Chemical Indicators of Anthropogenic Impacts on the Plitvice Lakes (Croatia) - Lessons for Lake Conservation and Environmental Management

The Plitvice Lakes National Park is situated in a pristine and sparsely populated area of the northwestern Dinarides, central Croatia. The basic geomorphological phenomenon of the Park consists of 16 karst lakes interconnected by numerous cascades and waterfalls, formed by travertine barriers. During the last century the area experienced significant changes regarding the prevailing anthropogenic activities, which posed a major challenge for environmental protection and lake conservation. Since the area was proclaimed a national Park in 1949, the traditional economy, based on timber cutting and sawmill activities, was replaced by a fast expanding tourism, accompanied by construction of several hotel capacities along the lakes’ shore. In this study, water and sediments were analysed for different organic and inorganic contaminants, using highly specific methods, in order to asses possible impacts of various anthropogenic activities on that protected ecosystem. The concentrations of typical anthropogenic contaminants in the water column of the Plitvice Lakes were generally rather low, which revealed pristine nature of the Lakes. However, some contaminants indicated slightly enhanced levels in the tributaries, which might be indicative of some, still unrecognised, contamination inputs into the Lakes. Moreover, the distribution of contaminants in the recent lake sediments was found to be highly indicative of characteristic historic phases of anthropogenic activities in the area. The most useful indicators of specific contamination sources were aliphatic and aromatic hydrocarbons, surfactants and some toxic metals.