| Abstract [eng] |
Many of the Lithuanian water bodies face with eutrophication, which is a very complex problem. One of the factors, nutrients, particularly phosphorus concentrations increase in water and bottom sediments. Biogenic material gain is usually associated with anthropogenic effects - from agriculture, from sewage treatment plant, farm, and more. Silt lakes revival is a complex problem: the water depth expansion, water quality improvement, removal of water pollution sources, the viability of the Lake Restoration - biocenoses breeding. Clean out the accumulated sludge can be hydraulically (by dredging) or mechanical (by excavators or clamshell crane) methods, as well as mixed methods, when used as dredgers and excavators. In addition to the technological clean up the water inflow and basin land-use optimization, it is necessary to further water phase of restoration - and hydrochemical limno-ecosystem hydrobiological structural components - functional balance. In this work was investigated Lentvaris and Didžiulis lakes, which are in Trakai district that have historically been affected by anthropogenic impact. Both lakes have been cleaned by removing the accumulated sludge. Lake water quality has been assessed by chemical parameters of the highest concentration levels and also by ecological status of lakes according to assessment results. Quality parameters measured before treatment in 2007, after treatment in 2009 and the latest 2011 data. Sludge removal of these lakes have been effective cleaning method, whereas the total clean-up lake water quality has improved in accordance with surveyed preferences. Basic chemical water quality indicators: BOD7, nitrite, nitrate, ammonium, phosphate, total phosphorus and nitrogen concentrations in Didžiulis and Lentvaris lakes, according to 2011 data does not exceed the limit values, fluctuations does not compromise water quality. According to the 2011 chemical parameters Lentvaris lake since 2007 total phosphorus amount decreased 91.6%, and Didžiulis lake - 81.7%. Trophic status of Lentvaris lake according to survey data of this year has changed from hypertrophic to mesotrophic class, and Didžiulis - eutrophic class. |
