5 water samples were taken from the irrigation channel nearby Kamendin, Sirig, Becej, Backo Gradiste, Backi Petrovac which is part of DTD (Danube-Tisza-Danube) system (Serbia, Yugoslavia). Content of Cd (cadmium), Pb (lead), Hg (mercury), As (arsenic), Cr (chromium), Ni (nickel), F (fluorine), Cu (copper), B (boron) in water samples was analyzed. The origin of these elements in the waters and the effect of potentional pollutant was analyzed. Also, deviation of content of these elements from permissible amounts which were announced in the Book of Regulation was commented.

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.

Products of wet and dry deposition of aero-pollutants, reached by over-boundary or internal-boundary transport, are significant source of pollution, almost, whole territory of Serbia (Yugoslavia). Products of wet and dry deposition endangere surface storages in two ways: (1) directly, by deposition on surface storages; (2) indirectly, by deposition on surface of catchment areas, and further transporting through hydrographic system. In the period 1992-1996 investigations were carried out at some localities in Serbia (Yugoslavia). Their results show that recorded quantities significantly over pass MDK (maximal permitted quantity). Investigations included analysis of samples of precipitation (rain and snow), soil and sediment from hydrographic system.

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.

MPI - Metal Pollution Index is being proposed with an aim improving the freshwater pollution control, monitoring and classification based on fish metal body burden. This is a simple mathematical model which enables presentation of Cd, Pb, Cu, Zn and Al fish liver concentration as a single value. After thorough studies of bioaccumulation, biomagnification and tissue distribution patterns, liver of Carassius auratus gibelio has been chosen as sentinel organ. Normal distribution and biological variation assessment is being achieved by using normalizers - reference values (liver concentrations of selected elements in fish from reference sites Vruje and Moharac micro water reservoirs, Serbia (Yugoslavia)). Selected representative sites have been evaluated according to new classification of freshwater ecosystem based on MPI values.

From two locations in the Vizelj channel (Serbia, Yugoslavia) in the early spring and before irrigation water samples were systematically taken in order to examination the content of harmful and dangerous matter. Content of Cd, Pb, Hg, As, Cr, Ni, F, Cu, B in water samples was analyzed. The origin of these elements in the water and the effect of potentinal pollutants were analyzed. Also, deviation of content of these elements from permissible amounts which were announced in the Book of Regulation was commented.

According to microbiological parameters, waters of both small rivers of eastern Backa, Serbia (Yugoslavia), are slightly and moderately polluted by organic matter at the most of the investigated localities in summer season. The satisfactory power of water selfpurification has been preserved in these aquatic ecosystems. In order to prevent further eutrophication processes, certain measures of river water protection and conservation should be undertaken, especially in stagnant parts of investigated waters. Also, the regular monitoring of water quality should be established.

Microbiological monitoring of river water quality is obligatory for use-related aspects such as drinking water production, irrigation and recreation. Assessment of the microbiological quality of water and sediment at the Velika Morava River was performed at five sites, during 2010 and 2011. By applying standard procedures for sanitary correctness and organic load assessment, total of 16 parameters were analyzed. Results of analysis indicated that microbiological water quality of the Velika Morava River is unsatisfactory.

Regular monitoring of water quality of the Danube river in the backwater zone includes analysis of the sediment. It is well known that sediment is a sink place for the non degradable compounds and it reveales the long term water quality status in the reservoir. This paper presents the general results on the Iron Gate reservoir siltation. as well as some data regarding pollution level, based on investigations carried in the period of 2001-2002. The investigations included organic load of the sediment, heavy metals and organic pollutants content. The degree of pollution is evaluated on the basis of various criteria, also compared to results of previous case studies.

The paper presents theoretical model of the pollutant density changes in water environment. Spreading of the pollutant is modeled by strong pointed force on the pollution system in the water. This force appears as a strong short term pressure in certain point of the system after which it starts to move in one direction. Results of applying of this model shows that density of the pollution depends on mass of the pollution and the speed of the spreading of the pollutant in the aquatic system. One dimensional result of the pollutant density that is received, i.e. pointed direction of the pollutant stands only in the cases of precisely fixed conditions defined by modeling. For any other values that exceed these values the pollutant density value is equivalent zero value.