Geological development and structure of the earth. Earth's crust and hydrosphere

Introduction

In this paper, the topic "Hydrosphere and Earth's atmosphere" is considered.

The liquid shell of the Earth, which covers 70.8% of its surface, is called the hydrosphere. The oceans are the main reservoirs of water. They contain 97% of the world's water reserves. The currents in the oceans carry heat from the equatorial regions to the polar regions and thereby regulate the Earth's climate to a certain extent. Thus, the Gulf Stream, starting from the coast of Mexico and carrying warm waters to the coast of Svalbard, leads to the fact that the average temperature of northwestern Europe is much higher than the temperature of northeastern Canada.

According to modern concepts, the presence of large bodies of water on Earth played a decisive role in the emergence of life on our planet. Part of the water on Earth, with a total volume of about 24 million km 3, is in a solid state, in the form of ice and snow. Ice covers about 3% of the earth's surface. If this water were turned into a liquid state, then the level of the world ocean would rise by 62 meters. Every year, about 14% of the earth's surface is covered with snow. Snow and ice reflect from 45 to 95% of the energy of the sun's rays, which ultimately leads to a significant cooling of large areas of the Earth's surface. It has been calculated that if the whole Earth were covered with snow, then the average temperature on its surface would drop from the current +15 C to 88 C.

The average temperature of the Earth's surface is 40 C higher than the temperature that the Earth should have, illuminated by the sun's rays. This is again connected with water, more precisely, with water vapor. The fact is that the sun's rays, reflected from the surface of the Earth, are absorbed by water vapor and are again reflected to the Earth. This is called the greenhouse effect.

The air shell of the Earth, the atmosphere, has already been studied in sufficient detail. The density of the atmosphere near the Earth's surface is 1.22 10 -3 g/cm 3 . If we talk about the chemical composition of the atmosphere, then the main component here is nitrogen; its percentage by weight is 75.53%. Oxygen in the Earth's atmosphere is 23.14%, of other gases, the most representative is argon - 1.28%, carbon dioxide in the atmosphere is only 0.045%. This composition of the atmosphere is preserved up to an altitude of 100-150 km. At high altitudes, nitrogen and oxygen are in the atomic state. From a height of 800 km, helium predominates, and from 1600 km, hydrogen, which forms a hydrogen geocorona extending to a distance of several Earth radii.

The atmosphere protects everything living on Earth from the harmful effects of ultraviolet radiation from the Sun and cosmic rays - high-energy particles moving towards it from all sides at almost light speeds.

Let's take a closer look at the Earth's hydrosphere and atmosphere.

1. Hydrosphere

Hydrosphere(from hydro ... and sphere) - an intermittent water shell of the Earth, located between the atmosphere and the solid earth's crust (lithosphere) and representing a combination of oceans, seas and surface waters of land. In a broader sense, the composition of the hydrosphere also includes groundwater, ice and snow in the Arctic and Antarctic, as well as atmospheric water and water contained in living organisms. The bulk of the water in the hydrosphere is concentrated in the seas and oceans, the second place in terms of the volume of water masses is occupied by groundwater, the third is the ice and snow of the Arctic and Antarctic regions. Surface waters of land, atmospheric and biologically bound waters make up fractions of a percent of the total volume of water in the hydrosphere (Fig. 1). The chemical composition of the hydrosphere approaches the average composition of sea water.

Surface waters, occupying a relatively small share in the total mass of the hydrosphere, nevertheless play an important role in the life of our planet, being the main source of water supply, irrigation and watering. The waters of the hydrosphere are in constant interaction with the atmosphere, the earth's crust and the biosphere. The interaction of these waters and mutual transitions from one type of water to another constitute a complex water cycle on the globe. The hydrosphere was the first place where life originated on Earth. Only at the beginning of the Paleozoic era did the gradual migration of animal and plant organisms to land begin.

Water types	Name	Volume, million km 3	Quantity in relation to the total volume of the hydrosphere,%
sea waters
Ground (excluding soil) water	unpaved
Ice and snow (Arctic, Antarctica, Greenland, mountain ice regions)
Surface waters of land: lakes, reservoirs, rivers, swamps, soil waters
Atmospheric waters	atmospheric
	biological

Rice. 1. Types of waters of the hydrosphere

2. Atmosphere

Atmosphere Earth (from the Greek atmos - steam and sphaira - ball) - a gaseous shell that surrounds the Earth. The atmosphere is considered to be that area around the Earth in which the gaseous medium rotates together with the Earth as a whole. The mass of the atmosphere is about 5.15-10 15 tons. The atmosphere provides the possibility of life on Earth and has a great influence on various aspects of human life.

