engleski

Molecular markers of anthropogenic influence on Plitvice Lakes, Croatia

Dated recent sediments (0-30 cm) from the pristine karst lakes situated in the Plitvice National Park, Croatia, were analysed for different organic compounds in order to determine the possible impact of anthropogenic activities on that protected ecosystem. The Plitvice Lakes are situated in a sparsely populated area of the Northwestern Dinarides, but during the last several decades, they have been exposed to an intensive tourist traffic, reaching 1 million visitors per year in the late 1980s. The selected molecular markers encompassed various types of hydrocarbons and one major class of surfactants. For hydrocarbon analyses, sediment samples were extracted by dichloromethane, separated into aliphatic and aromatic fractions and subsequently analysed by computer-assisted high-resolution gas chromatography mass spectrometry (HRGC/MS). Analysis of surfactant-residues was performed by liquid chromatography-tandem mass spectrometry (LC/MS/MS) after an extraction of sediment samples with methanol. Based on characteristic molecular markers, four major sources of biogenic and/or xenobiotic organic compounds into the lakes were recognised: a) phytoplankton, b) higher terrestrial plants c) oil pollution and/or pyrolytic processes and d) detergents. The profile of phytoplankton marker, n-heptadecane, indicated an increasing eutrophication in the past 100 years, while the maxima of the specific biomarkers of higher plants coincide with the periods of increased timber cutting and sawmill activities. The profiles of pyrolytic polycyclic aromatic hydrocarbons suggested a decreasing trend since the area was proclaimed a National Park. In contrast, the concentration of some xenobiotic chemicals, in particular residues of linear alkylbenzene sulphonates, reached rather high values in the most recent sediments, reflecting an increasing input of detergent-derived chemicals via untreated wastewaters from the hotels situated near the shoreline of the Plitvice Lakes.

molecular markers; hydrocarbons; surfactants; lake sediments

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