Average salinity of water. What determines the salinity of ocean waters

The waters of the White Sea are less freshened due to the freer communication with the ocean. In its basin, the salinity of surface waters is 24-26% o, in Gorla 28-30% o, and in the bays it is much lower and fluctuates strongly under the influence of surge and tidal fluctuations in the level. Sometimes in Dvinsky, Kandalaksha and Onega bays, almost fresh water is replaced by water with a salinity of 20-25% o. [...]

The waters of the inland seas located in tropical latitudes, where there is little rainfall, few rivers, and high evaporation, are distinguished by higher salinity than ocean waters. These are the Mediterranean, Red and Persian Gulf seas. The Mediterranean Sea, characterized by a negative freshwater balance and difficult water exchange with the ocean through the narrow Strait of Gibraltar, has a salinity of surface waters higher than that of the ocean. From the Strait of Gibraltar to about. Sicily it is 37-38%, in the eastern part of the sea 39% 0 and more. [...]

The salinity of the surface waters of the seas is often significantly different from the salinity of the oceanic waters (sometimes it exceeds it, sometimes it turns out to be less). These differences are determined by the conditions of water exchange between the seas and the ocean, the influence of climate and land runoff. The salinity of the surface waters of the seas, the water exchange of which occurs more or less freely, is close to that of the ocean. Differences can be significant when water exchange is difficult. [...]

The salinity of the Ocean is not constant. It depends on the climate (the ratio of precipitation and evaporation from the surface of the Ocean), the formation or melting of ice, sea currents, near the continents, on the inflow of fresh river waters. In the open Ocean, salinity ranges from 32-38%; in the marginal and Mediterranean seas, its fluctuations are much greater. Experiencing fluctuations in the amount of dissolved salts, sea water is distinguished by the exceptional constancy of their ratio to each other. The ratio of dissolved substances is preserved in different parts of the Ocean, on its surface and in deep layers. Taking into account this regularity, a method for determining the salinity of sea waters by the amount of any one element contained in them, most often chlorine, is constructed. [...]

The ocean is the main acceptor and accumulator of solar energy, since water has a high heat capacity. The water envelope (hydrosphere) includes: salty waters of the World Ocean and inland seas; fresh land waters concentrated in mountain ice, rivers, lakes, swamps. Consider environmental performance aquatic environment. [...]

The ocean belongs to the group of saline waters, while seawaters are sometimes brines (for example, the Red Sea) or half-spill (for example, the Sea of ​​Azov), that is, they have a sharply different concentration, less or more than the average, little change in composition ocean water. The transition is sometimes quite abrupt. [...]

In the ocean, the difference in temperature and salinity is small, but the described process enhances vertical mixing of water. [...]

The volume of water on the globe is measured at 1386 million km3, which means that each of us has 350 million m3 of water, which is equal to ten such reservoirs as Mozhaiskoye on the river. Moscow. Unfortunately, there is every reason for this. After all, a person needs not just any water, but only fresh water, that is, containing no more than 1 g of salt per 1 liter, and at the same time it must be of high quality. It is known that 97.5% of the water is concentrated in the World Ocean, the salinity of which is 35% a, or 35 g / l. Fresh water accounts for only 2.5%, while more than 2/3 of it is conserved in glaciers and snowfields, and only 0.32% falls on lakes and rivers. The most important river waters used for a wide variety of needs make up only 0.0002% of the total water reserves [Lvovich, 1974]. [...]

In the Pacific Ocean to the north of the subpolar front, the North Pacific intermediate water is formed with a salinity of 33.6 to 34.6% o, which then spreads to the south at depths of 500-1500 m. [...]

In all oceans and seas, there is a constant ratio of salts that make up the water. The total mass of salts in seawater is 48-1015 tons, or about 3.5% of the total mass of ocean water. This amount of salts would be enough for the formation of a salt layer up to 45 m thick over the entire surface of our planet. For every 1000 g of ocean water there are 35 g of salts, i.e. the salinity of the oceans averages 35%. [...]

The world's oceans are heterogeneous in terms of both salinity and temperature. It is possible to distinguish between isometric areas, layers and the thinnest layers. The highest water temperature in the ocean (404 ° C) was recorded at a hot spring 480 km off the west coast of America. Water heated to such a temperature did not turn into steam, since the source was located at a considerable depth under conditions of high pressure. The cleanest water in the world is recorded in the Weddell Sea in Antarctica. Its transparency corresponds to that of distilled water. At the same time, the waters of the World Ocean are in constant motion, their temperature and currents affect the state of the air masses and determine the weather and climatic conditions in the adjacent territories. [...]

The area of ​​salt water (seas, oceans) is just over 70% of the Earth's surface. Fresh waters (less than 1 g / l of salt) make up slightly less than 6% of the reserves or, in absolute terms, 90 million km3. But the trouble is that only about 3% of fresh water is easily accessible reserves such as rivers, lakes and reservoirs, the rest is glaciers and underground waters. Thus, we can only use about 2.5 million km3 of water. But some of this water is contaminated and unusable. [...]

The average salinity of waters on the surface of different oceans is not the same: Atlantic 35.4% o, Pacific 34.9 ° / oo, Indian 34.8% o-In table. 10 shows the average salinity at the surface of the oceans in the southern and northern hemispheres. [...]

