Heavy metal contamination in sediments of Rzeszów Reservoir (Poland)

Sediments of Rzeszów Reservoir were characterized by a higher content of zinc compared to other heavy metals (Cu, Cr, Ni and Cd). The strongest correlations between pairs of heavy metals were Cr-Ni, Ni-Zn, Cu-Ni and Cr-Zn, while there was also a clear relationship between the total chromium and nickel content and the pH value, as well as the percentage of organic matter in the sediments (Cr, Zn, Cu, Ni). The content of chromium and copper occurred at levels exceeding the geochemical background, and the sediments could be classified as of purity class 2 (according to the PIG criterion) or class 3 (according to the Müller’s classification). Ecotoxicological criteria indicate that levels of chromium, nickel and cadmium could affect aquatic life. However, the heavy metals differ in mobility and bioavailability. The highest percentage of ion exchangeable fraction was recorded for nickel, and the lowest for chromium. This means that sediments have a greater ability to release nickel into the water column, as a result of which they are a secondary source of pollution for the aquatic ecosystem.