In most lakes, the age-old reserves of water are extremely slowly renewed: an average of 1.5% per year from the total reserve, while Baikal has only 0.3%. The gradual degradation of lakes depends on the intensity of flushing from the fields of phosphorus and nitrogen compounds - an integral part of fertilizers, from the introduction of sewage containing mineral and organic contaminants, and from the deposition of plant and animal remains.
As a result of these processes, the lake is polluted, their biological productivity decreases, and the regime changes. Lakes either turn into swamps, or die. A considerable role in this is played by the prolonged discharge of toxic industrial effluents.
The natural processes of formation of lakes, especially those without drainage, usually lead to their gradual degeneration into swamps. Marshes, or stagnant ponds, also contribute to the overall water cycle. Despite the fact that the area of peat bogs alone in the whole world is more than 1 · 106 km3, at present a serious problem of protection of marshes has arisen. To this end, as well as to study the prospects for their rational use in 1967, a special international organization was established within the framework of UNESCO, uniting scientists from 18 countries. The rate of drainage of the marshes is so high that in many places it threatens to completely disappear. However, such an outcome is completely unacceptable. Usually hundreds of bird species are abundant in the marshes, valuable fur-bearing animals (nutria, muskrat). Often bogs are magnificent berry-berry (and a lot of evil mosquitoes): there, without any use of human labor and fertilizers, grow cranberries and cloudberries.
Marshes are the only source and pantry of invaluable wealth - peat. Power stations work on peat. Peat - the most important chemical raw materials for the production of mineral-ammonia fertilizers, alcohols, acids, dyes. Medicines prepared from peat are treated with eye diseases, burns, inflammatory processes.
It is difficult to overestimate the role of bogs in natural balance. Particularly important is the so-called upland bogs. In them, as in a huge sponge, excess moisture accumulates over the course of the summer to feed streams and rivers, to maintain the humidity of the air. Wherever the upper marshes hurriedly dried up, the groundwater level immediately decreased, the rivers became shallower, turned into barren meadow solonchaks.
Thus, marshes as natural objects are of great value. The water cycle in the marshes is tens of times slower in comparison with rivers or flowing lakes, and poisoning, the destruction of marshes along with all their unique plant and animal world can come quickly and irreversibly.
The majestic Dnieper is born in the moss of a small swamp in the north of the Smolensk region. Reserves of Dnieper water are significantly replenished in the Pochinkovsky forestry, where the river is fed by a marshy massif with a total area of 1400 hectares. Maintenance of the water regime of the Dnieper is facilitated by the creation on all its length of a water protection zone with a width of 50 ... 300 m.
They also use marshes in Lithuania as well. 32 cranberry preserves are established in the swampy territories, reclamation work and peat extraction are prohibited.