - PO43- - photometric, with (NH4)6Mo7O24; - 137Cs - gamma-beta-spectrometer MKC-AT 1315, minimal level determination of activity - 2 Bk kg-1. The hand net (ISO 7828) was used for macro-zoobenthos sampling. The type of bottom sedimentation in the reference sites was practically the same: the silted sands, sampling area 1.25 m2, and the number of samples per site - 3.
3. Results and discussion Major environmental conditions The physical, chemical and biological factors served the basis for classification of the condition of the investigated sites. The results of the research work showed that the ecological parameters of the river water during the spring period are determined by two major processes - the spring overflow of the rivers and indirect influence of radioactive contamination of the territory in this part of the river basin.
Spring overflow of the rivers The south-eastern part of the Dnieper basin within the territory of Belarus is the vast lowland with a big number of different types of mires. The spring overflow of the rivers is followed by water seeping from mires into the river streams and correspondently decreasing of the active reaction of the water. The value of the active water reaction is closely connected with the width of the riverbed and amount of discharge of the water. The minimal values of pH (such as 6.0) in water were observed in the rivers of the second order, while in the rivers of the third order the values of water pH are close to neutral (Table I).
The water seeping from mires into the river streams is followed by decrease of the active reaction and increase of conductivity. In some cases, (the Rivers Vedrich and Ipa) it has lead to the high water-color index. There was found no significant correlation between the pH-level and conductivity, although the weak inverse correlation of the color index and conductivity was observed (r=-0.42). This fact confirms the influence of the water seeping from mires on hydrochemistry of the river water. The amount of dissolved oxygen in all the samples was high and showed positive correlation with the rate of flow. The overflow of rivers has resulted in the increased levels of ammonium and nitrogen and total phosphorus concentration due to the erosion caused by organic and non-organic fertilizers as well as other substances that had come from adjoining agricultural fields. Maximum concentration of NO3- anions was observed in the Ipa and Berezina rivers although their sources were deferent. The agricultural fields were the main source of NO3- anions for the River Ipa as there are neither towns nor big villages in this part of the river basin. Waste waters from the town of Svetlogorsk have been the major source of NO3- anions for the River Berezina (Table II). The value of NO2- just as the total concentration of phosphorus in water was low in most of the samples with the exception of the Vedrich River site (NO2- concentration) as well as the sites on the Rivers Usa and Berezina (the total phosphorus concentration) gained the levels of 0.1 mg dm-3 and 2.8 μg dm-3, correspondingly.
Nuclear contamination The south-east part of the Dnieper basin in the territory of Belarus is located in the area that has undergone the radio-active contamination as a
Sozh -1
Sozh -2
Iput’
Besed’
Vedrich
Ipa
Usa
Factors Rate of flow, (m sec-1)
Berezina
Vedernia
Table I. Environmental factors for different rivers.
0.18
0.04
0.15
0.30
0.01
0.29
0.39
0.46
0.37
pH
7.0
6.5
6.5
6.5
6.5
6.0
6.0
6.5
6.0
9.0
7.47
8.73
5.95
5.46
-
-
7.55
9.28
810
286
267
683
770
430
896
520
588
11
18
18
18
15
21
19
16
13
Rivers
Dissolved oxygen, (mg dm-3) Conductivity (μS) Water-color index, (Co-scale)
64
V. Semenchenko, N. Rybianets
Table II. Hydrochemical characteristics of the investigated sites Sozh-1
Sozh-2
Berezina
Iput’
Besed’
Vedrich
Ipa
Usa
Vedernia
Rivers
Parameters NO3-, (mg dm-3)
0.873
0.675
3.492
0.595
0.833
0.766
7.282
0.897
0.151
NO2-, (mg dm-3)
0.002
0.002
0.039
0.003
0.003
0.100
0.073
0.039
0.013
NH4+, (mg dm-3)
<0.05
0.257
<0.002
0.003
<0.05
<0.05
<0.05
0.247
0.063
“Total” phosphorus, (mcg dm-3)
1.31
1.70
2.88
0.95
1.01
1.37
1.77
2.83
2.19
result of the Chernobyl disaster. In the seal zone no agricultural or other types of economic activity held. It is necessary to point out that the specific activity of 137Cs in the river water does not exceed 0.2 - 0.5 Bk dm-3. During the spring overflow, particles of nuclear contamination go down to the rivers from the adjacent lands and accumulate in the bottom sediments. The high density of sedimentation contamination spotted in both the Vedernia and Sozh Rivers (Site 1, 0.28 and 2.61 Bk dm3 consequently) indicates that their beds are situated in the contaminated zone. A very high content of 137Cs in the Sozh are associated with the by broad flood (erosion by contaminated substances from adjacent lands) and the low rate of flow (acceleration process of sedimentation 137Cs on the bottom).
