The results of the examination point out on heterogenity of the phytoplankton community. The presence of 212 taxa has been noted. In the way of quality the green algae are dominant. In all the aspects of the quantitative analysis the domination of Bacillariophyta has been noted, first of all the centric forms. The amount of nutrients on the locality of border with Hungary is considerable, thus during low water and high temperature, the intensive algae development is usual.

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.

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.

Water quality studies of the Danube river in Belgrade region (Serbia and Montenegro) were performed at five locations, in June and September, 2003. Results of the qualitative, quantitative and saprobiological analyses of plankton and macrozoobenthic communities were used for the water quality assessment and the categorization of the watercourse examined. The bioindicator analysis points to the presence of mild organic pollution, water quality varying between the 2nd and 3rd class.