Origin and role of the atmosphere

The modern Earth's atmosphere is apparently of secondary origin and was formed from gases released by the solid shell of the Earth (the lithosphere) after the formation of the planet. During the geological history of the Earth, the atmosphere has undergone significant evolution under the influence of a number of factors: dissipation (volatilization) of atmospheric gases into outer space; release of gases from the lithosphere as a result of volcanic activity; dissociation (splitting) of molecules under the influence of solar ultraviolet radiation; chemical reactions between the components of the atmosphere and the rocks that make up the earth's crust; accretion (capture) of the interplanetary medium (for example, meteoric matter). The development of the atmosphere was closely connected with geological and geochemical processes, as well as with the activities of living organisms. Atmospheric gases, in turn, had a great influence on the evolution of the lithosphere. For example, a huge amount of carbon dioxide that entered the atmosphere from the lithosphere was then accumulated in carbonate rocks. Atmospheric oxygen and water coming from the atmosphere were the most important factors that affected the rocks. Throughout Earth's history, the atmosphere has played a large role in the weathering process. This process involved atmospheric precipitation, which formed rivers that changed the earth's surface. No less important was the activity of the wind, which carried fine fractions of rocks over long distances. Temperature fluctuations and other atmospheric factors significantly influenced the destruction of rocks. Along with this, the atmosphere protects the Earth's surface from the destructive action of falling meteorites, most of which burn up when they enter the dense layers of the atmosphere.

The activity of living organisms, which had a strong influence on the development of the atmosphere, itself to a very large extent depends on atmospheric conditions. The atmosphere traps most of the sun's ultraviolet radiation, which has a detrimental effect on many organisms. Atmospheric oxygen is used in the process of respiration by animals and plants, atmospheric carbon dioxide - in the process of plant nutrition. Climatic factors, in particular the thermal regime and the regime of moisture, affect the state of health and human activity. Agriculture is especially dependent on climatic conditions. In turn, human activity has an ever-increasing impact on the composition of the atmosphere and on the climate regime.

The structure of the atmosphere

Numerous observations show that the atmosphere has a clearly defined layered structure (Fig. 2). The main features of the layered structure of the atmosphere are determined primarily by the features of the vertical temperature distribution. In the lowest part of the atmosphere - the troposphere, where intense turbulent mixing is observed, the temperature decreases with increasing altitude, and the decrease in temperature along the vertical is on average 6 ° per 1 km. The height of the troposphere varies from 8-10 km in polar latitudes to 16-18 km near the equator. Due to the fact that air density decreases rapidly with height, about 80% of the total mass of the atmosphere is concentrated in the troposphere. Above the troposphere there is a transition layer - the tropopause with a temperature of 190-220 K, above which the stratosphere begins. In the lower part of the stratosphere, the decrease in temperature with height stops, and the temperature remains approximately constant up to an altitude of 25 km - the so-called. isothermal region (lower stratosphere); higher temperature begins to increase - inversion region (upper stratosphere). The temperature reaches a maximum of ~270 K at the level of the stratopause located at an altitude of about 55 km. The layer of the atmosphere, located at altitudes from 55 to 80 km, where the temperature again decreases with height, is called the mesosphere. Above it is a transitional layer - the mesopause, above which the thermosphere is located, where the temperature, increasing with height, reaches very high values (over 1000 K). Even higher (at altitudes of ~ 1000 km or more) is the exosphere, from where atmospheric gases are dissipated into the world space due to dissipation and where a gradual transition from the atmosphere to interplanetary space occurs. Usually, all layers of the atmosphere above the troposphere are called the upper, although sometimes the stratosphere or its lower part is also referred to the lower layers of the atmosphere.

All structural parameters of the atmosphere (temperature, pressure, density) have significant spatial and temporal variability (latitudinal, annual, seasonal, daily, etc.). Therefore, the data in Fig. 2 reflect only the average state of the atmosphere.

The layered structure of the atmosphere has many other diverse manifestations. The chemical composition of the atmosphere is heterogeneous in height. If at altitudes up to 90 km, where there is intense mixing of the atmosphere, the relative composition of the constant components of the atmosphere remains practically unchanged (the entire thickness of the atmosphere is called the homosphere), then above 90 km - in the heterosphere - under the influence of the dissociation of atmospheric gas molecules by the ultraviolet radiation of the Sun, a strong change in the chemical composition of the atmosphere with altitude. Typical features of this part of the atmosphere are layers of ozone and the airglow itself. A complex layered structure is characteristic of atmospheric aerosol - solid particles of terrestrial and cosmic origin suspended in the atmosphere. The most common aerosol layers are below the tropopause and at an altitude of about 20 km. Layered is the vertical distribution of electrons and ions in the atmosphere, which is expressed in the existence of D-, E- and F-layers of the ionosphere.