The oceans are the watery shell of the Earth, with the exception of water bodies on land and glaciers in Antarctica, Greenland, polar archipelagos and mountain peaks. The oceans are divided into four main parts - the Pacific, Atlantic, Indian, Arctic oceans. The waters of the World Ocean, going into the land, form seas and bays. The seas are relatively isolated parts of the ocean (for example, the Black, Baltic, etc.), and the bays protrude into the land not as significantly as the seas, and differ little from the World Ocean in terms of the properties of the waters. In the seas, the salinity of water can be higher than that of the ocean (35%), as, for example, in the Red Sea, up to 40%, or lower, as in the Baltic Sea, from 3 to 20%. [...]

Typically, water contains various impurities of organic and inorganic origin. Distinguish between salty and fresh water. The bulk of water on our planet is salty water, forming the salty World Ocean and most of the mineralized underground waters of deep occurrence (1.5 ... 2 km). [...]

Ocean fronts arise from a variety of mechanisms. Sometimes they look very distinct in the fields of temperature and salinity, and are almost not expressed in the density field. Sharp changes in properties at the fronts turn out to be significant due to the fact that they affect the dynamics. A review of satellite observations of temperature fronts was made in. The main climatic frontal zones (where fronts are most often recorded) in the North Pacific Ocean are shown in Fig. 13.11; they were discussed in Rodin's work. One of the important types of fronts is associated with Ekman convergence in the surface layer. Examples of such fronts are subtropical ones, which are observed at latitudes from 30 ° N. NS. up to 40 ° S NS. Their changes associated with fluctuations in the Ekman divergence were studied in the work. The second type of fronts is formed at the boundary of water masses (see). Such a front separates, for example, the waters of the subarctic and subtropical gyres. In the northern part of the Pacific Ocean (Fig. 13.11), this front is located at a latitude of 42 ° N. NS. It was formed at the meeting point of the cold Oyashio current directed to the equator with the warm current of the polar direction - the Kuroshio. On the surface, this front is well pronounced in the temperature and salinity sections, but in the density field it is weakly noticeable. [...]

In the World Ocean, physical, chemical, biological and other processes continuously occur that alter the salinity, that is, reduce or increase the concentration of the solution. However, regardless of the absolute concentration of the solution, the quantitative ratios between the main ions remain constant. Therefore, it is enough to know the concentration of one of the components in order to determine the rest. To determine salinity, the sum of Cl + Br + I ions, called chlorinity, is used, the concentration of which is highest in seawater. [...]

The bulk of the water is concentrated in the oceans. Its average depth is more than 4000 m, it covers an area of ​​361 million km2 (71% of the earth's surface), and is distinguished by high salinity (3.5%). Continental bodies of water cover about 5% of the Earth's area. Of these, surface waters (lakes, rivers, swamps, etc.) account for a very small part (0.2%), glaciers - 1.7%. Groundwater makes up about 4% of the total volume of the hydrosphere. The entire planetary water reserve reaches 1450 million km. [...]

Seawater contains 89% chlorides, 10% sulphates and 0.2% carbonates, while fresh waters contain 80% carbonates, 13% sulphates and 7% chlorides. The water of closed seas such as the Caspian is not typically sea water. It is significantly less saline and contains three times more carbonates than ocean water. According to modern concepts, the salinity of the seas and oceans is "primary", which did not change during geological periods.[ ...]

Processes that change oceanological characteristics are constantly taking place in the World Ocean. As a result of uneven changes in these characteristics, horizontal and vertical gradients appear, along with which processes develop, aimed at leveling the properties of water masses, at destroying gradients. These are the processes of vertical and horizontal exchange, i.e. mixing. Changes in temperature, salinity and density with depth are associated with the vertical gradients of these values. The gradient of each of these values ​​can be positive or negative. If the density gradient is positive (the density increases with depth), the water masses are in a stable state, if negative, they are unstable: light waters tend to rise, and heavy ones - to sink. An increase in density under the influence of a decrease in temperature or an increase in salinity on the surface causes a lowering of the upper layers of water and a rise of the lower ones. As a result, the density of water in the upper, mixed layer decreases, while in the underlying layer it increases. In the water layer located above the jump layer, the water mixing processes occur most intensively; this layer is called the active layer. Below the layer of the jump, the water becomes stable, since here the temperature decreases with depth, and the salinity and density increase. [...]

Fluctuations in salinity over time are insignificant. Annual fluctuations in the open parts of the oceans do not exceed 1% o, at a depth of 1500-2000 m salinity is almost unchanged (differences in 0.02-0.04% o). Significant fluctuations in salinity are observed in coastal regions, where the inflow of fresh water is more intense in spring, as well as in polar regions due to the processes of freezing and melting of ice. [...]

Fresh water reserves account for less than 2% of water resources. The average salinity of the waters of the World Ocean is 3.5 g / l (in the oceans there are 48-1015 tons of table salt), drinking water should contain no more than 0.5 g / l, plants die from water with a content of 2.5 g / l of salt. Approximately 3/4 of the world's fresh water reserves are found in the ice of Antarctica, the Arctic, and glacial mountains. About 35 thousand sea ​​ice and icebergs are included in the volume of the oceans. But 10-15 thousand icebergs break off annually only from the coast of the Arctic and Greenland. The annual river flow is estimated at 41 thousand km '. In Europe and Asia, where 70% of the population lives, only 39% of the world's river water reserves are concentrated. Lake Baikal, the most abundant in the world (23 thousand km3), contains 20% of the world's reserves of surface fresh water. Russia has the world's largest underground water storage - the West Siberian artesian basin with an area of ​​3 million km2, which is almost 8 times more area Baltic Sea. [...]

