Assessment of the Microbiological Quality of the River Tisa in Serbia

Stoimir Kolarević1, Jelena Knežević-Vukčević1, Momir Paunović2, Zoran Gačić3, Branka  Vuković-Gačić1

1 University of Belgrade, Chair of Microbiology, Faculty of Biology, Studentski trg 16, 11000 Belgrade, Serbia, e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
2 University of Belgrade, Institute for Biological Research  ¨Siniša Stanković¨,
3 University of Belgrade, Institute for Multidisciplinary Research

Abstract

Microbiological examination of river water is obligatory for use-related purposes such as drinking water production, irrigation and recreation. To evaluate the present state of water quality, samples of water and sediment taken from three sites on the River Tisa were analyzed. By applying standard procedures for an assessment of sanitary quality and organic load, a total of 16 parameters were analyzed. The results of analyses indicated that water quality was unsatisfactory at all sampling sites.

Key words: Microbiological quality, sanitary pollution, the River Tisa

 

 

Introduction

Microbiological examination of river water is obligatory for use-related purposes such as drinking water production, irrigation and recreation. The quality of sediment, as a dynamic and integral component of aquatic ecosystems, has become of increasing interest for river water quality evaluation. The basin of the River Tisa extends across 5 countries. The total length of the river is 1,358 km. The Serbian reach of the Tisa extends for a distance of 168 km that covers the middle and lower waterway. The River Tisa is an important waterway, not only for Serbia, but also for other countries in the region. Besides the intensive ship traffic, the river is under the influence of hydromorphological alterations, settlements, industrial “hot-spots”, and agriculture (Csanyi, 2002; Literathy et al., 2002). This low-land river flows through a region with an extensive agricultural production (over 470,000 ha), whose wastewater degrades the water quality due to high concentrations of nitrogen and phosphorus. Thus, detailed knowledge on the extent and the origin of microbial faecal pollution is crucial for watershed management activities in order to maintain safe waters according to their quality targets (Farnleitner et al., 2001).

In this study we performed complex microbiological analyses, based on previous knowledge (Stanković et al., 1995, 1996, 1997a, b; Zlatković et al., 2010; Kolarević et al., 2010), in order to evaluate the anthropogenic impact of wastewater that originates from large urban settlements, such as Senta, Bečej and Zrenjanin and the present state of water quality of the River Tisa in Serbia. The study includes an analysis of the sanitary quality of water and sediment sampled from sites during the spring and autumn of 2010.




The ecological aspect of microbiological analyses included monitoring of the dynamics of bacterial populations during the seasons, the isolation of bacteria resistant to mercury and organic load assessment.

Faecal indicator bacteria like total coliforms, faecal coliforms (thermotolerant coliforms), E. coli and intestinal enterococci (faecal streptococci) are excreted by humans and warm-blooded animals, a significant number pass sewage treatment plants and survive for a certain time in the aquatic environment (Kavka et al., 2002). The coliform bacteria differ considerably in their pathogenic properties, and besides the intestines of vertebrates and invertebrates, they can also be present in the soil. Therefore, for sanitary quality assessment, three groups of coliform bacteria were monitored. Total coliforms can indicate severe water pollution, but this does not have to be directly correlated with an anthropogenic source of pollution, while faecal coliforms are used to indicate fecal pollution. Faecal coliforms to Enterococci ratio was used to indicate the origin of pollution. A ratio lower than 1.5 indicates pollution by waterflow, while a ratio higher than 4 is typical for anthropogenic pollution (Geldreich and Kenner, 1969). The presence of P. aeruginosa, Bacillus sp., Proteus sp. and sulphite reducing clostridia in potable water is undesirable, as subsequent growth is often associated with a deterioration of water quality.

Since an integrated approach gives a complete picture of the present state of the water ecosystems, physical and chemical parameters must be observed. Therefore, in this study we monitored temperature, pH, turbidity, specific conductivity, dissolved oxygen, oxygen saturation, NH4+ (mg/L), NO3- (mg/L) and PO4- (mg/L).