Water quality The ecological water quality has been assessed by application of the data on the species richness, structure of macroinvertebrate community and biotic indices. Taxa richness can be assessed on the different levels of taxonomy groups. Number of species and pollution-sensi- 50% tive groups of macroinvertebrate community 40% was using for the analysis. The different patterns of macroinverte30% brate community (taxa richness, number of sensitive taxa, composition of community, 20% biotic indices) can be used as a measure of ecological water quality. We used a species rich- 10% ness of macrozoobenthos and number of sensitive taxa as a measure of ecological water 0% quality. It was found that the maximal species richness is observed in the Besed' and Iput rivers - 38.6% and 37.7% of total number of the observed species (Fig. 2). The lower value
equals 34.2% - we observed that in the Vedernia and Berezina rivers, a distinctively lower value of the species richness -18.4 - 25.4% - was found in the Vedrich, Uza, and Sozh rivers, while the lowest one observed in the Ipa river - 14.1%. The number of sensitive taxa (EPT) is very often used for estimation of the water quality (DeShon 1995). This index comes in close correlation with species richness and other biotic indices (Mandaville 2002; Semenchenko, Moroz 2005). The list of sensitive taxa is presented in Table III. Some of these species are rare not only for the Republic of Belarus, but also the rest of the European continent: Isoperla difformis, Nemoura dubitans, (Plecoptera), Heptagenia coerulans (Ephemeroptera), Brachycentrus subnubilus (Trichoptera). Only three rivers (the Vedernia, the Iput' and the Besed') have high EPT values of the contaminated substances (Table IV). As a rule, the EPT index equals 12-14 for the lowland rivers having a high degree of the water quality in the central part of Europe. In comparison with the species richness, the EPT index can more precisely identify the stu-
1
2
3
4
5
6
7
8
9
Fig. 2. Species richness (% of total number) in different rivers (1 - the Sozh-1; 2 - the Sozh-2; 3 - the Berezina; 4 - the Iput'; 5 - the Besed'; 6 - the Vedrich; 7- the Ipa; 8- the Usa; 9 - the Vedernia)
65
State of small rivers in Belarus: the Dnieper case study
Table III. List of sensitive taxa (Plecoptera, Ephemeroptera, Trichoptera) in different rivers
died sites considering their water quality, but this index does not have any gradations, thus it can be used only in combination with other indices or reference sites. The following biotic index was used for assessment of the water quality: 1. Trent Biotic Index (TBI) (Woodiwiss 1964), 2. Extended Biotic Index (EBI) (Woodiwiss 1978) 3. Biological Monitoring Working Party (BMWP) (Wright et al. 1993). 4. Average Score Per Taxon (ASPT) (Wright et al. 1993). 5. EPT (Ephemeroptera +Plecoptera+Trichoptera) Index By means of standard gradations of indexes the limits of the different levels of ecological status were established.
