The paper presents aquatic macroinvertebrate community at four investigated localities of the Gradac river. Sampling was carried out during 2003 and 2006. Community structure and composition, together with field data, were used to estimate the water quality status of the river. A total of 87 taxa have been recorded. Insects were found to be the most diverse component, especially Ephemeroptera. Insects were dominant in the regard of the quantitative structure of the community, as well. Recorded community indicates good water quality, ranged between oligosaprobic and beta-mesosaprobic status (1st-2nd class according national classification scheme).

The analysis of breaks and gaps frequences in the fish species Alburnus alburnus from different localities of rivers Kolubara, Sava and Danube, were showed the highest values that were above the presumed critical zone (3.0-3.5% of changes). At some of localities examined in May and October 2008, these values were much more elevated that the level of spontaneous changes normally seen in the controls in laboratory animals and in fish of relatively clean waters. Results that were obtained for these localities indicate to periodical or permanent contamination with genotoxic agents.

This paper presents the data of sediment quality in the zone of three sources for water supply in Novi Sad, Serbia. The data indicate that the sediment in the area of these sources contain petroleum products (mineral oils) above the permissible concentrations. Only in one sample of sediment was detected DDT / DDD / DDE in the location of the source against the Strand wells RB-1 in a concentration which can specify as the maximum risk. The data indicate a significant anthropogenic influence of refinery waste water and urban waste water, motor boats in the marine (source Strand) and anchor of ships (source Petrovaradinska Ada) on the quality of sediment in these sources.

Qualitative and quantitative phytoplankton analysis was determined using standard microscopic methods and high performance liquid chromatography (HPLC) in the Bay of Kotor, seasonally, from April 2008 to March 2009. Diatoms represents dominant group of microphytoplankton with maximum in spring period. Dinoflagellates reached maximum value in summer period, and followed by cyanobacteria bloom. Dominant biomarkers, fucoxanthin, alloxanthin, 19'-heksanoloksifukoxanthin, zeaxanthin and chlorophyll b, show a similar distribution as the appropriate phytoplankton assemblages during the researches in Kotor Bay.

It has been established that processing by CTA - peat, under normal pressure, significantly reduces COD of tested wastewater, but at the same time, quickly comes to a stoppage, due to clogging. Results show that filtration process needs to be done under increased pressure. Based on gained results it could be concluded that CTA-peat represent efficient means of eliminating organic matters from wastewaters.

Quality of groundwater from aquifers used for water supply in the town of Zrenjanin, does not meet the drinking water quality requirements. Among the basic problems are the high content of natural organic matter and arsenic, but also sodium and boron. This paper presents one of possible alternative of technological solutions for drinking water preparation in Zrenjanin. Research has lasted three years. The paper presents a only an outline of the drinking water preparation processes.

In order to protect the natural resources used, it is necessary that plant production has such a concept that its influence with the optimization minimizes the required yield. For this purpose it is necessary to adjust the measures taken for the purpose of regulation of water-air regime, especially in the area where land reclamation is applied. The difficult task require harmonization of approaches that are often contradictory, therefore it is necessary to make preparations for the changes in the existing principles of the existing land reclamation practices. These changes reflect primary in the rational use of resources that could result in the protection and improvement of biodiversity and therefore stable ecosystem in the agricultural area.

The aim of this paper is to present the current distribution of the species Corbicula fluminea and Corbicula fluminalis with new findings in Serbia. During the investigation performed from 1998-2008, these taxa were detected at 19 localities. It is noted that C. fluminea is well adapted to particular aquatic ecosystems, whereas C. fluminalis seems to be rare in Serbian waters. Wide distribution of alien clams, according to our results, showed that heavily modified main water ways are suitable recipient areas for introduction and adaptation of allochthonous organisms.

The paper presents the results of aquatic macroinvertebrates community analyses of the Milesevka river (Lim river watershed; Sava river basin) with aim to evaluate saprobiological status. Sampling was carried out on five localities during 2005. A diverse community (62 taxa) has been recorded during the investigation. Results of saprobiological investigation indicate satisfactory water quality, which is, according to national legislative, within 1st and 2nd quality class.

During the summer 2009 physical, chemical, biochemical and bacteriological analyses of water of rivers Mušnica and Suški Potok were performed. Microbiological analysis point out that waters belong to the 2nd class by Kohl. The river Mušnica had slightly polluted water, and river Suški Potok had very slightly polluted water. According to the Regulation on Classification of Surface Waters in Republic of Srpska (Bosnia and Herzegivina) all the observed parameters belong to the first or second water quality class. Only the stream Suški Potok has chloride concentration that exceeds a third-class quality. On the basis of observed characteritics it can be concluded that Mušnica and Suški Potok have a satisfactory water quality.