The Influence of Dam on Alkalization Processes of the Lower Tisa River

THE INFLUENCE OF DAM ON ALKALIZATION PROCESSES OF THE LOWER TISA RIVER

Nemes, K. 1, Matavuly, M. 1, Bugarski, R. 2, Lozanov-Crvenković, Z. 1, Belić, S. 3 1University of Novi Sad, The Faculty of Sciences1 2Hydrometeorological Service of the Republic of the Serbia 3Faculty of Agriculture, University of Novi Sad 21000 Novi Sad, Serbia [email protected]

Abstract

The changeability of plankton dynamics was represented in our study of the lower river Tisa (157 – 9.5 r km) with characteristic changes of water trophic degrees depending on hydrometeorological station and influence of seasonal river water supply over the old reconstructed Danube-Tisa-Danube canal network. Therefore, the selected parameters of alkalization processes such as phosphatase enzyme activities- PAI, sodium adsorption ration- SAR, abundance of bacterioplankton, phosphate and iron content were compared and interpreted by matrices analyses and categorized graphs. PAI and oligotrophic bacteria were found to positively influence on SAR at the impounded water stretch St Novi Becej. At the downstream stations, the association of PAI and suspended solids was considerable. The obtained results of SAR index was found to be in negative relation with the iron content in boundary stretch St Martonos while at the St Novi Becej neutral phosphatase enzyme activities were positively correlated with the iron content. Therefore, we estimate relation of the SAR, PAI and iron content. Our study revealed that abundance of oligotrophs and centric diatoms influence on alkalization processes in Serbian part of the Tisa River, and are suitable for investigation of Ecological potential of regulated water bodies. The occurrence of brackish water diatom Entomoneis paludosa and small centric algae Cyclotella meneghiniana pointed to considerable problems of detailed canal network usage supplied by the river Tisa.

Keywords: PAI, SAR, Dam, alkalization processes, river Tisa, Serbia.

INTRODUCTION

Concerning drought and flood conditions in the past in agricultural Vojvodina province of the Republic of Serbia, the construction of the canal network begun in the XVII century and was finished in 1977 when the Novi Becej Dam was put into the operation on the lower river Tisa (Tisza, Tissa). This Dam, situated at the 63rd killometre, make possible gravitational release of water into the Banat region from the Tisa river for purposes of irrigation of 300 000 ha of land as well as other requirements (Vajda, in Milovanov, 1972). The dam has 7 water gates of 24.5 m each, and a waterlock. The river Tisa formes a reservoir above the dam where the main channel is only a fraction of the total water surface in Hungary too (Honti et al. 2008). In the assessment of ecological potential (Directive 2000/60/EC) of ecohydrographical regions (Brilly et al. 2006), by the characteristic type of changes of water trophic degrees and influence on water supply after the gate, comparisons were made between long-term cation measurement and plankton research at four sampling stations. The lower part of the Tisa River, from the Moris mouth to its mouth into the Danube is 178 km long, and its makes a border of the Banat Region on the Tisa left-hand bank. The segment of the River is characterized by an almost horizontal riverbed (total slope is only 6m), and it is about the peak of elevation 64 m. In this segment the Tisa receives the waters of its main Banat tributaries- the Zlatica, Old Begej, Navigable Begej and Great Backa canal (Munteanu, 1997).

MATERIAL AND METHODS

The heterotrophic plate count in the colony forming units of bacteria (CFU cm-3) was determined by means of cultivation on nutrient agar in the period of 5-7 days at a temperature of 22°C. The oligotrophs were counted on ten times diluted nutrient agar (Gajin et al. 1992). The phosphatase enzyme reaction took place at 30°C by the use of substrate p- nitrophenylphosphate (5% final concentration of reaction mixture; the concentration of p- nitrophenol) was determined by measurement of absorption at 420 nm (Flint & Hopton, (1976); pH of un-filtered water samples was adjusted for acid (pH 5), neutral (pH 7) and alkaline (pH 9) conditions of water and average values of phosphatase activities were described as PAI index by Matavulj (1986); PAI- (In Serbian: indeks fosfatazno-enzimske aktivnosti) was chosen as an indicative parameter in evaluation and description of ecological potential: good (0.10-2.30 µmol pNP s-1 dm-3), moderate (2.30 - 5.00 µmol pNP s-1 dm-3), poor (5.00-10.00 µmol pNP s-1 dm-3), and bad potential (>10.00 µmol pNP s-1 dm-3). Chlorophyll a and physico-chemical analyses and was determined by the use of standard methods (APHA, 1995; HYDROLOGICAL YEARBOOKS, 1981-1987; 1998-2006) and toxicity test in accordance with Teodorović, (2004). The SAR index (Sodium adsorption ratio) was calculated according to guidelines for interpretations of irrigation water quality SAR=+ Na/( Ca Mg )/2 (Ayers & Westcot, 1976). Miliequivalents were calculated from miligrams per liter (Belic et al. 1997; Dalmacija, 2002). All data were analyzed using categorized graphs and correlation matrices by the software Statistica 8 (2008).