If the density sea ​​water unchanged, then the ocean is called homogeneous. If the vertical distribution of density depends only on pressure, then one speaks of a barotropic ocean. If the density of seawater is determined by temperature, salinity and pressure, then the ocean is considered baroclinic. [...]

For every 1000 g of ocean water, there are 35 g of salts, i.e. the salinity of the oceans averages 35% o (ppm). [...]

According to modern concepts, the salinity of the seas and oceans is "primary", which did not change during geological periods. Thus, the question of how water appeared on Earth requires study and clarification. [...]

Being an excellent solvent, water contains dissolved salts, gases, organic substances, the content of which in water can vary over a wide range. If the concentration of salts is less than 1 g / kg, the water is considered fresh, with a salt concentration of up to 25 g / kg - brackish, and at a higher concentration - salty. In the ocean, the concentration of salts is about 35 g / kg, in fresh lakes and rivers, 5-1000 mg / kg. Sea water is a multicomponent system that includes water molecules, anions and cations of salts, as well as many impurities. Good mixing of sea waters leads to equalization of the content of salt components in different parts Of the World Ocean, and therefore we can talk about the constancy of the salt composition of oceanic waters. To characterize salinity, the S value is used - salinity, which determines in grams the mass of dissolved solid matter contained in 1 kg of seawater, provided that bromine and iodine are replaced with an equivalent chlorine content, all carbon dioxide salts are converted to oxides, all organic matter is burned at a temperature of 480 ° WITH. This definition of salinity goes back to the previously accepted definition of salinity from chlorine by titration of seawater. Salinity is measured in thousandths - ppm (% o). The constancy of the salt composition of seawater makes it possible to determine the salinity by the content of one component. [...]

Similar expressions can be written for the salinity and density of sea water. The first term on the right is the class of phenomena that make up the subject of classical oceanography; the second term - inhomogeneities related to the phenomenon of a fine thermohaline structure; the third term is Reynolds microturbulence; ¿Ig - values ​​of spatial and temporal scales, delimiting structural elements water masses due to a thin layered structure and turbulence. As a rule, the irregularity of the vertical salinity profiles is greater than the irregularity of the temperature distributions. Sea water has another interesting property. If in the atmosphere the rates of molecular diffusion of heat and moisture are almost the same, then the rates of diffusion of heat and salt in the ocean differ by two orders of magnitude (K = 1.4 10 3 cm2 / s, 1 = 1.04 10 5 cm2 / s), which leads to such a phenomenon as differential diffusion convection, which is one of the mechanisms responsible for the formation of a fine thermohaline structure of sea waters. [...]

Since the information on the fields of temperature and salinity makes it possible to calculate currents only relative to a certain given level, the velocities of stationary geostrophic currents in the ocean cannot be determined absolutely accurately. Therefore, it is also impossible to find the exact values ​​of the transfers and compare them with the calculations by the Sverdrup ratio. However, some comparisons can still be made. So, for example, in Fig. 12.7.6 shows the currents of the North Atlantic at a depth of 100 m relative to currents at a depth of 1500 m. If we assume that the latter currents are relatively weak, then Fig. 12.7.6 can be considered as a picture of near-surface geostrophic currents. There are many striking coincidences with fig. 12.7, a, which indicates that the effect of wind largely explains the pattern of surface circulation. On the other hand, significant differences, which can also be seen in these figures, indicate the importance of other factors, such as buoyancy forces. Worthington's calculations, in particular, show that the sinking of the Greenland Sea carries large masses surface waters from the North Atlantic, and this significantly affects the overall circulation pattern. [...]

The uneven distribution of temperature as well as salinity is mainly caused by mixing processes and sea currents. In the surface layers, within the active layer of the sea, the layering of water masses is mainly associated with the processes of vertical exchange, and at depth, the inhomogeneity of oceanological characteristics is associated with the general circulation of the waters of the World Ocean. The heterogeneity of the waters of the oceans and seas, associated with the processes of vertical and horizontal exchange, determines the presence of intermediate cold or warm layers with low or high temperatures. These layers can be of convective (due to mixing) and advective origin. The latter are associated with the delivery (askes), i.e., horizontal invasion, of water masses carried from outside by currents. An example is the presence of warm Atlantic waters in the entire central part of the Arctic Ocean, which can be traced at depths from 150-250 to 800-900 m. contacts arise? vertical gradients of oceanographic characteristics. The transition layer, in which the gradients of temperature, salinity, density, and other properties are large, is called the jump layer. These layers can be temporary, seasonal, and permanent in the active layer and at its border with the waters of the depths. Deep-sea observations in various regions of the World Ocean (Fig. 14) show that in open regions, except for the polar regions, the temperature changes noticeably from the surface to a depth of 300-400 m, then up to 1500 m changes are very insignificant, and from 1500 m it almost does not change. At 400-450 m the temperature is 10-12 ° C, at 1000 m 4-7 ° C, at 2000 m 2.5-4 ° C and from a depth of 3000 m it is about 1-2 ° C. [...]

If you do not touch the dirty drains and poisonous drains, then since ancient times the waters are divided into salty and fresh. Salt waters, in comparison with fresh ones, contain an increased concentration of salts, primarily sodium. They are not suitable for drinking and industrial use, but great for bathing and water transport... The salt composition of saline waters in different water bodies varies quite strongly: for example, in the shallow Gulf of Finland the waters are less salty than in the Black Sea, and in the oceans the salinity is much higher. Let me remind you that salt water is not necessarily sea water. There are well-known pools with exceptionally salty waters that have no connection with the sea, such as the Dead Sea in Palestine and the salt lake Baskunchak. [...]

