Distribution of heavy metals in freshwater ecosystem of a small stream impacted by urban drainage

摘要

This paper focuses on the study of heavy metals' remobilisation possibilities and changes of distribution coefficients leading to remobilisation in a stream as a result of changing conditions caused by urban drainage. The paper also reports consequent changes of bioaccumulation coefficient for different species of the benthic community, which seems to be the best indicator of aquatic community quality in small urban streams. The paper presents results obtained during field monitoring as well as results obtained during laboratory experiment. The field monitoring identified in the study area (the Botic Creek) three heavy metals (Cu, Zn and Pb), which are the main sources of toxicological risk in this area. Based on the monitoring, these elements were used for laboratory experiment, where their behaviour during changing conditions was studied. The experiment shows that changing conditions in the stream, caused by urban drainage, significantly impact the fate of heavy metals in aquatic ecosystems and that these elements have different preferences to bind to a particular geochemical fraction of sediment, which consequently means different bioavailability.