RESULTS AND DISCUSSION

Following the results of research showed in categorized graphs and tables, the succession of parameters is interpreted (Figure 1-6; Table 1-5).

Scatterplot (Seasonal dynamics of phosphatase enzyme activities in Serbian part of the Tisa River)

21.6.82. 15.9.82. 22.6.83. 6.9.83. 26.6.84. 2.10.84. 26.6.85. 9.8.85. 15.12.02.

activity: pH 5 3.7.03. 2.12.03. 31.7.04. 17.3.05.

21.6.82. 15.9.82. 22.6.83. 6.9.83. 26.6.84. 2.10.84. 26.6.85. 9.8.85. 15.12.02. day

activity: PH 7 3.7.03. 2.12.03. 31.7.04. 17.3.05.

21.6.82. 15.9.82. 22.6.83. 6.9.83. 26.6.84. 2.10.84. 26.6.85. 9.8.85. 15.12.02.

activity: pH 9 3.7.03. 2.12.03. 31.7.04. 17.3.05. -101234567-101234567-101234567-101234567 Martonos Novi Becej Zabalj Titel activity (μmol pNp s-1 dm -3)

Figure 1. Shows features of PAI index: acid, neutral and alkaline phosphatase enzyme activities (µmol pNP s-1 dm-3) of four sampling stations (1982-2005).

Table 1-4. Correlation matrix of parameters in Serbian part of the Tisa River at four sampling stations: temperature\total suspended solids\ oxygen\ pH condition\ conductivity\sodium adsorption ratio- SAR index\ phosphate concentration\phosphatase enzyme activities on pH 5, pH 7 and pH 9\PAI\abundances of bacterioplankton oligotrophs-O and heterotrophs- H\ ratio of O/H \iron content.

Correlations (Tisa- parameters) Marked correlations are significant at p < .05000 N=12 St Martonos 165 river km

T TSS O2 pH EC SAR PO4 pH 5 pH 7 pH 9 PAI O H O/H Fe T 1.00 -0.03 -0.76* 0.28 0.73 0.32 0.32 -0.13 -0.41 -0.31 -0.23 0.14 0.36 -0.38 0.20 TSS -0.03 1.00 -0.19 -0.22 -0.49 -0.54 0.03 0.40 0.42 0.37 0.47 0.64* 0.74* -0.06 0.85*

