High concentrations heavy metals accumulate in sediments of some lakes, possibly excerting adverse effects on lake-dwelling organisms. Sediment samples were collected from the surface layer of the profundal zone in 14 lakes located near Konin, in the southern part of the Gniezno Lake District, in order to determine the content of Ag, As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sr, V, Zn, Ca, Fe, Mg, Mn, P, S and TOC. Significant differences in the content of trace elements in sediments of the lakes were observed. A very high copper content was found in sediment of the lakes included in the cooling system of the Konin-Pątnów power plant, esepecially in comparison with its content in sediments of the lakes outside that system. The lake sediment samples from lakes within the power plant cooling system are also characterized by higher levels of barium, mercury, manganese, strontium and zinc, but lower concentrations of lead, sulfur and organic matter. In the sediments of lakes within the power plant cooling system, the geometric means of the content of elements were as follows: 385 mg kg-1 Cu, 309 mg kg-1 Ba, 20 mg kg-1 Pb, 613 mg kg-1 Sr, 129 mg kg-1 Zn and 0.152 mg kg-1 Hg; and in sediments of the lakes whose water was not used by the power plant cooling system: 14 mg kg-1 Cu, 93 mg kg-1 Ba, 33 mg kg-1 Pb, 193 mg kg-1 Sr and 63 mg kg-1 Zn. The copper pollution of sediments of the lakes Licheńskie, Gosławskie, Pątnowskie, Wąsowsko-Mikorzyńskie and Ślesińskie is most likely created by passing the lake water through the Konin-Pątnów power plant cooling system. Copper brought to the lakes in water discharged from the cooling system probably originates from corroded heat exchangers made of copper or copper alloys.

19.1.2014