Sea water has an unpleasant bitter-salty taste, which is why it is impossible to drink it. However, it is not the same in all seas. Many are interested in what the salinity of the water depends on, and experts find many explanations for this.
Water in all seas on the planet has a different composition. Salinity, which is measured in ppm, depends on the geographic location of the water bodies. According to experts, the farther north the sea is, the higher this indicator. Consequently, the seas and oceans of the southern part of the planet are less salty.
However, there are exceptions to any rule - the water in the oceans is much saltier than in the seas, and regardless of the region. Researchers do not provide an explanation for this geographical division. Perhaps the answer lies at the very beginning of the development of life on our planet?
It is known that water salinity is influenced by:
- sodium chlorides;
- magnesium chlorides;
- other salts.
Probably, certain areas of the earth's crust are rich in deposits of such substances, in contrast to neighboring regions. Although this explanation is rather fragile: if we take into account the factor of sea currents, sooner or later the salinity level should have leveled out anyway.
Causes of increased salinity
Scientists have put forward several theories that explain this phenomenon. Some argue that the increased amount of salt is the result of the evaporation of water from rivers flowing into it. Others are supporters of the theory that the high salinity is explained by the washing away of stones and rocks. And some associate this composition of water with active volcanoes.
It may seem strange to many that the hypothesis that an increased amount of salt in the sea appears with the water of the rivers flowing into it. Nevertheless, any river moisture contains salt. Of course, there is much less of it than, say, in any ocean.
Therefore, when a river enters the sea, its composition is desalinated. But after the evaporation of river water, salt remains in the reservoir. Of course, the amount of river impurities is small, but considering that the process lasts for millions of years, a lot of them have accumulated in seawater. They settle at the bottom, forming huge rocks and boulders there for thousands of years. But the sea current is very strong - it can destroy any stones. This process is quite long and constant. By the way, it is he who is responsible for the bitter taste of sea water.
The existence of underwater volcanoes can be attributed to explanations that indicate what determines the salinity of seawater. They periodically emit large amounts of various substances, including salts.
Volcanoes were very active during the formation of the Earth. They emitted acids into the atmosphere. It is assumed that due to the frequent acid rain, the water in the seas and oceans was initially acidic. However, when interacting with magnesium, calcium or potassium, salts were obtained. It was in this way that the water acquired the salinity familiar to everyone.
There are other assumptions that include:
- Salt-carrying winds.
- Soils, which, by passing water through themselves, enrich it with salts and throw it into the ocean.
- Salt-forming minerals that penetrate hydrothermal vents under the oceans.
Which sea is the saltiest
Sea water is perhaps the most abundant substance on Earth. Many people associate a full and healthy vacation with warm waves and sunny beaches. As mentioned above, all reservoirs have their own mineral composition. But which of the seas is the saltiest?
Scientists have come to a consensus that this is the Red Sea. One liter of its water contains 41 g of salts. Compared to other bodies of water, this is a very high indicator. For example, in the Mediterranean Sea it is 39 g, much less salt in the Black Sea -18 g, and even less in the Baltic - only 5 g. But in the water of the oceans it is equal to 34 grams.
Why is the sea salty: Video
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Remember: How are the waters of the planet divided by salinity? Why do travelers and sailors take fresh water on sea voyages?
Keywords:sea water, salinity, water temperature, ppm.
1. Salinity of waters. In all seas and oceans, water tastes bitter-salty. It is impossible to drink such water. Therefore, sailors leaving on ships to sail, take with them a supply of fresh water. Salt water can be desalinated in special installations that are available on ships.
Basically, table salt is dissolved in sea water, which we eat, but there are other salts (Fig. 92).
* Magnesium salts give the water a bitter taste. Aluminum, copper, silver, gold are found in the ocean water, but in very small quantities. For example, 2000 tons of water contains 1 g of gold.
Why are ocean waters salty? Some scientists believe that the primary ocean was fresh, because it was formed by the waters of rivers and rains that abundantly fell on the Earth millions of years ago. Rivers have brought and continue to bring salt to the ocean. They accumulate and lead to the salinity of ocean water.
Other scientists suggest that the ocean, during its formation, immediately became salty, because it was replenished with salty waters from the bowels of the Earth. Future research may answer this question.
Rice. 92. The amount of substances dissolved in ocean water.
** The amount of salts dissolved in ocean water is sufficient to cover the land surface with a layer of 240 m thick.
It is assumed that all naturally occurring substances are dissolved in seawater. Most of them are found in water in very small quantities: in thousandths of a gram per ton of water. Other substances are found in relatively large quantities - in grams per kilogram of seawater. They determine its salinity. .
Salinity sea water is the amount of salts dissolved in water.
