During hydrobiological investigations of the river Dulenska (Serbia, Yugoslavia) in June 1996, algological samples were taken at this river. In the algae community are found 34 taxa from two divisio: Bacillariophyta (28) and Chlorophyta (6). While qualitative composition of the algae colony was relativelly uniformed quantitative one was changeable along the course of the Dulenska river. By saprobiological analysis, it was found that the quality of water was changing along the course of the river. At the upper and middle course of river the water belonging to the second class. At lower course of the river (below Rekovac) water quality was getfing worse and it belonging to the third class.

The monitoring the content of organochlorine insecticides and polychlorinated biphenyls in heterogeneous system of water-sediment is of a primary interest for the researching of contamination of the aquatic ecosystem because of high bioconcentration factors of these compounds and their bioaccumulation in flora and fauna of the aquatic basin. The sampling of water and sediment were done in the Boka Kotorska Bay (south Adriatic Montenegro Seaside), and estuary Bojana - Ulcinj, Montenegro (Yugoslavia), in AuTumn of 1995. The residues of organochlorine insecticides and polychlorinated biphenyls were determined by gas chromatography, Varian 3400 with capillary columns OV-101, length 25 m, with ECD. The residues of isomers of HCH (hexachlorocyclohexane), DDT and PCB (polychlorinated biphenyls) were identified in all investigated samples.

Neither soil nor water has very distinct function when seen in isolation. Therefore, analyses of water and soil can get real value only by their linkages. Taking into consideration irrigated land, water and soil interaction degree can cause different changes of soil, plants and aquifer A. All negative changes which are occur in the soil (in case of using unsuitable water quality for irrigation or applying of not rational fertilizers amount) have influence to the changes aquifer A quality. Interaction between soil and aquifer A are require investigation of groundwater quality changes relating to plant production, especially in irrigation. Intensity and type of aquifer A properties change, in case of different soil use in agricultural production, have been studying since 1991 at the Lysimetric Station Rimski Sancevi (Serbia, Yugoslavia). The results are point out satisfactory quality of aquifer A after irrigation with wastewater and well water, and applying of different mineral fertilizers amount. The soil capability to receive water with unsuitable quality, to influence their change and change of aquifer A quality as the final recipient, are showed by received results.

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.

During one-year examination of the Vlasina river and its main tributaries, the Luznica and Gradska rivers, Serbia (Yugoslavia), in May 1996, the samples were taken for biological and chemical analysis of the watercourse in the spring aspect. Sampling was performed on the five localities of the Vlasina river, and two tribute localities near the mouth thus including all critical points where the changes of physico-chemical water parameters and qualitative/quantitative biocenoses compositions due to the increasing anthropogenic influence could occur. Data on phytoplankton, zooplankton, periphyton and benthos were analysed together with the physico-chemical water parameters in order to determine communities composition and structure and bioindicator species. Based on these results the status of aquatic environment i.e. water quality, was evaluated.

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.

Owing to the habit of most of Yugoslavs to prepare coffee without filtering, the large part of used coffee comes to recipients. In this paper, the influence of coffee deposits reaching recipients in Yugoslavia is analyzed. Results of laboratory examination of the biodegradability and kinetic of biodegradability of coffee deposits are also presented.

The river Tara (Montenegro, Yugoslavia) is under the treatment of the international (UNESCO) and domestic legal protection, so the prescribed quality of its water is the 1st class. Permanent measurement of the water quality of this river shows that due to the influence of the human factor, its quality has been endangered. Examination of the data collected through many years at all the measurement station along its current shows that the quality of water and pollution estimate have changed.

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.

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