O2 -0.76* -0.19 1.00 0.32 -0.43 0.15 -0.45 -0.03 0.24 0.20 0.07 -0.16 -0.49 0.37 -0.52 pH 0.28 -0.22 0.32 1.00 0.34 0.65* -0.48 -0.29 -0.26 -0.20 -0.33 -0.08 -0.14 -0.00 -0.41 EC 0.73* -0.49 -0.43 0.34 1.00 0.64* 0.22 -0.33 -0.47 -0.44 -0.40 -0.04 -0.06 -0.14 -0.24 SAR 0.32 -0.54 0.15 0.65* 0.64* 1.00 -0.10 -0.41 -0.40 -0.36 -0.36 -0.45 -0.44 -0.15 -0.60* PO4 0.32 0.03 -0.45 -0.48 0.22 -0.10 1.00 -0.26 -0.37 -0.39 -0.17 0.22 0.01 0.19 0.24 pH 5 -0.13 0.40 -0.03 -0.29 -0.33 -0.41 -0.26 1.00 0.89* 0.95* 0.91* 0.03 0.28 -0.34 0.40 pH 7 -0.41 0.42 0.24 -0.26 -0.47 -0.40 -0.37 0.89* 1.00 0.97* 0.87* 0.13 0.15 -0.03 0.34 pH 9 -0.31 0.37 0.20 -0.20 -0.44 -0.36 -0.39 0.95* 0.97* 1.00 0.91* 0.04 0.17 -0.18 0.28 PAI -0.23 0.47 0.07 -0.33 -0.40 -0.36 -0.17 0.91* 0.87* 0.91* 1.00 0.07 0.23 -0.26 0.35 O 0.14 0.64* -0.16 -0.08 -0.04 -0.45 0.22 0.03 0.13 0.04 0.07 1.00 0.68* 0.39 0.59* H 0.36 0.74* -0.49 -0.14 -0.06 -0.44 0.01 0.28 0.15 0.17 0.23 0.68* 1.00 -0.34 0.71* Fo/H -0.38 -0.06 0.37 -0.00 -0.14 -0.15 0.19 -0.34 -0.03 -0.18 -0.26 0.39 -0.34 1.00 -0.12 Fe 0.20 0.85* -0.52 -0.41 -0.24 -0.60* 0.24 0.40 0.34 0.28 0.35 0.59* 0.71* -0.12 1.00

Correlations (Tisa- parameters) Marked correlations are significant at p < .05000 N=12 St Novi Becej 65 river km

T TSS O2 pH EC SAR PO4 pH 5 pH 7 pH 9 PAI O H O/H Fe T 1.00 -0.01 -0.82* -0.12 0.81* 0.30 0.39 0.19 0.25 0.16 0.13 -0.32 -0.24 0.10 0.11 TSS -0.01 1.00 -0.05 0.08 -0.25 -0.49 0.09 0.60* 0.75* -0.24 0.70* 0.22 0.01 0.01 0.85*

O2 0.82* -0.05 1.00 0.31 -0.58* 0.01 -0.45 -0.48 -0.44 -0.45 -0.34 0.28 0.25 -0.31 -0.17 pH -0.12 0.08 0.31 1.00 -0.17 -0.05 0.21 -0.19 -0.14 -0.43 -0.26 -0.03 0.10 -0.49 0.24 EC 0.81* -0.25 -0.58* -0.17 1.00 0.29 0.35 0.07 0.15 0.43 0.10 -0.24 -0.17 0.11 -0.19 SAR 0.30 -0.49 0.01 -0.05 0.29 1.00 -0.32 -0.62* -0.63* -0.23 0.59* -0.41 -0.20 -0.23 -0.52 PO4 0.39 0.09 -0.45 0.21 0.35 -0.32 1.00 0.21 0.24 0.01 0.10 -0.43 -0.26 -0.27 0.52 pH 5 0.19 0.60* -0.48 -0.19 0.07 -0.62* 0.21 1.00 0.93* 0.46 0.90* 0.18 -0.06 0.40 0.46 pH 7 0.25 0.75* -0.44 -0.14 0.15 -0.63* 0.24 0.93* 1.00 0.39 0.96* 0.17 -0.04 0.28 0.60* pH 9 0.16 -0.24 -0.45 -0.43 0.43 -0.23 0.01 0.46 0.39 1.00 0.45 0.12 -0.05 0.60* -0.34 PAI 0.13 0.70* -0.34 -0.26 0.10 -0.59* 0.10 0.90* 0.96* 0.45 1.00 0.34 0.12 0.27 0.52 O -0.32 0.22 0.28 -0.03 -0.24 -0.41 -0.43 0.18 0.17 0.12 0.34 1.00 0.82* 0.15 0.05 H -0.24 0.01 0.25 0.10 -0.17 -0.20 -0.26 -0.06 -0.04 -0.05 0.12 0.82* 1.00 -0.33 -0.02 Fo/H 0.10 0.01 -0.31 -0.49 0.11 -0.23 -0.27 0.40 0.28 0.60* 0.27 0.15 -0.33 1.00 -0.22 Fe 0.11 0.85* -0.17 0.24 -0.19 -0.52 0.52 0.46 0.60* -0.34 0.52 0.05 -0.02 -0.22 1.00

