Effectiveness of the Reclamation of Jelonek Lake Based on Selected Physical and Chemical Parameters of Water

Taking a decision about a modification of elements making up the ecosystem requires thorough knowledge about the manipulated system and predicting all possible results of such interference. Turning back the effects of anthropopression demands taking immediate action not only within the lake basin in the form of technological remediation measures. Primarily, these should be protective action, involving the organization of water supply and sewage disposal in the basin and (which is much more difficult) reduction of biogenic substance flow to the lake. Remediation ventures have been applied throughout the world, not always with success. They are thought to be risky, long-term and demanding considerable financial outlays. For this reason, they must be carefully planned by a team of experts and conducted under permanent supervision. The article presents effects of restoration of lake Jelonek based on the analysis of water quality parameters. The lake has been completely degraded and reached the saprotrophic state due to discharge of domestic wastewater from the neighbouring living estate, and of agricultural. The lakes restoration was initiated by dosing of coagulants for sediment. The aim of the study carried out was the analysis of selected physical and chemical indicators in the waters of the lake Jelonek in Gniezno. In water samples taken from three points following parameters were determined: temperature, pH, nitrogen, nitrates, nitrites, ammonium nitrogen, phosphorus and phosphates. Measurements were conducted since October 2010 till may 2011, regularly once a month. The water was taken in the current on depth of 20 cm. The temperature and pH of the water were characteristic for the studied seasons and had no significant impact on the content of nutrients. The result of carrying out restoration lakes and tributary pollution mitigation procedures was to reduce the amount of nitrite and total phosphorus. Treatments conducted on lake Jelonek not bring the expected improvement in terms of total nitrogen content, nitrate and phosphate