Municipal budgetary educational institution
“Lyceum, Arzamas, Nizhny Novgorod Region
Research work for grade 3 "Why is the water in the sea salty?"
Performed:
student 3 "A" class
Ilyina Natalya
Supervisor:
Perepelova
Marina Alekseevna
Arzamas, 2013
Introduction. Target. Tasks.Formulation of the problem.Development of hypotheses.Chapter 1. Finding a solution and collecting material.
- What is salt? Why is the sea so salty? Why can't you drink sea water? Who salted the sea so much?
Chapter 3. Properties of sea water.
- What is useful sea water?
- What is the salinity of the sea? How is sea salt extracted?
- Why is the Dead Sea one of the saltiest on Earth? Is it true that salt purifies the air?
Conclusion.
INTRODUCTION
Object of study: salty water seas and oceans.Purpose of the study: Learn the history of the appearance of salt, determine its properties, substantiate the validity of the existence of various hypotheses, conduct your own experiments and observations and find out why the water in the sea is salty?
Research objectives: 1) Read literature and articles on the topic.2) Find out what the salinity of the sea is and how salt is mined.3) Empirically determine the properties of salt.
Methods: Comparison - compare the properties of salt and fresh water.Experiment - conduct experiments.Analysis – analyze the received information.Comparison - compare your hypotheses with the hypotheses of scientists.
Formulation of the problem.
It was this question that interested me when one summer, together with my mom and dad, I was relaxing on the sea. Going to the beach, dad said: “do not forget to take water with you, otherwise you will suddenly want to drink.” How so, I was surprised, because there is a whole sea of water.You can’t drink sea water, my mother said, because it is salty.When we came ashore, the first thing I rushed to the sea, scooped up water with my palm and tasted it. The water was so salty that it even tasted bitter.
The sea was warm and gentle. I sat by the water's edge and thought. Why is sea water salty?
Development of hypotheses.
I have the following assumptions (hypotheses).
1) Suppose that water destroys stones - minerals, thus mineral salts enter the water.
2) Suppose that water from rivers and lakes enters the seas along with particles accumulated and dissolved in it different salts.
3) Or maybe someone just salted it, like mom salts the broth?
CHAPTER 1.
Finding a solution and collecting material.
What is salt and what does it consist of? When a hungry person sits down at the table, and dinner is not yet ready, he impatiently begins to eat bread and salt. It never occurs to anyone that because of this white crystalline powder lying in an ordinary salt shaker, people could once fight, kill each other, sell into slavery and roam from one country to another. It even happened that a grain of salt could change the fate of a person, and a few grains of this amazing powder returned life to a dying person. And today, table salt is fraught with many hidden, amazing and far from well-known properties. No living organism can live without salt. Salt keeps food from rotting. It lowers the melting temperature of snow and ice. Many necessary medicines are prepared from salt, and salt is needed for the production of the most ordinary items - soap, glass, fabrics, paper, and much more. Therefore, the old Russian proverb “You can’t live without salt” is true even today.Salt has a crystal lattice.This can be seen if you put a cup of salt water in a warm place. After a while, the water will evaporate, and the salt will fall out at the bottom of the cup in the form of shiny cubic crystals.There is an expression “water wears away a stone”. many, many years picture 1 waves beat against the shore, water droplets, eternal wanderers and eternal workers fall into the same place, a hole forms in the stone, then it collapses. From the destroyed stones - minerals, mineral salts enter the water, and the water becomes salty.
The sea, one might say, is not just salty, it is bitter, unpleasant in taste. After all, it is not for nothing that people in distress on the high seas without a supply of fresh water can die of thirst, because it is impossible to drink sea water.
But why is the sea so salty? Scientists think that in ancient times, millions and millions of years ago, when the waters of the seas accumulated in the vast depressions of the land, they were fresh. Who then salted them so hard?
Yes, all the same droplets of water, eternal wanderers and eternal workers.
The rivers run uncontrollably to the sea. All rivers of the world. They run to it in long winding paths, they flow into the lakes on one side and flow out on the other to continue their run to the sea. To sea! To sea! Why?