Statistically significant correlation between parameters as standard indicators of water quality may be observed from table 1-4. The obtained results of SAR index was found to be in negative relation with the iron content in St Martonos while at the St Novi Becej phosphatase enzyme activities of pH 7 were positively correlated with the iron content. Increasing conductivity was not related to the phosphatase enzyme activities only to the SAR index at St Titel. Considering that the competitive inhibition of the neutral phosphatase enzyme by phosphate is a property common to alkaline phosphatase in a variety of microorganisms, neutral phosphatase activity was found to be related with the phosphate concentration in the river Tisa at the St Martonos and St Novi Becej. correlated with the heterotrophs and downstream with oligotrophs. In northern sector, oligotrophs and iron content were correlated, too. PAI was found to positively influence on SAR index with oligotrophic bacteria contrary to heterotrophs at the St Novi Becej. At the same site, the association of PAI and temperature is not considerable. In impounded water stretch, positive correlation of phosphate with the phosphatase enzyme activities is shown (Table 4).

Marked correlations are significant at p < .05000 N=12 (Casewise deletion of missing data) St Titel 9.5 river km

T TSS O2 pH EC SAR PO4 pH 5 pH 7 pH 9 PAI O H O/H Fe T 1.00 -0.50 -0.17 -0.42 0.56 0.16 0.30 0.05 -0.06 -0.25 -0.15 0.19 -0.12 -0.29 -0.01 TSS -0.50 1.00 -0.14 0.29 -0.49 -0.10 -0.05 0.23 0.40 0.60 0.66* -0.11 -0.08 0.46 0.41

O2 -0.17 -0.14 1.00 0.81* -0.05 0.23 -0.18 -0.26 -0.40 -0.53 -0.36 0.46 0.55 -0.28 -0.25 pH -0.42 0.29 0.81* 1.00 -0.15 0.39 -0.08 -0.25 -0.39 -0.33 -0.17 0.26 0.34 0.07 -0.20 EC 0.56 -0.49 -0.05 -0.15 1.00 0.39 0.53 -0.04 -0.40 -0.35 -0.22 0.32 0.07 -0.32 -0.32 SAR 0.16 -0.10 0.23 0.39 0.39 1.00 -0.14 -0.37 -0.64* -0.57 -0.57 -0.17 -0.34 0.16 -0.52 PO4 0.30 -0.05 -0.18 -0.08 0.53 -0.14 1.00 0.52 0.22 0.20 0.45 0.34 0.39 -0.43 0.48 pH 5 0.05 0.23 -0.26 -0.25 -0.04 -0.37 0.52 1.00 0.88* 0.75* 0.75* -0.27 0.30 -0.57 0.69* pH 7 -0.06 0.40 -0.40 -0.39 -0.40 -0.64* 0.22 0.88* 1.00 0.90* 0.82* -0.34 0.15 -0.31 0.72* pH 9 -0.25 0.60 -0.53 -0.33 -0.35 -0.57 0.20 0.75* 0.90* 1.00 0.88 -0.41 -0.02 -0.03 0.58 PAI -0.15 0.66* -0.36 -0.17 -0.22 -0.57 0.45 0.75* 0.82* 0.88* 1.00 -0.02 0.16 -0.05 0.79* O 0.19 -0.11 0.46 0.26 0.32 -0.17 0.34 -0.27 -0.34 -0.41 -0.02 1.00 0.59 -0.15 0.07 H -0.12 -0.08 0.55 0.34 0.07 -0.34 0.39 0.30 0.15 -0.02 0.16 0.59 1.00 -0.73* 0.17 Fo/H -0.29 0.46 -0.28 0.07 -0.32 0.16 -0.43 -0.57 -0.31 -0.03 -0.05 -0.15 -0.73* 1.00 -0.11 Fe -0.01 0.41 -0.25 -0.20 -0.32 -0.52 0.48 0.69* 0.72* 0.58 0.79* 0.07 0.17 -0.11 1.00

Correlations (Tisa- parameters) Marked correlations are significant at p < .05000 N=12 St Zabalj 37 river km

T TSS O2 pH EC SAR PO4 pH 5 pH 7 Z pH 9 PAI O H O/H Fe T 1.00 -0.00 -0.04 -0.00 0.52 0.10 0.29 0.06 0.07 0.06 0.03 -0.72* -0.81* -0.01 0.06 TSS -0.00 1.00 0.09 -0.03 -0.35 -0.29 0.35 0.69* 0.68* 0.70* 0.69* 0.09 0.38 -0.20 0.57*