Vedrich
Ipa
Usa
Vedernia
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Besed’
10 11 12
Iput’
1 2 3 4 5 6 7 8 9
Order Plecoptera Isoperla difformis (KLÁPALEK, 1909) Nemoura dubitans MORTON, 1894 Nemoura flexuosa AUBERT, 1949 Nemoura sp. Order Ephemeroptera Siphlonurus aestivalis EATON, 1903 Cloeon dipterum (LINNAEUS, 1761) Centroptilum luteolum (MÜLLER, 1776) Baetis fuscatus (LINNAEUS, 1761). Baetis sp. Heptagenia coerulans (ROSTOCK, 1877) Heptagenia flava ROSTOCK, 1878 Leptophlebia marginata (LINNAEUS, 1767) Paraleptophlebia submarginata (STEPHENS, 1835) Ephemera vulgata LINNAEUS, 1758 Caenis horaria (LINNAEUS, 1758) Caenis sp. Order Trichoptera Hydropsyche angustipennis (CURTIS, 1834) Hydropsyche sp. Anabolia sp. Drusus annulatus (Stephens, 1837) Halesus radiatus (CURTIS, 1834) Limnephilus flavicornis (FABRICIUS, 1787) Limnephilus griseus (LINNAEUS, 1758) Limnephilus politus MCLACHLAN, 1865 Limnephilus rhombicus (LINNAEUS, 1758) Limnephilus sp. Brachycentrus subnubilus CURTIS, 1834 Silo pallipes (FABRICIUS, 1781) Molanna sp. Triaenodes bicolor (CURTIS, 1834) Mystacides longicornis (LINNAEUS, 1758) Oecetis sp. Hydroptila sp. Total
Berezina
1 2 3 4
Sozh-2
Rivers
Sozh-1
taxa
-
-
+ -
+ -
-
+
-
-
+ -
+ + + + + -
+ + + -
+ + + -
+ + + + +
+ + + + + -
+ -
+ -
+ + -
+ + -
-
+ -
-
+ -
+ + +
+ -
+ -
+ +
-
5
+ 5
+ + -
+ + + + + 12
+ + + + + + 14
+ + + + 7
+ + 5
+ 5
+ + + + + + + + + 12
6
The comparative analysis of different biotic indices has demonstrated that the BMWP/ASPT and the EPT are the most adaptable criteria for the process of bioindication (Pinder, Farr 1987; Semenchenko, Moroz 2005). The highest values of indices were observed in the Rivers Iput', Besed' and Vedernia (Table IV). In the process of analysis of the data it was also found out that the TBI sensitivity is low, and the index does not properly reflect the ecological situation in the river. So, the TBI was excluded from the analysis when reference sites were determined. In most cases, the water quality in different rivers can be characterized as good or very good. In the sites of the Sozh river the water quality is fluctuating from "very good" to "moderate" with the minimum EPT values.
66
V. Semenchenko, N. Rybianets
Table IV. Biotic indices value and water quality at the different rivers' sites Sozh - 1
Sozh -2
Berezina
Iput’
Besed’
Vedrich
Ipa
Usa
Vedernia
Rivers
TBI
very good 10
very good 8
very good 8
very good 10
very good 10
very good 10
very good 10
very good 9
very good 8
EBI
Good 8
moderate 7
good 9
very good 10
very good 11
very good 11
very good 11
very good 11
good 8
BMWP
moderate 32
good 56
good 85
very good 105
good 68
good 71
good 59
good 54
good 66
ASPT
very good 4.57
excellent 5.11
very good 4.96
excellent 5.82
very good 4.94
very good 4.73
very good 4.92
very good 4.70
excellent 5.04
EPT
4
4
5
9
9
5
4
5
9
Indices
The integrated approach with the use of hydro-chemical data, species richness, sensitive taxa and indices allows to make a conclusion that the Iput', Besed' and Vedernia rivers sites can be recommended to be established as reference sites.
4. Conclusions The results of the carried out investigation of the south-east part of the Dnieper river basin have proved the necessity of applying the integrated approach in assessing the ecological quality of the river water. Such an approach should be based on the joint analysis of both the abiotic and biotic components of the river ecosystem, as well as the peculiarities of the water-producing area of the river. In particular, the major source of supply for the biogenic elements during the research period are the adjacent agricultural lands as well as urban waste that affects the big rivers mostly such as the Berezina and the Sozh. The characteristic feature of the investigated part of the river basin is the supply of the water seeping from the adjacent mires that leads to increase of the water colour and decreasing of the pH level. This phenomenon is especially pronounced during the spring overflow of the rivers. In this context a work-out of special set of guidelines is extremely necessary that can help to identify the reference aligning with consideration of the indicated peculiarities of the basin. So, a river which water-producing area includes the mires can be recognized as one with the natural ecological composition, yet, the biodiversity there may be
low. According to Boom (2000), such rivers should possess a distinctively higher ecological status as compared to those having a wider biodiversity index although the river as such is considered to be disturbed. The reference aligning can also be used as the base for creation of a network of the protected land, the data on such reference aligning (biodiversity, species richness, natural condition of the environment, etc.) being a compulsory element of such a network.
