why lakes are salty other fresh and got the best answer
Answer from Zhenok Rain[guru]
On the geographical maps the lakes are painted either blue or lilac. Blue color means that the lake is fresh, and lilac - that it is salty.
The salinity of the water in the lakes is different. Some lakes are so saturated with salts that it is impossible to drown in them, and they are called mineral lakes. In others, the water is only slightly salty in taste. The concentration of dissolved substances depends on what kind of water the rivers bring them. If the climate is humid and the rivers are full of water, the lakes are fresh. In deserts, there is little rainfall, rivers often dry up or they don’t exist at all, which is why the lakes are salty.
Among the large lakes of the world, most of all are fresh. This is due to the fact that the water in them is flowing and does not stagnate, which means that the salts brought by the rivers are carried away by them into the seas and oceans.
The freshest lakes on the planet are Baikal in Asia, Onega and Ladoga in Eastern Europe, Upper in North America. But the freshest of them should still be considered Lake Benern - the largest of the lakes Western Europe. Its water is the closest to distilled, there are slightly more soluble minerals in Baikal and Lake Onega.
The freshwater lake of the largest area of the water surface - Lake Superior - one of the Great Lakes of North America. Its area is 83,350 square kilometers.
Mountain glacial lakes are especially poor in salts, the waters of which feed glaciers and snowfields.
If the reservoir is not flowing, then the water in it becomes first slightly brackish, and then salty.
The most saline lakes on our planet can be considered lakes in which the salt content per liter of water is more than 25 grams. Such lakes, in addition to Lake Tuz in Turkey, include Lake Air in Australia, the Dead Sea on the Arabian Peninsula, Molla-Kara in Turkmenistan, Lake Dus-Khol in Tuva and others.
In the center of Turkey, south of Ankara, at an altitude of 900 meters above sea level, there is a lake on which you can walk on foot in summer. This drainless Lake Tuz is 80 kilometers long, about forty-five kilometers wide and average depth- two meters. It is not only small, but also very salty - up to three hundred and twenty-two kilograms of salt per ton of water. In spring, due to winter and spring precipitation, the lake overflows and increases almost seven times, occupying a huge area of 25,000 square kilometers. In the summer, when the water evaporates, the lake becomes quite small, and a dense crust of salt forms on its surface from several centimeters to two meters thick.
The Dead Sea is the deepest and saltiest of the salt lakes. Its greatest depth is over 400 meters, and it is located 395 meters below the level of the oceans. One liter of water Dead Sea it contains 437 grams of salt.
Some of the lakes are brackish-fresh. The most amazing of them is Lake Balkhash. Its western part is fresh, and the eastern part is brackish. The reason for this peculiarity lies in the fact that the Ili River flows into the western part of the lake, and the eastern part lies surrounded by deserts, where the water evaporates very strongly. Therefore, on geographical maps, the western part of Balkhash is shown blue, and the eastern part is lilac.
The huge Lake Chad, located on the outskirts of the Sahara, is fresh on top and brackish at the bottom. Fresh river and rain water, falling into the lake, does not mix with brackish water, but rather floats on it. Freshwater fish live in the upper layer, and those caught in the lake in ancient times sea fish stay at the bottom.
A source:
Answer from Department for interaction with POWC[newbie]
.
Answer from Albina Sapitsyna[active]
PATAMU))))))
Answer from Katya Shubina[newbie]
Not quite right with stock. but the point is to feed the lakes if the lake is fed from a salty spring ( mineral spring) then it is salty, for example, Yarovoye lake is itself salty and nearby is a lake Hot key fresh. Nearby it is in 10-15 meters.
Answer from Victoria Volgina[newbie]
Salt water becomes in drainless lakes in a hot arid climate. Due to the high evaporation, the salts contained in the water accumulate in the lake, making it salty.
In natural waters there are always impurities in the form of suspended or dissolved substances, and they can be considered as a very complex solution, representing a true solution in relation to some substances, and colloidal in relation to others.
With the help of special methods of filtration from natural waters, it is possible to isolate the colloidal part, separating it from water and electrolytes. In this way, for example, it was established that in the entire water mass of Lake Baikal there are about 55 thousand tons of solid matter in a finely divided phase. In general, in the hydrosphere (on the whole Earth), the order of concentration of colloids is expressed by the value x · 10 -5%, where x does not exceed the order of hundreds.
However, water is of particular interest as a true solution, because the concentration of molecularly dissolved substances is immeasurably more significant than the concentration of colloids.