Yes, because the level of the seas and oceans is always below the level of land. And the path of water always goes downhill. That is why all rivers flow to the seas, dissolve some rocks and carry away with them particles of different salts. But then an underground stream broke free, ran along the ground, fell into a river and mixed its waters with it, and the waters of these rivers also contain salts, because the river washes them out of the soil.
Why can't you drink sea water?
If we drink sea water, we risk getting not only indigestion, but also dying - due to dehydration of the body: in order to remove excess salt, the body begins to use water from tissue cells, and this leads to dehydration and death. At the same time, compresses, baths, rinses and other procedures using sea water help to cure many diseases: when applied externally, a high concentration of both positive and negative ions gives healing.
Sea water is not suitable for drinking. But in it, many millions of years ago, life originated. The first living organisms appeared in it, which are called microorganisms (“micro”, means small). They grew, changed and became more complex. Many turned into amazing animals and got out on land. And later long years the first people walked the earth. This process is called evolution. And the sea is called the cradle of life.If the water in the seas and oceans were absolutely clean and fresh (such water is called distilled), then there would be neither animals nor people on earth.
Who could have salted the sea so much? Of course, no one specially salted the sea.But in poems and fairy tales you can find a mention of this. One example is the Norwegian fairy tale “Why is the water in the sea salty”.
One day a sailor stole a magic windmill that could grind anything you wanted. He took her to sea on his ship and demanded that the mill grind salt.When there was enough salt, he ordered the mill to stop, but did not know magic words. Soon there was so much salt that the ship and the mill sank to the bottom of the sea, and the mill continued to grind salt. She continues to grind it until now, that's why the sea is so salty ...It would be nice if the salinity of sea water were explained as simply as in this Norwegian fairy tale.
But scientists still don't have consensus why, the water in the seas and oceans is salty.
CHAPTER 2
Observation and experiments.
Having studied the material on this topic, I wanted to conduct my own little experiments.I decided to create my own little sea. She poured water into a glass and threw in a pinch of salt. I stirred it like waves in the sea and tried it. What did the water taste like? Where did the salt go? Of course, the salt dissolved and the water became salty.This is a simple confirmation that when minerals enter the water, they dissolve, giving sea water a specific taste.figure 2
I did another experiment.I took a piece of clay, added some earth and sand to it. Made a small cup out of this. She poured some water into it. Similarly, sea water, like giant bowls, fills huge depressions and depressions in the earth. Then she gently shook the cup, as if the sea was agitated. And I saw that dirt and sand appeared at the bottom of the cup, and the water became cloudy. This water washes away dirt, sand and clay from the walls and from the bottom of the cup. In the same way, various substances enter the sea water from the bottom and shores of the seas.We carry out the third experiment. To do this, I prepared a supersaturated solution. AT warm water dissolved salt in small portions. When the salt ceased to dissolve, the solution was poured into another container and allowed to cool. She dipped a woolen thread into the solution. A day later, the growth of salt deposits was discovered. How interesting, I threw a pinch into the water fine salt, and got large crystals.A week later, beautiful cubic crystals grew near the salt.The water in the glass evaporated. The walls and bottom of the glass were covered with salt crystals.This is because the saturated solution table salt moves along the rope to its lowest point due to the capillary effect. The force of gravitycauses the liquid to move along the rope. After the salt solution rises from the glass along the rope, it begins to move down. Due to the capillary effect, the rope pulls the brine out of the glass.
CHAPTER 3
properties of sea water.
Exploring this topic I wanted to know a little more about salt water. I began asking everyone about sea water, looking for answers to my questions in magazines and encyclopedias. And here's what I found out.Which water on earth is more salty or fresh? Salt water is much more. There is little fresh water. Its reserves are found in rivers and lakes.
Which water boils faster, salt water or fresh water? This is easy to find out by putting two identical pots of water on the fire. Salt water in one of them. After a while, we will notice that fresh water will boil faster.