Composition of the atmosphere

Unlike the atmospheres of Jupiter and Saturn, which consist mainly of hydrogen and helium, and the atmospheres of Mars and Venus, the main component of which is carbon dioxide, the earth's atmosphere consists mainly of nitrogen and oxygen. The Earth's atmosphere also contains argon, carbon dioxide, neon and other constant to variable components. The relative volume concentration of permanent gases, as well as information on the average concentrations of a number of variable components (carbon dioxide, methane, nitrous oxide, and some others) related only to the lower layers of the atmosphere, are given in Table 1.

The most important variable constituent of the atmosphere is water vapour. The spatial and temporal variability of its concentration varies widely - at the earth's surface from 3% in the tropics to 2 10 -5% in Antarctica. The bulk of water vapor is concentrated in the troposphere, since its concentration decreases rapidly with height. The average content of water vapor in the vertical column of the atmosphere in temperate latitudes is about 1.6-1.7 cm of the "precipitated water layer" (the layer of condensed water vapor will have such a thickness). Data on the content of water vapor in the stratosphere are contradictory. It was assumed, for example, that in the altitude range from 20 to 30 km, the specific humidity strongly increases with height. However, subsequent measurements indicate a greater dryness of the stratosphere. Apparently, the specific humidity in the stratosphere depends little on height and amounts to 2–4 mg/kg.

Table 1. Chemical composition of dry atmospheric air near the earth's surface

The variability of water vapor content in the troposphere is determined by the interaction of evaporation, condensation, and horizontal transport. As a result of the condensation of water vapor, clouds form and atmospheric precipitation occurs in the form of rain, hail and snow. Processes of phase transitions of water proceed mainly in the troposphere. That is why clouds in the stratosphere (at altitudes of 20-30 km) and mesosphere (near the mesopause), called mother-of-pearl and silver, are observed relatively rarely, while tropospheric clouds usually cover about 50% of the entire earth's surface.

Ozone has an impact on atmospheric processes, especially on the thermal regime of the stratosphere. It is mainly concentrated in the stratosphere, where it causes the absorption of ultraviolet solar radiation, which is the main factor in heating the air in the stratosphere. The average monthly values of the total ozone content vary depending on the latitude and season within 0.23-0.52 cm (this is the thickness of the ozone layer at ground pressure and temperature). There is an increase in the ozone content from the equator to the pole and an annual variation with a minimum in autumn and a maximum in spring.

An essential variable component of the atmosphere is carbon dioxide, the variability of the content of which is associated with the vital activity of plants (photosynthesis processes), industrial pollution and solubility in sea water (gas exchange between the ocean and the atmosphere). Typically, changes in carbon dioxide content are small, but sometimes they can reach noticeable values. In recent decades, there has been an increase in carbon dioxide content due to industrial pollution, which may have an impact on the climate due to the greenhouse effect created by carbon dioxide. It is assumed that, on average, the concentration of carbon dioxide remains unchanged throughout the thickness of the homosphere. Above 100 km, its dissociation begins under the influence of ultraviolet solar radiation with wavelengths shorter than 1690 A.

One of the most optically active components is atmospheric aerosol - particles suspended in the air ranging in size from several nm to several tens of microns, formed during the condensation of water vapor and entering the atmosphere from the earth's surface as a result of industrial pollution, volcanic eruptions, and also from space. Aerosol is observed both in the troposphere and in the upper atmosphere. The aerosol concentration decreases rapidly with height, but this trend is superimposed by numerous secondary maxima associated with the existence of aerosol layers.

Conclusion

hydrosphere atmosphere earth shell

Each of us from the course of natural history and geography knows that we live at the bottom of the ocean of air - the atmosphere.

The uppermost shells of the Earth - the hydrosphere and atmosphere - differ markedly from other shells that form the solid body of the planet. By mass, this is a very small part of the globe, no more than 0.025% of its total mass. But the significance of these shells in the life of the planet is enormous. The hydrosphere and atmosphere arose at an early stage in the formation of the planet. The hydrosphere and atmosphere are the main shells of the biosphere.

The biosphere occupies a special place among the community of the Earth's shells. It captures the upper layer of the lithosphere, almost the entire hydrosphere and the lower layers of the atmosphere. The biosphere was understood as the totality of the living matter inhabiting the surface of the planet, together with the habitat. The significance of this system goes beyond the limits of the purely terrestrial world; it represents a link on a cosmic scale.