5. References Boon, P.J. 2000. The development of integrated methods for assessing river conservation value. Hydrobiologia 422/423, 413-428. DeShon, J.E. 1995. Development and application of the invertebrate community index (ICI). In: Davis, W.S and Simon, T.P. [Eds] Biological assessment and criteria: Tools for water resource planning and decision making. Lewis Publishers, Boca Raton, Florida. pp. 217-243 Hunsacker, C.T., Levine, D.A. 1995. Hierarchical approaches to the study of water quality in rivers. Bioscience 45, 3, 193-203. Karr, J.R. 1991. Biological integrity: A long-neglected aspect of water resource management. Ecological Applications 1, 66-84. Mandaville, S.M. 2002. Benthic Macroinvertebrates in Freshwaters - Taxa Tolerance Values, Metrics, and Protocols. Soil&Water Conservation Society of Metro Halifax, Halifax. Canada.
State of small rivers in Belarus: the Dnieper case study Semenchenko, V.P., Moroz, M.D. 2005. Comparative Analysis of Biotic Indices in the Monitoring System of Running Water in a Biospheric Reserve. Water Resources 32, 2, 200-203. Pinder, L.C.V. and I.S. Farr. 1987. Biological surveillance of water quality. Archiv für Hydrobiologie 109, 619-637. Woodiwiss, F.S. 1964. The biological system of stream classification used by the Trent River Board. Chemistry and Industry 11, 443-447. Woodiwiss, F.S. 1978. Comparative study of biologicalecological water quality assessment methods. Sum-
67
mary Report. Commission of the European Communities. Severn Trent Water Authority. UK. Wright, J.F., Furse, M.T., Armitage, P.D., Moss, D. 1993. New procedures for identifying running-water sites subject to environmental stress and for evaluating sites for conservation, based on the macroinvertebrate fauna. Archiv für Hydrobiologie 127, 319-326. Zalewski, M. 2004. Ecohydrology as a system approach for sustainable water biodiversity and ecosystem service. Ecohydrology and Hydrobiology 4, 229-235.
The state and water quality of small rivers in Belarus: the case study of the Dnieper river basin
Vitaly Semenchenko1, Natallia Rybianets2 1
Institute of Zoology, National Academy of Sciences of Belarus, 27, Ul. Academycheskaia, Minsk-72, 220072, Belarus e-mail: [email protected] 2 Centre for Coordination of Cooperation with the UNESCO and Other International Organizations, National Academy of Sciences of Belarus, 66, Prospekt Nezavisimosti, Minsk -72, 220072, Belarus e-mail: [email protected]
Abstract For the assessment of ecological water quality in small rivers of the south-western part of the basin of the River Dnieper on the territory of Belarus the integrated approach was implemented based on hydrological, hydro-chemical and biological data. The rivers overflow has been determined as the main factor triggering the inflow of the water seeping from mires and also the pollution of the watershed that has led to decrease of the pH level, change in the color of the water, and also concentration of nitrogen and phosphorus in the water. The water quality was assessed on the basis of species diversity, the amount of sensitive macro-invertebrate community species as well as the biotic indices. In most of the cases, the water quality could be defined as "good" or "very good". The indicated river reference sites were selected on the basis of the integrated (common) analysis of abiotic and biotic characteristics. It is clear that the most credible information on water quality could be obtained only on the basis of an approach which includes abiotic and biotic components. Key words: hydrological and hydro-chemical factors, species richness, biotic indices.
1. Introduction The ecological situation in the river basin is assessed on the basis of integrated analysis of biotic and abiotic components (Zalewski 2004). The aim of the analysis is to determine a set of ecological indicators as the components for management of the water resources in the basin of the River Dnieper (Hunsaker, Levin 1995). The principal advantage of the indicators lies in simplification of the scientific data into
characteristics acceptable for the management. As a rule, the ecological indicators are based on the biotic component and include the species diversity, the community structure and the biotic indices. The main advantage of ecological indicators is their reflection of a cumulative effect of the chemical, physical and biological influences, thus ecological quality of the water resources being assessed with the help of these ecological indicators.