Rice. 93. Salinity of surface waters of the World Ocean
Salinity is expressed in p about m and l laye, that is, in thousandths of a number, and is denoted - ° / oo. The average salinity of the World Ocean is 35 ° / oo. This means that each kilogram of sea water contains 35 grams of salt (Fig. 92). The salinity of fresh river or lake waters is less than 1 ° / oo.
The most saline surface waters are in the Atlantic Ocean, the least salty - in the Arctic (see Table 2 in Appendix 1).
The salinity of the oceans is not the same everywhere. In the open part of the oceans, salinity reaches its highest values in tropical latitudes (up to 37 - 38 ° / oo), and in the polar regions, the salinity of the surface oceanic WD decreases to 32 ° / oo (Fig. 93).
The salinity of water in the marginal seas usually differs little from the salinity of the adjacent parts of the ocean. The water of the inland seas differs from the water of the open part of the oceans in salinity: it rises in the seas of the hot zone with a dry climate. For example, the salinity of water in the Red Sea is almost 42 ° / oo. This is the saltiest sea in the World Ocean.
In the seas of the temperate zone, which receive a large amount of river waters, salinity is below average, for example, in the Black Sea - from 17 ° / oo to 22 ° / oo, in the Azov Sea - from 10 ° / oo to 12 ° / oo.
* The salinity of sea water depends on precipitation and evaporation, as well as currents, river inflow, ice formation and ice melting. When seawater evaporates, salinity increases, and when precipitation falls, it decreases. Warm currents usually carry saltier water than cold ones. In the coastal strip, sea waters are desalinated by rivers. When sea water freezes, salinity increases, while people thaw, on the contrary, decreases.
The salinity of sea water changes from the equator to the poles, from the open ocean to the shores, with increasing depth. Salinity changes cover only the upper water column (up to a depth of 1500 - 2000 m). Deeper salinity remains constant and is approximately equal to the average ocean.
2. Water temperature. The temperature of the ocean water near the surface depends on the input of solar heat. Those parts of the World Ocean located in tropical latitudes have a temperature of + 28 0 C - + 25 0 C, and in some seas, for example, in the Red, the temperature sometimes reaches + 35 0 C. This is the warmest sea in the World Ocean. In the polar regions, the temperature drops to - 1.8 0 С (Fig. 94). At a temperature of 0 ° C, fresh water from rivers and lakes turns into ice. Sea water does not freeze. Solutes interfere with its freezing. And the higher the salinity of sea water, the lower its freezing point.
Fig. 94. World ocean surface water temperature
With strong cooling, seawater, like fresh water, freezes. Sea ice forms. They constantly cover most of the Arctic Ocean, surround Antarctica, in winter they appear in the shallow seas of temperate latitudes, where they melt in summer.
* Up to a depth of 200 m, the water temperature changes depending on the season: in summer the water is warmer, in winter it becomes colder. Below 200 m, the temperature changes due to the influx of currents of warmer or colder waters, and in the bottom layers it can increase due to the influx of hot waters from faults in the oceanic crust. In one of these springs at the bottom of the Pacific Ocean, the temperature reaches 400 0 C.
The temperature of the waters of the oceans also changes with depth. On average, for every 1,000 m of depth, the temperature decreases by 2 0 C. At the bottom of deep-water depressions, the temperature is about 0 0 C.
1. What is called the salinity of sea water, how is it expressed? 2. What determines the salinity of sea water and how is it distributed in the World Ocean? What explains this distribution? 3. How does the temperature of the World Ocean waters change with latitude and depth? 4*. Why does salinity in tropical regions reach the highest values for the open ocean (up to 37 - 38 ° / oo), and salinity is much lower in equatorial latitudes?
Practical work.
Determine the salinity if 25 g of salts are dissolved in 1 liter of sea water.
2 *. Calculate how much salt you can get from 1 ton of Red Sea water.
Contest for experts ... There is a sea on earth, in which a person can be on the surface of the water like a float (Fig. 95). What is the name of this sea and where is it located. Why does the water in this sea have such properties?
Rice. 95 "Sea", in which those who cannot swim can swim.
I had a chance to ride to the seas in my life. Indeed, everyone is different! Somewhere you can safely swim and even dive - and even eyes hardly sting. And somewhere you can't even dip your head, otherwise the hair will turn into straw from the salt, and your eyes will be red until the next day. But what is the reason for this differences in the salinity of water in different seas?
What determines the salinity of sea water
For a while it seemed to me that it was just self-deception. Indeed, why should there be any differences between the seas!
But long hours on the Internet and for books prompted me: the salinity of the water is really different for each sea. AND it depends on the following things:
The ratio of all these parameters determines how salty the sea will be.
Which sea is the saltiest and why
The most the Dead Sea is considered the saltiest- where for every liter of water there is about 200 grams of salt.
Such a high concentration of salts leads to its consequences. At sea, simply living organisms cannot inhabit- do not withstand water salinity. That is why the sea got its name.
