International audience

International audience

The paper provides a report on the quality of water of the Kolubara river and its tributaries, the Ljig and the Pestan, for the period 1992-1996, on the basis of results obtained in the course of regular examinations carried out by the Republic Hydrometeorological Service of Serbia (Yugoslavia). The examination of the waters of the Kolubara river region is significant in view of the vinicity of developed industry, since the wastewater of such an industry represents a potential pollutant of the adjacent rivers. The paper also provides a separate review of the heavy metals contents of the examined rivers. The obtained results indicate to periodical deviations of the water from the required quality, that represents, without any doubt, the pollution of anthropogenic origin.

Thermal stratification is regularly found in deep lakes, while shallow water bodies remain usually mixed. Despite comparative shallowness, Sava lake (artificial lake), Serbia (Yugoslavia) exibit a prolonged summer stable stratification. Temperature differences between epilimnion and hypolimnion can reach 10 deg C. The steep gradients of up to 3.5 deg C/meter recorded in the metalimnion. The highest differences during a single typical summer day was 1.7 deg C between 0.2 and 0.5 m. Maximum annual thermal accumulation was 112440 J/square cm in 1996.

Drainage of industrial and communal effluents, directly into the water flow, as many hydrotechnical activities, significantly influence the schedule and balance of the processes that take place into water. In this paper, there are represented the results of systematic control of the water quality of the Danube river and DTD (Danube-Tisza-Danube) channel on the parts Vrbas-Bezdan and Becej-Bogojevo, at the control station network of the Republic Weather Bureau (the Republic of Serbia), for the period of 1991-1996. The results show that the most adverse influence of anthropogenic factor is on the part of the flow of the DTD (Danube-Tisza-Danube) channel from Vrbas to the flow into Tisza river.

Over the last several years, the investigations of the natural zeolites application in the sorption processes have been intensified. Purification of waste waters in order to remove lead, cadmium, copper and other heavy metals, is one significant example of such application. In this paper, the investigations results on characteristics of the natural and chemically activated zeolites from the region of Vranje (Serbia, Yugoslavia), are presented. The experiments with zeolites were performed after determination of their physico-chemical characteristics. Adsorptive characteristics were investigated under laboratory conditions, in a liquid medium, depending on granulation and concentration of the heavy metals. As the obtained results show, these natural materials can be used to remove heavy metals from the waste waters.

Perch (Perca fluviatilis) suitability as a water indicator was studied in field and laboratory investigations. It was found out that hematological status of this fish species was a valuable indicator of both temporary and periodical deterioration of dissolved oxygen saturation and can be used as reliable test for water quality evaluation. The anlyzed hematological parametrs were tested for their sensitivity and reliability as indicators of water quality changes. Values of different parameters were given for perch kept under optimal and unfavourable conditions of water oxygen saturation.

The aim of this paper is to survey and point to the critical parts of this typically valley river in the chosen period of time, which is, because of its low flow, small turbulence and exceptional social and industrial significance, very susceptible to ecological catastrophes. This paper contains the elaborated state of water quality in Yugoslav part of the river Tisza, during two periods of observation, with usual (1988-1991) and specific (1992-1995) river ecosystem exposure to pollutants. The average annual data of concentration for characteristic parameters in the monitoring stations were compared with method of multiobjective iterative compromise optimalization (MICO) of the influence that different categories of polluters have on the river ecosystem. On the basis of analyzed concentrations of selected parameters and results obtained with method of MICO, it is possible to conclude that the improvement in quality of Yugoslav part of the river Tisza has occurred during the period of 1992-1995.

There were estimated of water quality of the river Banja and its trubutary Pocibrava, Serbia (Yugoslavia), during the period 1991-1994 by seasonal investigations of benthos fauna composition as bioindicators. The results have shown higher diversity of the Pocibrava bottom fauna community (66 taxa) than in the river Banja (53 taxa) where it was more uniform. Both water flows were receiving some organic loading and by the use of macrobenthos indicator organisms it was concluded that they belong to beta-mesosaprobic water quality class.

Primary production of phytoplankton and diversity and biomass of zooplankton of the Sava reservoir (artificial lake), Serbia (Yugoslavia), was studied during the summer and autumn in 1996. The study results were compared with the research results by Perisic et al. (1984) obtained before the dredging of the lake bottom, when bottom sediments with macrophytes were removed. It was found that the water quality was improved in comparison with previous period.