This is because it takes more heat to heat salt water to the boiling point than pure water. Fresh water will boil faster. And now I will put in both saucepans small potatoes. What do I see! Potatoes cook faster in salt water. Just salt water provides more high temperature, so food cooks faster.
Is it possible to get fresh drinking water from salt water?
This can be verified through scientific experience.
Pour some water into a small bowl and dissolve a few tablespoons of salt in it. We put a cup on the bottom, stretch the film on top, and put a pebble on the film, so that we get a small depression, but the film does not touch the cup. Let's put this device in the sun.
The water in the basin will begin to heat up and evaporate. However, the film will delay it, and a clean figure 7 drinking water drop by drop into the cup. Salt does not evaporate - it remains at the bottom of the basin.
Another one interesting feature associated with the melting of ice from fresh and salt water. I froze cups fresh water and an aqueous salt solution, then placed in the same conditions for defrosting, and it turned out that the salt ice melted faster. Salt - chemical compound sodium and chlorine, lowers the freezing point of water, preventing its molecules from combining and forming ice crystals.Everyone knows that water freezes at 0, and sea water at -2 degrees Celsius.I think that everyone saw - they sprinkle salt on the road in ice and the ice melts even when negative temperature. Why?
But the fact is that by sprinkling salt on ice, we get a mixture of salt and ice in which the ice begins to melt. This is because the freezing point of this mixture is much lower.
In what water is it easier to learn to swim? Of course, in salty. Salt increases the density of water. The more salt in the water, the more difficult it is to drown in it. In the famous Dead Sea, the water is so salty that a person without any effort can lie on its surface without fear of drowning.Let's do one more experiment.figure 9
What are the benefits of sea salt? The healing power of the sea has been known since ancient times. Even Hippocrates in the 4th century BC. was talking about healing properties sea water. Sea water improves skin elasticity, has antiseptic, anti-inflammatory and analgesic properties, relieves stress and increases vitality. It has a beneficial effect on the cardiovascular system, helps with diseases of the musculoskeletal system, radiculitis, polyarthritis, stimulates metabolic processes in the body.
CHAPTER 4
Salinity of the sea.
What elements are included sea salt?Although scientists have been studying sea water for more than a hundred years, its chemical composition has not yet been fully understood. However, scientists have been able to identify various chemical substances dissolved in salts. Sea salt contains a huge amount of trace elements necessary for health.
- Potassium and sodium are involved in the regulation of nutrition and cell cleansing. Calcium takes part in blood coagulation, forms cell membranes. Magnesium is an anti-stress mineral, has an anti-allergic effect, a lack of magnesium accelerates the aging process. Bromine calms the nervous system. Iodine regulates hormonal metabolism. Chlorine is involved in the formation of gastric juice and blood plasma. Manganese is involved in the formation of bone tissue and strengthens the immune system. Zinc is involved in the formation of immunity. Iron is involved in the transport of oxygen and the formation of red blood cells. Selenium prevents cancer. Copper prevents the development of anemia. Silicon gives elasticity to blood vessels and strengthens tissues.
Sea water is significantly different from fresh water. If we take and boil water taken, for example, from the Black, Dead and Mediterranean seas, then we will see that it boils at different temperatures. The effect of swimming in these seas will cause no less surprise, since the efforts that have to be expended in order to stay afloat in all three cases turn out to be different.
In the 70s of the XVII century, Robert Boyle made the first reliable measurements of the total salt content in water taken from different depths of the ocean off the coast of England, after which he suggested the constancy of the salt composition of sea water.
salinity, - conditional value. It reflects the weight in grams of all salts dissolved in a liter of sea water, is measured in tenths of a percent and is denoted by ‰ - ppm.
- river runoff, precipitation, evaporation, formation and melting sea ice;
- vitality marine organisms, formation and transformation of bottom sediments;
- respiration of marine organisms, plant photosynthesis, bacterial activity.
It is because of the differences in salinity surface water Black (17–18‰), Mediterranean (36–37‰) and Dead (260–270, and sometimes 310‰) seas, their density also differs significantly and swimming in them requires different efforts. Salt is what leads to the fact that the boiling point of sea water exceeds 100 ° C, and the freezing point is below zero.