62
V. Semenchenko, N. Rybianets
The Dnieper basin is the biggest one in the territory of Belarus. Different parts of the basin have their own specific ecological situation. But there are typical factors predominantly influencing the water quality all around the basin. In most of the cases, these factors are common for both small and medium-size rivers alike. As different from the situation in the big rivers, the major problem for the small ones is caused by the lack of proper control of their condition. As a result, it leads to poor information on the condition of the river basins and, consequently, to difficulties in identification of reasons leading to changes in the water quality. The southern part of the Dnieper basin in the territory of Belarus has suffered a strong impact owing to the land-reclamation activities. In many cases, the land-reclamation works are the main reason for changes in the ecological and hydrological situation in the area. There are many soil-reclamation canals in this part of the basin that form a dense land-reclamation net. At places, the water courses of the rivers are either align or shaped by dams. All these factors cause modifications in the hydrological regimes, and, as a result overall changing of the ecological situation in the basins of the rivers. Under such circumstances, the rivers could not be classified as "natural" or undisturbed. For the research purposes, several control sites were selected on condition that they are located in the territories that had not undergone the land-reclamation.
Fig.1. Investigated part of Dnieper river basin
2. Materials and methods The part of the Dnieper basin under research is located in the south-eastern part of Belarus (Fig 1). All the data obtained was collected during the spring (May) of 2005 from the rivers differently ordered: the Rivers Vedernia, Ipa and Usa making the second order; the Rivers Besed', Sozh, Beresina and Iput' making the third order. Determination of potential reference sites and assessment of the ecological situation in this part of the river basin were the major purposes of the investigation. The characteristics under research were defined as components of two groups. The environmental characteristics: pH, dissolved oxygen content, water color index, conductivity, rate of flow, biogenic elements, and the biological characteristics: species richness of macroinvertebrate community, Ephemeroptera + Plecoptera + Trichoptera Taxa (EPT) as well as various biotic indices. These characteristics are the basic ones for the choice of the reference sites. The following equipments and methods were used in the research: - pH measurement - pH-meter (Hanna, CHECKER 1); - conductivity index - conduct-meter (Hanna, HI 8633); - dissolved oxygen level - Winkler' method; - water color - Cobalt Scale; - NH4+ - photometric, Nessler' method; - NO2- - photometric, Griss' method;
63
State of small rivers in Belarus: the Dnieper case study
- NO3- - photometric, with salicylic Na; - PO43- - photometric, with (NH4)6Mo7O24; - 137Cs - gamma-beta-spectrometer MKC-AT 1315, minimal level determination of activity - 2 Bk kg-1. The hand net (ISO 7828) was used for macro-zoobenthos sampling. The type of bottom sedimentation in the reference sites was practically the same: the silted sands, sampling area 1.25 m2, and the number of samples per site - 3.
3. Results and discussion Major environmental conditions The physical, chemical and biological factors served the basis for classification of the condition of the investigated sites. The results of the research work showed that the ecological parameters of the river water during the spring period are determined by two major processes - the spring overflow of the rivers and indirect influence of radioactive contamination of the territory in this part of the river basin.
Spring overflow of the rivers The south-eastern part of the Dnieper basin within the territory of Belarus is the vast lowland with a big number of different types of mires. The spring overflow of the rivers is followed by water seeping from mires into the river streams and correspondently decreasing of the active reaction of the water. The value of the active water reaction is closely connected with the width of the riverbed and amount of discharge of the water. The minimal values of pH (such as 6.0) in water were observed in the rivers of the second order, while in the rivers of the third order the values of water pH are close to neutral (Table I).
The water seeping from mires into the river streams is followed by decrease of the active reaction and increase of conductivity. In some cases, (the Rivers Vedrich and Ipa) it has lead to the high water-color index. There was found no significant correlation between the pH-level and conductivity, although the weak inverse correlation of the color index and conductivity was observed (r=-0.42). This fact confirms the influence of the water seeping from mires on hydrochemistry of the river water. The amount of dissolved oxygen in all the samples was high and showed positive correlation with the rate of flow. The overflow of rivers has resulted in the increased levels of ammonium and nitrogen and total phosphorus concentration due to the erosion caused by organic and non-organic fertilizers as well as other substances that had come from adjoining agricultural fields. Maximum concentration of NO3- anions was observed in the Ipa and Berezina rivers although their sources were deferent. The agricultural fields were the main source of NO3- anions for the River Ipa as there are neither towns nor big villages in this part of the river basin. Waste waters from the town of Svetlogorsk have been the major source of NO3- anions for the River Berezina (Table II). The value of NO2- just as the total concentration of phosphorus in water was low in most of the samples with the exception of the Vedrich River site (NO2- concentration) as well as the sites on the Rivers Usa and Berezina (the total phosphorus concentration) gained the levels of 0.1 mg dm-3 and 2.8 μg dm-3, correspondingly.
