Water trophy assessment of the cooling system of the “Dolna Odra” power plant on the basis of algae indicator organisms

The paper presents the results of water trophy assessment from various stations of the cooling system of the “Dolna Odra” (Poland) power plant. The assessment was made based on the indicator phytoplankton species collected four times at four sites located in different parts of the hydrological system cooling the technical infrastructure of the power plant. The sites were characterised by water with a natural temperature for individual seasons, as well as by thermals changed as a result of the discharge of cooling waters. For each site, the saprobic index was calculated based on indicator species. The analysis showed that the changes in trophic conditions, both in waters with changed thermals and in waters not subject to the influence of after-cool waters, are not subject to significant changes. The waters of all studied sites in the analysed periods of the year should be classified according to Sladeček and Sládečková (1996) to the waters of the β–mesosaprobic zone, with a saprobic index value ranging from 1.51 to 2.50 (average S = 2.0). This zone is characterised by the course of biochemical processes under aerobic conditions, as a result of which complete oxidation of the intermediate products of decomposition of organic compounds takes place.