The objective of this study has been to determine the potential toxicological effect of heavy metals accumulated in bottom sediments of a lowland retention reservoir located in north-eastern Poland. For this purpose the ecotoxicological (TEL, PEL) criteria were selected to quantify sediment contamination. The potential ecological risk was assessed. The analyzed reservoir was characterized by significant spatial variation in concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) and As related to organic carbon (Corg.) in bottom sediments during its 30-year-long life. Thus, the highest organic matter content and heavy metal accumulation were reported in the reservoir’s riverine and transitional zones, whereas the predominance of mineral fractions in the lacustrine zone did not favour the metal content. One kilogram of sediment dry matter contained 39.9 mg Zn, 20.5 mg Pb, 11.0 mg Cr, 9.1 mg Ni, 7.2 mg Cu, 1.29 mg As and 0.39 mg Cd on average. Nonmetric multidimentional scaling (NMS) revealed distinct elemental fingerprints in each sampling site, while a two-way hierarchical agglomerative cluster analysis (TWHCA) provided insight into metal association and pollution distribution. It emerged that the riverine and transitional zones of the reservoir underwent progressively increasing contamination of the sediments, mainly due to a high content of Cd, Cr, Cu, Ni and Pb, although only three of these metals, i.e. Cd, Ni and Pb, reached levels that could produce an adverse effect on aquatic organisms. The application of geochemical and ecotoxicological indices is a helpful tool for the risk assessment of environmental pollution and for supporting decision making to ensure water source security.  

22.3.2017