Accumulation of zinc in water, sediments and bleak fish (Alburnus alburnus L.) in the ecosystem of the Dunajec River

Zinc present in water penetrates into the organism of a fish either directly, through the skin and gills, or indirectly, with food taken into the alimentary canal. The toxocity of this metal is associated with the transporting function of blood, which distributes it over the whole organism. The aim of this paper was to assess the zinc content in water and bottom sediments collected from the Dunajec River, and also in selected organs of bleak (Alburnus alburnus L.). The bioaccumulation factors for this element in the muscles, liver, skin and bones of the fish were calculated from the results of the research, which was carried out in 2011. Samples of water and bottom sediments were collected twice, in July and October, at 5 research points located in Szczepanowice, Janowice, Wróblowice, Lusławice, and Zakliczyn. Twenty-nine specimens of bleak were provided by members of the Polish Angling Association (PZW — Polski Związek Wędkarski), from catches performed in the second half of July. The zinc concentration in the samples was determined by inductively coupled plasma atomic emission spectrometry at a wavelength of 206.200 nm, conducted on an Optima 7600 DV spectrometer made by Perkin Elmer. The limit of detection for zinc was 5.9 μg · dm-3. High concentrations of zinc in the water were found, indicative of anthropogenic enrichment of the river with this element. The zinc content in the analysed sediments was below the geochemical background value for bottom sediments in Poland. Zinc concentrations in the fish varied within a range from 152.6 to 352 mg ∙ kg-1 in the skin, from 158.8 to 271.3 mg ∙ kg-1 in the bones, from 27.32 to 97.35 mg ∙ kg-1 in the muscles, and from 82.39 to 230.7 mg ∙ kg-1 in the liver. The mean content of zinc in individual organs decreased in the following order: skin > skeleton > liver > muscles. Zinc concentrations in individual organs of the fish were comparable with the ones determined eslewhere in environments polluted with this element.