The microbiological quality of the groundwater was monitored by determining relevant physiological groups of bacteria (organotrophic bacteria) which are indicators of water organic pollution. Standard high nutritive medium (Nutrient Agar) and low nutritive medium (R2A agar) were used. The enzymatic activity was also estimated based on IFA determination (index of phosphatase activity). According to the number of organotrophic bacteria and categorization by Kohl (Kohl, 1975) water is generally classified in category II. IFA showed variation of water quality, which varied from polluted to very pollute. The results showed organic pollution of groundwater and confirmed the sensitivity of enzymatic methods. In addition, cultivation methods confirmed superiority of low nutritive media.

The aim of this work is to present the trophic state of water at the pelagic zone of lake Prespa, reviewing the result of defined parameters of physico-chemical and algological aspect. Investigations are done according to standard limnological methods and the samples for analysis were collected from one vertical profile (0, 5, 10 and 15 m) monthly during 2008 year. Water categorization, on the basis of gathered data from analyses of the sampling localities was done according to the OECD-regulations, positive law regulations of the Republic of Macedonia and Nürnberg classification system. Data from this investigating period point out that this area of the lake Prespa is by great influence of the anthropogenic factor and intensive eutrophication.

The aim of this work is to present the water quality of littoral zone of lake Prespa, based on defined physico-chemical parameters (NO3, NO2, NH3, total nitrogen). Samples for analysis were collected with a monthly dynamics during 2007 year (April-December). This period is not chosen by chance, in regard to that the lake basin is constantly under the anthropogenic influence and climate changes that have been registered by this time. According to the obtained results of the performed analyses, basis of the water act of RM and OECD regulation, a categorization of the after was made in the respective measuring points.

Investigation in this study should indicate to importance of aquatic macrophytes in accumulation of toxic metals in aquatic ecosystems and control of their pollution, as well as to establish which plants are well hiperacumulators and test species for remediation, in order to protection, regeneration and conservation of the Gruža lake as reservoir that is important for water supply and as particular natural ecosystem. Obtained results showed that species Lemna gibba L. was reliable indicator of surrounding conditions (environment), as well as good accumulator of heavy metals, so it could be used to remediate aquatic ecosystems.

Complex hydrodynamics and thermal regimes of temperate lakes have a major impact on temporal and spatial distributions of water quality indices. Transport processes in lakes are driven primarily by external forces such as wind and solar radiation but also depend on the inflow and outflow regimes. This paper presents a simplified ID model developed to calculate seasonal variations in vertical distributions of temperature and dissolved oxygen in Lake Zavoj in southern Serbia. Model results that were based on monthly averaged meteorological data are in good agreement with measured vertical profiles of temperature and dissolved oxygen. The simplified model is an efficient tool for long-term prediction of water quality indices in deep, medium and long residence time lakes.

In order to determine the stable isotope content of hydrogen (2H/1H) and oxygen (18O/16O) from surface water and the Zavoj Lake, a sampling campaign was carried out in November 2011. Vertical profiles of water samples were collected in the sections close to the dam to check whether there was any detectable influence from the inflowing Visočica River and wheter there was a vertical isotopic stratification of the lake water. Temperature gradient of up to 5.5 deg C between surface and about 60 m depth is observed. Dominant process of mixing the inflowing Visočica River and water leaking from diversion tunnel appear close to the dam.

This paper provides an assessment of the Mlava River on the Danube River sediment quality. The contents of Zn, Cu, Pb, Cr, Ni, Cd and As were detected in the surface sediment. Based on the obtained concentrations of these seven metals sediment quality pollution category was determined with respect to PLI (pollution load index) and I geo (geo-accumulation index). It is found that M4 site, according to PLI and I geo (As and Cd) values can be classified as very highly polluted.

In this paper aquatic macroinvertebrate community of the Peštan River was presented, including the characterisation of the species with regard to saprobic conditions and preference to the mineral substrate type. Sampling was carried out during 2011 at man stream and tributaries. A total of 52 taxa have been identified. According to the ecological classification of the taxa with regard to saprobic conditions for the main stream, the most species belong to the alpha-mesosaprobic group while majority of the species from the tributaries were characterised as beta-mesosaprobic species. The most of registered species preffered substrate type characteristic for lowland river. Results of saprobiological analysis indicate poorer status of the main stream in regard to tributaries.

The aim of this study was to analyze nine heavy and trace elements (Zn, Fe, Al, As, Cu, Sr, B, Cd and Ba) of the three tissues (muscle, liver and gills) in sterlet (Acipenser ruthenus), black sea shad (Alosa immaculata) and barbel (Barbus barbus). All three species were sampled on the Danube (1173, 1319 and 863 rkm) in Serbia. The obtained concentations of heavy metals and trace elements were used for obtaining an overview of the presence of the abovementioned elements in a descending order and calculate the value of MPI (Pollution Metal index), which represents the total quantity of heavy metals and trace elements per tissue and species. In all the analyzed specimens iron (Fe) and zinc (Zn) were dominant, followed by strontium (Sr) and aluminum (Al), and the other trace elements and heavy metals. The least represented metals were barium (Ba) and cadmium (Cd). MPI values were the highest in liver, followed by gills and muscle of all species; with the exception of barbel, which had extremely high MPI values in the gills.

Serbia has a large number of various and for the application convenient mineral and spring waters for using. It is wide base that makes possible to develop practically everything that is abroad known for the application and perspectively possible. Serbia has well developed bottle industry of high quality mineral waters. Present and future seek, and Serbia has great chances to develop a new program production the world highest quality oligomineral waters, with the exclusive chemical composition, ecological safety and origin, suitable for everyday use drink and making food. In that aspect have been finished first completely new experiments and obtained the world significant first results, that are promising new program of production food naturally enriched with essential microelements in the most suitable chemical form for physiology of nutrition. The main aim in research theory and particularly practical application of marketing concept in increment sale of the mineral waters, is to analyze them in details and to use them as the basis for the suggestion of the appropriate measures and activities to help the manufacturer of the mineral waters, to incorporate the marketing concept as the way of business organizational and business strategy.