The ripe fruits of lagenaria are so light that they do not sink in salt water and are able to swim in the ocean for a long time without damage and without losing germination by seeds. Since ancient times, accidentally falling into Atlantic Ocean, the fruits of the Lagenarius, picked up by the ocean currents, sailed from the coast of West Africa to Brazil or across the Pacific Ocean came from South-East Asia in Peru, and from there the ancient inhabitants of the South and North America spread throughout the continent. [...]

All of these factors determine the regime and changes in the salinity of oceans and seas. Since salinity is the most conservative, established property of the waters of the World Ocean, we can talk about the balance of salts. The incoming part of the salt balance is composed of the input of salts: a) with the continental runoff, b) with atmospheric precipitation, c) from the Earth's cedars in the form of degassing products of the mantle, d) during the dissolution of rocks at the bottom of the oceans and seas. [...]

The hydrosphere is the watery shell of the Earth, which includes oceans, seas, rivers, lakes, groundwater and glaciers, snow cover, and water vapor in the atmosphere. The Earth's hydrosphere is 94% represented by the salty waters of the oceans and seas, more than 75% of the total fresh water conserved in the polar caps of the Arctic and Antarctica (Table 6.1). [...]

The salinity of the water in the World Ocean is 35 g / l, and at a salinity of 60 g / l, the bulk of the cells cannot exist. The removal of salts by rivers into the ocean would double the concentration of salts every 80 million years, if not for the natural processes that remove salts from the ocean water. Under these conditions, the relative stability of ocean salinity has been maintained for several hundred million years. [...]

Biochemical properties. All biochemical processes of decomposition of organic matter in wastewater in the seas and oceans are much slower than in freshwater basins. This is due to the fact that the concentration of salts in salt water is higher than in fresh water and therefore the osmotic pressure decreases, with the help of which the microbial cell absorbs nutrients necessary for its life (Gaultier, 1954). Accordingly, the decrease in the BOD value in seawater in the process of its self-purification occurs much more slowly than in fresh [...]

Temperate and tropical land belts with their humid climate and developed biostrome continue on the ocean as belts with high biological productivity. Subtropical desert belts of land with a poorly developed biostream are equally traced over the ocean. Ultimately, the lack of moisture both on land and in the ocean leads to a similar result for bios - deserts appear, almost devoid of life "2. [...]

A small amount of work, of course, could not accommodate the huge amount of information that is associated with the problem of water desalination. But we tried to show that the idea of ​​obtaining fresh water from the colossal salt waters of the seas and oceans still occupied the minds of ancient thinkers and has now acquired real forms, not only technological, but also technical solutions... Today, entire cities have grown on the sun-scorched, waterless land thanks to the found ways to desalinate sea waters on an industrial scale. [...]

With regard to this project, M. Ewing's forecast about the consequences of the implementation of the dam construction is known. According to this forecast, the cessation of the influx of more saline waters into the Atlantic Ocean could, in three decades, lead to such a decrease in salinity in it, which would entail a complete change in the circulation of ocean waters, which could ultimately result in the cessation of the flow of warm waters of the Gulf Stream into the Arctic and cooling there with simultaneous warming in continental Europe. At one time, this forecast caused a negative reaction from another well-known oceanologist G. Stommel, who pointed out that on the basis of M. Ewing's assumptions, one could just as well have predicted reverse processes. This example is given in order to show the complexity and ambiguity of such predictions when state of the art ocean science even for stationary processes exchange of water masses. [...]

Different water masses are separated by frontal zones or frontal surfaces, in which the gradients of the characteristics of the water masses are sharpened. Quasi-stationary climatic frontal zones are the natural boundaries of the main water masses in the ocean. In the open ocean, there are five types of fronts: equatorial, subequatorial, tropical, subpolar, polar. The frontal zones are distinguished by the high dynamics of the processes taking place in them. In the coastal zone, in the estuarine zone, fronts are formed that separate shelf or runoff waters from the waters of the deep-water part. The formation of this or that type of front depends on external conditions. According to the data of subsurface towing of temperature and salinity probes (measurements were carried out at a depth of 30 cm) with a front width of about 70 m, the salinity and temperature gradients are 2.2% o and 1.1 ° per 10 m, respectively. inflow of fresh river waters over saline and dense sea waters. In the case of the influx of Baltic waters into the lagoon, a front of intrusion of heavy sea waters into the lighter waters of the lagoon is formed. A typical estuarine front is observed during the propagation of a wedge of salty sea waters along a deep sea channel. A typical change in temperature, salinity, and density when crossing the front is shown in Fig. 6.5. [...]

This type of renewable energy resources is perhaps the most exotic, and the youngest in terms of development time: the first technical ideas date back only to the 70s. of our century. The renewal of this type of resources is associated with the transformation of part of the thermal energy of the ocean during the evaporation of water from its surface. This, as already noted, consumes about 54% of the total balance of energy coming from the Sun. When fresh water enters in the form of precipitation and river runoff back into the ocean in the process of mixing with salt water, energy is released, which is almost proportional to the magnitude of the change in the entropy of the fresh - ocean water system, which is a measure of the orderliness of this system. The very change in entropy is an unobservable phenomenon, therefore, for example, at the mouths of rivers there are no noticeable manifestations of the release of additional energy. The energy of dissolution can be determined by first finding the value of the equilibrium osmotic pressure arising on a thin film separating fresh and oceanic waters and having the ability to pass only water molecules. The penetration of H2O molecules continues until the pressure of the solution column equilibrates the osmotic pressure, as a result of which equilibrium conditions are established between the solution and the solvent. [...]