How is sea salt extracted? The method of extracting salt from sea water was suggested to man by nature itself. In a dry and hot climate, water evaporates quickly and salt is deposited on the banks and bottom. Observing the process of salt deposition, man learned to arrange auxiliary devices for the extraction of salt where climatic conditions allowed it, for which they built pools that communicated with the sea and with each other. Today, a network of pools is being created, located near ecologically clean coastal zones. Wooden boards serve as a protection. Under the influence of the sun and wind, the salt evaporates. Then assembled by hand. With this technology, the natural composition of salt is preserved. 95 If all the sea salt is spread evenly over the surface of the land, you get a layer more than 150 meters thick - about a 45-story building!Another comparison can be made: if all the oceans were dried up, then the resulting salt was enough figure 11 on construction of a wall 230 km high. and 2 km thick. Such a wall could circle the entire globe along the equator.But salt layers can also be located underground. And on the surface - in this case they form salt lakes. These deposits arose over many periods of the life of the Earth. The source of such deposits is sea water, from the salts of which both fossil salt deposits and salt lakes were formed. Thus, salt deposits are the remains of a dried-up ancient ocean.CHAPTER 5
Where does the salt in the seas come from?
Scientists have discovered several sources of salt.1. One of them is soil. When rainwater seeps through soil and stones, it dissolves the smallest particles of minerals, including salts and their constituent chemical elements. Then water currents carry them to the sea. This process is called erosion. Of course, the salt content of fresh water is very low, so it cannot be tasted.
2. Another source is salt-forming minerals in the depths of the earth's crust under the ocean floor. Water seeps through cracks in the crust, gets very hot and is thrown back, saturated with minerals dissolved in it. Deep-sea geysers spew the resulting mixture into the sea.
3. During reverse process underwater volcanoes throw huge amounts of hot rock into the ocean, and thus chemical elements enter the water.4. Another source of replenishment of the seas with minerals is the wind, which carries small particles from the land to the sea.Thanks to all these processes, sea water contains almost all known chemical elements. But the most common salt is sodium chloride, or common table salt. It makes up 85% of all salts dissolved in sea water and is what gives it its salty taste.
Why does the salt composition remain constant?
The salinity of sea water changes with different parts ocean and sometimes depends on the time of year. The highest salinity among open waters is observed in the Red Sea and in the Persian Gulf, where evaporation is very strong. In maritime zones, which receive a lot of precipitation and a huge amount of fresh water from large rivers, salinity is usually below average. Low salinity is also observed in the polar ice melting zones, which are frozen fresh water. On the other hand, when the sea is covered with ice, the water becomes more salty. But in general, the salt composition of sea water remains surprisingly constant.A lot of salt accumulates in the seas, because only pure water. All minerals remain in the sea. Although the sea continues to replenish with minerals, the salt content is always constant - about 35 grams per liter of water.Why is the Dead Sea one of the saltiest? The Dead Sea is located between the Palestinian Authority, Israel and Jordan. It is the third lake in the world after Assal Lake and Kara-Bogaz-Gol Lake in terms of salinity. The rivers flowing into the Dead Sea carry dissolved salts and other minerals. Since the Dead Sea coast is the lowest place on the land surface, the water in this sea is used only for evaporation, which is why in summer its level can drop by 25 millimeters per day. For this reason, the salt content in upper layers water reaches about 30 percent, which is almost ten times higher than in the Mediterranean Sea. Since the density of water increases with increasing salinity, bathers, like floats, float on the surface. And they don't need inflatable mattress to read the newspaper while lying on your back.But the saltiest lake on our planet is Lake Assal. Its salinity is 35%.Lake Assal is located in the central part of Djibouti, in the Danakil Desert. The lake has dimensions of 16x6 km and is located 153 m below sea level. Lake Assal is the lowest point in Africa.Is it true that Withdoes it purify the air?
One study found that air pollution prevents precipitation from clouds over land. However, polluted clouds over the ocean produce rain much faster. This is due to the presence of salt crystals in the air from splashes of sea water.