The atmosphere of the Earth is fundamentally different from the atmospheres of other planets: it has a low content of carbon dioxide, a high content of molecular oxygen and a relatively high content of water vapor. There are two reasons why the Earth's atmosphere is distinguished: the water of the oceans and seas absorbs carbon dioxide well, and the biosphere saturates the atmosphere with molecular oxygen formed in the process of plant photosynthesis. Calculations show that if we release all the carbon dioxide absorbed and bound in the oceans, simultaneously removing from the atmosphere all the oxygen accumulated as a result of the vital activity of plants, then the composition of the earth's atmosphere in its main features would become similar to the composition of the atmospheres of Venus and Mars.

The atmosphere is made up of several layers. The bottom layer is the troposphere. Over different latitudes of the earth, its thickness is different. Above the troposphere is the tropopause with a constant low temperature. Above it is the stratosphere up to a height of 50 kilometers. Mesosphere 55-80 kilometers. Thermosphere 80-1000 kilometers. Exosphere 1000-2000 kilometers. Traces of gases were found at an altitude of 20,000 kilometers. Above 600 kilometers, helium predominates, and above 1600 kilometers, hydrogen.

In the Earth's atmosphere, saturated water vapor creates a cloud layer covering a significant part of the planet. Earth's clouds are an essential element in the water cycle that occurs on our planet in the system hydrosphere - atmosphere - land.

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Atmosphere

The atmosphere is a gas shell that surrounds the Earth and rotates with it as a whole. The atmosphere consists mainly of gases and various impurities (dust, water drops, ice crystals, sea salts, combustion products). The concentration of gases that make up the atmosphere is almost constant, with the exception of water (H 2 O) and carbon dioxide (CO 2). The content of nitrogen by volume is 78.08%, oxygen - 20.95%, argon, carbon dioxide, hydrogen, helium, neon and some other gases are contained in a smaller amount. The lower part of the atmosphere also contains water vapor (up to 3% in the tropics), at an altitude of 20-25 km there is a layer of ozone, although its amount is small, but its role is very significant.

The history of the formation of the atmosphere.

The atmosphere was formed mainly from gases released by the lithosphere after the formation of the planet. Over billions of years, the Earth's atmosphere has undergone significant evolution under the influence of numerous physicochemical and biological processes: dissipation of gases into outer space, volcanic activity, dissociation (splitting) of molecules as a result of solar ultraviolet radiation, chemical reactions between atmospheric components and rocks, respiration and metabolism of living organisms. So the modern composition of the atmosphere is significantly different from the primary, which took place 4.5 billion years ago, when the crust was formed. According to the most common theory, the Earth's atmosphere has been in four different compositions over time. Initially, it consisted of light gases (hydrogen and helium) captured from interplanetary space. This is the so-called primary atmosphere (570-200 million years BC). At the next stage, active volcanic activity led to the saturation of the atmosphere with gases other than hydrogen (hydrocarbons, ammonia, water vapor). This is how the secondary atmosphere was formed (200 million years ago - today). This atmosphere was restorative. Further, the process of formation of the atmosphere was determined by the following factors:

· constant leakage of hydrogen into interplanetary space;

chemical reactions occurring in the atmosphere under the influence of ultraviolet radiation, lightning discharges and some other factors.

Gradually, these factors led to the formation of a tertiary atmosphere, characterized by a much lower content of hydrogen and a much higher content of nitrogen and carbon dioxide (formed as a result of chemical reactions from ammonia and hydrocarbons).

With the advent of living organisms on Earth, as a result of photosynthesis, accompanied by the release of oxygen and the absorption of carbon dioxide, the composition of the atmosphere began to change. Initially, oxygen was spent on the oxidation of reduced compounds - hydrocarbons, the ferrous form of iron contained in the oceans, etc. At the end of this stage, the oxygen content in the atmosphere began to grow. Gradually, a modern atmosphere with oxidizing properties formed.

During the Phanerozoic, the composition of the atmosphere and the oxygen content underwent changes. Thus, during the periods of coal accumulation, the oxygen content in the atmosphere significantly exceeded the current level. The content of carbon dioxide could increase during periods of intense volcanic activity. Recently, man has also begun to influence the evolution of the atmosphere. The result of his activities was a constant significant increase in the content of carbon dioxide in the atmosphere due to the combustion of hydrocarbon fuels.

The structure of the atmosphere.

The atmosphere has a layered structure. There are troposphere, stratosphere, mesosphere and thermosphere. The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere accounts for about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere.

The troposphere is the lower, most studied layer of the atmosphere, with a height of 8–10 km in the polar regions, up to 10–12 km in temperate latitudes, and 16–18 km at the equator. Approximately 80-90% of the total mass of the atmosphere and almost all water vapor are concentrated in the troposphere. In the troposphere, physical processes occur that determine this or that weather. All transformations of water vapor take place in the troposphere. Clouds are formed in it and precipitation, cyclones and anticyclones are formed, turbulent and convective mixing is very strongly developed.