O2 -0.04 0.09 1.00 -0.36 0.06 0.18 0.02 -0.09 -0.11 -0.12 0.23 0.51 -0.18 0.77* -0.15 pH -0.00 -0.03 -0.36 1.00 -0.20 -0.04 0.23 -0.22 -0.26 -0.22 -0.47 0.02 0.08 -0.06 0.11 EC 0.52 -0.35 0.06 -0.20 1.00 0.30 0.37 -0.08 -0.12 -0.15 -0.02 -0.55 -0.67* -0.19 -0.26 SAR 0.10 -0.29 0.18 -0.04 0.30 1.00 -0.37 -0.33 -0.36 -0.39 -0.24 -0.00 -0.08 0.22 -0.49 PO4 0.29 0.35 0.02 0.23 0.37 -0.37 1.00 0.25 0.18 0.22 0.21 -0.41 -0.32 -0.19 0.37 pH 5 0.06 0.69* -0.09 -0.22 -0.08 -0.33 0.25 1.00 0.98* 0.97* 0.92* -0.10 0.18 -0.37 0.51 pH 7 0.07 0.68* -0.11 -0.26 -0.12 -0.36 0.18 0.98* 1.00 0.99* 0.93* -0.09 0.17 -0.34 0.57* pH 9 0.06 0.70* -0.12 -0.22 -0.15 -0.39 0.22 0.97* 0.99* 1.00 0.91* -0.08 0.16 -0.31 0.66* PAI 0.03 0.69* 0.23 -0.47 -0.02 -0.24 0.21 0.92* 0.93* 0.91* 1.00 0.03 0.12 -0.13 0.48 O -0.72* 0.09 0.51 0.02 -0.55 -0.00 -0.41 -0.10 -0.09 -0.08 0.03 1.00 0.51 0.50 -0.01 H -0.81* 0.38 -0.18 0.08 -0.67* -0.08 -0.32 0.18 0.17 0.16 0.12 0.51 1.00 -0.27 0.00 Fo/H -0.01 -0.20 0.77* -0.06 -0.19 0.22 -0.19 -0.37 -0.34 -0.31 -0.13 0.50 -0.27 1.00 -0.00 Fe 0.06 0.57* -0.15 0.11 -0.26 -0.49 0.37 0.51 0.57* 0.66* 0.48 -0.01 0.00 -0.00 1.00

After the dam the sedimentation in the river system properly function to the phosphorus transformation estimated by phosphatase enzymes in matrices analyses. Compared with the iron content, the phosphate was correlated only there. Probably, the stagnation increases downstream estimated with increased metal concentration such as copper and zinc (Knežev, 2006). The matrices analyses revealed that neutral phosphatase and associated the parameters of the water quality indicate alkalization of the Tisa river. In the impounded water stretch the SAR index is more related to other parameters, especially phosphatase enzyme activities contrary to the downstream water stretch. The iron is related with the other parameters in impounded water stretch, respectively. In the Danube River, the iron concentration in 2000 was correlated with the concentration of phosphate 2002. After the two years of our research, the phosphate concentration influenced on parameters of alkalization processes, too. In Tisa, while the iron was positively correlated with the neutral phosphatase enzyme activities, the results of indices SAR were significantly negatively related with the neutral phoshatase enzyme activities. This means that increasing of SAR is influenced with the iron decreasing processes regulated by the phosphorus availability. During the 2002 year The Danube River was characterized with the phosphatase enzyme increasing (Nemes et al. 2008)

Box Plot (Seasonal dynamics of SAR index of the river Tisa in Serbia)

