In this paper, we used similarity index, such as Sorensen similarity index (S), Jaccard similarity index (Cj) and Percentage Similarity Index (PSC), to show similarities and contrasts within the qualitative structure of zooplankton of various bays within Boka Kotorska. This kind of statistical overview was made for Boka Kotorska Bay for the first time, so we believe that it is a valuable contribution to recent studies on zooplankton. Tables show the results for each index individually, as well as the smallest and greatest similarity among the bays. We also presented the number of recorded species in the Boka Kotorska Bay arranged by months for three different years.

The paper presents the seasonal overview of horizontal distribution and abundance for the species of genus Oithona in Bokokotorski Bay. Three species have been recorded. Oithona helgolandica and Oithona plumifera have a wide horizontal distribution within the Adriatic Sea, while Oithona nana is a typical euritherm and eurihaline form that occupies shallow and closed coastal areas along the eastern coast of Adriatic. Also presented are seasonal oscillations and quantitative presence of these species in the Copepoda population during 2002.

The 1st South-Eastern European Interlaboratory Study: WATER ANALYSIS - 2003 was organized by International Scientific Committee on the basis of international European and regional experiences. The total of 38 laboratories took part in WATER-ANALYSIS 2003. Three laboratories were from Greece, two from the Republic of Srpska (Bosnia and Herzegovina), eight from Romania and all others from Serbia and Montenegro. Two samples were prepared from water of the river Danube and the task for participants was to determine trace elements: Al, As, Cd, Cu, Mn, Fe, Pb, and Zn. Results of determination of arsenic (As) and aluminium (Al) are presented in this paper.

Potentiometric stripping analysis (PSA) is highly sensitive electroanalytical method for determination of traces of heavy metals. In this paper detection limit and linearity of potentiometric stripping analysis for lead was investigated. Method was successfully used for determination of traces of lead ion (detection limit 5 microgram/cubic dm) in stream water of river Ibar, before and after joint of potential pollutant.

Problematics of humic substances removal from surface water with low mineralization and temperature near zero was presented. In this analysis very large spectar of solutions especially for this area was included. More detailed data obtained with this patent solution (7) in laboratory conditions on purificaton of raw water are presented in the analysis. Comparing the new technology with existing purification state and many unsuccessful attempts to obtain the standards gives the possibility of choosing the best drinking water treatment solution for plant on mountain Kopaonik. General estimation of different methods that can give necessary water purification level was done. Technoeconomic and ecological analysis of different water purification methods was realised and the a rational solution with high effects on protection of the environment was given.

The paper outlines the significance of studying and analysing sediment deposition issues in drainage canals in Vojvodina, Serbia (Serbia and Montenegro). This problem needs to be properly addressed considering the total length of the canal network, that is, the total volume of sediment to be removed by dredging if the functional performance of the canal network is to be restored and maintained. Much of the effort needs to be focused to the polluted sediments with a severe risk for the environment. Sediment pollution is caused by the point and non-point sources of pollution. Taking one drainage canal as the example, essential chemical properties of the sediment and hazardous and toxic substances contents (heavy metals, PAHSs and PCBs) are being analysed and presented in the paper.

The diffusion of erosive processes in Serbia and frequency of torrential floods are the factors of degradation of environment. Communities in Serbia are obliged to make Plans for announcement of erosive regions and for protection by torrential floods on water courses out of regular system of defense. An example of Belgrade is presented in this paper, where the Plans for announcement of erosive regions and defense by torrential floods were carried out. These documents are the basis for water protection and usage of natural resources on the concept of sustainability.

A new concept for the determination of reference low flows of natural watercourses - the guaranteed minimum - has recently been introduced into the water management practice. Appreciating the significance underlying the definition of low flows in all segments of water management (municipal and industrial water supply, wastewater discharge, irrigation, navigation, hydropower, water protection, etc.), the author believes that all aspects of the problem must duly be considered, examined and identified. The doubts and issues raised by the guaranteed minimum concept in the domain of random-probabilistic phenomena, such as river discharge, are discussed in the paper.

The paper contains description of potential approaches to better defining of distribution curves parameters for low water levels on water courses that sporadically dry up, also including additional information on the length of dry period. Computed results are given for the example of minimum annual discharge on several rivers in the Velika Morava basin, Serbia (Serbia and Montenegro).

Wastewater from the Novi Sad Oil Refinery, Serbia (Serbia and Montenegro) had been previously discharged to the Danube river between the raw water wells. In order to protect water supply source, the collector discharge was displaced downstream, outside the raw water wells area. In 2004, the quality of Danube river water and sediment was monitored at the sites of the old and new collector discharge of the Oil Refinery wastewaters, as well as at two control (reference) sites. The paper presents chemical quality parameters of water and sediment, characterizing oil contamination. Significantly increased contents of oil contaminant were measured in the Danube river sediment at the old discharge site compared to other sampling points, which is a consequence of many-year accumulation, as well as in the Danube river water at the new discharge site, as a consequence of the present wastewater discharge.