To evaluate precision and reliability of recently introduced Metal Pollution Index as a method for metal pollution monitoring of surface waters, a series of toxicity tests with Daphnia magna have been undertaken. The sampling sites (the River Danube wetlands and Hydrosystem DTD (Danube - Tisza - Danube), Serbia, Yugoslavia) for this study have been chosen according to previously recorded high MPI values. Chemical characterization and WET (whole effluent toxicity) testing of selected waste waters at the chosen sampling sites, and the recipient water toxicity testing upstream and downstream the discharger evaluated the validity of MPI, and, on the other hand, discriminated the effects of background pollution. The results of acute and chronic toxicity tests of water and sediment corresponded well with MPI values, which leads to a conclusion that MPI could be regarded as a reliable and precise method for metal pollution monitoring of surface waters.

This paper is an abstract of the operative program for water protection in the Republic of Serbia (Yugoslavia) for the next five-year period of time. There is a short review on the present water protection status, particularly status of wastewater treatment plants. It includes layouts of water protection solutions in different fields, by priorities, as well as assessment of necessary capital investments for their implementation.

Possibilities of application of transmembrane enzymes as a biological component of a biosensor for water quality control and detection of toxical substances were performed. Synaptic plasma membranes (SPMs) were adsorbed on nitrocellulose filters. The adsorption of SPMs was followed by determination of the transmembrane enzyme Na,K-ATPase. The optimal conditions for SPM adsorption on nitrocellulose filters were determined: 25 microgram per nitrocellulose filter disc during 1 hour of incubation, on - 20 deg C. The ATPase activity of adsorbed SPM showed, that almost 30% of enzymic activity was detected on nitrocellulose filters in mentioned conditions. This results showed that adsorption of SPM on solid support enhancing enzymatic stability and enable its industrial and analytical application.

In the scope of the Program of surface water quality examinations in the Republic of Srpska (Bosnia and Herzegovina), hydrometric measurements and water quality examinations had been realized, where zooplankton and microzooperiphyton researches have been performed. Sampling were performed in the period from 6th to 20th May 2000, at 13 water courses with taken in total 21 samples. In qualitative structure of examined fauna, Rotatoria, Cladocera and Copepoda groups were treated, with ascertained in total 109 taxa from 41 genus. In qualitative structure periphyton taxa are predominant. On the basis of bioindicatory species structure it is noticed that dominant species are oligasaprobic and oligobetamesosaprobic character.

The work gives the regime of surface water flows with hydrographic net and the regime of waters at hydrologic stations for the period of 1988-1998. Consequently in this paper will be designed a resonant indicator which is derived out of the composite index group of WQI for the flow field in the period under research. Depending on the index points won at the examined profiles, estimation of waterflows quality will be adapted to the goals of indicator users, in this case to the public. Indicators of the type very poor, poor, good, very good and excellent. Hereto it is important to mention that hereby validity of original composite indicator will have to be sacrificed.

As a result of this study the overload by pollutants and low quality of canal water in the zone downstream of Vrbas and Srbobran towns (Serbia, Yugoslavia) has been recorded. Regarding to started work on demudification of canal bottom in the industrial zone of Vrbas town, in the course of 2000 the additional investigations of mud profile downstrean of wastewater discharge into the canal have been done. In the investigated mud samples the extremely high number of organotrophic bacteria was found (up to 1.7 x 10**10 cfu/ml), but also high number of conditionally pathogenic bacteria (opportunistic bacteria) was recorded. Also, the high number of fecal (thermo-tolerant) coliform bacteria (Escherichia coli and Klebsiella - Enterobacter - Citrobacter group of bacteria), as well as the presence of colifags was found. Such findings indicate possible bad consequences to the health of humans contacting this mud, as well as to the ground water quality, indirectly, via drainage water.

The paper deals with evaluation of surface water quality in Vojvodina (Serbia, Yugoslavia) by integral methods. The aim was to emphasize streams and localities where water quality is insatisfied condition longer period of time. The profiles, chosen according to continuity of quality problems which are not results of short excesses, rightfully could be named as a "black points".

Withdrawal of water from surface water network should be concerned with preservation of the environment, meaning that the low flow regime in streams should be preserved within the range of natural regime. In order to formulate criteria for minimal allowed flows in streams, it was necessary to perform statistical analysis of low flows in rivers in Serbia (Yugoslavia). The criteria for water withdrawal are proposed on the basis of characteristic ratios between minimum and mean flows. Different criteria are proposed for cold and warm seasons.

The investigations of the macrozoobenthos of the Crvena Reka river (Serbia, Yugoslavia), left tributary to the Nisava river, were performed during July in 1999. Samples were collected from 15 localities, from the spring of the Crvena Reka river (originating from Toponicka and Vetska rivers) to the lower course, the aim being to investigate the diversity of macrozoobenthos of these running waters which had not been investigated. The community of macroinvertebrates of the Crvena Reka river and the streams, which make it, consists of 54 determined taxa (at species and genus level) from 16 animal groups. Larvae of Ephemeroptera and Trichoptera have the greatest diversity, each having ten determined taxa. The middle course of the Topnicka river (locality T4) is characterized by the greatest diversity (25 taxa), while the springs (due to constant ecological parameters) have poor diversity with two and one determined taxa in locality V1 and V2, respectively. The water quality of the investigated river and streams, which make it, on the basis of the results of saprobiological analysis, is of beta-mezosaprobic quality, i.e. second class of quality in most localities.