Above the troposphere is the stratosphere. The stratosphere is characterized by a constant or rising temperature with height and exceptionally dry air, with almost no water vapor. Processes in the stratosphere practically do not affect the weather. The stratosphere is located at an altitude of 11 to 50 km. A slight change in temperature in the 11-25 km layer (the lower layer of the stratosphere) and its increase in the 25-40 km layer from -56.5 to 0.8 ° C (the upper layer of the stratosphere) are characteristic. Having reached a value of about 0°C at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and the mesosphere. It is in the stratosphere that the ozonosphere layer (“ozone layer”) is located (at an altitude of 15–20 to 55–60 km), which determines the upper limit of life in the biosphere.

An important component of the stratosphere and mesosphere is O 3 , which is formed as a result of photochemical reactions most intensively at an altitude of ~ 30 km. The total mass of O 3 at normal pressure would be a layer 1.7-4.0 mm thick, but even this is enough to absorb the life-damaging UV radiation of the Sun.

The next layer above the stratosphere is the mesosphere. The mesosphere begins at an altitude of 50 km and extends up to 80–90 km. The air temperature to a height of 75--85 km drops to? 88 ° С. The upper boundary of the mesosphere is the mesopause, where the temperature minimum is located; above, the temperature begins to rise again. Then a new layer begins, which is called the thermosphere. The temperature in it is growing rapidly, reaching 1000 - 2000 ° C at an altitude of 400 km. Above 400 km, the temperature almost does not change with height. Temperature and air density strongly depend on the time of day and year, as well as on solar activity. In the years of maximum solar activity, the temperature and air density in the thermosphere are much higher than in the years of minimum.

Next is the exosphere. The gas in the exosphere is very rarefied, and hence its particles leak into interplanetary space (dissipation). Further, the exosphere gradually passes into the so-called near space vacuum, which is filled with highly rarefied particles of interplanetary gas, mainly hydrogen atoms. But this gas is only part of the interplanetary matter. The other part is made up of dust-like particles of cometary and meteoric origin. In addition to extremely rarefied dust-like particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.

The value of the atmosphere.

The atmosphere provides us with the oxygen we need to breathe. Already at an altitude of 5 km above sea level, an untrained person develops oxygen starvation and, without adaptation, a person's performance is significantly reduced. This is where the physiological zone of the atmosphere ends.

Dense layers of air - the troposphere and stratosphere - protect us from the damaging effects of radiation. With sufficient rarefaction of air, at altitudes of more than 36 km, ionizing radiation, primary cosmic rays, has an intense effect on the body; at altitudes of more than 40 km, the ultraviolet part of the solar spectrum, which is dangerous for humans, operates.

Ozone, located in the upper atmosphere, serves as a kind of shield that protects us from the effects of ultraviolet radiation from the sun. Without this shield, the development of life on land in its modern forms would hardly have been possible.

It is extremely important for theory and practice, since life appeared together with the hydrosphere and is closely connected with it.

The hypothesis of "Hot" and the hydrosphere dominated until the middle of the 20th century. It was based on the theory of the astronomer P. Laplace (1749 - 1827), who believed that all the planets arose from the solar matter, torn out by the force of gravity of a star flying near the Sun. Planets were formed from clots of solar matter, which then cooled for a long time. The earth cooled until a crust formed on its surface, and only then rains poured from the cooled atmosphere. Water accumulated in depressions, forming various reservoirs. Thus, the age of the hydrosphere was significantly inferior to the age of the Earth, and the formation of the hydrosphere seemed to be a relatively short event in the life of the planet. But gradually accumulated facts that contradicted the hypothesis of the "hot" formation of the Earth and the hydrosphere.

Scientists have found that hot dense in the presence of solid - the formation is very stable, as evidenced by the planet Venus, whose atmospheric temperature is approximately 400 ° C. In addition, in the oldest rocks discovered on Earth, whose age is about 3.8 billion years. years, imprints of single-celled organisms were found that could only exist in the presence of liquid water. All this confirmed the theory of the "cold" formation of planets from dust that revolved around the Sun. In this cloud, clots arose, which became the embryos of future planets. Small clumps were captured by larger ones, which grew and absorbed the main mass of the dust cloud, forming planets. According to the calculations of one of the creators of this theory, V. S. Safronov, the process of planet formation began 4.65 billion years ago.