Currently, work on the organization of irrigated agriculture for the cultivation of perennial grasses and vegetables in the steppe zone continues, but small irrigated fields with an area of ​​tens (not more than 200-300) hectares are being created, water intake is carried out from artificial reservoirs in which spring snow water accumulates. Watering from lakes is prohibited, where interference with the hydrological regime is especially dangerous, since it can lead to irreversible changes in their ecosystems (for example, to the disappearance of fish and water bloom, i.e., the massive development of cyanobacteria, etc.). HYDROSPHERE (G.) - the water envelope of the Earth, including oceans, seas, rivers, lakes, groundwater, glaciers. G.'s structure of the Earth is shown in table. 16. G. is 94% represented by salt waters of the oceans and seas, and the contribution of rivers to the planet's water budget is 10 times less than the amount of water vapor in the atmosphere. [...]

Only the uppermost layers, 100-200 m thick, can be called true pelagic: locally, foraminifera and pteropods make up more than 50% of them, while siliceous microfossils are rare. The increased salinity of the waters of the Red Sea probably prevents the development of radiolarians, and the appearance of these microorganisms in the section of Quaternary sediments corresponds to the interglacial epochs of high sea level, when the limitation of water exchange with the ocean was minimal. Coccoli-toforites can withstand more severe conditions, however, during the maximum of the last glaciation, the salinity was so high that even the most tolerant forms eventually disappeared.

Rating of seas by salinity

There are about 80 seas on our planet. Of course, the Dead Sea would have ranked # 1, as its waters are famous for their salinity. The Dead Sea is one of the saltiest bodies of water on Earth, salinity is 300-310 ‰, in some years up to 350 ‰. But scientists call this reservoir a lake.

1. Red Sea with a salinity of 42 ‰.

The Red Sea is located between the shores of Africa and Asia. In addition to salinity and warmth, the Red Sea can boast of its transparency. Many tourists love to relax on its shore.

2. The Mediterranean Sea has a salinity of 39.5 ‰.

The Mediterranean Sea washes the shores of Europe and Africa. In addition to salinity, it can also boast of its warm waters - in summer they warm up to 25 degrees above zero.

3. Aegean Sea with 38.5 ‰ salinity.

The waters of this sea with a high concentration of sodium can irritate the skin. Therefore, after bathing, it is better to take a fresh shower. In summer, the water warms up to 24 degrees Celsius. Its waters wash the shores of the Balkan Peninsula, Asia Minor and the island of Crete.

4 . The Ionian Sea with a salinity of 38 ‰.

It is the densest and saltiest Greek sea. Its waters allow poorly swimming people to hone this skill, as the high density will help keep the body afloat. The area of ​​the Ionian Sea is 169 thousand square kilometers. Washes the shores of southern Italy, Albania and Greece.

five . Sea of ​​Japan, salinity of which is 35 ‰

The sea is located between the continent of Eurasia and the Japanese islands. Also, its waters wash Sakhalin Island. The water temperature depends on geographic location: in the north - 0 - + 12 degrees, in the south - 17-26 degrees. The area of ​​the Sea of ​​Japan is over 1 million square kilometers.

6. Barents Sea with salinity 34.7-35 ‰

This is the marginal sea of ​​the Arctic Ocean. It washes the shores of Russia and Norway.

7. The Laptev Sea with a salinity of 34 ‰.

The area is 662 thousand square kilometers. It is located between the New Siberian Islands and Severnaya Zemlya. The average annual water temperature is 0 degrees Celsius.

8. Chukchi Sea with a salinity of 33 ‰.

In winter, the salinity of this sea rises to 33 ‰, while in summer the salinity slightly decreases. The Chukchi Sea has an area of ​​589.6 thousand km². The average temperature in summer is 12 degrees Celsius, and in winter it is almost 2 degrees Celsius.

9. White Sea also has a high salinity. In the surface layers, the indicator has stopped at 26 percent, but at depth it rises to 31 percent.

10. The Laptev Sea. At the surface, salinity is recorded at 28 percent

The sea has a harsh climate with temperatures below 0 ° C for more than nine months of the year, sparse flora and fauna, and a low coastal population. Most of the time, with the exception of August and September, it is under ice. The salinity of sea water near the surface in the northwestern part of the sea in winter is 34 ‰ (ppm), in the southern part - up to 20-25 ‰, in summer it decreases to 30-32 ‰ and 5-10 ‰, respectively. The melting of ice and the runoff of Siberian rivers have a strong effect on the salinity of surface waters.

Topic: Properties of the World Ocean waters.

Target: to form ideas about the properties of the waters of the World Ocean and to acquaint students with the factors of nature that affect them.

Planned results:

Personal: developing interest and cognitive activities by communication theoretical material with daily events in the life of students, to form the ability to work in groups, to increase interest in the study of the subject; develop independence, the ability to work in a team.

Metasubject: develop the ability to present information in different forms and be able to read it; teach to find the information that is necessary for solving educational problems.

