Investigation of the nutrients and chlorophyll a concentrations, as indicators of trophic level, in the period from September 2003 to August 2004 in three sampling locations in the inner part of Boka Kotorska Bay varied widely. Nitrate concentration ranged from 0.0 to 2.42 mg/l at the surface and from 0.02 to 3.88 mg/l at the bottom, nitrate concentration from 0.02 to 0.21 mg/l at the surface and from 0.01 to 0.6 mg/l at the bottom, phosphate concentration from 0.03 to 0.18 mg/l at the surface and from 0.01 to 0.22 mg/l at the bottom, silicate concentration from 0.0 to 1.42 mg/l at the surface and 0.45 mg/l at the bottom respectively. Value of phytoplankton biomass, as represented by chlorophyll a, ranged from 1.02 to 8.68 mg/cubic meter and from 0.49 to 5.23 mg/cubic meter at the bottom. According to the UNEP criteria during the investigated period it can be concluded that the area in question is mesotrophic with the exception of December when it is eutrophic.

During the study we recorded narrow margins between zooplankton distribution and the ecological characteristics of water in Bokakotorska Bay (Adriatic sea, Montenegro). Various species show different vulnerability to environment quality. Some are defined as indicators, with low tolerance for the ecological variation of environment, and their distribution is limited to the particular type of water masses within the sea. The limiting factors are different for various species, and their indicator status is determined by their distribution. The indicator type, based on monitoring of particular species, may define a biotope, with the help of statistical analyses that identify the main time and spacial behavior patterns of a species, and my allow future ecosystem changes to be anticipated. In this paper we paid particular attention to the indicator species Oithona nana (Giesbrecht).

In this paper two different combinations for wastewater treatment are proposed for specific problems that Vojvodina (Serbia) has with arsenic. Both proposed technologies take into account treatment of water and treatment of waste. In this paper the concrete solution for water treatment is proposed for water that contains arsenic (the concentration is around 100 microgram/L) in Obrovac and Palic. With these water treatment plants the removal of ammonia (measured concentration was above the maximum allowed value, from 1.35-2.5 mg/L) is also included in case of Obrovac wastewater plant, and for Palic the proposed treatment plant the removal of iron (measured concentration was above the maximum allowed value, from 1.35-2.5 mg/L) is also included. With both treatment plants and with both proposed technologies the overall treatment of water is planned.

The paper analyses application of different methods for removal of the high content of ammonia from groundwater sources of the Grocka municipality neighborhoods Umcari and Pudarci. According to the relevant data from this field method, biochemical oxidation with the Nitrosomonas and Nitrobacter bacteria was used. Parameters of biological processes of the ammonia oxidation were defined on the pilot model located at the groundwater source. On the pilot model, consisting of a trickling filter and a fast gravel filter, quantitative oxidation NH4 to NO3 was done. Purification plant was designed with parameters of the pilot model, with minimal investment and exploitation expenses, without undesired side products and ecological risks characteristic for procedure of chemical oxidation of ammonia, which recommends this procedure as the optimal solution.

Conventionally treatment method in potable water preparing, such as coagulation/flocculation, sedimentation and filtration has been shown reduction in efficiency of the contents of natural organic matter. There has been developed many alternative NOM removal technologies, in recent years. It has been made significant research effort in finding optimal drinking water treatment for NOM range reduction prior disinfection, that can minimise the formation of disinfection by-products and reduce the residual required to control bacterial regrowth in the distribution system, which is a consequence of coagulant with humic matter settling. Conventionally treatment modified by MIEX resin appliance meet the current water quality standards, with significant reduction of the coagulant quantity.

The paper considers legal framework for the surface waters quality control as per our Regulation and Directive 75/440/EEC in terms of required quality of surface waters intended to be used for the drinking water production. Research has been done in eight accumulations designed for water supply in Serbia, and water quality index has been determined using WQI method during the period 2000-2004. The water quality in these accumulations was within the treshold values in relation to the required quality.

Microbiological and saprobiological characteristics of river Moraca and Skadar lake for period of 2004/2005 are done at localities: Pernica, Moraca estuary and Vranjina (Skadar Lake). The objective of the research is to establish quality of water of these aquatic ecosystems based on microbiological and saprobiological analyses, as well as, to show need for protection of these water ecosystems from permanent contaminations, mainly by sewage should be pointed out. Saprobiological index is determined based on Gulyas Pal, and Pantle Buck is used to determine saprobiological level.

One of the key issues related to the water quality in the Iron Gate reservoir is the pollution of the sediment. Sediment deposits retained in the Iron Gate reservoir originate from a wide river basin with more then 80 million inhabitants and highly developed municipal and industrial infrastructure. Besides mineral river sediment, various organic and inorganic matters entered and deposited within the Iron Gate reservoir. Sediment research objective was to assess the content of contaminants and nutrients which potentially could enter the water column.

In the frame of the project Water Supplying of the Cities and Protection of the Groundwater Quality in the Velika Morava Valley, was obtained the analysis of potential polluters of groundwater source of city Smederevska Palanka - Trnovce. This paper presents results of water physical, chemical and microbiological characteristics of soil. According to the results of research and way of usage of the soil, it was concluded that agricultural production does not have negative influence on quality of the groundwater source.