Time and spatial variability in concentrations of selected metals and their species in water and bottom sediments of Dzierzno Duze (Poland).

Poland is an industrialized country in which industries (especially the heavy ones) have had a tremendous influence on the environment. It is particularly visible in the Upper Silesia region, where the observed air, soil and water pollution levels are the most highest. The aim of this study was to determine the time and spatial variability in: concentrations of selected metals (Co, Ni, Zn, Cr, Mn, Pb, Cd), and, to a limited extent, of Cu, V, Al and Sr; concentrations of inorganic ions (Cl-, SO42-, Na+, K+, Ca2+ and Mg2+) and values of pH, conductivity and redox potential. The enlisted parameters were determined for the water and bottom sediments of Dzierzno Duze, a water reservoir located in Poland (Upper Silesia region). Additionally, fractions of a few characteristic metals were determined in the bottom sediments of the discussed reservoir with the BCR method. The investigation was carried out in 2017. It showed that the reservoir surface water was not polluted with the determined metal contents. However, it was highly polluted with the inorganic ions. The metal contents determined in the bottom sediments were high. If the conditions for releasing them from the bottom sediments had been favorable, this situation could have posed a potentially considerable environmental threat.

Time and spatial variability in the concentrations of selected metals in water and bottom sediments of Plawniowice and Dzierzno Male reservoirs (Poland).

The migration of metals and metalloids between bottom sediments and water and the other way round is a complex process. Understanding those mechanisms is essential for recognizing transformations taking place in water reservoir ecosystems. The objective behind the following study was to define time and spatial correlations in the changes in total concentrations of selected elements (Cr, Zn, Co, Mn, Cu, Ni, Pb, As, Ba, Sb, Sr and V) in waters and bottom sediments from two water reservoirs located in Upper Silesia (Poland), i.e., Plawniowice and Dzierzno Male. The research was carried out to demonstrate whether the bottom sediments deposited in the discussed reservoirs could pose an environmental threat due to the possible release of toxic metals and metalloids into the pelagic zone. The obtained results constitute material helping to describe the bioavailability of particular elements. They also expose the existing environmental threats for such water reservoirs and their users.

Assessment of the restoration measures in a man-made reservoir: do oligochaete communities respond to the improvement of water quality?

Studies were carried out in a man-made reservoir that was undergoing restoration using selective hypolimnetic withdrawal (Plawniowice reservoir, Southern Poland). The aim of the research was to assess the changes in the composition of oligochaete fauna in relation to water quality and to estimate whether indices based on oligochaetes may be useful in the assessment of a reservoir's recovery from eutrophication. Samples were collected in the first, fifth, and eighth year of the restoration during the summer stratification at 22 sites along six transects that covered depths from 2 to 15 m. The results of the survey indicated an improvement in some physical and chemical water parameters in respect to those during the period prior to the restoration measures. The present study showed an increase in the oligochaete diversity and a decrease in their abundance accompanied by a shift toward a larger share of taxa that are characteristic of mesotrophic and oligotrophic conditions. This study detected slow changes in the values of the trophic indices based on oligochaetes toward mesotrophic conditions. Discriminant analysis, performed using stepwise forward selection, demonstrated a good separation of samples from 2004 and 2011 according to trophic condition (TC) and biotic quality index (BQI) indices. The present data shows that metrics based on Oligochaeta may be useful for detecting changes in the trophic status.