At school they ask quite a lot of interesting questions. Some of them at first glance seem quite simple and easy to answer, although in fact everything is far from so simple. Tell me, do you know why the water in the sea is salty? We strongly doubt this, since even scientists do not know the exact answer!

Versions and hypotheses

Let's start, perhaps, with this - when did water bodies on Earth become salty? This probably happened a long time ago. But when exactly? Some historians claim that this happened millions of years ago, even before the dinosaurs became extinct. Others are sure that some time ago the seas consisted exclusively of fresh water... You can’t tell who’s right and who’s wrong now.

• But let's return to our main question. If you believe school course, then the reservoirs became salty thanks to the rivers. But how can this be, 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, albeit in microscopic quantities. Nevertheless, they are there, although we cannot taste them. Based on this, it turns out that rivers not only desalinate the seas, but also salinize them. After river water enters sea water, the nth part of it is influenced natural environment evaporates, but the salts do not disappear anywhere and remain in the sea. Scientists have even found out that it is thanks to rivers that the World Ocean receives almost three million tons of a wide variety of substances and elements. Huge number! Imagine that such a cycle in nature has been going on for more than one million years? Then it’s 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 salts that fall into the sea precipitate and over time, huge rock layers and rocks begin to form from them. In addition, river and sea water contain too much different substances and elements. So, in the first there is negligible amount of table salt, but there is 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 always been salty. Theoretically, in this case, river water could become salty, but the laws of nature intervene here - seas and oceans cannot flow into rivers, this happens exactly the opposite even in our time.

• According to the third version, its significant role animals played. Thus, one of the scientists claims that once upon a time river water was practically no different from sea water. Many animals used it for drinking. If you haven't forgotten yet, it contains a large number of calcium, so necessary for the development of the skeleton of living beings. So, the animals gradually fished out from the rivers all the elements they needed, 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 a 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, 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, even over a huge period of time? We doubt it.

• This theory is supported by many experts. They say it's all the volcanoes' fault. When the earth's crust first began to form, there was enormous volcanic activity on Earth. Gases from volcanoes contained vapors of fluorine, bromine and chlorine, so acid rain occurred periodically. It was they who formed the seas, which, of course, were also acidic. However, this water entered chemical reaction with hard rocks, extracting from them alkaline elements such as sodium, potassium, magnesium and calcium. This is how salts formed, which neutralized the acidity of the water, gradually making it salty. The composition of the water finally stabilized about 500 million years ago.

Bottom line

But 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 be able to solve this mystery of nature.

Water is one of the most powerful solvents. It is capable of dissolving and destroying any rock on the surface of the earth. Streams of water, streams and drops gradually destroy granite and stones, and leaching of easily soluble components occurs from them. No strong rock can withstand the destructive effects of water. This is a long process, but inevitable. Salts that are washed out from rocks, attach sea ​​water bitter-salty taste.

But why is the water in the sea salty and the water in rivers fresh?

There are two hypotheses about this.

Hypothesis one

All impurities dissolved in water are carried by streams and rivers into the seas and oceans. River water is also salty, but it contains 70 times less salts than sea water. Water from the oceans evaporates and returns to the earth in the form of precipitation, and dissolved salts remain in the seas and oceans. The process of “supplying” salts to the seas by rivers has been going on for more than 2 billion years - time sufficient to “salt” the entire World Ocean.

Clutha River Delta in New Zealand.
Here Clutha is divided into two parts: Matau and Koau,
each of which flows into the Pacific Ocean.

Sea water contains almost all the elements that exist in nature. It contains magnesium, calcium, sulfur, bromine, iodine, fluorine, and small amounts of copper, nickel, tin, uranium, cobalt, silver and gold. Chemists have found about 60 elements in sea water. But most of all sea water contains sodium chloride, or table salt, which is why it is salty.

This hypothesis is supported by the fact that lakes that have no drainage are also salty.

Thus, it turns out that initially the water in the oceans was less salty than it is now.

But this hypothesis does not explain the differences in chemical composition sea ​​and river water: chlorides (salts) predominate in the sea of hydrochloric acid), and in rivers - carbonates (salts of carbonic acid).

