EN
Investigations on the Upper Vistula River course (from 11 to 337 km) in years 1997-1998 comprised: chemistry of water and sediments, indicators of water quality, such as bacteriological indices, metabolic activity of seston, phytoseston indicator taxa, algal growth test, zooseston assemblages, benthic diatom indices and occurrence of oligochaetes fauna. The pollution impact was reflected by distinct changes in chemistry of water and sediments, as well as by bacteriological indicators and alga growth test. No distinct changes have been noted in the structure of benthic diatom communities. Some improving tendency in the water quality was evident between 248-337 km of the river course, where the most tolerant to pollution taxa were partly replaced by less tolerant species. Some changes revealed an increase in numbers of beta-mesosaprobic and meso-eutraphentic Chlorococcales, which dominated over dense populations of cyanobacteria. Benthic animals assemblages indicated a decrease in pollution level between 248-337 km of the river course. In the case of zooseston no evident effect was observed. The sector of the river received on 95 km high load of chlorides from coalmines until last site on 337 km. Load of chlorides was constant, whereas their concentrations diminished. Nitrate concentration arose together with loadings. Phosphate concentrations were constant similarly to loadings, excluding site at 337 km of the rivercourse, where load arose. COD had similar pattern as chlorides. It seems to be better to operate on a greater number of specialised indices or parameters than mixed them into one, which might be confusing index.