The paper summarizes the results on the quality of surface water of the Gornji Banat region (Serbia, Yugoslavia). Based on different classifications, statistic data processing was made and the conclusions on the usability of the water for irrigation are given. According to the results obtained there is an urgent need for efficient measures to improve the quality of canal water and the control the polluters.

As it consequence of soil erosion the contamination of water occurs. Namely, in the soil erosion process on the slopes of watersheds, together with soil particles (sediment) the organic matter, mineral fertilizers and nutrients are washed as well as pesticides applied in the agriculture production. By sediment reaching the water courses and reservoires the mechanical and chemical contamination of water is caused. In the paper sediment transport and losses of humus (organic matter) and nutrients (in the process of sediment transport) are presented in the three small torrential watershed in Western Serbia (Yugoslavia). Average annual specific transport of sediment was in the range between 50.0 cubic meter/year per square km (Lonjinski Potok) and 220 cubic meter/year per square km (Dubosnickog Potoka). In each tone of suspended sediment on average was 73.15-103.20 kg of humus, 2.88-5.93 kg of nitrogen, 0.63-1.50 kg of phosphorus, 2.63-3.81 kg of potassium, 6.76-14.27 kg of calcium and 5.18-9.33 kg of magnesium.

Previous studies clearly indicated that membrane enzymes - ATPases i.e. Na, K-ATPase and Mg-ATPase, responded to presence of various organic and inorganic pollutants. In this work effect of mercury and cadmium on these enzymes activities was investigated in synaptic plasma membranes partially immobilized on microliter plate. Comparing those activities with the control enzyme activities obtained with native and partially immobilized mambranes it was concluded that: a. both metals exerted a concentration-dependent inhibition of investigated enzymes, b. for partially immobilized membranes estimated half maximum inhibition (IC50) values for Na, K-ATPase were IC50 (Hg) = 0.9 micromol/cubic cm, IC50 (cd) = 35 micromol/cubic cm and for Mg - ATPase IC50 (Hg) = 3.5 micromol/cubic cm, IC50 (Cd) = 36 micromol/cubic cm; for native membranes IC50 for Na,K-ATPase were IC50 (Hg) =3.3 micromol/cubic cm, IC50 (Cd) = 2 micromol/cubic cm and for Mg ATPase IC50 (Hg) = 2.3 micromol/cubic cm, IC50 (Cd) = 0.2 mmol/cubic cm. Obtained results indicate avaibility of microtitar plates for partially immobilization of membranes with aim to form a new biosensor for heavy metals detection.

In this paper given are basic characteristics and projected functions of the DTD (Danube-Tisza-Danube) Hydrosystem (Yugoslavia), then types, origin and some characteristics of muds - sediments in the hydrosystem channels. It is estimated that in hydrosystem channels gets in averagely about 1.28x10**6 tons of deposits annually, and of that amount in channels are settled about 0.64 x 10**6 cubic meter annually. In 1980-1996 period, it is mudded from channels of the main channel network averagely about 0.19 x 10**6 cubic meter/year, and in 1991-1996 period, usually only about 0.056 x 10**6 cubic meter/year, i.e. about 10 of average amounts which are deposited during the year. Also explained are numerous undesirable influences of muds - sediments on water quality in channels, as well as functions of the DTD (Danube-Tisza-Danube) Hydrosystem in general. At the end, measures for gradually improving conditions that are influenced by muds - sediments are, proposed.

Testing performed by five glass cups has been a try to show form and extent of water reservoir soil base influence on its water quality. At the some time a possibility of alleviation of eutrophication by means of certain safety precautions have been examined. During the test performed on a model of parameters (water temperature, air temperature, O2, chlorophyll a, total nitrogen, etc) have been monitored. The results of actions reffer to a fact a soil base influences deterioration of water quality, especially immediately after water reservoir filling, but the mentioned negative influence of the soil base could be decreased applying certain safety precautions.

Mountain Goc is one of the regions with the highest water potential in Central Serbia (Yugoslavia), with specific annual runoff of 12-17 l/s per square km. Upper part of the catchment area of the Gvozdacka River has 111 springs, on the surface of 13.3 square km. 33 springs has volume yield from 0.5 to 2.5 l/s, with physical and chemical parameters of high water quality. These springs never dry up, even during years with low amount of precipitation. The upper part of the catchment area of the Gvozdacka River is under association Abieti-Fagetum, which is one of the worthiest in Serbia (Yugoslavia). Besides annual amount of precipitation, characteristics of soil, hydro-geological attributes of rock masses, influence of vegetation on processes of interception and evapotranspiration, which are very important factors for preservation of springs and their volume yield, also the system of forest ecosystems management. Not adequate measures in exploitation of forests lead to decreasing of volume yield of springs, and often to their disappearing.

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.

Quality, high and stable yield in plant production often depends on irrigation. This paper deals with analysis of water usability for irrigation on some irrigation systems in Vojvodina (Serbia, Yugoslavia) during 1997. Included irrigation systems are characteristic taking into consideration soil type, way of irrigation, cropped area and production level (intensity), in fact - water requirements. This irrigations, which are organized for three years period, will provide the base for recommendation of chemical and biological dimension, water and soil sampling points and frequency. The main reason for mentioned investigation is poor legislation in this field in the Republic of Serbia and FR Yugoslavia.

Hydrological, psamological and pluviographical measurements in experimental watershed area in the watershed of River Topciderska (Serbia, Yugoslavia) was analyzed. Interrelations between suspended sediment concentration in streams on the one hand and runoff, rainfall, rainfall intensity and index of previous rainfall on the other hand was came from this analyze. Effects of these parameters on suspended sediment concentration was considered for a single rainfall epizode, during the period of torrential waves and as annual value. Specific coefficients (coefficient of annual rainfall structure and coefficient of annual runoff structure) were used in this paper, with help of them effects of torrential waves and intensity rainfall on average annual suspended sediment concentration were considered.

This paper analyzes the results on water quality in the Medjuvrsje water reservoir (Serbia, Yugoslavia) in the period 1994-1997. The water reservoir was erected for the needs of electric engineering in 1953 as far as 182 km along the Zapadna Morava river stream issuing from the Ovcarsko-Kablarska crag. All the tributaries of the Zapadna Morava flow in torrents, thereby depositing drift onto reservoir and inducing eutrophication process. Water regime in the water reservoir is conditioned by power plant operation, with daily oscillations about 30 cm causing turbulence in aquatic biota, including fish as the most developed aquatic vertebrate by their evolution level and greatest in biomass. Hydrochemical and some hydrobiological parameters influencing productivity of the water reservoir, were assessed. From hydrochemical aspect, this water reservoir contained water, the quality of which was found to be within 2nd-3rd class. The water was, however, loaded with high concentration of NH3, Fe, BPK5 and suspended substances inducing its quality to be out of the class range.