As a consequence of bombing of Novi Sad Oil Refinery, Serbia (Serbia&Montenegro), the spillage of large amounts of oil and derivatives caused hydrocarbons pollution of the area surrounding the Refinery and the river Danube, thus directly endangering the entire water source "Ratno ostro". As a measure of protection in the division zone of the Refinery and the water source area, a hydraulic barrier was constructed. Within the process of monitoring piezometer water quality and the water supplied by protection system wells, microbiological analyses of water were carried out with the aim of supervising the barrier functioning. The results have shown that bacterial populations in polluted areas exhibit a duel role: they act as bioindicators of a certain pollution, but at the same time they take part in the process of selfpurification.

This work presents a short review of the existing situation, nature conditions and recognised facts which are important for the sea- pollution of the oil, and another kind of the spill ship oils, inside of the Boka Bay and in the area of the open Adriatic Sea. The proposed original and innovative action concerns the large scale application of a new technique for a cleaning up waterborne oil spills, based on the magnetic separation method by using the material "CleanMag", an oleophillic, and porous material which also is magnetic with an increased density lower than that of the water.

The work is concerned with the study of groundwater quality in respect of hydrocarbons content, carried out on several sites on the territory of the Oil Refinery Novi Sad (Serbia, Serbia&Montenegro). In the course of four year that elapsed since the time spillage of crude and oil derivatives and deposition of burning products on the Refinery soil (April-June 1999) the processes of passive in situ bioremediation have been taking place on the contaminated area. By comparing the results for three contamination zones in a circle of 270 m from the site at which the spillage occurred, a certain increase in content of mineral oil was observed in deeper water-bearing layers at a distance of 200 and 270 m from the spillage site. A content of BTEX components the "movement" of the pollution was observed from the close zone 1 via the farther zone 2 to the farthest zone 3, which indicates that the intensity of bioremediation and all physico-chemical processes in general, taking place on the pollution site, is not sufficient to prevent pollution spreading. The assumption that the zone in question in probably a limiting zone is based on the results of the fourth sampling campaign, in which BTEX components were not detected on any of the locations of the zones 2 and 3.

Some physiological groups of bacteria can be good indicators of the oil pollution of the environment. Oil contamination represents a special problem because of their persistence and possibility of reaching drinking water supply sources. The destruction of the Novi Sad Oil Refinery in the hinterland of water supply source Ratno Ostrvo has endangered drinking water supply of the city of Novi Sad. As an acceptable protection measure appeared the solution with the hydraulic barrier located along the east side of the Refinery, bordering with the water supply source. Physiological groups of bacteria relevant to oil contamination (hydrocarbon-oxidizing and lipolytic bacteria) were detected in the waters of the barrier wells. The appearance and population of this microflora in the water of these wells were more pronounced compared with the waters of a control piezometer in the hinterland of the water supply source.

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.