Hypothesis two

According to this hypothesis, the water in the ocean was initially salty, and it was not the rivers that were to blame, but the volcanoes. Proponents of the second hypothesis believe that during the period of education earth's crust When volcanic activity was very high, volcanic gases containing vapors of chlorine, bromine and fluorine rained down as acid rain. Thus, the first seas on Earth were... acidic. By entering into a chemical reaction with hard rocks (basalt, granite), the acidic water of the oceans extracted alkaline elements from the rocks - magnesium, potassium, calcium, sodium. Salts were formed that neutralized sea water - it became less acidic.

As you decrease volcanic activity the atmosphere was cleared of volcanic gases. The composition of ocean water stabilized approximately 500 million years ago - it became salty.

But where do carbonates disappear from river water when they enter the World Ocean? They are used by living organisms - to build shells, skeletons, etc. But they avoid chlorides, which predominate in sea water.

Currently, scientists have agreed that both of these hypotheses have a right to exist, and do not refute, but complement each other.

Geography

Natural science

The world

Why is the sea salty?

“Why is the sea salty?” - one of children's favorite summer questions. In our new column “Why” we will regularly answer in clear and in simple language for the most interesting questions preschoolers and schoolchildren, as well as hold exclusive competitions!

Why is the sea salty? Why does a hedgehog need needles? Why did they add “-s” to many words in the last century? Why do cats purr and what do they do? Is it possible to create a time machine according to the laws of physics? As a parent or teacher of primary and secondary schools, you will hear these questions more than once. We will be happy to answer them.

Why is the sea salty?

The answer to this question must begin with an explanation of where the water in the sea and ocean comes from. In rivers we find springs and springs - underground springs, but where does the water, and salty one, come from in the sea?

Reserves of both the Black Sea and Atlantic Ocean replenished by fresh water from rivers and precipitation in the form of snow or rain. Both consist of fresh water (in fact, also salty, just in a very small concentration). But unlike rivers, water from oceans and seas does not flow anywhere, but only evaporates when it gets under Sun rays. When evaporation occurs, the salts remain.

Another factor in the salinity of the sea is the movement of the rivers themselves flowing into it. On the way to the seas and oceans, river flows wash the salts that make up the stone out of the rocks and bring them with them to the sea, albeit in small quantities.

It turns out that the sea has become salty? Was it fresh before that? No, that's not true. The main reason, which modern scientists agree with, is the process of formation of the sea itself, which was just as salty millions of years ago. The fault for this is not the rivers, which did not exist then, but the volcanoes that covered our planet.

The water of the primary ocean was formed from volcanic gases, the composition of which is approximately the following: 75% of water accounts for 15% carbon dioxide and about 10% of various chemical compounds. These compounds include methane, ammonia, sulfur, chlorine and bromine, as well as various gases. So when the products of the eruption fell to the ground in the form of acid rain, they reacted with the bottom of the future sea, and as a result we got a salty solution.

How much salt is there in the sea?

About 35 are dissolved in one liter of sea water grams of salt.

How much water is there in the sea?

If we take the average depth of the world's oceans to be 3703 meters, and take the average surface area to be 361.3 million square kilometers, we get 1.338 billion km 3

Which seas are the freshest and saltiest?

Let's start with another record holder - the largest sea. The absolute champion in this category is the Sargasso Sea, which is located inside the Atlantic Ocean. Its area reaches 8.5 million square kilometers.

But the freshest sea is in Russia, and this sea is the Baltic. Compared to the waters of the Atlantic, its sunshine is 5 times lower. Why? About 250 rivers flow into the Baltic Sea, which “desalinize” the waters.

What about the saltiest sea?

Record holder for percentage salts - Red Sea. Its salinity is about 41 grams per liter of water! This phenomenal content explains unique properties sea: it is very easy to float in it, and being there is quite good for your health.

Why is the Red Sea so salty? The point is the fumes, which we wrote about at the very beginning. From this sea the water evaporates with enormous speed due to high temperature and low humidity, so the rains simply do not have time to “desalinate” it, and besides, very little of it falls.

Question - competition

Using the data above, calculate how much TOTAL salt is dissolved in ALL the seawater on our planet?

Send your answers in private messages to our communities at

Municipal budget educational institution

“Lyceum” Arzamas, Nizhny Novgorod region

Research work for grade 3 "Why is the water in the sea salty?"

Performed:

student of 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 2. Observations and experiments.
Chapter 3. Properties of sea water.