Subject: to form an idea of ​​children about the properties of ocean water: salinity, temperature, transparency; develop the skills to calculate the salinity of the waters of the World Ocean; show the relationship between the properties of the waters of the World Ocean and latitude.

Lesson type: learning new material.

Teaching methods: heuristic, explanatory-illustrative, problematic.

Forms of student work: collective, group, work in pairs.

Equipment: physical map hemispheres, presentation, computer, salt, water, slide.

During the classes:

Organizing time(greeting students).

Hello! This is how a greeting usually sounds, which has a deep meaning: "To say hello is to wish you health!" Greet each other, smile. Sit down, watch your posture.

So, we continue with you to study the theme of the World Ocean. Look at the desk. Unfortunately, the topic of the lesson is "washed out by water".

(the topic of the lesson is written on the board, but words in the topic are missing, except for the word WOD )

Guys, you need to help me restore it. To do this, let’s solve the tasks on the cards with you. And make a word from the first letters of the terms.

(I distribute cards to each row, which they solve as a team and make up a word)

Updating previously learned.

Card number 1

Solid precipitation during the cold season. (Snow)

Oscillatory motion of water. (Waves)

Visible clusters of water droplets and ice crystals in the troposphere. (Clouds)

Wound Medicine (Iodine)

Distance from wave crest to base (Slope)

Lower atmosphere (Troposphere).

The only substance on Earth that is in three states (Water).

Cluster of islands (Archipelago).

Card number 2

Winds reversing twice a year (Monsoons).

A thin layer of ice crystals deposited from the water vapor of the atmosphere on the cooled surface of soil, grass, objects (Hoarfrost).

Water droplets settling on the surface of the earth, plants, objects during condensation of water vapor in the air (Dew).

All moisture dropped from the atmosphere to the ground (Precipitation).

Oscillatory movements of water (Waves).

Visible clusters of water droplets and ice crystals in the troposphere (Clouds).

Water shell of the Earth (Hydrosphere).

Card number 3

A small piece of land, surrounded on all sides by water (Island).

Long-term weather regime typical for a particular area (Climate).

The largest continent (Eurasia).

The difference between the highest and the lowest temperature (Amplitude).

Plain, located at an altitude of 0 to 200 meters above sea level (Lowland).

Coldest continent on Earth (Antarctica).

Well done boys! You have correctly solved your cards and determined the topic of our today's lesson "Properties of the waters of the World Ocean". This topic is not so new because you watch TV, read books, travel with your parents and have an idea of ​​sea water. What associations do you have when you hear these words ( children's answers)

Okay, let's now formulate the purpose of our lesson with you. ( Children formulate the goals of the lesson, I highlight them on the slide in the presentation)

Learning new material.

Conversation with students based on known material:

What does ocean water taste like? Why?

Find the answer to the question in a paragraph in your textbook. (Working with the tutorial)

So what is salinity, find the definition of this term in the textbook. (Read out definition)

Salinity is measured in ppm -% 0. What unit does ppm look like? (on the %)

What does salinity show? ( how much salt is in the water)

The average salinity of the World Ocean is 35 ppm. What does it mean? ( One liter of ocean water contains 35 grams of salt).

Can we now make water with the average salinity of the World Ocean?

Can!!! And try to bring the average salinity of the ocean 35 ppm in a liter jar (1 tablespoon - 30 grams of salt, 1 teaspoon - 10 grams).

(students doing the experiment)

This is one of the properties of the waters of the World Ocean.

Now listen to the message about the Red Sea and find out what other properties the waters of the World Ocean have.

(the student has prepared a report on the Red Sea)

What properties were discussed in the message, except for salinity. That's right, it's temperature, transparency. But the most important of these properties is SALINITY.

Let's create a cluster.

Properties

? ? ?

Now let's solve the problem.

Solving the problem of determining salinity.

How many grams of salt of various substances can be obtained from 1 ton of Black Sea water, if its salinity is 18 ppm? How many times less will its amount be than from 1 ton of Red Sea water, the salinity of which is 42 ppm?

V = 1 t.

Salinity of the Black Sea - 18 ppm

Salinity of the Red Sea - 42 ppm

Find: how much salt can be obtained from 1 ton of water in these seas.

1 t - 1000 l.

1000 * 18 = 18000 (kg) - the mass of salt that can be obtained from the Black Sea water.

1000 * 42 = 42000 = 42 kg.

42/18=2,3

Answer: from the water of the Red Sea you can get 2.3 times more salt than from the water of the Black Sea.

Physical education."Sounds of the rain"

The rain starts - we rub our hands;

It's raining harder - clap our hands;

It rains even harder - clapping on the front of the legs;

The downpour has begun - we stamp our feet;

The rain gradually subsides - everything is repeated in the reverse order.

So, please remind me of the salinity of the Red Sea and the salinity of the Black Sea (18 and 42 ppm)

And also compare - the average salinity of the Baltic Sea is 11 ppm, in the central part - 6-8 ppm, in the Gulf of Finland up to 1 ppm. What is the conclusion? ( salinity in different seas is different).

What more questions do you think we should answer in today's lesson? ( Why is salinity different in different parts of the World Ocean? What Causes Affect Salinity?)

Independent work students.

- You will solve this problem yourself, working with the textbook. Read the text carefully and fill in the diagram, the time to work is 5 minutes.

Fill in the cluster at the board.

T Evaporation temperature Precipitation

0°

What conclusion can be drawn from these data? ( When moving from the equator to the poles, the temperature decreases in the same way as on land).