Nuclear contamination The south-east part of the Dnieper basin in the territory of Belarus is located in the area that has undergone the radio-active contamination as a
Sozh -1
Sozh -2
Iput’
Besed’
Vedrich
Ipa
Usa
Factors Rate of flow, (m sec-1)
Berezina
Vedernia
Table I. Environmental factors for different rivers.
0.18
0.04
0.15
0.30
0.01
0.29
0.39
0.46
0.37
pH
7.0
6.5
6.5
6.5
6.5
6.0
6.0
6.5
6.0
9.0
7.47
8.73
5.95
5.46
-
-
7.55
9.28
810
286
267
683
770
430
896
520
588
11
18
18
18
15
21
19
16
13
Rivers
Dissolved oxygen, (mg dm-3) Conductivity (μS) Water-color index, (Co-scale)
64
V. Semenchenko, N. Rybianets
Table II. Hydrochemical characteristics of the investigated sites Sozh-1
Sozh-2
Berezina
Iput’
Besed’
Vedrich
Ipa
Usa
Vedernia
Rivers
Parameters NO3-, (mg dm-3)
0.873
0.675
3.492
0.595
0.833
0.766
7.282
0.897
0.151
NO2-, (mg dm-3)
0.002
0.002
0.039
0.003
0.003
0.100
0.073
0.039
0.013
NH4+, (mg dm-3)
<0.05
0.257
<0.002
0.003
<0.05
<0.05
<0.05
0.247
0.063
“Total” phosphorus, (mcg dm-3)
1.31
1.70
2.88
0.95
1.01
1.37
1.77
2.83
2.19
result of the Chernobyl disaster. In the seal zone no agricultural or other types of economic activity held. It is necessary to point out that the specific activity of 137Cs in the river water does not exceed 0.2 - 0.5 Bk dm-3. During the spring overflow, particles of nuclear contamination go down to the rivers from the adjacent lands and accumulate in the bottom sediments. The high density of sedimentation contamination spotted in both the Vedernia and Sozh Rivers (Site 1, 0.28 and 2.61 Bk dm3 consequently) indicates that their beds are situated in the contaminated zone. A very high content of 137Cs in the Sozh are associated with the by broad flood (erosion by contaminated substances from adjacent lands) and the low rate of flow (acceleration process of sedimentation 137Cs on the bottom).
Water quality The ecological water quality has been assessed by application of the data on the species richness, structure of macroinvertebrate community and biotic indices. Taxa richness can be assessed on the different levels of taxonomy groups. Number of species and pollution-sensi- 50% tive groups of macroinvertebrate community 40% was using for the analysis. The different patterns of macroinverte30% brate community (taxa richness, number of sensitive taxa, composition of community, 20% biotic indices) can be used as a measure of ecological water quality. We used a species rich- 10% ness of macrozoobenthos and number of sensitive taxa as a measure of ecological water 0% quality. It was found that the maximal species richness is observed in the Besed' and Iput rivers - 38.6% and 37.7% of total number of the observed species (Fig. 2). The lower value
equals 34.2% - we observed that in the Vedernia and Berezina rivers, a distinctively lower value of the species richness -18.4 - 25.4% - was found in the Vedrich, Uza, and Sozh rivers, while the lowest one observed in the Ipa river - 14.1%. The number of sensitive taxa (EPT) is very often used for estimation of the water quality (DeShon 1995). This index comes in close correlation with species richness and other biotic indices (Mandaville 2002; Semenchenko, Moroz 2005). The list of sensitive taxa is presented in Table III. Some of these species are rare not only for the Republic of Belarus, but also the rest of the European continent: Isoperla difformis, Nemoura dubitans, (Plecoptera), Heptagenia coerulans (Ephemeroptera), Brachycentrus subnubilus (Trichoptera). Only three rivers (the Vedernia, the Iput' and the Besed') have high EPT values of the contaminated substances (Table IV). As a rule, the EPT index equals 12-14 for the lowland rivers having a high degree of the water quality in the central part of Europe. In comparison with the species richness, the EPT index can more precisely identify the stu-
