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.

The work describes optimization on the process of separation of a synthetic dye, methyl orange, from water by sorption on iron(II) hydroxide, using response surface methodology. It was established that the optimum sorption conditions for dye removal on iron(II) hydroxide are: pH 9.1, iron(II) concentration 128 mg/l, dye concentration 10 mg/l, whereby the highest efficiency of dye removal is close to 90%.

The paper provides experimental results of testing the content of heavy metals, and other harmful and dangerous matters of the Sava river sludge (Serbia, Yugoslavia). The testing carried out by the Republic Hydrometeorological Service of Serbia (Yugoslavia), has been in compliance with the program of testing the Sava river water and sludge quality along the river flow. The establishing of sludge pollution range is not based upon values of maximum allowable concentrations. The most complex is the issue of heavy metals contents, since these also represent the natural contents of soil and minerals. However, considering the process of migration and distribution of heavy metals, and other harmful and dangerous matters discharged from utilities, industrial and power supply facilities, provides the basis for estimating the environmental pollution as well.

A complex ichthyological analysis of the individual sections of the DTD (Danube-Tisza-Danube)-Backa canal system (Serbia, Yugoslavia) performed during 1996 vegetation period 23 fish species from 7 families. On the basis of the occurrence and abundance of indicators and limnosaprobic parameter, water quality of the analyzed canal sections was found to be beta-mesosaprobic index ranging from 2.15 to 2.21. The obtained results show that water quality of this DTD (Danube-Tisza-Danube) canal sections (Bajski Kanal, Odzaci-Sombor, Vrbas-Bezdan and Novi Sad-Savino Selo canals) corresponds to its purpose. The fish community representing an important factor of a whole aquatic biocenose, in addition to its undoubtedly indicator values also representing an active factor in the process of selfpurification and quality preservation of whole hydrosystem.

Water quality observation is an important task which must performed at every water reservoir, especially at those whose water is used for water supply. In the purpose of easier and faster entering to storied data, for all potential users, and in the purpose of performing faster verification and handling data, two models are designed: 1) data base and 2) information system for dam observation and water quality management. These two models are parts of the Information System of Serbia for Water Resources Management, who is in development. Methodological bases of those two systems are presented in the paper.

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.

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.

The results of the determination of PCB (polychlorinated biphenyls) residues by gas chromatography, in the samples of underground water of one alluvial well of the river Danube (Serbia, Yugoslavia) have been presented. The residues of PCB (polychlorinated biphenyls) in examined samples (February-March period, 1997) were detected.

Spectrophotometric method for determination of inorganic phosphate liberated in hydrolysis of ATP catalyzed by ATPase was modified in order to obtain faster procedure, which could also be used in none laboratory conditions. The modification has some advantages compared to the most used Pennial method: a) the reagents are stable for several months; b) the 45 min procedure of phosphomolibdate extraction by isobutanole-benzene is ommited, and the method is not dangerous for the analyst; c) color develops after 20 min. The method was tested on the determination of inorganic phosphate in the presence of cadmium nitrate as inhibitor of ATPase activity. The results were compared to the results obtained by Pennial method. The results obtained have shown some good agreements.

The work is concerned with the possibility of inactivation of galvanic sludge formed in treatment of wastewaters of electroplanting plants by imbedding the waste in a glass material. Glass can be synthesized in contact with the waste by mixing and heating with glass constituents. The efficiency of inactivation was monitored by leaching the obtained materials. The results of leaching tests showed that the highest amount of electroplanting sludge (about 30%) can be inactivated by vitrification of the following mixtures: 26.3% of electoplanting sludge, 43.7% of sand, and 30.0% of Na2CO3 at 1000 deg C; 30% of galvanic sludge, 49% of sand and 21% of Na2CO3 at 1100 deg C.