Now look at this data, what they are talking about:

Depth

Temperature

15,5

1000

2000

3000

5000

4. Reflection.

So, we have studied the topic.

What topic in the lesson did we study with you?

What new did you learn in the lesson?

What have you learned?

What were the difficulties?

What would you like to learn more?

Summarizing:

- So, we have finished the lesson, we learned what properties sea water has and what they depend on. You did a good job and got the following marks.

(I comment and give marks for the lesson).

Home assignment: § 32, r.t

We will answer the following questions.

1. What is called the salinity of sea water?

Sea water is special type natural waters. The most important characteristic of sea water is salinity - the amount of salts dissolved in 1 liter of water. The unit of measure for salinity is ppm (means 1/1000 part of the number and is denoted by the ‰ sign). The average salinity of the waters of the World Ocean is 35 ‰. This means that 35 g of salts are dissolved in 1 liter of sea water.

2. What is the salinity of different parts of the World Ocean?

In those areas of the oceans where heavy rainfall falls, large rivers flow, ice melts, and the salinity of the waters decreases. The minimum salinity (2 ‰) is noted in the Gulf of Bothnia of the Baltic Sea. The increased evaporation of water from the ocean surface with a small amount of precipitation leads to an increase in salinity. The waters of the Red Sea have the highest salinity: at the surface 42 ‰, and at some points near the bottom - more than 280 ‰ (Fig. 90). The sea water tastes bitter and salty. This is due to the composition of the dissolved salts. Salt taste to sea water is given by table salt, bitter - by magnesium salts. If all the salts dissolved in the waters of the oceans are evaporated and evenly distributed over the surface of the Earth, then our planet will be covered with a layer of salt 45 cm thick.

3. At what temperature does sea water freeze?

Sea water has no specific freezing point. The temperature at which ice crystals begin to form depends on salinity: the higher the salinity, the lower the freezing point. At a salinity of 35 ‰, the freezing point of sea water is -1.9 ° C. The density of sea ice is less than that of sea water. Therefore, floating ice rises above the water surface by 1 / 7-1 / 10 of its thickness (Fig. 92).

4. How does the temperature of the water in the World Ocean change?

The unique property of water as a substance is its ability to slowly heat up and slowly cool down. Therefore, the ocean accumulates a huge amount of heat and serves as a regulator of the temperature of the surface layers of the air.

The surface temperature of the water depends on the amount solar heat and varies significantly at different latitudes (Fig. 91) The temperature of the surface waters of the tropical zone reaches 27 - 29 ° С. As we move to the polar regions, the surface water temperature decreases, reaching negative values: from -1.5 to -1.7 ° C in the Arctic Ocean and the seas surrounding Antarctica.

When diving into the depths of the ocean, a decrease in water temperature is observed everywhere (the exceptions are the polar regions). In the upper layer of water, already at a depth of 300 - 500 m, the temperature drops sharply. Below the water temperature decreases smoothly. At depths of more than 3000 - 4000 m, the water temperature fluctuates between +2 and -1 ° С.

5. Why are currents formed in the World Ocean?

The waters of the oceans are constantly in motion: ocean water moves both vertically and horizontally.

The wind, due to the force of friction and pressure, causes oscillatory movements of the surface water. This is how wind waves appear (up to 25 m in height) (Fig. 94, 95).

Surface water can travel great distances. In the ocean, there is a whole system of peculiar "rivers without banks" - currents that are born for various reasons. main reason formation of currents - constant winds that affect the sea surface. Surface waters begin to move in the direction of the wind - this is how wind (drift) currents are formed. They carry huge masses of water.

6. Which currents are called warm and which are called cold?

Currents can be warm or cold. The water temperature of warm currents is higher than that of the surrounding waters. The water of the cold currents has a lower temperature than the surrounding waters. Warm currents are formed near the equator, where the sun heats the water more strongly. The amount of solar heat in the direction from the equator to the poles decreases, therefore the currents directed to the poles are warm, and the currents directed to the equator are cold.

Surface currents on the map are shown with arrows of two colors. On maps, blue arrows indicate cold currents, and red arrows indicate warm ones.

The role of currents in ocean life is enormous. They transfer heat, feed for living organisms, and are the pathways for fish and marine animals.

7. What are the causes of ebb and flow?

The moon and the sun by the force of their gravity cause tidal phenomena on Earth. A tidal wave causes the water level in the ocean to rise. Highest level water at high tide is called full water. At low tide, the water level goes down, the lowest water level at low tide is called low tide. The height of the tide corresponds to the difference in the levels of high water and low water and is determined mutual arrangement Earth, Moon and Sun. The main features of the tide are determined by the Moon, tk. the lunar force acts 2.5 times stronger than the solar one. In addition, the height of the tide depends on the geographic location, the depth of the sea and the shape of the coastline.

We will learn how to draw up a text outline describing the ocean and describe the ocean according to the plan, draw up a schematic map with the "route of the global ocean conveyor".

1. Salinity of sea water

Fill in the missing words.

The salinity of seawater is the amount of salt in water dissolved in 1 liter (1000 g) of water.

The average salinity of the World Ocean is 35%.

The main salts of sea water are table salt and magnesium salt.

How many grams sea ​​salt do you need to dissolve in a liter of fresh water to get seawater with a salinity equal to the salinity of the World Ocean?

Table 1

table 2

2. Sea water temperature

Fill in the missing words.

