Environmental Conditions in Polish Lakes with Different Types of Catchments

The research covered three groups of lakes: urban lakes in Kartuzy in the East Pomeranian Lake District, a group of Barczewo lakes in the Olsztyn Lakeland, and a group of Leginy lakes in the Mrągowo Lakeland. The water bodies were evaluated in terms of water dynamics, oxygen saturation, mineral pollution, and trophic status. The lake complexes differed fundamentally in land-use types in the surrounding areas. The lakes from each group were different. Electrolytic conductivity was highest in urban lakes, especially in Lake Karczemne which has been a sewage receptacle for many years. In the group of urban water bodies, the trophic state index was highest in Lake Karczemne (TSI (SD) and (TP), within the limits of hypertrophy, R2 = 0.886). In this group of lakes, organic matter limited visibility (R2 = 0.943). In the lakes surrounded mainly by forests, TSI was lower and indicative of oligo/mesotrophy in Lakes Kierźlinskie and Dluzek. Lake Dluzek was characterized by extremely low electrolytic conductivity (43–87 μS cm−1). TSI (TP) exceeded the reference standards in all examined lakes. In eight water bodies, primary production was limited by nitrogen (TSI (Chl) – TSI (TN) > 0 and TSI (TN) – TSI (TP) < 0, TN/TP < 10), which promoted cyanobacterial blooms.