WORLD FAMOUS GREAT LAKES

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More than 12 thousand years ago Europe and North America were ice deserts.  The woods, didn't rustle, the rivers, didn't flow. Ice laid from the horizon to the horizon. Huge blocks of ice, moving to the south, swept away everything on the way, pulled down the mountains, moving titanic stones and ploughed deep hollows of the improbable sizes. When the glacier receded, on its borders remained so-called moraines, borders from stones, sand, gravel.

The basin of the Great Lakes was formed at the time of ice age. When the glacier started to thaw, behind these blockages in deepening where ice laid, the lakes have arisen.

Now on the USA and Canada boundary are five big lakes, connected with each other by the short rivers, forming together the biggest congestion of fresh water on Earth. Lake Erie, lake Huron, lake Michigan, lake Ontario, lake Superior. Common area of these lakes, are 246.000 km². When glaciers receded, lakes received a drain to the Atlantic Ocean through St. Laurent’s river. On coast of these lakes situated the largest industrial port cities of the USA and Canada. The basin of the Great Lakes – one of the largest water catchment system on a planet; the pool contains 18 % of stocks of fresh water. Due to very strong maintenance of this pool, by the USA and Canada, pollution of surface and underground water has began. Oxygen level in the lakes decrease considerably, the amount of mercury and various poisonous substances exceeded limits and this became the reason of mass death of fishes.

The biggest part of pollutants was dumped into the Great Lakes. Believing that the ecological system of lakes is capable for self-recreation, throughout the 18th and 19th centuries, lakes were often used as sewage, rubbish pits.

Especially clear such "destination" of the lake, became noticeable with rapid growth of the industry and the population of the cities. The polluted sewage water, corpses of the died animals rather often were dumped to the river, it was distinctive feature of that time. People didn't bare in mind that the river flows further and, respectively, along on a river course, water already will be polluted or poisoned. This kind of treatment of unique ecological system of the Great Lakes started to change in the 20th century. Change in that relation happened due to the people who realized and estimated importance of availability of pure fresh water and understood, how water can influence health (rendering both positive, and a negative effect). However, owing to rapid development of the industry and negligent attitude of many people, polluted became not only the Great Lakes, but also the adjacent rivers, and also inflows of lakes. On account of such amount of pollutants, Lake Erie became practically "dead". But already since the end of 1980 it was possible to reach reduction of volume of toxic substances for 82 %, and in a consequence of it declared earlier «the dead lake» became the world's largest area of production of a perch. But even such large reduction didn't give completely desirable result. Toxic substances arrived to these lakes together with sewage and acid rains in a very big volume. It also became the reason that Canada was the first who signed the Kyoto Protocol on regulation of emissions in the atmosphere of green house gases for the industrial enterprises. But despite this according to experts, the Great Lakes, which remain the main source of fresh water in Canada, could face other environmental problems.

So, a global warming can cause reduction of lakes level on 1 m by the middle of the XXI century, what can lead to serious ecological consequences. Shortage of water can raise the question about necessity of a transfer of a part of a rivers drain or fencing of lake waters that creates threat to steady use of water resources. Experts forecasted, that frequency of large floods which occurred earlier to periodicity of 1 time in 500 years, within the XXI century will increase in 10 times. Deficiency of water in the USA and Canada already started. People in America for irrigation of the territories were using underground waters. Reduction of underground water stocks involves increase of water consumption from superficial sources what the Great Lakes are, in particular. At the same time sharply growth of the cities and an intensification of agriculture led to large-scale growth of excess of pesticides, fertilizers, herbicides and other chemical preparations which in turn a direct or indirect way get to the Great Lakes. In additives to it on coast of lakes there are largest port cities as Chicago and Toronto. It is also one of significant reasons of pollution of lakes, as large port always dense populated and as we know the more people, the garbage they produce. Moreover, during traffic of all boats and ships chance of leakage of petrol and others combustible to these lakes is increase.

Deterioration of characteristic of water of lakes as a result of activity of the human being, forced him to find a way of improvement of lakes. In this sense the history of Great American Lakes is indicative. Its condition have been improved as a result of the carried-out events, but it is quite early to speak about good ecological condition of these lakes, as this program are expected to continue for several decades.

              We must take care of lakes, since they are integral part of a landscape and live cell of nature. What beauty has given to us by these lakes!  And how much our nature would paled if these lakes suddenly disappeared?!