The temperature of sea water from the equator to the poles decreases from 27 to -1.7 ° С.

The temperature of sea water during immersion drops to + 2 ° С.

With a salinity of seawater 35%, the freezing point of seawater is -1.9 ° C.

Table 3

Table 4

The diagram (Fig. 1) shows the currents of surface waters of one of the regions of the World Ocean. Determine the ocean region by the outlines of large islands, sign the names of currents and islands. Check the correctness of the assignment using the atlas hemisphere map.

Using the satellite image (textbook, p. 157, fig. 95), determine the main direction of movement of sea waters in the southeastern part of the Baltic Sea.

The direction is north-east.

4. Ebb and flow

5. An example of describing the ocean

Based on the text of the textbook (pp. 157 - 158), make a plan for describing the Arctic Ocean. Using your plan, describe the other ocean (optional).

1) Area and volume in the World Ocean.

2) The location of the ocean relative to the continents.

3) The connection of the ocean with other oceans.

4) The number of islands in the ocean.

The Atlantic Ocean is the second largest ocean on Earth after the Pacific Ocean. It lies between Greenland and Iceland in the north, Europe and Africa in the west, and Antarctica in the south.

The area is 91.6 million km2, of which about 16% are seas, bays and straits. The area of ​​coastal seas is not large and does not exceed 1% of the total area. The volume of water is 329.7 million km³, which is equal to 25% of the volume of the World Ocean. The average depth is 3736 m, the greatest is 8742 m (the Puerto Rico trench). The average annual salinity of ocean waters is 35 ‰. The Atlantic Ocean has a heavily indented coastline with a pronounced division into regional water areas: seas and bays.

Pathfinder School

The work plan is given in the textbook (pp. 158 - 159).

Conclusion. The global ocean conveyor belt has a closed loop and consists of warm and cold branches.

) or PSU (Practical Salinity Units) of the practical salinity scale (Practical Salinity Scale).

Salinity in ppm is the amount solids in grams, dissolved in 1 kg of seawater, provided that all halogens are replaced by an equivalent amount of chlorine, all carbonates are converted to oxides, organic matter burned.

In 1978, the practical salinity scale (Practical Salinity Scale 1978, PSS-78) was introduced and approved by all international oceanographic organizations, in which salinity measurement is based on electrical conductivity (conductometry), and not on water evaporation. In the 1970s, oceanographic CTD probes were widely used in marine research, and since then, water salinity is measured mainly by the electric method. Laboratory salt meters are used to check the operation of conductivity cells that are immersed in water. In turn, standard seawater is used to test the salt meters. Standard seawater, recommended by the IAPSO international organization for the verification of salt meters, is produced in the UK by Ocean Scientific International Limited (OSIL) from natural seawater. If all measurement standards are met, salinity measurements can be accurate to 0.001 PSU.

PSS-78 scale gives numerical results close to measurements mass fractions, and differences are noticeable either when measurements are required to better than 0.01 PSU, or when the salt composition does not match the standard ocean water composition.

• Atlantic Ocean - 35.4 ‰ The highest salinity of surface waters in the open ocean is observed in the subtropical zone (up to 37.25 ‰), and the maximum is in the Mediterranean Sea: 39 ‰. In the equatorial zone, where the maximum amount of precipitation is noted, salinity decreases to 34 ‰. A sharp desalination of water occurs in the estuarine areas (for example, at the mouth of La Plata - 18-19 ‰).
• Indian Ocean - 34.8 ‰. The maximum salinity of surface waters is observed in the Persian Gulf and the Red Sea, where it reaches 40-41 ‰. High salinity (more than 36 ‰) is also observed in the southern tropical zone, especially in eastern regions, and in the northern hemisphere also in the Arabian Sea. In the neighboring Bay of Bengal, due to the desalination effect of the Ganges runoff with Brahmaputra and Ayeyarwaddy, salinity is reduced to 30-34 ‰. The seasonal difference in salinity is significant only in the Antarctic and equatorial zones. In winter, desalinated waters from the northeastern part of the ocean are carried by the monsoon current, forming a tongue of low salinity along 5 ° N. NS. This language disappears in the summer.
• Pacific Ocean - 34.5 ‰. The tropical zones have the maximum salinity (maximum up to 35.5-35.6 ‰), where intense evaporation is combined with a relatively small amount of precipitation. To the east, under the influence of cold currents, salinity decreases. A large number of precipitation also lowers salinity, especially at the equator and in the western circulation zones of temperate and subpolar latitudes.
• Arctic Ocean - 32 ‰. Several layers of water masses are distinguished in the Arctic Ocean. The surface layer has a low temperature (below 0 ° C) and low salinity. The latter is explained by the freshening effect of river runoff, melt water and very weak evaporation. Below, a subsurface layer is distinguished, colder (down to −1.8 ° C) and more salty (up to 34.3 ‰), formed when surface waters are mixed with the underlying intermediate water layer. The intermediate water layer is Atlantic water coming from the Greenland Sea with a positive temperature and increased salinity (more than 37 ‰), extending to a depth of 750-800 m. winter time also in the Greenland Sea, slowly creeping in a single stream from the strait between Greenland and Svalbard. The temperature of deep waters is about -0.9 ° C, salinity is close to 35 ‰. ...

The salinity of ocean waters varies with latitude, from the open ocean to the shores. In the surface waters of the oceans, it is lowered in the equator, in the polar latitudes.