The water droplets that settle on the polluted particles are too small to become raindrops and therefore remain in the cloud. Sea salt crystals serve as condensation nuclei, attracting the smallest water droplets and forming larger ones. This is how rain falls on the earth, which cleanses the atmosphere of pollution.
CHAPTER 6
Conclusions:
Having studied the material on the topic, and after conducting a series of experiments, I came to the conclusion that my first two hypotheses were fully confirmed, and the third has no scientific justification.I found out that the water in the sea is salty, either because the water destroys the stones, or because all the rivers run to the seas, dissolving some rocks, and carrying away particles of different salts with them.Some scientists believe that rivers brought salt to the sea. Water is the strongest solvent capable of destroying any rock into earth's surface. Rivers carry impurities dissolved by water into the seas and oceans. Water from the ocean evaporates and returns to earth again, continuing its eternal cycle. And the dissolved salts remain in the seas.
Other scientists refute this version, arguing that substances dissolved in sea water were washed out of igneous rocks by flowing waters.Thus, scientists still do not have a single answer to the question: Why is the water in the sea salty?
During the study, the hypotheses put forward were mostly confirmed. Thanks to the research, I learned a lot of new and interesting things. I hope that the knowledge gained will be useful to me at school.
CONCLUSION.
Today there are two main versions of the answer to the question “Why is the water in the sea salty?” One of them is traditional, the other is modern.Traditionally it was thought thatsalty sea water , because rivers bring salt into the sea, washing it out of the rocks along which their channel passes. In river water, there is also salt, only it is 70 times less than in sea water. Every year, rivers add one sixteen millionth of the salt of its total volume to the World Ocean.
Sea water constantly evaporates (and the salts remain in the sea!), then returns again in the form of precipitation to land, enters rivers, is again enriched with salt from rocks,
figure 13 which the rivers carry to the sea. It is not surprising that over millions of years of such a water cycle in nature, the World Ocean has pretty much “salted out”. This answer to the questionwhy is the sea water salty , explains and a large number of salt in lakes that do not have a runoff. But he does not explain why the salts in sea and river water have different chemical compositions (and they do!). Therefore, another, more modern hypothesis arose,why is the sea water salty . According to the modern hypothesis, sea water was originally salty, since the primary ocean on Earth is a condensate of gases from volcanic eruptions. These gases contain water and chemical elements and among them are the so-called "sour fumes" consisting of chlorine, fluorine, bromine and inert gases. Pouring acid rain on the surface of the Earth, the products of volcanic eruptions entered into a chemical reaction with solid rocks, as a result of which a saline solution was formed.At present, scientists have agreed that both of these hypotheses,
why is the sea water salty , have the right to exist and complement each other.Despite various hypotheses, the appearance of salt in sea water, there is a unified approach to measuring the level of salinity.The salinity of water is the content in grams of all minerals dissolved in one kilogram of water.About 35 grams of salt are dissolved in 1 liter of sea water.95Bibliography.
1. Children's magazine. Stories about the world around for children. The Adventures of a Droplet. Editor Yu.A. Mayorov. No. 8 2010.2. Journal. Planet Earth. No. 3 2008. Article. Salinity of the sea. What it is?Doctor of Geography D.Ya.Fashchuk.3. Journal. World around us. No. 5 2006. Article. Amazing Properties water.V. Golovner, M. Aromshtam.4. Dictionary Russian language / Compiled by M.S. Lapatukhin, E.V. Skorlupovskaya, G.P. Snetova; Ed. F.P. Filin. – M.: Enlightenment, 1997.5. Encyclopedia for the curious. Why and why? Editor T.Frolova. Moscow: Makhaon, 2008.6. Your own observations and experiments.7. Pochemuchka 2009. Cognitive experiments for children.8. Collection. Tales of the peoples of the world. 1988. Norwegian fairy tale. Why is sea water salty?9. Collection of poems. Sea. Verse. Why is sea water salty?10. Magazine. Around the world. No. 7 1999. Article. Why the water in the sea is salty - two hypotheses.11. Magazine. Around the world. No. 3 1997. Article. Salt and fresh water.12. Newspaper. healthy image life. No. 4 2010. Beneficial features salt water.13. Seas and oceans. V.G. Bogorov, St. Petersburg, 1996.At school, they ask quite a lot of interesting questions. Some of them at first glance seem quite simple and it is easy to answer them, although in fact everything is far from being so simple. Tell me, do you know why the water in the sea is salty? We strongly doubt this, since even scientists don't know the exact answer!
