Evaluation of the natural susceptibility of shallow lakes to degradation

Intensification of agriculture and development of industry in Poland have resulted in increased pollution of the environment. Numerous chemical compounds, particularly of organic origin, became activated in catchment areas, introduced to rivers and lakes and cause their eutrophication. This problem relates particularly to shallow lakes with slow turnover rates. In this situation studies have been undertaken with the objective of evaluating the susceptibility of lakes to degradation. The studies are concentrated in an area of NE Poland abounding in lakes.This paper summarises the results of studies in 17 lakes and stresses the importance of the catchment area in supplying biogenic material. The degree of importance of the catchment area was evaluated in a simplified way in accordance with the author's own method. A large variety of catchment types were identified with respect to their impact on lakes and were classified into 4 groups of lake susceptibility to degradation.