Distribution and potential risk assessment of heavy metals and arsenic in sediments of a dam reservoir: a case study of the Loje Retention Reservoir, NE Poland
Treść / Zawartość
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 variations in heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) and As related to organic carbon (Corg.) concentrations in bottom sediments during its 30-year-long life. Thus, the highest organic matter content and heavy metals accumulation was reported in the reservoir’s riverine and transitional zones, whereas predominance of mineral fractions did not favor metal content in the lacustrine zone. 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 two-way hierarchical agglomerative cluster analysis (TWHCA) provided insight to 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, as well as a tool supporting decision-making for water source security.