Large lakes of Europe: resource potential and ecological problems

Abstract

Natural water bodies with surface area exceeding 100 km² refer to the big lakes. Currently there are 141 such lakes in Europe. According to the given estimation, nearly 2310 km³ of fresh water are concentrated there. The large lakes are situated almost in all the landscape zones, from tundra in the North up to the Mediterranean in the South-West and steppe in the South-East, however, the majority of them (about 80 %) is concentrated in Boreal zone that occupies nearly 40 % of Europe. The difference in origin of the beds and the variety of natural and climatic factors determine a wide variety of lake ecosystems. Due to high population density on the most part on the European continent and to active development of industry and agriculture, water bodies are under the significant anthropogenic load. The greatest anthropogenic impact on the lakes fell at the second half of the XX^th century, during this period the increasing of biogenic load was especially high. Many lakes have changed their status from oligotrophic to meso- and eutrophic. Measures on the improvement of lakes' ecological state being taken since 1970s in the number of European countries (change of agricultural practice, sewage treatment, removing the especially dangerous part of the wastewater outside the basin and a severe legislative policy) have led to the first positive results as early as by 1980. The clearest examples are the prealpine lakes Bode see, Geneva, Como and Maggiore, where the phosphorus load for the period of 1975-2010 decreased by 3-8 times. However, the measures taken on many large were insufficient to reduce the concentration of biogenic substances in the water, the role of environmental factors in the formation oflake ecosystems and its response to anthropogenic influence, and, above all, to biogenic loads, is shown in the paper. The results of taken restoration measures are also revealed.