Any water contains certain salts in solution, but if the salinity of the water is less than 0.3‰, then such water is called fresh water. Consequently, less than 0.3 g of dissolved salts are contained in 1 thousand g of fresh water. When the salinity is from 0.3 to 24.695‰, the water is called brackish, and when the salinity is above 24.695‰, it is called salty. The value of 24.695‰ was chosen as a boundary between brackish and saline waters because only at this salinity value, the freezing point of water and its highest density are equal (-1.332°). If the salinity is less than 24.695‰, then with continuous cooling, the water will first reach its highest density, and then it will freeze; if the salinity is more than 24.695‰, then water under similar conditions will freeze before it reaches its highest density.
For obvious reasons, it is difficult to expect a high concentration of salts in flowing waters. But in stagnant reservoirs, especially those deprived of runoff and subjected to increased evaporation, a lot of salts accumulate. In accordance with this, lakes are divided into fresh and salt, or mineral.
in the lakes marine origin, i.e., in reservoirs separated from the sea, the presence of salts in the water is, as it were, a "hereditary" phenomenon. In the process of further independent existence of such a relict lake, its hereditary features either increase (it becomes saltier than the parent water basin) or weaken (desalination). As for continental salt lakes, salts enter them due to chemical weathering of crystalline rocks, leaching of various sedimentary rocks, dissolution of ancient salt deposits by groundwater, etc.
The main factors in the distribution of mineral lakes are the climate and the presence of drainage basins, as well as the composition of the rocks that make up the area, and the groundwater regime. Steppes and deserts are the birthplace of salt lakes, since there is little precipitation, evaporation is high, and the relief is predominantly flat, and therefore the runoff is weak. Large lakes Tibet - Namtso (Tengri-Nur), Kukunor, etc. - belong to salt lakes.
But salt lakes can also be in a humid climate if there are salt deposits nearby; in this case, the origin of the salt lake is influenced not by the modern climate, but by the climate of the geological past, in which salt deposits could form. Thus, the small salt lakes of the Lena-Vilyui Plain are fed by salt springs that come out of the salt-bearing strata of Paleozoic rocks.
Mineral lakes are quite diverse in terms of the composition of dissolved salts. Soda lakes are widely represented in Western Siberia (Lake Tanatar, Petukhovskie lakes, etc.), in Transbaikalia (Lake Doroninskoe), and Yakutia. Bitter-salty, or sulfate lakes, which precipitate mainly Glauber's salt, are found in the Kulunda steppe, in the Crimea, in the Caucasus (Batalpashinsky lakes), in the deserts of Central Asia, etc. Salt (chloride) lakes are among the most common - their many in the Crimea, in the Kulunda steppe in the Volga region and other places. The Kulunda steppe, in terms of the number of mineral lakes (there are several thousand of them here) and their diversity (soda, salt, Glauber lakes), is undoubtedly an area for the development of a large chemical industry in the future.
The concentration of salts in mineral lakes varies over a very wide range. It differs not only in different lakes, reaching up to 37% in some cases, but often changes noticeably in the same lake depending on the water level in the latter, i.e., depending on the volume of the water mass. Thus, the salinity of the Great Salt Lake in Utah, in accordance with fluctuations in the water level in the lake, varies from 13 to 22%.
If you find an error, please highlight a piece of text and click Ctrl+Enter.
LAND WATER Option 1 1. A water stream flowing in a deepening - a channel - developed by it: a) a lake; b) flow; c) a river; d) flow. 2. The place where the river flowsinto another river, sea or lake: a) tributary; b) mouth; c) a waterfall d) a lake. 3. This river is so immense, you need to swim for several months to understand how much water dominates the Earth here. Its depths - more than 90 meters - are not found in every sea. The river really seems like a sea: after all, standing on one side, you can’t see the other at all. What river are we talking about? a) Volga; b) Limpopo; c) Lena; d) Amazon. 4. The highest waterfall in the world: a) Angel; b) Iguazu; c) Victoria; d) Ilya Muromets. 5. Part of the bottom of the river valley, flooded during the flood of the river, is called: a) bank; b) meadow; c) floodplain; d) flood. 6. In the past, this lake was connected to the ocean and was the sea. Now it's the most big lake on the planet. a) Baikal; b) top; c) Ladoga; d) Caspian. 7. Name the longest river in the world: a) Mississippi; b) Rhine; c) Nile; d) Amazon; d) Lena. 8. Which of these lakes is Australian? a) Air b) Victoria; c) Baikal; d) Michigan. LAND WATER Option 2 1. The catchment area of the river and its tributaries: a) flood; b) river system; c) river basin; d) source. 