Versions and hypotheses
Let's start, perhaps, with this - when did the water bodies on Earth become salty? It probably happened a very long time ago. But when exactly? Some historians claim that this happened millions of years ago, even before the dinosaurs died out. Others are sure that some time ago the seas consisted exclusively of fresh water ... Now you can’t tell who is right and who is not.
- But back to our main question. If you believe the school course, then the reservoirs became salty thanks to the rivers. But how is it, you ask, because the water in the rivers is fresh! We will agree with you, but we will add that it also contains dissolved salts, however, in microscopic quantities. However, they are there, although we do not taste them. Based on this, it turns out that the rivers not only desalinate the seas, but also salt them. After the river water enters the sea, its nth part evaporates under the influence of the natural environment, but the salts do not go anywhere and remain in the sea. Scientists even found out that it is thanks to the rivers that the World Ocean receives almost three million tons of the most various substances and elements. Huge number! And imagine that such a cycle in nature has been going on for far more than one million years? Then it is clear why the water in some reservoirs is so salty ...
It would seem that the answer has been found. But wait! Other experts who support other theories say that almost all the salts that fall into the sea precipitate and over time huge stone layers and rocks begin to form from them. In addition, river and sea water contain too different substances and elements. So, in the first one there is negligibly little table salt, but there are a lot of carbonates, lime and soda, and the second is known for a large amount of table salt and sodium. In general, not everything is so obvious.
- The second theory on this issue is also very interesting. Those experts who support it argue that over the past several billion years that our planet has existed, the rivers have always been fresh, and the seas have been salty. Theoretically, in this case, river water could become salty, but the laws of nature intervene here - the seas and oceans cannot flow into rivers, this happens exactly the opposite even in our time.
- According to the third version, animals played a significant role. So, one of the scientists claims that once river water practically did not differ from sea water. It was used for drinking by many animals. If you have not forgotten, it contains a large amount of calcium, which is so necessary for the development of the skeleton of living beings. So, the animals gradually fished out all the elements they needed from the rivers, among which were salts. This happened over hundreds of millions of years, as a result of which the rivers practically got rid of sodium chloride. Of course, this theory has the right to life, although it sounds very far-fetched. Why? It's simple - the reserves of sea salt are simply huge. So, if it is evenly distributed over land, then it will cover our entire planet with a layer more than a hundred meters thick! Can you imagine that fish and animals could eat so much mineral, albeit for a huge period of time? We doubt it.
- This theory is supported by many experts. They say volcanoes are to blame. When Earth's crust had just begun to form, there was tremendous volcanic activity on Earth. The gases from the volcanoes contained vapors of fluorine, bromine and chlorine, so acid rains periodically occurred. It was they who formed the seas, which, of course, were also acidic. However, this water entered into a chemical reaction with solid rocks, extracting from them such alkaline elements as sodium, potassium, magnesium and calcium. This is how salts were formed, which neutralized the acidity of the water, gradually making it salty. The composition of water finally stabilized about 500 million years ago.
Outcome
And there is no result as such, because neither we nor scientists know the answer to the question posed. But we still hope that someday a specialist will solve this riddle of nature.
Since ancient times, people have been looking for an answer to the question of why the sea is salty. In fact, the water of all seas and oceans has such a taste, only the level of salinity is different for everyone. The biological diversity of a particular sea largely depends on this indicator.
But first, salt. Where does it come from? Both soils and rocks contain particles of various salts, and rainwater dissolves them. Rain streams drain into rivers, which carry salt particles to the sea. And then everything, as in a school textbook: under the influence sun rays an evaporation process takes place (when water evaporates, and salt accumulates in sea depths), and in the form of precipitation, it returns to the earth again, washing out salt particles from the soil ...