The modern size of the planet, including the Earth, was reached in 100 million years. Then the young Earth was dominated by harsh and cold, over which the black sky stretched. Celestial bodies fell to the surface, but they did not cause the roar of explosions, since the atmosphere did not yet exist or was very thin. From the impacts of celestial bodies, heat accumulated in the thickness of the planet, and the surface without a protective atmospheric shell cooled. When celestial bodies hit the Earth, a thick layer of regolith was formed - a mixture of debris and dust. The surface of our planet consisted of it. Among the celestial bodies were comets - ice cosmic formations. Impacts of celestial bodies on the Earth "warmed up" it from the inside. As a result, heavier substances rushed to its center, while light and volatile substances rose to the surface. This process provided the main heat for heating the bowels of the planet. The extra heat comes from radioactive decay. It melted the rocks in the depths of the planet. As a result, through the vents and giant cracks formed on the Earth, molten water began to pour out onto the surface, and with it, a hot spinning top, water vapor, which quickly condensed. This process is called degassing. It began 4 billion years ago, as evidenced by the most ancient rocks found on Earth. The atmosphere owes its formation to degassing, which continues even now on our planet. From the moment of outpouring of magma and degassing, geological is counted. This period is considered the beginning of the formation of the hydrosphere. The recent discovery of water in molecular form in dusty cosmic clouds, as well as ice particles, means their presence in the original matter of the Earth, the mass of which was replenished due to the fall of comets. It is possible that during the impacts of celestial bodies, ice particles melted and water was forced out to the surface of the planet even in the pregeological period. At the same time, it filled the pores of the regolith that covered the Earth's surface. Thus, the formation of the hydrosphere could begin as early as the pregeological period of the life of our planet.

The origin of the hydrosphere and the history of ocean waters

Stages of evolution of the hydrosphere

The main causes and types of sea level fluctuations. Ocean level changes in the geological past

Origin and evolution of the atmosphere

Causes of climate change

Earth's climates in the geological past

The origin of the hydrosphere and the history of ocean waters

World Ocean as the main component of the hydrosphere occupies 361 million km 2 (about 71% of the earth's surface), having a huge volume of water (1.37 million km 3 ), what is 94% of the volume of the entire hydrosphere Earth. V in the ocean, the mass of salts is 4.8-10 18 T. In every liter of sea water, there is an average of 35 g of salts. 97% of ocean salinity is due to 4 ions: chloride (55.2%), sodium (30.4%), sulfate (7.7%) and magnesium (3.7%). In general, sea water contains about 80 chemical elements, but only 12 of them have a concentration of more than 1 million -1 (chlorine, sodium, magnesium, sulfur, calcium, potassium, bromine, carbon, strontium, boron, silicon, fluorine).

The world ocean appeared on our planet more than 1 billion years ago and has undergone a complex evolution. Its history over the past 150 million years has been studied in more detail in connection with deep-sea drilling.

ORIGIN OF THE HYDROSPHERE. The history of water is connected with the history of volatile substances. According to modern concepts water vapor and gases of the primary atmosphere were once in the bowels of the Earth and arrived at its surface as a result of internal heating with the most fusible substances of the mantle in the process of volcanic and magmatic activity. For a long time it was believed that the initially molten Earth in the early stages of its development was enveloped in a powerful atmosphere with water vapor, and during subsequent cooling, the vapor condensed into liquid water, while it was originally fresh. Salty and mineralized ocean water became later, as a result of the removal of dissolved substances from the surface of the continents. But such ideas about the formation of the hydrosphere, which were very popular in their time, contradict the latest data obtained.

Since water belongs to the volatile substances of our planet, it is natural that its history is connected with the fate of other volatiles. If we compare the amount of volatiles in the composition of the upper geospheres of the Earth with the amount that could be released in the process of weathering and processing of the rocks of the earth's crust, then we get a big difference, which is called an excess of volatiles. The excess of volatiles for individual components is tens and even hundreds of times greater than the amount that came as a result of weathering of the bedrocks of the lithosphere. For example, there is an excess of volatile carbon dioxide 83 times, and chlorine 60 times more than it could come from the primary earth's crust during its weathering and processing.

The calculations performed strongly suggest that natural gases of the depths The earths played an exceptionally important role in the formation of the upper shells of our planet. This role is seen more obvious if we compare the composition of the excess volatiles with the composition of the gases of volcanoes and igneous rocks. Comparison of the relevant geochemical data indicates that the composition of the excess volatiles is in general close to the composition of volcanic gases arising and escaping from the Earth's mantle. This means that the origin of the waters of the World Ocean and gases of the atmosphere is associated with the processes of degassing of the Earth's mantle. .

Thus, the ocean arose from vapors of mantle material, which were released together with outpourings of the main lavas on the surface of the primitive Earth.