What are the benefits of sea water?

Chapter 4. Salinity of the sea.

What is sea salinity? How is sea salt obtained?

Chapter 5. Where does the salt in the seas come from?

Why is the Dead Sea one of the saltiest on Earth? Is it true that salt purifies the air?

Chapter 6. Conclusions.
Conclusion.

INTRODUCTION

Object of study: salty water seas and oceans.
Purpose of the study: Find out the history of the appearance of salt, determine its properties, justify 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 extracted.3) Determine the properties of salt experimentally.
Methods: Comparison - compare the properties of salt and fresh water.Experiment - conduct experiments.Analysis – analyze the information received.Comparison - compare your hypotheses with the hypotheses of scientists.

Formulation of the problem.

It was this question that interested me when one summer I was relaxing at the seaside with my mom and dad. When getting ready to go to the beach, dad said: “don’t forget to take water with you, otherwise you’ll suddenly get thirsty.” How can this be, I was surprised, because there is a whole sea of ​​water there.You can’t drink sea water, my mother said, because it’s salty.When we came to the shore, the first thing I did was rush to the sea, scoop up water with my palm and taste it. The water was so salty that it even tasted bitter.
The sea was warm and gentle. I sat down by the water and thought. Why is the water in the sea salty?

Development of hypotheses.

I have the following assumptions (hypotheses).
1) Let's assume that water destroys stones - minerals, thus mineral salts get into the water.
2) Let us assume that water from rivers and lakes enters the seas along with particles of various salts accumulated and dissolved in it.
3) Or maybe someone just salted it, like mom salts 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 a person’s fate, and a few grains of this amazing powder could restore life to a dying person. And these days salt contains many hidden, surprising and far from known properties. No living organism can live without salt. Salt protects 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 still true today.
Salt has a crystal lattice.You can verify this by placing a cup of salt water in a warm place. After some time, 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 stones.” Many, many years picture 1 waves beat on the shore, droplets of water, eternal wanderers and eternal workers end up in the same place, a hole forms in the stone, then it collapses. Mineral salts enter the water from destroyed stones - minerals, and the water becomes salty.
The sea, one might say, is not just salty, it is bitter and unpleasant to the taste. It is not without reason that people in distress on the open sea without a supply of fresh water may 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 huge depressions of the land, they were fresh. Who then salted them so tightly?
Yes, all the same droplets of water, eternal wanderers and eternal workers.
Rivers uncontrollably rush towards the sea. All rivers globe. They run towards him long winding paths, they flow into the lakes on one side and flow out from the other to continue their run to the sea. To sea! To sea! Why?
Yes, because the level of seas and oceans is always lower than land level. And the path of water always goes downhill. That is why all rivers flow to the seas, dissolve some rocks and carry with them particles of various 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 not only getting an upset stomach, but also dying due to dehydration: in order to remove excess salt, the body begins to use water from tissue cells, and this entails dehydration and death. At the same time, compresses, baths, rinses and other procedures using sea water help to recover from many diseases: when applied externally, it gives healing properties high concentration both positive and negative ions.

Sea water is not suitable for drinking. But life began in it many millions of years ago. The first living organisms appeared in it, which are called microorganisms (“micro”, meaning small). They grew, changed and became more complex. Many turned into amazing animals and made it to land. And after many years, the first people already walked on 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 no animals or people on earth.
Who could salt the sea so much? Of course, no one salted the sea on purpose.But in poems and fairy tales you can find mention of this. One example is the Norwegian fairy tale “Why the sea is salty.”
One day a sailor stole a magic mill that could grind whatever you wanted. He took her out to sea on his ship and asked the mill to 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 to this day, which is why the sea is so salty...It would be nice if the salinity of sea water could be explained as simply as in this Norwegian fairy tale.
But scientists still do not have a consensus on why the water in the seas and oceans is salty.

CHAPTER 2.

Observation and experiments.

