engleski

Chemical indicators of anthropogenic impacts in sediments of the Plitvice Lakes

The anthropogenic impact on the Plitvice Lakes was investigated using a combination of inorganic and organic constituents, including major elements (Al, K, Fe), trace metals (Li, Ag, Cd, Sn, Pb, Bi, Cr, Co, Ni, Cu, Zn and Sb), polycyclic aromatic hydrocarbons (PAHs) and anionic surfactants of linear alkylbenzene sulfonate (LAS) type. Dated cores of recent sediments from the two largest lakes, Lake Prošće and Lake Kozjak, were analysed for the selected contaminants using highly specific methods, including inductively coupled plasma mass spectrometry (ICP/MS), gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). The distribution of inorganic constituents reflected primarily the geological background of the area. The concentration of all elements was significantly higher in the Lake Prošće, which was due to the comparatively higher terrigenous input into that lake. The concentration of toxic metals was relatively low in both lakes, except for Cd (>1 mg kg-1) and Pb (up to 40 mg kg-1). The vertical profiles of these metals suggested that elevated concentrations of Cd were of natural origin, while Pb was predominately of recent anthropogenic origin. A similar distribution pattern like for Pb was observed for pyrolytic polycyclic aromatic hydrocarbons (PAHs), suggesting the same prevailing mechanism of input. The characteristic diagnostic PAH ratios revealed that higher PAHs prevailingly originated from the combustion of biomass and fossil fuels. LAS were found in rather high concentrations in the recent sediment layers (up to 4.7 mg kg-1), suggesting that contaminated household and hotel wastewaters reach the Lakes, very probably by leaking through the porous karst rocks. 14

lake sediments; karst sediments; Plitvice lakes; trace metals; hydrocarbons; surfactants

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