Reclamation process of degradation lakes reservoirs

Abstract

The negative impact on the status of surface water bodies of the Baltic Sea and Baltic Sea region is caused by both diffuse pollution, which is essentially due to the pollution load caused by agricultural activities, as well as concentrated pollution, which results in an urgent problem - pollution with biogenic materials. By reducing pollution from agriculture, ensuring adequate domestic and individual wastewater management, lakes may require additional means to achieve their good status: to apply biological methods to improve water bodies (macrophytes, duckweeds). Hydrochemicals are increasingly being promoted in the world to reduce eutrophication of water bodies by using a method of chemical bonding/precipitation of excess phosphorus without removing the accumulated sludge. However, there is a strong public resistance. Based on the studies conducted in 2014-2018, only 20% of the studied lakes (total of 40 lakes studied) do not meet the criteria for good ecological status according to the phosphorus concentration in water. At lakes Latežeris and Luksnėnai the concentration of Pb shows indicator values of a bad ecological class, at lakes Draudeniai, Paežeriai and Mastis these indicator values are classified as being of a very bad class, while at the lake Talkša and in ponds Bubliai and Stepanioniai indicator values are classified as being of the average ecological class. Only significant amounts of phosphorus concentrations were found in the sludge of lakes Mastis and Draudeniai, but both of these lakes are shallow (average depth is 2.6 and 1.5 m, respectively), therefore the chemical phosphorus binding method cannot be applied. In the analysis of phosphorus concentrations in the sludge of other lakes, it was found that the highest concentrations of Pb were at lakes Spira, Kiementa, Antakmenas, Gauštvinis, Veisiejas and in the pond Vaitiekūnai. The average depth of these lakes is also low, but none of them has a bad status according to Pb. [...].