HISTORY OF OCEANIC WATERS. Volcanic and intrusive rocks make up at least 90% of the modern earth's crust, and deeper than 10-30 km, the upper shell of the Earth is entirely composed of igneous material that came from even greater depths.

Currently, there are about 800 active volcanoes on our planet, confined to seismic belts. In the recent past, volcanic activity was more intense. According to G. Menard, only at the bottom of the Pacific Ocean there are about 10,000 volcanic seamounts (more than 1 km high), at the bottom of the Atlantic Ocean - about 4,000 volcanoes, etc. According to statistical calculations, it was found that over the past 180 million years, an average of 30 km 3 volcanic material. Moreover, about 75% of volcanic rocks accumulated at the bottom of the oceans, 20% - on islands in the transition zones from oceans to continents, and only 5% on land. Considering that the oceans occupy 71% of the Earth's surface, it is easy to calculate that approximately 3/4 of the volcanic rocks are basalt cloaks underlying the oceans.

According to direct observations and calculations, the amount of water (in the form of vapors) released during known volcanic eruptions of basalts usually varies between 3–5%, and in some cases up to 8%, relative to the mass of erupted rocks.

All these data allow us to assert that the outpouring of basalts has always brought, as a result of degassing, to the earth's surface an average of 7% of juvenile water in the form of water vapor. Various gases also came to the surface of the Earth (at the first stages of its evolution) from its depths - CH 4, CO, CO 2, H 3 BO 3, NH 3, S, H 2 S, HC1, HF, and a small amount of inert gases. Among the volcanic gases that formed the primary atmosphere and hydrosphere, water vapor and carbon dioxide were in the first place. If the temperature of the surface of the newborn Earth exceeded 100°C, then water in a vaporous state formed the atmosphere for some time. When the temperature dropped below 100°C, which probably occurred in the polar regions, water began to condense and form primary reservoirs. The conditions of the planet's surface began to obey latitudinal zonality. The water cycle began on the surface of the globe, which led to the removal of a number of chemical elements from the surface of the primary land areas into emerging water bodies.

The first portions of volcanic water on the surface of the Earth were acidic . They were characterized by the presence of those anions that are still found in sea water, with the exception of the SO 4 2- ion, which arose later, due to the creation of an oxidizing environment in the biosphere. This means that the first condensed waters on Earth were mineralized, and the actual fresh waters of the hydrosphere arose somewhat later, as a result of evaporation from the surface of reservoirs.

Strong acids, which were part of the juvenile waters, intensively destroyed the primary aluminosilicate rocks, extracting from them alkaline and alkaline earth elements, as well as divalent cations - iron and manganese. The land surface was washed by acid rains and was the site of hydrolysis and hydration of the corresponding minerals. The same processes, but of a slightly different scale, took place at the bottom of the reservoirs, where the first weathering products were carried. During the water cycle, Na + , K + , Mg 2+ , Ca 2+ cations were removed from the lithosphere and a significant part of them began to linger in the ocean. In this regard, it can be considered that most of the cations of ocean water arose as a product of weathering of the primary lithosphere .

Restoring the evolution of the hydrosphere, one should note the dynamic nature of the entire water shell of the Earth as a whole. Under modern conditions, for 3000 years, the amount of evaporated water involved in the cycle is equal to the mass of water in the World Ocean, and for 9 million years, the process of photosynthesis processes a mass of water equal to the entire ocean. In the process of the water cycle in the biosphere, there is an exchange of its parts of different intensity within specific accumulations (reservoirs, glaciers, rivers, groundwater). As already noted, the lowest activity of water exchange in the hydrosphere falls on glaciers (8000 years), and the highest activity, after atmospheric moisture, is characterized by river waters, which are replaced on average every 11 days.

Hydrosphere

Water is almost ubiquitous on Earth. It forms its own shell. Which is called the hydrosphere. This shell penetrates into all other spheres of the Earth, since it, like water, is "everywhere". Here a broad interpretation of the hydrosphere is given, which includes all types of natural waters. The hydrosphere covers the waters of the World Ocean, surface waters, atmospheric waters, ground and ground ice, all types of water of the earth's interior and biogenic waters, that is, it is possible to distinguish aboveground, ground and underground hydrosphere.

The subject of study of hydrogeology is underground hydrosphere - this is the most complex water terrestrial shell. Its complexity is explained by several circumstances: 1) a very thin layer of the underground hydrosphere accessible for study (up to 5-12 km); 2) the presence in the underground hydrosphere, in addition to the liquid, solid and vapor phases, of several specific types of water (physically bound, chemically bound, etc.); 3) specific and diverse conditions and processes of interaction of water with the water-containing medium (rocks, gases, living organisms). With all this, it should be remembered that the underground hydrosphere is primary in relation to the terrestrial and aboveground water shells. First, underground waters were formed, which, in the process of the evolution of the Earth, passed into the ground and above-ground state. Gradually, the nature of water exchange between the shells acquired a modern look.