1
2
3
4
5
6
7
8
9
Fig. 2. Species richness (% of total number) in different rivers (1 - the Sozh-1; 2 - the Sozh-2; 3 - the Berezina; 4 - the Iput'; 5 - the Besed'; 6 - the Vedrich; 7- the Ipa; 8- the Usa; 9 - the Vedernia)
65
State of small rivers in Belarus: the Dnieper case study
Table III. List of sensitive taxa (Plecoptera, Ephemeroptera, Trichoptera) in different rivers
died sites considering their water quality, but this index does not have any gradations, thus it can be used only in combination with other indices or reference sites. The following biotic index was used for assessment of the water quality: 1. Trent Biotic Index (TBI) (Woodiwiss 1964), 2. Extended Biotic Index (EBI) (Woodiwiss 1978) 3. Biological Monitoring Working Party (BMWP) (Wright et al. 1993). 4. Average Score Per Taxon (ASPT) (Wright et al. 1993). 5. EPT (Ephemeroptera +Plecoptera+Trichoptera) Index By means of standard gradations of indexes the limits of the different levels of ecological status were established.
Vedrich
Ipa
Usa
Vedernia
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Besed’
10 11 12
Iput’
1 2 3 4 5 6 7 8 9
Order Plecoptera Isoperla difformis (KLÁPALEK, 1909) Nemoura dubitans MORTON, 1894 Nemoura flexuosa AUBERT, 1949 Nemoura sp. Order Ephemeroptera Siphlonurus aestivalis EATON, 1903 Cloeon dipterum (LINNAEUS, 1761) Centroptilum luteolum (MÜLLER, 1776) Baetis fuscatus (LINNAEUS, 1761). Baetis sp. Heptagenia coerulans (ROSTOCK, 1877) Heptagenia flava ROSTOCK, 1878 Leptophlebia marginata (LINNAEUS, 1767) Paraleptophlebia submarginata (STEPHENS, 1835) Ephemera vulgata LINNAEUS, 1758 Caenis horaria (LINNAEUS, 1758) Caenis sp. Order Trichoptera Hydropsyche angustipennis (CURTIS, 1834) Hydropsyche sp. Anabolia sp. Drusus annulatus (Stephens, 1837) Halesus radiatus (CURTIS, 1834) Limnephilus flavicornis (FABRICIUS, 1787) Limnephilus griseus (LINNAEUS, 1758) Limnephilus politus MCLACHLAN, 1865 Limnephilus rhombicus (LINNAEUS, 1758) Limnephilus sp. Brachycentrus subnubilus CURTIS, 1834 Silo pallipes (FABRICIUS, 1781) Molanna sp. Triaenodes bicolor (CURTIS, 1834) Mystacides longicornis (LINNAEUS, 1758) Oecetis sp. Hydroptila sp. Total
Berezina
1 2 3 4
Sozh-2
Rivers
Sozh-1
taxa
-
-
+ -
+ -
-
+
-
-
+ -
+ + + + + -
+ + + -
+ + + -
+ + + + +
+ + + + + -
+ -
+ -
+ + -
+ + -
-
+ -
-
+ -
+ + +
+ -
+ -
+ +
-
5
+ 5
+ + -
+ + + + + 12
+ + + + + + 14
+ + + + 7
+ + 5
+ 5
+ + + + + + + + + 12
6
The comparative analysis of different biotic indices has demonstrated that the BMWP/ASPT and the EPT are the most adaptable criteria for the process of bioindication (Pinder, Farr 1987; Semenchenko, Moroz 2005). The highest values of indices were observed in the Rivers Iput', Besed' and Vedernia (Table IV). In the process of analysis of the data it was also found out that the TBI sensitivity is low, and the index does not properly reflect the ecological situation in the river. So, the TBI was excluded from the analysis when reference sites were determined. In most cases, the water quality in different rivers can be characterized as good or very good. In the sites of the Sozh river the water quality is fluctuating from "very good" to "moderate" with the minimum EPT values.