2.4 2.0 1.6 1.40 1.22 1.22 1.27 1.13 1.2 1.10 1.01 0.99 0.97 1.03 1.00 0.89 0.79 0.86 0.79 0.75 0.8 0.4 St Martonos 0.0 2.4 2.0 1.43 1.42 1.6 1.23 1.21 1.22 1.01 1.02 1.07 1.14 1.09 1.2 0.79 0.84 0.89 0.86 0.96 0.8 0.69 0.4 St Novi Becej St Novi 0.0 2.4 2.0 1.6 1.13 1.24 1.20 1.14 1.30 1.2 0.93 1.01 0.88 0.92 1.04 0.96 0.94 SAR meq/l 0.83 0.75 0.73 0.81 0.8 St Zabalj 0.4 0.0 2.4 2.0 1.6 1.34 1.16 1.29 1.17 1.18 1.08 1.04 0.98 1.00 1.08 0.97 1.04 1.04 1.2 0.80 0.78 0.90 0.8 St Titel 0.4 0.0 I II III IV I II III IV I II III IV I II III IV DJF MAM JJA SON series

Median 25%-75% Non-Outlier Range Outliers Extremes

Figure 2-3. Seasonal dynamics of the conductivity and SAR index (meq/l) of the Tisa River downstream the boundary station St Martonos 157 r km, right riverbank (M), St Novi Becej- 65 r km, left rivebank (NB), Zabalj 37 r km, left riverbank (Z), Titel 9.5 r km, middle current (T) shown on the four series I (1981-1983), II (1984-1986); III (1999-2002), IV (2003-2005) (HYDROLOGICAL YEARBOOKS, 1981-2005). Histogram (SAR indeks of the lower river Tisa) 16 14 12 10 8

site: M 6 4 2 0 16 14 12 10 8

site: NB 6 4 2 0 16 14 12 10 No of obs 8

site: Z site: 6 4 2 0 16 14 12 10 8

site: T 6 4 2 0 -0.2 0.2 0.6 1.0 1.4 1.8 2.2 -0.2 0.2 0.6 1.0 1.4 1.8 2.2 -0.2 0.2 0.6 1.0 1.4 1.8 2.2 -0.2 0.2 0.6 1.0 1.4 1.8 2.2 0.0 0.4 0.8 1.2 1.6 2.0 2.4 0.0 0.4 0.8 1.2 1.6 2.0 2.4 0.0 0.4 0.8 1.2 1.6 2.0 2.4 0.0 0.4 0.8 1.2 1.6 2.0 2.4 series: I series: II series: III series: IV SAR meq/l

Figure 4. Histogram of frequences of the SAR index (meq/l) of the Tisa River downstream the boundary station St Martonos 157 r km, right riverbank (M), St Novi Becej- 65 r km, left rivebank (NB), Zabalj 37 r km, left riverbank (Z), Titel 9.5 r km, middle current (T) shown on the four series I (1981- 1983), II (1984-1986); III (1999-2002), IV (2003-2005) (HYDROLOGICAL YEARBOOKS, 1981-2005).

After the Dam, it was noted that SAR index decrease while the conductivity increase in the river (2-4). SAR index estimated by the categorized graphs showed increase of alkalization processes in second and fourth period of research throughout the seasonal dynamics (Figure 3-4). Obviously, in spring the calcium and magnesium are highly consumed and are showing the trend of decreasing (Figure 2-4). The last series of research was characterized with the similiar SAR dynamics in the river. Majority of the samples fall into C2- S1 good water class for irrigation after Vucic, (1976). High SAR induces soil dispersion and structure deterioration leading to infiltration problems, specific ion toxicity, could induce nutrient deficiency or toxicity, and ultimately could reduce crop yealds or even crop failure (Ghafoort et al. 2001). According to the results of SAR and Ecological potential, the control of the matter introduced into the soil in such a way which will not cause undesirable changes either in the soil properties or in the food produced on it, when shown water is used of irrigation it is important. Dynamics of SAR index is related with the phosphatase enzyme activities and pH condition of water at the boundary station and downstream stations (Figure 1-5, Table 1-4). Considering negative ions and alkalization processes, the bicarbonate concentration are decreasing and are showing relation to alkaline phosphatase enzyme activities (in preparation). Therefore, the evaporation processes are meaningfully concerned in next study of the river Tisa. Concerning River Tisa trophic condition assessment, at the St Martonos, the algal biomass vary in the last series of research 103.14 in July ’03 together with oligotrophs 9800 cfu cm-3 and slow down to 13.35 mg m-3 in August ’04 when oligotrophs increased their number 46 300 cfu cm-3. Downstream the river, before the dam, the chlorophyll a varied between 32.04 together with bacteria 9400 (July ’03) and 6.41 together with 21 370 cfu cm-3 in August ’04, respectively. At the confluence to The Danube River, the chlorophyll a decreased in 3.34 in July ’03, and reached peak next year 13.35 mg m-3, when bacteria abundance varied between 8120 cfu cm-3 to 63350 cfu cm-3. In last series of research in June 2007, while the dominance of centric diatom Cyclotella meneghiniana the PAI- 0.45 µmol pNP s-1 dm-3 was sustained of activities at 100 r km: acid: 0.60 neutral: 0.64, alkaline: 0.12 µmol pNP s-1 dm-3 and PAI 1.11 µmol pNP s-1 dm-3 at 56 r km: acid: 2.96, neutral: 1.28, alkaline: 0.89 µmol pNP s-1 dm-3. By the comparison with The Danube River water in residential area, the range was between 1.30-1.95 and at the municipal waste water discharge at the riverbank- 3.09 µmol pNP s-1 dm-3. The river Tisa indicates moderate Ecological potential by the increased of mediane of PAI, except in impounded river water stretch (Figure 5).

