The evolution of the eutrophication of the Palic Lake (Serbia)

Eutrophication is a world-wide environmental issue. The Palic Lake is a shallow lake typical for the Pannonian plain. The Lake itself was in a very bad condition during the late sixties of the last century; polluted and hypertrophic. Due to inadequate water quality, it was dried out in 1971 and re-established in 1977 and since then its trophicity has been worsening. The lake has recreational purposes but it is also a collector for treated municipal waste waters coming from the lagoons for active sludge water treatment. The sewage discharges from rapidly developing towns in the watershed and the growing use of fertilizers in agriculture increased the nutrient load to the Lake in the last decades. A steady increase of phosphorus loading is the most important factor of the lake eutrophication. The result of the accelerated eutrophication is the enormous amount of sediment at the bottom of the Palic Lake. Therefore, in the lake that covers an area of 565 ha and volume of 10 million m(3), there was 1.900.160 m(3) of sediment. The sediment thickness varied from 0.3 to 1.2 m. In summer 2010, the recreational part of the lake (sector IV) was 1.311.356 m(3) of sediment, characterized with concentrations of total phosphorus (TP) of 2885 mg/kg, 4300 mg/ kg total nitrogen (TN) and 39000 mg/ kg total organic carbon TOC. The sediment of the Palic Lake was not loaded with high concentrations of heavy metals. Everything mentioned supports the fact that the restoration of this aquatic system is necessary and applied measures have to be grounded on the principles of ecoremediation technologies.