After studying 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 tasted 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 get into the water, they dissolve, giving sea water a specific taste.

figure 2

I conducted another experiment.I took a piece of clay and added some earth and sand to it. I made a small cup out of this. I poured some water in there. Likewise, 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 bottom of the cup. In the same way various substances enter sea water from the bottom and shores of the seas.We carry out the third experiment. To do this, I prepared a supersaturated solution. Dissolve salt in small portions in warm water. When the salt stopped dissolving, the solution was poured into another container and allowed to cool. I dipped a woolen thread into the solution. A day later, an increase in salt deposits was detected. How interesting, I threw a pinch of fine salt into the water and got large crystals.After a week, the salt grew beautiful cubic crystals.The water in the glass has evaporated. The walls and bottom of the glass were covered with salt crystals.This happened because the saturated solution of table salt moves along the rope to its lowest point due to capillary effect. Earth's 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 solution out of the glass.

CHAPTER 3.

Properties of sea water.

Exploring this topic, I wanted to know a little more about salt water. I started 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? There is much more salt water. There is little fresh water. Its reserves are found in rivers and lakes.
Which water boils faster, salty or fresh? This is easy to find out by putting two identical saucepans of water on the fire. Salt the 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 boiling point than pure water. Fresh water will boil faster. Now I’ll put small potatoes in both saucepans. What I see! The salted water cooked the potatoes faster. Simply salt water provides more high temperature, due to this, food cooks faster.

Is it possible to get fresh drinking water from salt water?

This can be verified through scientific experiment.

Pour some water into a small bowl and dissolve a few tablespoons of salt in it. Place a cup on the bottom, stretch the film over the top, and place a pebble on the film so that there is 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 retain it, and a clean Figure 7 drinking water will settle drop by drop into the cup. The 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 the cups with fresh water and 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 everyone has seen it - when there is ice, they sprinkle salt on the road and the ice melts even at sub-zero temperatures. 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 happens because the freezing point of this mixture is much lower.

Which water is easier to learn to swim in? Of course, 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 can lie on its surface without any effort, 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, and stimulates metabolic processes in the body.

CHAPTER 4.

Salinity of the sea.

What elements are included in sea salt?

Although scientists have been studying seawater for more than a hundred years, its chemical composition has not yet been fully understood. However, scientists were able to identify different chemical substances, dissolved in salts. Sea salt contains great amount microelements essential for health.

Potassium and sodium are involved in regulating nutrition and cleaning the cell. Calcium takes part in blood clotting and forms cell membranes. Magnesium is an anti-stress mineral, has an anti-allergic effect, magnesium deficiency 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 process of formation of red blood cells. Selenium prevents cancer. Copper prevents the development of anemia. Silicon gives elasticity to blood vessels and strengthens tissue.

What is sea salinity?

Sea water is significantly different from fresh water. If we take and boil water taken, for example, from the Black, Dead and Mediterranean seas, we will see that it boils at different temperatures. The effect of swimming in these seas will cause no less surprise, since the effort that has to be expended to stay afloat is in all three cases turn out to be different.

In the 70s 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 that the salt composition of sea water was constant.

salinity, - conventional value. It reflects the weight in grams of all salts dissolved in a liter of sea water, measured in tenths of a percent and denoted ‰ - ppm.

- river flow, precipitation, evaporation, formation and melting sea ​​ice;

- vital activity of marine organisms, formation and transformation of bottom sediments;

- respiration of marine organisms, plant photosynthesis, bacterial activity.

It is because of differences in salinity surface waters 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 causes the boiling point of sea water to exceed 100°C and the freezing point to be below zero.

How is sea salt obtained? The method of extracting salt from sea water was suggested to man by nature itself. In dry and hot climates, water quickly evaporates and salt is deposited on the shores and bottom. Observing the process of salt deposition, man learned to arrange auxiliary devices for extracting salt where climatic conditions They made it possible to do this, for which they built pools that communicated with the sea and with each other. Today, a network of swimming pools is being created located near ecologically clean coastal areas. The fencing is made of wooden sides. Under the influence of the sun and wind, the salt evaporates. Then it is assembled by hand. With this technology, it remains natural composition salt. 95 If all the sea salt were evenly distributed over the surface of the land, the result would be a layer more than 150 meters thick - approximately a 45-story building!Another comparison can be made: if you dry up all the oceans, then the resulting salt will be 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 Earth's life. The source of such deposits is sea water, from the salts of which both deposits of fossil salts and salt lakes were formed. Thus, the 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 the soil and stones, it dissolves the smallest particles of minerals, including salts and their constituent chemical elements. Then water currents carry them out to sea. This process is called erosion. Of course, the salt content in fresh water is very low, so it cannot be determined by taste.
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, becomes very hot and is released back, saturated with minerals dissolved in it. Deep-sea geysers spew the resulting mixture into the sea.
3. During the reverse process, underwater volcanoes release huge amounts of hot rock, and thus chemical elements enter the water.4. Another source of replenishment of the seas with minerals is the wind, which carries fine particles from land to sea.Thanks to all these processes, sea water contains almost all known chemical elements. But the most common salt is sodium chloride, or regular table salt. It makes up 85% of all salts dissolved in sea water, and it is this that gives it its salty taste.