The separation of the Earth's shells occurred about 4 billion years ago. According to the hypothesis of American scientists, 4.25 billion years ago, the Earth collided with a space object the size of Mars. From the collision, the surface layer of the Earth 1000 km thick melted, the Earth received an impulse and spun around its axis with an ecliptic of 23 0, which stabilized the Earth's day (24 hours). 90% of the substance of the cosmic body was absorbed by the Earth, and 10% formed a “ring” similar to Saturn, which then gathered and formed the Moon. At first, it was 15 times closer to Earth. All this led to the separation of the shells of the Earth. Due to the heating of the mantle substance, according to Academician A.P. Vinogradov, it was divided into two phases: refractory (dunites) and fusible (basalts).

During this process, the most volatile components of basaltic magma, water vapor and gases, rushed to the Earth's surface. The mechanism of this grandiose process of melting and degassing of the mantle A.P. Vinogradov was reproduced experimentally (zone melting). The mantle contains approximately 20·10 8 tons of water, and 7.5 - 24% of this amount migrated to the earth's crust and the World Ocean, i.e. participated in the creation of the hydrosphere. 1·10 4 tons could come from space with meteorites, i.е. 4 orders of magnitude smaller. The upper layers of the atmosphere could give even less water (silver clouds discovered by Vernadsky).

Thus, the mantle is the only source of water on Earth.

1. Evolution of the hydrosphere began at the turn of the Archean - Proterozoic, when a dynamic balance was established between water and gases. At the same time, a granite layer formed, geosynclines and platforms separated, and continental seas arose. All this marked the beginning of the atmosphere and the regular hydrological cycle of water.

According to A.P. Vinogradov, volatile substances became a source of anions in the salt mass of ocean water, and all the main cations were formed during the destruction of rocks.

At an early stage, there was almost no oxygen in the atmosphere, but there were CO 2, NH 3, NH 4, H 2 S, Hcl, etc.

2. Approximately 2.0 - 2.7 billion years ago there was a change in reducing conditions in the atmosphere and on the surface to oxidizing ones, and the source of O 2 was photochemical reactions with H 2 O and CO 2 in the upper layers of the atmosphere.

3. The emergence of life. In connection with intense cosmic and ultraviolet radiation, complex organic compounds were formed from CH 4, NH 3, H 2, H 2 S, CO 2, H 2 O, etc., and on their basis at a certain depth in the ocean (under the screen of the water layer ) the simplest organisms developed, but they did not exist on land (since the ozone screen did not yet exist. Its formation caused the first deep biological revolution, since the reduction of H 2 O in the process of life led to the release of free oxygen, which was the beginning of the formation of modern oxygen- nitrogen atmosphere and ozone screen, and life was able to develop on land.As a result of the formation of the atmosphere, the radiogenic and photogenic synthesis of complex organic molecules ceased.

4. In the early Paleozoic, aНСО 3 – СОˉ 3 equilibrium, which ensured the stability of the composition of ocean waters. With the advent of life on Earth, the processes of weathering changed in the direction of intensification under the influence of CO 2 . As a result of photosynthesis, oxygen in the atmosphere is currently renewed in 2–3 thousand years, and carbon dioxide in 350–500 years (excluding the modern greenhouse effect), and all the water of the World Ocean passes through photosynthetic plants in several million years.

5. Formation of fresh water on Earth.

The main factors in the appearance of fresh water on Earth are the emergence of life, the formation of the modern atmosphere, the dismemberment of the earth's crust into platforms and geosynclines. All this has an age of 2.5 - 3.0 billion years. It was the emergence of a large hydrological water cycle that led to the formation fresh groundwater from atmospheric precipitation.

Concerning the composition of the waters of the World Ocean, there are ambiguous opinions. Some believe that it was formed in the early Paleozoic. Others are in favor of significant changes in composition even over the last 0.5-0.6 billion years. For example, Yu.P. Kazansky established 5 hydrogeological types of oceanic waters during the evolution of the hydrosphere from the Archean to the Cenozoic, and the modern sulfate-chloride sodium-calcium composition appeared, according to his data, in Perm. Along with the water exchange between the world ocean and the underground hydrosphere, there has been and is salt exchange. The composition of the World Ocean reflects the conditions of previous eras, and due to the huge water masses, it reacts poorly to outside influences. The isotopic ratio of H 2 /H 1 and O 18 / O 16 does not change over 300 - 500 million years. This consistency is used as the Standard middle ocean water (SMOW) standard.