Low flows are a good measure of the waste water recipient self-purification capability. The regional statistical analysis is an objective way of assessment of the required low flows. This paper presents the principles and key phases of the regional statistical analysis. The advantages of this method are a reduction of the outliers influence and the assessment of low flows on ungauged streams and stream profiles. The method is illustrated with the results obtained by the required low flows regional statistical analysis in Serbia (Yugoslavia) with 59 hydrological gauge stations in the scope, which data has the same length of 39 years, from the year 1956 to 1994.

The aim of this paper is to find out the most efficient method of determination of toxic PCB in the natural way in aquatic system. According to the preliminary research, positive degradative response of PCBs was obtained by the selection of micro fungi species.

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 river Timok with its watershed area is one of very imperilled running water on the territory of Serbia (Yugoslavia). By several years investigations of colonies bottoms (phytobenthos, microzoobenthos and macrozoobenthos) and plankton we have found the following: great diversity and specific phytobenthos and bottom fauna (frequency of certain taxa is considerably larger in relation to the other areas, and new taxa have been recorded). Stated specific structure of phytobenthos and bottom fauna have considerably reflected to right estimation of water quality of tested area.

Problems encountered in evaluating surface water quality arise from the requirements of relevant regulations that these evaluations should be made in the last favourable hydrologic conditions during design flow rate (required minimum flow). However, the major part of measurements of water quality parameters is not performed under such conditions and the result must be corrected for the conditions under required minimum flow. Two possible approaches to solving this problem are presented in this paper and explained using an example of the Juzna Morava river basin up to the Station Korvingrad, Serbia (Yugoslavia). This basin is unhomogeneous regarding its hydrologic characteristics and mass flow of pollutants. The results of analysis are presented in the cartography form using the GIS technology.

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.

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.

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.

In this paper, the results of statistical analysis of then years water quality data of Tamis river at the Romanian-Yugoslav border ("Jasa Tomic" Control Station) are presented. Following changes of analyzed water quality parameters at the Romanian-Yugoslav border a strong trend of deterioration has been observed during analyzed period. Because of periodical accidentally high organic content (COD, BOD) and concentration of ammonia and organic nitrogen in river water, it is concluded that upstream discharging of farm waste waters was the main reason of deterioration of water quality along the Yugoslav part of Tamis river.

The state of India's environment has been deteriorating steadily over the past two decades. Ambient standards of air, water and soil pollution are routinely exceeded with potentially disastrous consequences. Recognising the seriousness of the problem, the Indian government has recently introduced a series of measures which concentrate on practical aspects of implementation. | However, there are few studies available which can guide the formulation of policies in terms of the most appropriate choice of instruments which can contain pollution and protect India's environment. | That is the central purpose of this pioneering study - namely, to assess the efficacy of alternative instruments for pollution abatement based both on theoretical explorations and real-life case studies. The authors begin by reviewing the existing policy regime and analysing its impact on the quality of air and water in India's cities and rivers respectively. They then proceed to assess the choice of instruments for pollution control by linking economic and environmental systems.