After the year 1983 the Box Plot (PAI of the lower river Tisa) increasing of eutrophication of 7 water was noted, then the poorly Medi a n 25%-75% Non-Outlier Range Outliers changed moderate trophic Extremes 6 condition was detected in period )

-3 5 1984-85. In water quality dm

-1 -1 research of phosphatase pH 4 activities, the range of PAI was 3 2,38 between 0-7 which reflected third

2 1,73 water class, although mediane 1,44 decreased in impounded river 1 0,84

PAI index (µmol pNP s water stretch, and increased

0 downstream (Figure 5).

-1 -1 Figure 5. PAI index (µmol pNP s St Martonos St Novi Becej St Zabalj St Titel dm-3) of four river sampling stations (Tisa River, 1982-2005).

Table 5. The Ecological potential of water during the accidental point source of pollution by the toxic cyanide wave in the river Tisa downstream fron the boundary St Martonos to the confluence of the river Tisa to the Danube River in February 2000. The measured concentration of cyanide was 0.17 and 0.2 mg/l of the first “toxic” day 12.2.2000.

Samp. St station St N. St N. St N. St N. St Martonos St Padej St Titel St Titel Slankame Becej Becej Becej Becej → n Par.↓ hour 9 11 10.5. 11.5 13.5 16.3 8 11.3 14 pH 8.5 7.9 6.94 7.85 Hetero- 110000 344000 58000 422000 694000 335000 95000 145000 86000 trophs 0 Oligo- 146000 310000 103000 716000 1176670 252250 446000 610000 390000 trophs 0 0 0 0 Fo/H 3.42 4.34 3.45 4.47 3.07 6.5 4.69 4.2 4.53 index PAI 1.5 0.93 1.53 2.79 0.92 4.66 0.96 1.14 1.25 Activity pH 5 2.02 0.88 1.85 3.4 1.31 6.03 1.58 1.35 1.31 Activity 1.47 0.8 1.37 2.68 0.7 5.61 0.7 0.83 1.37 pH 7 Activity 1.01 1.11 1.38 2.24 0.74 2.36 0.61 1.25 1.08 pH 9 PAI 1.50 0.93 1.53 2.77 0.92 4.67 0.96 1.14 1.25

