Arsenic is inorganic spread out in nature. Toxicity of arsenic is different, depending on its form. However, current international and Serbian legislation in drinking water regulate maximum allowed concentration of 0.010 mg/l (of total arsenic), regardless of its form. Concentration of total arsenic in water of springs of mountain Avala (Serbia) is higher than 0.010 mg/l. This paper present determination of inorganic arsenic in drinking water of spring Sakinac (Avala), also determination which form is more represented, relation of As(III) and As(V) and implementation of legislation. We used stripping voltametry method and gain value of total arsenic-62.87 microgram/l, in which 3.97 microgram/l is As(III) and residue of 58.90 microgram/l is As(V). It is obvious that value of 62.87 microgram/l is higher than MAL, but the most abundant arsenic form is less toxic, so the question is whether the water from spring Sakinac can or cannot be used.

Groundwater from the middle Banat region (Serbia) which is used as a drinking water supply for Zrenjanin town contains a high amount of natural organic matter and a high content of arsenic. In this study a pilot-scale system was used to investigate the influence of different ozone doses (0.4-0.9 mg O3/mg DOC) during a pre-ozonation process on NOM removal by coagulation. Ferric chloride coagulant was chosen at a dose of 100 g/cubic meter, as a traditional coagulant which can also help in arsenic removal. The obtained results indicate that an ozone dose of 0.4 mg O3/mg DOC has the best influence on structural changes of NOM. The coagulation process with ferric chloride as coagulant had a significant influence on the arsenic content of the water, with the measured values in the water after coagulation in all three investigated treatment trains being below 10 microgram/l, which is the standard MCL in Serbian legislation.

Water bodies like rivers and lakes are directly affected by the waste water in sewerage systems. Sewage systems provide waste collection and convey wastewater from the population in sanitary safely way and away from material property. DPSIR analytical framework allows the analysis of interactions between sewerage systems and water bodies. Sewer systems describe the different standards that are elements of their functioning including plants and their maintenance, hydrological, hydraulic and other influences. This paper gives analytical framework of Driver, Pressure, State, Impact, Response (DPSIR) in relation to the functioning of the elements considered sewage systems which are described in the Serbian (European) standard - SRPS EN 752 - 2:2007.

In Laboratory for examination of waste waters in Belgrade sewerage system many analysis are being done to indicate the physical, chemical and biological characteristics of waste waters. Biochemical analyses which are being done include two parameters: biochemical oxygen demand (BOD) and newly introduced parameter index of phosphate activity (IFA). Determination of IFA is relatively fast biochemical method which can, within few hours, give information of present organic pollution and its results could be applied for categorization of waters. Analyses were conducted during 2008 and according to the results waste waters mainly belong to the 5th category of water, more, the examined waste waters were out of all water describing categories.

The analysis of the frequencies of chromosome breaks and gaps on the pike - Esox lucius L. individuals from different locations collected in two consecutive years, were showed the highest values that were above the level of spontaneous (under the level of 3%) changes. Frequences of changes in fish Esox lucius L. were higher than the level of the presumed critical zone (3.0-3.5%) at locality of Danube by Visnjica and within the zone by Grocka. In consecutice years in river Tamis by Pancevo, both obtained values of chromosomal changes in this fish also were above the critical zone. Physicochemical water analyses were shown high level of organic contamination and concentration of phenols above MDK values for the 1st, 2nd water categories which argued obtained cytogenetic results. The localities obviously has a risk of being permanent or periodical contaminated with genotoxic agents.

The stable isotope content of hydrogen (2H/1H), carbon (13C/12C), nitrogen (15N/14N), and oxygen (18O/16O) in surface water (the Sava river and channels) and groundwater (Ranney wells) were determined in Belgrade (Serbia) during July 2008. Detailed evaporation calculation has estimated that fraction of water loss to be between 10 and 20% in the channels using the local meteoric water line and the local evaporation line. Carbon-13 content in dissolved inorganic carbon is distinguished between surface water and groundwater indicating different evolution pathways of carbon. Based on carbon and nitrogen isotopic composition and C/N ratios, sources of inorganic carbon and of organic matter in analyzed waters are discussed.

The paper shows available water resources potential of karsts spring waters of Carpatho-Balkan region of east Serbia. Basic elements of water balance are also given, as well as quantitative indicators of low flows. Karsts spring yield is compared to the domicile waters of Serbia. We can also read certain comments and see an estimation maximum usage of these karsts waters.

This work shows the effects of opening the Itebej sluice gate on the metals content of the water and sediment of the Begej canal. A deterioration in water quality resulted, in particular on the first day after opening of the sluice gate, when high concentrations of Zn, Cr, Cu and Pb were detected. The metals content of the surface sediments across the canal at Klek had significantly higher concentrations of Pb, Cr, Zn, Cu and Hg five days after the opening, whereas there were no obvious changes at Itebej. From the metals content of the suspended sediment it can be concluded that the increase in metals contents occurred one day after opening the sluice gate.

Relatively dense network of irrigation channels in Vojvodina is exposed to various point and non-point pollutants impacts. Therefore, deposited channel sediments-sludges can be contaminated with high concentration of dangerous and harmful substances such as polycyclic aromatic hydrocarbons (PAH). These sediments could have long lasting harmful effects on environmental status, quality and usability of channel water, and especially on surrounding agricultural soil, where dredged sediments are deposited or scattered. In this paper above mentioned conclusions are illustrated by quality analysis of specific irrigation channels sediments in terms of PAH contents in them.

Due to drainage as a significant measure of land reclamation, large part of Vojvodina Province (Serbia) affected by excessive water could become an agricultural land. The stability of ecosystems could be decreased by degrading the biodiversity. Additionally, Vojvodina has cca 6% of sylvan landscape but according to documents of spatial arrangement planning that area should be 14%. In order to solve this problem the implementation of biological measure could increase drainage efficiency by improving biodiversity and increasing the area covered by sylvan landscape, which is likely to do using biological measures of drainage on low productivity areas and buffer strips along canal network.