Metal contamination in sediments of dam reservoirs: A multi-facetted generic risk assessment

The quality of bottom sediments is a key factor for many functions of dam reservoirs, which include water supply, flood control and recreation. The aim of the study was to combine different pollution indices in a critical generic risk assessment of metal contamination of bottom sediments. Both geochemical and ecological indices reflected that sediment contamination was dominated by Zn, Pb and Cd. The ecological risk indices suggested a high riks for all three metals, whereas human health risks were high for Pb and Cd. An occasional local contamination of sediments with Cr and Ni was revealed, although at levels not expected to cause concerns about potential ecological or health risk. Sediments from the Rybnik reservoir for Cu only revealed a high potential ecological risk. EF turned to be as being the most useful, whereas TRI (∑TRI) was the most important ecological index. All multi-element indices suggested similar trends, indicating that Zn, Pb and Cd taken altogether had the greatest impact on the level of sediment contamination and posed the greatest potential ecological and health risks to organisms. The use of sequential BCR extraction and ecotoxicity analyses allowed for a multi-facetted generic risk assessment of metals in sediments of dam reservoirs. [Display omitted] •The quality of sediments is a key factor for water ecosystem and public health.•Geochemical, ecological, chemical, and ecotoxicological indices were used.•Enrichment Factor and TRI (∑TRI) were the most useful indices.•Cd, Zn, Pb have the greatest impact on sediment contamination and risks to organisms.•Mobile fractions of metal and ecotoxicity tests are indispensable for risk assessment.