The reasons for this accumulation of salt are commonplace. Here only one river flows- Jordan. AND no river flows from the Dead Sea. Also, next to the Dead Sea very hot.
It turns out that salt simply has nowhere to go from the sea. The water evaporates, the salt does not disappear - and a concentrated brine solution is obtained.
But there is another plus - because of such salinity. it's almost impossible to drown in the Dead Sea... The water itself will push you to the surface.
Education
What is water salinity? Salinity of the World Ocean
March 29, 2017Our planet is 70% covered with water, of which more than 96% are oceans. This means that most of the water on Earth is salty. What is water salinity? How is it determined and what does it depend on? Can such water be used on the farm? Let's try to answer these questions.
What is water salinity?
Most of the water on the planet has salinity. It is commonly called seawater and is found in oceans, seas and some lakes. The rest is fresh, its amount on Earth is less than 4%. Before you understand what the salinity of water is, you need to understand what salt is.
Salts are complex substances that consist of cations (positively charged ions) of metals and anions (negatively charged ions) of acidic bases. Lomonosov defined them as "fragile bodies that can dissolve in water." Many substances are dissolved in seawater. It contains sulfates, nitrates, phosphates, sodium, magnesium, rubidium, potassium cations, etc. Together, these substances are referred to as salts.
So what is water salinity? This is the content of substances dissolved in it. It is measured in thousandths - ppm, which are denoted by a special symbol -% o. Permille defines the number of grams in one kilogram of water.
What determines the salinity of water?
In different parts of the hydrosphere, and even at different times of the year, the salinity of the water is not the same. It changes under the influence of several factors:
- evaporation;
- ice formation;
- precipitation;
- melting ice;
- river runoff;
- currents.
When water evaporates from the surface of the oceans, salts remain and do not erode. As a result, their concentration increases. The freezing process has a similar effect. Glaciers contain the largest supply of fresh water on the planet. During their formation, the salinity of the waters of the World Ocean increases.
The melting of glaciers is characterized by the opposite effect, decreasing the salt content. In addition to them, precipitation and rivers flowing into the ocean are a source of fresh water. The salt level also depends on the depth and nature of the currents.
Their greatest concentration is on the surface. The closer to the bottom, the less salinity. Warm currents affect the salt content in a positive direction, cold currents, on the contrary, reduce it.
Related Videos
Salinity of the World Ocean
What is the salinity of sea water? We already know that it is far from the same in different parts of the planet. Its indicators depend on geographical latitudes, climatic features of the area, proximity to river objects, etc.
The average salinity of the waters of the World Ocean is 35 ppm. The colder regions near the Arctic and Antarctic are characterized by a lower concentration of substances. Although in winter, when ice forms, the amount of salt increases.
For the same reason, the least salty ocean is the Arctic Ocean (32% o). The highest content is found in the Indian Ocean. It covers the area of the Red Sea and the Persian Gulf, as well as the southern tropical belt, where salinity is up to 36 ppm.
The Pacific and Atlantic oceans have approximately the same concentration of substances. Their salinity decreases in the equatorial zone and increases in subtropical and tropical regions. Some warm and cold currents balance each other. For example, not salty Gulf Stream and salty Labrador in the Atlantic Ocean.
Salinity of lakes and seas
Most of the lakes on the planet are fresh, as they are fed mainly by precipitation. This does not mean that there are no salts in them at all, it is just that their content is extremely small. If the amount of dissolved substances exceeds one ppm, then the lake is considered saline or mineral. The Caspian Sea has a record value (13% o). The largest freshwater lake is Baikal.
The salt concentration depends on how the water leaves the lake. Fresh water bodies are flowing, while more salty ones are closed and subject to evaporation. The determining factor is also the rocks on which the lakes were formed. So, in the area of the Canadian Shield, rocks are poorly soluble in water, therefore, the reservoirs there are "clean".
The seas are connected to the oceans through the straits. Their salinity is somewhat different and affects the average values of ocean waters. Thus, the concentration of substances in the Mediterranean Sea is 39% and is reflected in the Atlantic. The Red Sea, at 41% o, raises the average salinity of the Indian Ocean. The most salty is the Dead Sea, in which the concentration of substances ranges from 300 to 350% o.
Properties and significance of sea water
Salt water is not suitable for economic activities. It is not suitable for drinking and watering plants. However, many organisms have long been adapted to life in it. Moreover, they are very sensitive to changes in the level of its salinity. Based on this, organisms are divided into freshwater and marine.
Thus, many animals and plants living in the oceans cannot live in the fresh water of rivers and lakes. Edible mussels, crabs, jellyfish, dolphins, whales, sharks and other animals are exclusively marine.
A person uses fresh water for drinking. Salty is used for medicinal purposes. In small quantities, water with sea salt is used to restore the body. The therapeutic effect is produced by bathing and taking baths in seawater.