SYMPTOMS OF WATER EUTROPHICATION IN THE BACHMATY RESERVOIR

摘要

When analyzing the symptoms of eutrophication and water quality in a small retentionreservoir Bachmaty, an attempt to assess changes in its trophic condition beforeand after modernization, was undertaken. The study upon changes in water trophiclevel was carried out on a small retention reservoir Bachmaty located in Podlasieregion on the Orlanka river in the municipality of Dubicze Cerkiewne. Tests of watersamples collected from the surface layer of the coastal zone were performed once amonth, and the time of the research was divided into two periods. The first period wasconducted since April 2007 to March 2008 and since April 2009 to March 2010. Thesecond research period included the time immediately after the reservoir reclamation,which ended in May 2011. The study was conducted since May 2011 to March 2012and since April 2013 to March 2014. The trophic level of Bachmaty reservoir was alsoassessed according to the concentration criteria and based on the trophic status indices(TSI) calculated after Carlson’s as well as Kratzer and Brezonik’s. Reclamation of thereservoir, which consisted mainly in removing the sediments, caused a reduction in allTSI values. Analysing the overall trophic level index, i.e. the average of TSI (TP), TSI(TN), and TSI (Chl), water of the Bachmaty reservoir may be classified as eutrophicin individual years of the research, although a gradual decline in the TSI value couldbe observed directly after the reservoir modernizing. After testing it was found thatthe formation of the trophic level of Bachmaty reservoir was largely affected by theamount of total phosphorus supplied to the water. Water quality in the reservoirs, andalso the content of phosphorus compounds is largely determined by external supply