Monthly sampling in the Grosnica water reservoir near Kragujevac, Serbia (Yugoslavia), was carried out in the period October 1996 - September 1998. Comparison of the results with those obtained in 1950-1952 revealed changes in the qualitative and the quantitative composition of zooplankton. The presence of a considerably greater number of species was recorded, including some that were registered for the first time in this reservoir and which represent a very significant component in the dynamics of its zooplankton. A multi-fold increase of zooplankton production was also observed. The number of recorded species fluctuated from 26 in the winter to 59 in the summer. Average total abundance of zooplankton ranged from 100.7 ind./l (late spring to 2508.6 ind./l (summer). The results indicate an intensive process of eutrophication in the Grosnica water reservoir, the oldest artificial lake in the this part of Yugoslavia.

In this paper there were given research results obtained during many years of investigation of hydrophytes of the Tisza river, Serbia (Yugoslavia), and their bioindicating values. The plant world of the Tisza river is characterized by floristical diversity, with three characteristics band: band of submerged, band of floating and band of emerged hydrophytes. Among submerged plants these are distinguished by abundance, covering values and occurrence degree: Ceratophyllum demersum, Elodea canadaensis, Potamogeton crispus, Potamogeton perfoliatus and Potamogeton pectinatus. In the floating band species of the fam. Lemnaceae: Lemna minor, Lemna gibba, Spirodela polyrrhiza and Potamogeton fluitans are most frequent. In the closest coastal band, these species are most frequent: Typha angustifolia, Typha latifolia, Phragmites communis, Sagittaria sagittifolia and Typhoides arundinacea. On the basis of determined floristical composition and bioindicating values there can be noticed the organic pollution increasing trend.

It has been done the analysis of the physical and chemical characteristics of the water from two households in the village Berkovac in the foot of the mountain Maljen, Serbia (Yugoslavia). These households are supplying from two different springs. The water from the spring "Dobracinovica izvor" is contaminated and it is not for use, but the quality of the water from the hill Kulica is satisfactory. Both of them belong to the group of cold mineral waters.

The investigations of qualitative and quantitative composition of plankton and the bottom fauna of the Tisza river, Serbia (Yugoslavia), were conducted during 1998. According to the analyses of the indicator species of hydrobionts, saprobic index was calculated, and the estimation of the water quality of the lower flow of the dam near Novi Becej on the structure and abundance of the investigated organisms.

In this paper sediment production and sediment discharge and its influence on hydroenergetical potential as well as pollution of river Lim - upper flow, Montenegro (Yugoslavia), were taken into consideration. Besides of problems of sediment and water discharge protection - biological and technical measures for sanation the negative effects of erosion processes were recommended. Total annual sediment production for the river Lim - upper flow was 679,763 mE-3/year and annual sediment discharge was 312,013 mE-3/year. Such sediment (produced and discharged) has negative impact on the hydroenergetical potential and soil resources and also pollutes water with sediments and other harmful and hazardeous materials. Introduction of erosion control measures will reduce the negative effect of erosion on the tolarant level.

In our previous papers, it is concluded that wood sawdust can be applied as adsorbent for heavy metals removing from water. All earlier investigations are done in batches, while it is confirmed that different heavy metals are adsorbing with various efficacy on sawdust of different kind of wood. Adsorption of copper ions from model water is investigated in this paper, by its passing throw column filled with poplar and fir sawdust, granulation in the range 0.5-1 mm. Starting concentration of copper ions was the same in all experiments, and flowrates of model water and column geometry are varied. Certain volumes of water are taken on the column outlet, and copper ions concentration are determinated in this samples. On the basis of these results breakthrough curves are obtained, and adsorption parameters in dynamic conditions are determinated.

Removal of natural organic matter from water was investigated using granulated activated carbon. Groundwater from northern Banat region (Serbia, Yugoslavia) was used. Samples of raw water and water after coagulation were ozonated and than GAC adsorption was performed. The investigation was carried out under the static conditions to determine the GAC adsorption capacity and kinetic coefficients.

In this investigation the applied method for lead determination in traces, from 10E-6 - 10E-10 mol/cubic dm, was Potentiometric Stripping Analysis (PSA). The main attribute of this method is possibility to detect very low metal concentrations. The investigation results of level concentration of lead into the top, natural and atmospheric water from some towns of Serbia (Yugoslavia), including city of Belgrade, are given. The investigation was carried out in some towns of Serbia (Yugoslavia), including city of Belgrade, during the 1994-1995.

Activities of rat brain synaptic plasma membrane (SPM)Na(+)/K(+)-ATPase and Mg(2+)-ATPase were investigated by in vitro individual and simultaneous exposure to ions of the first transition series metals (Cu(2+), Zn(2+), Fe(2+)). All investigated metals produced a larger maximum inhibition of Na(+)/K(+)-ATPase than Mg(2+)-ATPase activity. Metal concentrations causing 50% inhibition of Na(+)/K(+)-ATPase activities were: Cu(2+) 7.1 microM Zn(2+) 19 microM Fe(2+) 25 microM. Simulataneous exposure to metal combinations: Cu(2+)/Zn(2+), Cu(2+)/Fe(2+) and Zn(2+)/Fe(2+) inhibited both the Na(+)/K(+)-ATPase and Mg(2+)-ATPase activity synergistically, i.e., more than the sum of the metal induced inhibitions assayed separately. It is also established that the plot of logarithm IC50 values of Na(+)/K(+)-ATPase activity vs. the ionic radius of (Cu(2+), Zn(2+), Fe(2+)) is a straight line that enables to predict the value IC50 for other metals of the first transition series. The results obtained show that Na(+)/K(+)-ATPase is promising as a biological component of biosensor.

During three years period from 1991 to 1994, investigation of the river Kolubara (Serbia, Yugoslavia) was carried out along 35 km of water course from Valjevo to Lajkovac. The macrozoobenthos community was composed of 117 determined taxa. Of the found taxa Oligochaeta were the most diverse with 40 taxa determined. The greatest diversity of macrozoobenthos community was foound at the river section in Valjevo, upstream the mouth of Gradac (69), while the community was most uniform downstream Valjevo at Bela Stena (24 taxa). A decrease as well as an increase in the macrozoobenthos diversity was not in accordance with similar decrease or increase in saprobic index values since they were in narrow range from 2.37 to 2.59.