ASSESSING THE ECOLOGICAL RISK OF MAN-CAUSED IMPACT ON THE ECOSYSTEM OF THE DNIESTER RIVER BASIN

The Basin of Dniester River, which flows into the Black Sea, an international river, crossing the Ukraine and the Republic of Moldova (RM) has being exposed to an intensive growing anthropogenic impact for a long time. There are four groups of ecological risk sources: industrial, agricultural, public and power generation-related. In the economical systems of the RM and Ukraine, the basin represented a multi-branch economical complex characterized by a concentration of industrial enterprises, bearing a potential ecological risk subject to a number of industries: mining, light, chemical, oil, machinery construction, food, radio-electronic etc. The main part of enterprises bearing ecological risk are situated in the upper basin, Lvov and Ivano-Francovsk regions of Ukraine accounted for 70% of the Dniester river water output. Another ponderable complex of large enterprises subject to ecological risks is situated in the lower basin - the big towns of Moldova: Chisinau, Tiraspol, Bender. A large part of the Dniester basin is involved in agricultural process. The middle and lower parts account for 70% of agricultural process. The intensive agricultural system being developed for several decades had not included ecological agricultural household methods, traditional methods of irrigation etc., having been based on the intensive fertilizer usage, monoculture system and environmentally ungrounded irrigation. These have been adversely impacted the ecological state of the basin, affecting the quality of soils, surface and ground waters, and the consequences being hardly redeemable. The ecological state of the river is affected mostly by the household system and the energy sector. In the upper stream, at the Dniester river inflow in Moldova, the barrage of Ukrainian Novo-Dniestrovsk hydroelectical power station SHE was built. The Ecological state of the river has been affected by the created basin and the operation of the station. The mean temperature of the river water decreased 2 0C. The impact of this fact has produced hydrobionts, and several species of fishes has been replaced with ones of a low nutritive and economical value. The fish productivity of the river has declined by 30 times. Along the middle and lower stream of the river the accumulation reservoirs of SHE Dubasari and CTEM Moldovan Thermoelectrical power stations are situated. Along with a positive role of water stream regulation and flood prevention, these have an adverse ecological impact. In the lower stream of the river the Cuciurgan accumulation lake is situated, which since 1965 has been representing the cooling lake of CTEM. Its operation has a deep adverse environmental impact on the river and accumulation lake by producing fluctuations of water level and temperatures during the day and increasing water turbulences. Another problem is the water mineralization of accumulation lake, which increases from 0,6 g/l in 1960 up to la 1,1 g/l in present. The water could be used for irrigations of agricultural fields. Herewith, the named sources represent heavily polluting sources of air basin. Yearly, only CTEM air emissions account for 27 kt NOx, 15 kt CO . These modifications in the quality of environmental components affect heavily the estate of basin ecosystem and health of population. In order to reduce the risks a complex approach to the basin management is required at the international collaborative level.

Contribution proposed for:   oral presentation