THE CONTRIBUTION OF THE KILIA BRANCH OF THE DANUBE TO POLLUTION NORTHWESTERN PART OF THE BLACK SEA

Abstract

The Danube River accounts for more than 60% of the river’s inflow into the Black Sea, and more than 35% of the inflow of all freshwaters into it, including precipitation. On average, the Danube annually brings about 203 km3 of water to the sea. The Kiliya Branch is separated from the Danube in the Reni area. In 1900, 70% of the Danube water entered the Kiliya Branch, in 1957 – 62.5%, in 1985 – 58.7%, and in 1999 – only 55.6%. Thus, the trend determines a sensitive decrease in runoff by an average of 0.173% per year during the 20th century. Calculations for 2005, 2010 and 2015 show the share of the runoff of the Kiliya Branch, equal to 51.2%, 49.8 % and 48.3% of the total flow of the Danube respectively. Due to its high-water content, the Danube has a noticeable impact on the entire northwestern part of the Black Sea. In the Odessa region of the Black Sea, mercury was found at 70% of the stations. The average mercury content here was 2.20±0.05 μg · g– 1 dw, the range was 0.00–0.69 μg · g– 1 dw. Since the total discharge of mercury from local sources (treatment facilities in Odessa, Chornomorsk and Pivdenyi, as well as drainage water in Odessa) is only 31.6 g per year, it is obvious that mercury was brought to the Odessa region of the Black Sea from the Danube. Long-term monitoring of the Danube seaside showed that annually from the Kiliya Branch to the Black Sea on average come the following amounts of dissolved form of heavy metals: 289.06 kg of copper, 692.39 kg of zinc, 142.03 kg of nickel and 26.68 kg of cadmium, and in suspended form 780.13 kg of copper, 2306.15 kg of zinc, 526.18 kg of nickel and 37.44 kg of cadmium. In general, it is: copper – 1066.19 kg, zinc – 2998.19 kg, nickel – 668.21 kg, cadmium – 64.12 kg, oil – 8356.9 kg, suspended matter – 5355.12 kg.