Seasonal changes in the concentrations of dissolved oxygen in the lakes of the “Bory Tucholskie” National Park

Abstract

The article presents the results of the examinations of dissolved oxygen vertical distribution (DO) in the deepest places of the lakes conducted at different times in the years 2003-2005, and even earlier. The authors draw particular attention to severe oxygen deficits in the deepest places of the lakes, both those deep and shallow lakes despite the fact that they are not so exposed to anthropopressure. They also point out to the similarity of the course of oxygen curves in the same lakes and seasons in consecutive years, and also differences between particular lakes. They have also determined minor correlation between the mean concentration of DO in the vertical distribution and the duration of period with the ice cover (R2=0.78).