66
V. Semenchenko, N. Rybianets
Table IV. Biotic indices value and water quality at the different rivers' sites Sozh - 1
Sozh -2
Berezina
Iput’
Besed’
Vedrich
Ipa
Usa
Vedernia
Rivers
TBI
very good 10
very good 8
very good 8
very good 10
very good 10
very good 10
very good 10
very good 9
very good 8
EBI
Good 8
moderate 7
good 9
very good 10
very good 11
very good 11
very good 11
very good 11
good 8
BMWP
moderate 32
good 56
good 85
very good 105
good 68
good 71
good 59
good 54
good 66
ASPT
very good 4.57
excellent 5.11
very good 4.96
excellent 5.82
very good 4.94
very good 4.73
very good 4.92
very good 4.70
excellent 5.04
EPT
4
4
5
9
9
5
4
5
9
Indices
The integrated approach with the use of hydro-chemical data, species richness, sensitive taxa and indices allows to make a conclusion that the Iput', Besed' and Vedernia rivers sites can be recommended to be established as reference sites.
4. Conclusions The results of the carried out investigation of the south-east part of the Dnieper river basin have proved the necessity of applying the integrated approach in assessing the ecological quality of the river water. Such an approach should be based on the joint analysis of both the abiotic and biotic components of the river ecosystem, as well as the peculiarities of the water-producing area of the river. In particular, the major source of supply for the biogenic elements during the research period are the adjacent agricultural lands as well as urban waste that affects the big rivers mostly such as the Berezina and the Sozh. The characteristic feature of the investigated part of the river basin is the supply of the water seeping from the adjacent mires that leads to increase of the water colour and decreasing of the pH level. This phenomenon is especially pronounced during the spring overflow of the rivers. In this context a work-out of special set of guidelines is extremely necessary that can help to identify the reference aligning with consideration of the indicated peculiarities of the basin. So, a river which water-producing area includes the mires can be recognized as one with the natural ecological composition, yet, the biodiversity there may be
low. According to Boom (2000), such rivers should possess a distinctively higher ecological status as compared to those having a wider biodiversity index although the river as such is considered to be disturbed. The reference aligning can also be used as the base for creation of a network of the protected land, the data on such reference aligning (biodiversity, species richness, natural condition of the environment, etc.) being a compulsory element of such a network.
5. References Boon, P.J. 2000. The development of integrated methods for assessing river conservation value. Hydrobiologia 422/423, 413-428. DeShon, J.E. 1995. Development and application of the invertebrate community index (ICI). In: Davis, W.S and Simon, T.P. [Eds] Biological assessment and criteria: Tools for water resource planning and decision making. Lewis Publishers, Boca Raton, Florida. pp. 217-243 Hunsacker, C.T., Levine, D.A. 1995. Hierarchical approaches to the study of water quality in rivers. Bioscience 45, 3, 193-203. Karr, J.R. 1991. Biological integrity: A long-neglected aspect of water resource management. Ecological Applications 1, 66-84. Mandaville, S.M. 2002. Benthic Macroinvertebrates in Freshwaters - Taxa Tolerance Values, Metrics, and Protocols. Soil&Water Conservation Society of Metro Halifax, Halifax. Canada.
State of small rivers in Belarus: the Dnieper case study Semenchenko, V.P., Moroz, M.D. 2005. Comparative Analysis of Biotic Indices in the Monitoring System of Running Water in a Biospheric Reserve. Water Resources 32, 2, 200-203. Pinder, L.C.V. and I.S. Farr. 1987. Biological surveillance of water quality. Archiv für Hydrobiologie 109, 619-637. Woodiwiss, F.S. 1964. The biological system of stream classification used by the Trent River Board. Chemistry and Industry 11, 443-447. Woodiwiss, F.S. 1978. Comparative study of biologicalecological water quality assessment methods. Sum-
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mary Report. Commission of the European Communities. Severn Trent Water Authority. UK. Wright, J.F., Furse, M.T., Armitage, P.D., Moss, D. 1993. New procedures for identifying running-water sites subject to environmental stress and for evaluating sites for conservation, based on the macroinvertebrate fauna. Archiv für Hydrobiologie 127, 319-326. Zalewski, M. 2004. Ecohydrology as a system approach for sustainable water biodiversity and ecosystem service. Ecohydrology and Hydrobiology 4, 229-235.