Assessment of the Surface Water Quality Using the Water Pollution Index: A Case Study of the Timok River (The Danube River Basin), Serbia

• Published in: Archives of environmental protection Vol. 38; no. 1; pp. 49 - 61
• Main Authors: Brankov, Jovana, Dragana MilijaÅ¡eviÄ, Ana MilanoviÄ
• Format: Journal Article
• Language: English
• Published: Warsaw Versita 2012; Polish Academy of Sciences
• Subjects: basins; biochemical oxygen demand; Borska Reka River; cadmium; case studies; chemical oxygen demand; coliform bacteria; copper; drinking water; Freshwater; heavy metals; iron; manganese; mercury; mining; municipal wastewater; nickel; nitrates; nitrites; organic pollution; orthophosphates; rivers; sulfates; surface water; suspended sediment; Timok River; water pollution; water quality; water quality analysis; watersheds; WPI (Water Pollution Index); zinc; Serbia; Danube River; Serbia, Danube R; Europe, Danube R
• ISSN: 2083-4810; 2083-4772; 2083-4810
• DOI: 10.2478/v10265-012-0004-x

The Timok River (202 km long, 4547 km² basin area) is located in East Serbia. It is a right tributary of the Danube River and one of the most polluted watercourses in Serbia. On the basis of the data provided by the Republic Hydrometeorological Service of Serbia, the paper presents an analysis of water quality and pollution using the combined physico-chemical WPI index (Water Pollution Index) calculated for two periods - 1993-96 and 2006-2009 at four hydrological stations: Zaječar-Gamzigrad (Crni Timok River), Zaječar (Beli Timok River), Rgotina (Borska Reka River) and Čokonjar (Timok River). The following parameters were taken into consideration: dissolved O², O² saturation, pH, suspended sediments, Five Day Biochemical Oxygen Demand (BOD⁵), Chemical Oxygen Demand (CODᴹⁿ), nitrites, nitrates, orthophosphates, ammonium, metals (Cu, Fe, Mn, Hg, Ni, Zn, Cd), sulphates and coliform germs. The average WPI values were calculated for the observed periods based on the comparison of the annual average values of the listed parameters and defined standard values for the I water quality class (according to the Regulation on the Hygienic Acceptability of Potable Water of the Republic of Serbia). The highest pollution degree was recorded in the Borska Reka River, where heavy metal levels (especially manganese and iron) were significantly increased. These metals are indicators of inorganic pollution (primarily caused by copper mining). Also, increased values of the organic pollution indicators (ammonium, coliform germs, Five-Day Biological Oxygen Demand - BOD⁵) in the Borska Reka and the Timok rivers are the result of uncontrolled domestic wastewater discharge.