2. The most full-flowing river in our country: a) Lena; b) Volga; c) Yenisei; d) Cupid. 3. Where is located Niagara Falls? a) in Asia; b) in Europe; c) in the USA. 4. Voids washed out by water in easily soluble rocks are called: a) springs; b) ravines; c) caves. 5. Find a match: 1. Waste lake; 2. endorheic lake. a) Baikal; b) Chad; c) Caspian; d) Aral; d) top. 6. On which bank of the great Russian river is the city of Kamyshin? a) on the left b) on the right. 7. Select the rivers of Africa: a) Yenisei; b) Congo; c) Nile; d) Mississippi; e) Niger; e) Volga. 8. What lakes have the following coordinates? Set the correspondence: 1. 7 ° S. sh.; 30° in. 2. 53° N. sh.; 105° E 3. 62° N. sh.; 32° in. e. a) Baikal; b) Tanganyika; c) Ladoga. LAND WATER Option 3 1. The place where the river begins is called its: a) tributary; b) source; c) channel; d) threshold. 2. The basin of this lake appeared 15–20 million years ago. This is one of the oldest lakes in the world. Some scientists see it as a nascent ocean. It is called the "well of the planet", as this lake is the deepest in the world. What lake are you talking about? a) top; b) Victoria; c) Nyasa; d) Baikal. 3. What lakes have the following coordinates? Set the correspondence: 1. 12 ° S. sh.; 35th c. d.; 2. 48° N sh.; 88°W d.; 3. 28°S sh.; 137° E e. a) Upper; b) Air; c) Nyasa. 4. Select artificial reservoirs from the listed water bodies: a) the Volga-Don Canal; b) the Aral Sea; c) Tsimlyansk reservoir; d) the Suez Canal; e) a pond; e) the Bering Strait. g) the Parana River. 5. Match the rivers and the continents through which they flow: 1. Africa; 2. North America; 3. Australia; 4. Eurasia; five. South America. a) Ob; b) Congo; c) Murray; d) Parana; d) Colorado. 6. A sudden rise in the water level in the river is: a) flood; b) high water; c) low water; d) floodplain. 7. Determine where the mouth of the Angara River is located: a) the Caspian Sea; b) the Lena River; c) Lake Baikal; d) the Yenisei River. 8. Lakes from which rivers originate are called: a) sewage; b) drainless; c) fresh. please help me with correct answers!
This deepest continental body of water contains one-fifth of the world's fresh water (excluding glaciers). More than 300 rivers flow into the lake and flow outEveryone who was on the beach could make sure that the water in the sea tasted salty. But where does salt come from if fresh water enters the ocean through rains, rivers and? Why the sea is salty and has it always been so - time to figure it out!
How is the salinity of water determined?
Salinity refers to the content of salts in water. Salinity is most commonly measured in ppm » (‰). A ppm is one thousandth of a number. Let's give an example: the salinity of water is 27 ‰, which means that one liter of water (that's about 1000 grams) contains 27 grams of salt.
Fresh water is considered to be water with an average salinity of 0.146 ‰.
Medium the salinity of the oceans is 35 ‰. Sodium chloride, also known as table salt, makes the water directly salty. Among other salts, its share in sea water is the highest.
The most salty sea is the Red Sea. Its salinity is 41‰.
Where does the salt in the seas and oceans come from
Scholars still disagree about whether sea water salty initially or acquired such properties over time. Depending on the versions, different sources of the appearance of salts in the World Ocean are also considered.
Rains and rivers
Fresh water always has a large number of salts, and rainwater is no exception. It always contains traces of substances dissolved in it, which were captured during the passage through the atmosphere. Getting into the soil, rainwater washes away a small amount of salts and eventually brings them to lakes and seas. From the surface of the latter, water evaporates intensively, falls again in the form of rain and brings new minerals from the land. The sea is salty because all the salts remain in it.
The same principle applies to rivers. Each of them is not completely fresh, but contains a small amount of salts captured on land.
Confirmation of the theory - salt lakes
The proof that salt comes through rivers are the most saline lakes: Bolshoye Salt Lake and the Dead Sea. Both are about 10 times saltier than sea water. Why are these lakes salty?, while most of the world's lakes are not?
Usually lakes are temporary storages for water. Rivers and streams bring water to lakes, and other rivers carry it away from these lakes. That is, water enters from one end, and leaves from the other.
The Great Salt Lake, the Dead Sea and other salt lakes have no outlets. All the water that flows into these lakes leaves only by evaporation. When the water evaporates, the dissolved salts remain in the water bodies. Thus, some lakes are salty because:
- rivers carried salt to them;
- the water in the lakes evaporated;
- salt remained.
Over the years, the salt in the lake water has accumulated to its current level.
Interesting fact: The density of salt water in the Dead Sea is so high that it practically pushes a person out, preventing him from sinking.