Daphnia 80 % O % O % O % 100 % 50 % 100 % 100 % 100 % mortality

The negative influence of cyanide on Ecological potential on the river during the pollution wave which was made about 2000 km in 4 weeks until it finnaly reached The Black Sea. When the pollution wave reached again the Romanian territory, the Yugoslavian, Romanian, Bulgarian and EU experts reached the conclusion that the pollution wave has a higher quantity of cyanide that could be discharged from Aurul pond (Arges-Wedea Water Department). On 11th February the pollution wave crossed the Hungary-Serbian border. Therefore, the toxic test was carried out concerning Daphnia mortality in the most critic cyanide concentration in February 2000 (Table 5). The Daphnia population abundance decrease in water characterized with high oligotrophic and heterotropic bacteria abundance in river water. Similarity with the research of Rotatoria abundance, the development in same physiological condition in winter season is characterized with neutral phosphatase enzyme activity while the processes of nutrient regeneration in the water have considerable effect on phytoplankton growth. As expected, hazardous substances physiologically excluded the necessary readily consumation of organics and oxygen of poikilotherm organisms and plankton which is sheathed by chitinous pancir such as Cladocera and Rotatoria. After the cyanide pollution, the investigation of Ecological potential was conducted in the river throghout the research of 2002. Estimated by comparison alkaline phosphatase was prominent from July to September in impounded river stretch. Before the Dam, on localities with the point sources of pollution, the alkaline phosphatase increase (Figure 1). In November, acid phosphatase enzyme activity increased almost double compared with the alkaline phosphatase activities. The obtained increase in alkaline enzyme activity by 10 fold, resulted in values in accordance with medical essays of Fehér (2002). On the other hand, the level of phosphatase enzyme activities after Flint & Hopton, (1976) and Matavuly (1986), more universaly determines activities of phosphatase enzymes which are applicable to physiological methodologies of water quality assessment. Typical cases of two purpose of use of detailed canal network is the supply of canal of irrigation system Becej II south, which is taking water from section Bogojevo-Becej of Main canal network-MCN and another one is Detailed canal network- DCN on region of upstream City Senta supplied from the water from the Tisa river and a long stream to the final consumer. In second drainage/irrigation DTD canal, after the Becej gate, in October poor water quality was determined during the low water level when PAI ranged from 9.03 at the site Becej water pump and at the end of a canal to 15 µmol pNP s-1 dm-3. The irrigation water quality belong to the poor category (C3-S2), similarity with the Old Begej River. Additionally, the presence of brackish water diatom Entomoneis paludosa and small centric algae Cyclotella meneghiniana pointed to considerable problems of detailed canal network usage supplied by the river Tisa. In drainage canals, due to rapid division, doughter cells become smaller, the cells capacity to absorb nutrient greater than in late spring and in early autumn consequently, cells can devide more rapidly and surface to volume ratio is bigger (Figure 6). Centric diatom Cyclotella meneghiniana, begun to appear in early spring and tend to dominate during the whole vegetation period in DTD hydrosystem of middle Banat (Nemeš, 2005). In Tisa, prominent centric diatoms contained of species with striae number greater then 10/10 µm in impounded River water (Figure 6). SEM micrographs shows on Cyclotella meneghiniana valve with granule with low attachment of bacteria on silicon pancir, contrary to Entomoneis paludosa. Cyclotella abundance in the river Tisza was positively correlated with the total suspended solids in Hungary (Kiss, 1974). Hence, the „siliceous stretch“ of the Serbian part of the Tisa River was characterized with the undulated valvae of Cyclotella meneghiniana. In impounded surface water relation of suspended solids was found to increase with the iron and pH 5 phosphatase enzyme activities (Table 1). During the occurrences of brackish water diatoms of the river Old Begej and drainage/irrigation canal water in Autumn, the number of striae in weakly silicified pennate diatom species E. paludosa ranged 26-30/10 µm and was slightly greater compared to taxonomical data 24/10 µm (Krammer & Lange-Bertalot, 1988). The greater number of striae supports the existance of Entomoneis paludosa in Banat waters, which have high ammount of suspended solids, compared to the sea waters- the natural habitat of algae Entomoneis paludosa (Figure 6).

a b

c d

e f g

Figure 6. SEM micrograph showing mechanical and corrasive silicon desintegration of Cyclotella meneghiniana of the Serbian part of the river Tisa (a-d) (June ’07) and in dominant diatoms Cyclotella meneghiniana, Entomoneis paludosa and Diatoma vulgare of the drainage/irrigation DTD canal (September ’06).

CONCLUSION

The alkalization processes determined by mediane of the SAR index revealed increase of the lower part of the river Tisa in Serbia during the 1982-2005. Therefore, the influence of dam on alkalization processes in Banat region is considerable system. Hence, our study revealed that bacterioplankton and centric diatoms, are partly controlling the alkalization processes in Serbian of the Tisa River, and are suitable for investigation of Ecological potential of regulated water bodies.

Acknowledgements

These studies were supported by the Ministry of Science of the Republic of Serbia (project No 1945, No 142058 and 144025). We are grateful to Center for Electron Microscopy of University of Novi Sad for the SEM research and to Institution Vode Vojvodine for participation in documentation.

References

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