Why does the salt composition remain constant?

The salinity of sea water changes in different parts ocean and sometimes depends on the time of year. The highest salinity among uncovered waters is observed in the Red Sea and the Persian Gulf, where evaporation is very strong. In marine areas that receive a lot of rainfall and huge amounts of fresh water from large rivers, salinity is generally below average. Low salinity is also observed in melt zones polar ice, which are frozen fresh water. On the other hand, when the sea becomes covered with ice, the water becomes saltier. But overall, the salt composition of seawater remains surprisingly constant.A lot of salts accumulate in the seas because only pure water. All minerals remain in the sea. Although the sea continues to be replenished 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 in terms of salinity after Lake Assal and Kara-Bogaz-Gol. Rivers flowing into the Dead Sea carry dissolved salts and other minerals. Since the shore of the Dead Sea is the lowest place on the land surface, the water in this sea is consumed only by evaporation, which is why its level can drop by 25 millimeters per day in summer. Due to this, the salt content in the upper layers of the water reaches approximately 30 percent, which is almost ten times higher than in the Mediterranean Sea. Since water density increases with increasing salinity, swimmers float on the surface like floats. And they don't need an air mattress to read the newspaper while lying on their back.But the saltiest lake on our planet is Lake Assal. Its salinity is 35%.
Lake Assal is located in central Djibouti, in the Danakil Desert. The lake measures 16x6 km and is located 153 m below sea level. Lake Assal is the most low point Africa.Is it true that WithDoes it purify the air?

One study found that air pollution prevents precipitation from falling from clouds over land. However, polluted clouds over the ocean produce rain much more quickly. This is explained by the presence of salt crystals in the air from the spray of sea water.

The water droplets that settle on the contaminated particles are too small to become raindrops and therefore remain in the cloud. Crystals of sea salt 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:

After studying the material on the topic and conducting a series of experiments, I came to the conclusion that my first two hypotheses were fully confirmed, and the third has no scientific basis.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 taking with them particles of various salts.Some scientists believe that rivers brought salt to the sea. Water is a powerful solvent that can destroy any rock earth's surface. Rivers carry impurities dissolved in water into the seas and oceans. Water from the ocean evaporates and returns to the earth again, continuing its eternal cycle. And dissolved salts remain in the seas.
Other scientists refute this version, arguing that substances dissolved in seawater 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 largely 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 believed thatsea ​​water is salty , because salt is brought to the sea by rivers, washing it out of the rocks along which their bed passes. River water also contains salt, but it is 70 times less than sea water. Every year, rivers add one sixteen millionth of the total salt 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, and is again enriched with salt from rocks,

Figure 13 which 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 become fairly salty. This answer to the questionwhy is the water in the sea salty , also explains the large amount of salt in lakes that have no drainage. But it does not explain why the salts in sea and river water have different chemical compositions (and this is exactly the case!). Therefore, another, more modern hypothesis arose,why is the water in the sea salty . According to the modern hypothesis, sea water was initially salty, since the primary ocean on Earth is a condensate of gases volcanic eruptions. These gases contain water and a lot chemical elements and among them are the so-called “acid fumes”, consisting of chlorine, fluorine, bromine and inert gases. Spilling acid rain onto the Earth's surface, the products of volcanic eruptions entered into a chemical reaction with solid rocks, resulting in the formation of a saline solution.