The same process made the seas salty. Rivers carry dissolved salts to the ocean. Water evaporates from the oceans to fall again as rain and replenish rivers, but the salts remain in the ocean.
hydrothermal processes
Rivers and rains are not the only source of dissolved salts. Not so long ago, on the ocean floor were discovered hydrothermal vents. They represent places where sea water seeped into the rocks. earth's crust, has become hotter and is now flowing back into the ocean. Along with it comes a large amount of dissolved minerals.
underwater volcanism
Another source of salts in the oceans is underwater volcanism - volcanic eruptions underwater. It is similar to the previous process in that sea water reacts with hot volcanic products and dissolves some mineral components.
Lake
Lake - a natural closed reservoir formed on the surface of the land in a natural depression. The lake has no direct connection with the oceans. Unlike rivers, water does not flow in lakes.
The lakes on the maps are shown as volume objects in blue. On maps, they need to be shown along the coastline.
The largest lake in the world is the Caspian Sea. This lake is salty. It has no connection with the ocean, therefore it refers to lakes, although it used to be part of the ocean.
Rice. 1. Snapshot of the Caspian Sea
The deepest lake is Baikal, with a depth of 1642 meters. This lake contains 1/5 of all lake waters in the world and is the largest liquid freshwater object! The biggest freshwater lake by area in the world - Upper (North America).
Rice. 2. Lake Baikal on the map
Types of lakes by origin of basins
lake basin - the place (deepening) in which the lake is located.
According to the origin of the basins, the following types of lakes are distinguished:
1. Tectonic
2. Glacial
3. Volcanic
4. Staritsy
6. Karst
7. Thermokarst
Most deep lakes – tectonic, they are formed in cracks, breaks in the earth's crust during its movement. Examples: Baikal, Teletskoye, Victoria, Tanganyika.
Zaprudnye lakes form in valleys mountain rivers when the channel is blocked by collapsed rocks, glaciers, etc. Examples: Sarez, Ritsa.
Volcanic (crater) lakes form in craters extinct volcanoes. Examples: Toba, Kuril, Irasu.
Rice. 4. Kuril lake
Staritsy are formed in the valleys of the old channels of lowland rivers when the direction of the flow of the river and channel changes.
Rice. 5. Scheme of the process of formation of the oxbow lake
Karst lakes are formed as a result of soil failure over voids.
Glacial The lakes were formed as a result of the melting of an ancient glacier. There are many such lakes in the north of Eurasia and North America.
Rice. 6. Lakes of Karelia on the map
Other types of lakes
Lake waters are replenished due to precipitation, rivers, snowmelt, groundwater.
According to the position of the lake are divided into:
1. Ground
2. Underground
According to the water balance, the lakes are divided into:
1. Sewage (at least one river flows from such lakes)
2. Endorheic (rivers do not flow from such lakes)
According to the type of mineralization, the lakes are divided into:
1. Fresh
2. Mineral (salty)
One of the saltiest bodies of water on Earth is the Dead Sea, its salinity can reach 350 ppm! Initially, the lake was called "dead", because. it was thought that living organisms did not live in it due to the high concentration of salt.
Rice. 7. Dead Sea Salts
The highest mountain lake
Most alpine lake in the world is at the foot of the very high volcano in the world - Ojos del Salado (South America), which is located at an altitude of 6891 meters above sea level. This unnamed lake is a water-filled crater only 100 meters in diameter and up to ten meters deep.
meteorite lakes
This type of lakes is formed when meteorites fall in meteorite craters, then these craters are filled with water and turn into lakes. Example: Elgygytgyn.
Raspberry lakes
These lakes are distinguished by a light pink color and a pleasant smell. Such properties are given to these lakes by crustaceans, which, dying and decomposing, give salt the aroma of raspberries.
Bibliography
Main
1. Initial course of geography: textbook. for 6 cells. general education institutions / T.P. Gerasimova, N.P. Neklyukov. – 10th ed., stereotype. – M.: Bustard, 2010. – 176 p.
2. Geography. Grade 6: atlas. – 3rd ed., stereotype. – M.: Bustard; DIK, 2011. - 32 p.
3. Geography. Grade 6: atlas. - 4th ed., stereotype. – M.: Bustard, DIK, 2013. – 32 p.
4. Geography. 6 cells: cont. maps: M.: DIK, Drofa, 2012. - 16 p.
Encyclopedias, dictionaries, reference books and statistical collections
1. Geography. Modern illustrated encyclopedia / A.P. Gorkin. – M.: Rosmen-Press, 2006. – 624 p.
1. Federal Institute of Pedagogical Measurements ().
2. Russian Geographical Society ().
3. Geografia.ru ().
