Diatom indices and indicator system based on benthic diatom communities were used to estimate the water quality and its changes in the Vistula River on the sector between 10 and 337 km of its course. The results showed similar trend in the water quality changes along the river course as those obtained by chemical analyses. Significant correlation was found between the calculated index values and also between indices and selected water chemistry variables related to the organic pollution and trophic state. However, there was no correlation with the concentration of phosphates. Both results, the chemical as well as biological ones based on diatoms, showed differences in water quality along the investigated river sector. Natural, unpolluted water with low nutrient concentration was found only in the upper part of the river (up to 10.9 km of its course). The increased trophic state was observed in changes of all the calculated diatom index values and in the relative abundance of the indicators for eutrophic stage already from 36.6 km, raising up together with organic pollution level along the river course. The heavy pollution occurred mainly on the section from 66.2 km to 185.2 km. At the last part of the investigated sector especially on 336.7km, an improving tendency was observed. The seasonal changes in the diatom community structure and values of diatom indices were connected with fluctuations of current velocity observed in 1997 during big flood at the beginning of July. Distinct differences were found in August and October 1997, when the structure of diatom communities and the values of diatom indices indicated the lowest water quality in the whole investigated sector.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.