Chemical composition and water quality of surface waters in Ukraine

Summarizing of last decade data concerning Ukraine's surface waters chemical composition have been carried out. Changes of mineralization, pH, mineral forms of phosphorus and nitrogen, heavy metals and humic substances in water of main river basins were shown. It was found, that in basins of Zapadny Bug, Dnieper, Danube and Seversky Donets the tendency of pH increase is being observed for the long time. It also should be mentioned that almost for all studied river basins of Ukraine decreasing of phosphorus mineral forms concentrations were identified. That finding allows concluding about obvious discontinuance of global process of surface water eutrophication by phosphorus compounds. Also the comparative analysis of data sets obtained in early 60-s and for period of 1995-2000 indicated the tendency of N-min and NH4+ decreasing almost in 2 times. Relatively high concentrations of dissolved organic matter would be considered as a positive factor of water selfpurification from toxic forms of heavy metals. From another hand, results of field observation as well as computer thermodynamic modeling data have shown that under physicochemical conditions of Ukrainian surface waters trace metals are thermodynamically unstable in a phase of solution. Summarizing results of a long-term data processing concerning distribution of different classes of chemical substances in water, suspended matter, biological materials and sediments we would conclude, that despite significant man-caused impact Ukrainian surface water still possesses the self-purification ability.