Procena rizika po kvalitet površinskih vodnih tela na osnovu identifikovanih koncentrisanih izvora zagađenja / The risk assessment on the quality of surface water bodies based on the identified point sources of pollution

Research in this study included the concept of pressure and influence significance analysis as well as the methods for identification and classification of the pressure sources: characterisation and analysis of pressures; assessment of the water bodies’ status and assessment of impacts/risks that their good ecological status/potential is not achieved. Total number of registered polluters in Vojvodina is 185, 130 of them currently working. Most polluters discharge their waste water into the Tisa River, DTD Vrbas-Bezdan and Begej River, who are the recipients of 61% of the total volume of wastewater. Almost 70% of the total number of contaminants belongs to the processing industry, and among them the most common is food and beverage production. The average daily amount of discharged wastewater is approximately 140 000 m3/day. Total organic pollution emitted into the watercourses in the area of AP Vojvodina originates from the waste water is 33 tCOD/day and 15 tBOD/day. Half of the polluters discharge their waste water without any treatment; a quarter of them have primary wastewater treatment, while tertiary treatment is applied by only 3% of polluters. A very small number of polluters have their emitted pollutant concentration compatible with the prescribed emission limit values: for nutrients it is about 50%, while for the organic matter, it is only a quarter of the total number of polluters. From 37 watercourses, only three are classified as class 2, which corresponds to good quality water. Quality of the greatest number of watercourses corresponds to poor or bad status/potential (ie. classes 4 or 5). The biggest deviation from good status/potential is due to nutrients content and oxygen regime parameters. Results showed that high-risk pollutants are commonly nutrients and oxygen regime parameters, which probably represents the negative impact of waste water discharges. The total load of pollutants, and therefore the number of watercourses where the target load it exceeded, significantly increases with the increase of emitted loads from the point sources, but also with the reduction of water flow in rivers. The largest number of watercourses (20) in which the target load is exceeded, is due to COD and phosphorus. In the case of achieving the emission limit values for each polluter, the number of watercourses in which the targeted load is exceeded would be reduced by 15-50%, depending on the parameters, whereby the number of watercourses in which the targeted load it exceeded is not dependent on the load emitted but just on the water flow in the channels.