Currently, scientists agree that both of these hypotheses,

why is the water in the sea salty , have the right to exist and complement each other.Despite various hypotheses, the appearance of salt in sea water, a unified approach to measuring salinity levels.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.95

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1. Children's magazine. Stories about the world around us for children. Adventures of Droplet. Editor Yu.A. Mayorov. No. 8 2010.2. Magazine. Planet Earth. No. 3 2008. Article. Salinity of the sea. What it is?Doctor geographical sciences D.Ya.Fashchuk.3. Magazine. The world around us. No. 5 2006. Article. Amazing properties of water.V. Golovner, M. Aromshtam.4. Dictionary Russian language / Compiled by M.S. Lapatukhin, E.V. Skorlupovskaya, G.P. Snetova; Ed. F.P. Owl. – M.: Education, 1997.5. Encyclopedia for the curious. Why and why? Editor T. Frolova. M.: 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 the water in the sea salty?9. Collection of poems. Sea. Poem. Why is the water in the sea 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.

Having visited the beach for the first time, the child asks his parents: why is the water in the sea salty? This simple question baffles adults. After all, everyone knows that a bitter aftertaste will definitely remain on the lips and the whole body. Why is the sea salty? We begin to reason: fresh rivers flow into this part of the World Ocean. So it can't taste that bad! But you can’t go against the facts: the water is not fresh. Let's figure out at what stage the initial composition of H2O changes.

Why is the salinity increased?

There are several theories about this. Some scientists believe that salt remains from the evaporated water of flowing rivers, others - that it is washed out of rocks and stones, others associate this compositional feature with the action of volcanoes... Let's begin to consider each version in order:

The reservoir becomes salty from the water of the rivers that flow into it. Strange pattern? Not at all! Although river moisture is considered fresh, it still contains salt. Its content is very small: seventy times less than in the vast depths of the World Ocean. Therefore, falling into great body of water, rivers desalinate its composition. But the river water gradually evaporates, but the salt remains. The volumes of impurities in the river are small, but over billions of years a lot of them accumulate in sea water.

Salts flowing from rivers into the sea settle on its bottom. From them, huge blocks of stone and rocks are formed on the ocean floor over thousands of years. Year after year, the current destroys any stones, leaching easily soluble constituent substances from them. Including salt. Of course, this process is long, but inevitable. Particles washed out of rocks and rocks give the ocean an unpleasant, bitter taste.

Underwater volcanoes eject into environment many substances, including salts. During the formation of the earth's crust, volcanic activity was very high. They released acidic substances into the atmosphere. Frequent acid rain formed seas. Accordingly, first the water in components the ocean was acidic. But the alkaline elements of the soil - potassium, magnesium, calcium, etc. - reacted with acids and formed salts. Thus, water in various places of the ocean acquired the characteristics that are now familiar.

Other assumptions known today are related

• with the winds bringing salt into the water;
• with soils, passing through which fresh liquid is enriched with salts and enters the ocean;
• with salt-forming minerals located under the ocean floor and supplied through hydrothermal vents.

It is probably correct to combine all the hypotheses in order to understand the ongoing process. Nature gradually built all its ecosystems, closely intertwining things that were incompatible at first glance.

Where is the highest concentration of salt?

Sea water is the liquid that is most abundant on earth. It’s not for nothing that many people associate vacations primarily with the beach and coastal waves. Surprisingly, the mineral composition of the liquid in different bodies of water never coincides. There are many reasons for this. For example, salinity depends on the intensity of fresh water evaporation, the number of rivers, types of inhabitants and other factors. Which sea is the saltiest?

The answer is given by statistics: the Red Sea is rightfully called the saltiest. One liter of its water contains 41 grams of salts. If we compare with other reservoirs, then in a liter of liquid from the Black there are 18 grams of various salts, in the Baltic this figure is even lower - 5 grams. The chemical composition of Mediterranean is 39 grams, which is still lower than the above characteristics of Red. IN ocean water– 34 grams.

Reasons for the unique feature of the Red Sea:

On average, about 100 mm of precipitation falls above the surface per year. This is very little, considering that about 2000 mm of water evaporates per year.

No rivers flow into this reservoir; it is replenished only by precipitation and waters from the Gulf of Aden. And its water is also salty.

The reason is also the intensive mixing of water. In winter and summer, the layers of liquid change. Evaporation occurs in the upper layer of water. The remaining salts fall down. Therefore, the salinity of water in this part of the water expanse increases significantly.

The Dead Sea is sometimes called the saltiest. Its waters contain 340 grams of salt per liter of water. That’s why it’s dead: the fish die in it. But some features of this body of water do not allow it to be considered a sea: it does not have access to the ocean. Therefore, it is more correct to call this body of water a lake.