But this is only part of the answer to the question "why the sea is salty." The other part must be sought at the bottom of the sea. It is on the composition of the seabed, or rather on the rocks that form it, that the salinity of the sea largely depends. Chemical composition practically does not change, and since each sea or ocean has its own, they are able to survive, as a rule, only on their own territory. They cannot be moved from one sea to another. Also great value has an evaporation rate - the higher it is, the more salt is concentrated in sea water.
In general, there are many more reasons that affect the salinity level of the sea. So, for example, the salinity of the Black Sea is affected by the remoteness of the ocean, as well as the fact that many European full-flowing rivers carry their waters here. The huge flow significantly reduces the level of salinity, which leads to a decrease in the biological diversity of the Black Sea. In comparison with the Mediterranean, the number of inhabitants of the Black Sea depths is much more modest, and the diversity leaves much to be desired: here you will not meet starfish and hedgehogs, cuttlefish and octopuses, and squids. Vegetable world The Black Sea is also much poorer.
Why is the sea salty? There is one more point, the presence of which cannot be ignored when answering this question - land areas washed by the sea or ocean. As you can see, the answer is not as simple as it might seem at first glance.
Comparing the Black and Mediterranean Seas, their water worlds, the latter turned out to be in a more advantageous position, due to more high level salinity. And what is the most salty sea in the world? The answer to this question is simple - Red. If in the Black Sea the salt content is 17 grams per liter of water (in the Baltic - only five grams), then in the Red Sea this figure is more than twice as high - 35-41 grams per liter (depending on the coast).
This is due, first of all, to the absence of rivers flowing into the Red Sea, and they, as you know, carry water that in some way dilutes the sea, reducing the concentration of salts. Here the concentration is slowly but steadily increasing. In this case, denser layers of water fall below, cooler water is forced into the upper layers, carrying out natural mixing. In addition, the absence of rivers makes it possible for sea water to maintain its transparency and purity. And the wealth of the underwater world largely depends on this: the diversity and beauty of the inhabitants of the Red Sea is simply amazing.
Answering questions about why the sea is salty, and what one cannot but remember about the Dead, which, being drainless, is also called a lake. An extremely high concentration of salts in its water is constantly maintained by mineral springs, which make the water not only the most salty, but also simply unique in its composition, it is inimitable. It is the water, as well as the famous silt mud, which, by the way, also has a high content of mineral salts, attracts hundreds of thousands of tourists to the shores, who come from all over the world to improve their health.
Here's a mystery - why is the sea water salty, but not in rivers and lakes? There is currently no single correct answer to this question, and there are active disputes and discussions on this subject in the scientific world.
Scientists only distinguish two main theories, each of which seems to be true, but at the same time they contradict each other, and there are several strong arguments against each.
First theory. The seas and oceans acquired salinity as a result of slow and gradual processes.
So, according to this theory, sea water became salty as a result of the water cycle in nature. This process can be described in more detail as follows: rain gradually washed out and dissolved mineral salts contained in rocks and soils, rainwater fell into rivers. Rivers also wash out particles of various salts from the bottom, then this one fell into the seas and oceans under the influence of the current. Under the influence of solar heat, water over the seas evaporated and again fell to the ground in the form of rain and other precipitation - the process was repeated. And salt, of course, accumulated in the oceans for millions of years, gradually increasing the level of salinity. But here comes big question: Why has the salinity level of ocean water not increased and kept at the same level of 35 ppm (35 grams of salt per 1 liter of water) for more than 500 million years, while rivers have not stopped supplying mineral elements all this time?
Second theory. Ocean water was salty from the beginning.
On the early stages the formation of our planet from the depths of the mantle, along with the first water vapor, volcanic smoke was emitted into the atmosphere. These smokes were enriched with volcanic waste products - chlorine, phosphorus and bromine. Water mixed with these vapors, more like acid than water. The primary acidic water filled the future oceans and seas and destroyed the crystalline rocks of the earth's crust at the bottom, as a result, elements such as potassium, calcium, magnesium, sodium were released ... Then a simple chemical reaction took place, in which chlorine interacted with sodium, and in fact, salt was produced. Over time, the activity of volcanoes decreased and the level of salinity of the water stabilized.
Both theories do not give an exact answer, but only suggest a possible course of events and processes. The real reason for this interesting question we have yet to find out.
In contact with
Composition of sea water
To find out why salty sea, need to understand the composition of sea water. It contains almost the entire periodic table. The liquid is saturated with iodine, fluorine, bromine.
But the basis of the composition are chlorine and sodium. Sodium chloride is just common salt. This is what makes the water salty.
But here skin such a solution is of great benefit. Through them, salty water has a beneficial effect on the human body as a whole.
Even, which is saturated with iodine, perfectly stimulates protective functions human body.
Important! No matter how useful sea water is, it is absolutely unsuitable for drinking. Its composition is not suitable for saturating the body with moisture.
How did sea water originate?
It is a well-known fact that rivers flow into other bodies of water. But the water in the rivers is fresh. How then is it that the oceans have permanent salinity, and rivers - permanent freshness?
There are several versions of the presence of salt in sea water:
- According to one hypothesis, the fresh water of the rivers, getting into the reservoirs, simply evaporate. Although river waters also contain salts and other minerals, their presence is minimal. Therefore, the salinity of the rivers is simply not felt. The salt concentration in them is 70 times less than in the sea. Evaporation river water, mineral compounds remain in sea water, and thus a constant balance of salt and other trace elements is maintained in the oceans. This version explains why the rivers are fresh and the seas are salty. This process has been going on for billions of years, and thanks to it, the liquid is constantly saturated with salt. This hypothesis accurately answers the question: Where does the salt in the sea come from? This theory also explains why salinity is constant.
- The second version is associated with volcanic activity. And the answer to the question why the water in the seas is salty is closely associated with volcanoes. According to this hypothesis, the earth's crust arose due to magma ejections, due to the activity of volcanoes. Volcanic gases have compounds in the form of different chemical elements, which, when interacting with each other, form acid. She got into the water with acid rain and reacted with earthen rocks, as a result of such reactions, salt appeared. Gradually, over many millions of years, the water turned from acidic to salty. This hypothesis also explains why the water in the seas and oceans is salty. According to this theory, river carbonates do not affect sea water in any way, as they are immediately absorbed by underwater organisms that filter the water, and carbonates are used for construction purposes, to create shells.
But the composition of sea water and its salt content are not identical. Why does sea water have different densities? Density of sea salt water depends on the depth and intensity of evaporation.
The shallower the depth and the higher the temperature of the water, the more intense the evaporation and the more salt it contains. Conversely, the deeper and colder, the less evaporation, and, accordingly, less salt. But these discrepancies are quite small.
Both of these versions are recognized by scientists, and both have a place to be. Such processes could affect salinity, both individually and in combination, mutually complementing each other.
Rock salt
But besides these versions, there is another generally accepted hypothesis, according to which salts appear in liquids regularly from rocks. We can observe this version with our own eyes in our time.
The well-known postulate “water wears away stone” is actually not an exaggeration at all, but a scientifically proven fact. A drop of sea water, by gradual action, can dissolve even the strongest rock. Salts that are released from the dissolved stones fall back into the liquid. Thus, the salt balance is regularly maintained different ways over many billions of years.
Salt concentration in different seas
Salinity of different seas unequal. First, let's answer the question which seas have the lowest salinity. The Baltic has the lowest salinity, slightly higher salinity in the Black and Caspian Seas.
The most saline is the Red Sea. This is due to the fact that it is the warmest, and, accordingly, the evaporation in it is the most intense. And the more intense the evaporation, the saltier the solution.
In addition, not a single river flows into the Red Sea. And thus it does not desalinate. All these factors have influenced the fact that Red is the most salty. One liter of it has as part of 41 grams of salt.
The salinity of the Red Sea is also affected by its constant temperature. All year round it keeps at around 20-25 degrees of heat.