The hydrosphere of the earth and its boundaries. The hydrosphere is the water shell of the Earth. Environmental problems of the hydrosphere

The Earth's hydrosphere is the water shell of the Earth.

Introduction

The Earth is surrounded by an atmosphere and a hydrosphere, which are noticeably different, but at the same time complement each other.

The hydrosphere arose at the early stages of the formation of the Earth, like the atmosphere, influencing all life processes, the functioning of ecological systems, determining the emergence of many species of animals.

What is the hydrosphere

Hydrosphere translated from Greek means a water sphere or a water shell of the earth's surface. This shell is continuous.

Where is the hydrosphere

The hydrosphere is located between the two atmospheres - the gas shell of the planet Earth, and the lithosphere - a solid shell, which means land.

What is the hydrosphere made of?

The hydrosphere consists of water, which differs in chemical composition and is presented in three different states - solid (ice), liquid, gaseous (vapor).

The composition of the Earth's water shell includes oceans, seas, water bodies that can be salty or fresh (lakes, ponds, rivers), glaciers, fjords, ice caps, snow, rain, atmospheric water, and fluid flowing in living organisms.

The share of seas and oceans in the hydrosphere is 96%, another 2% is groundwater, 2% is glaciers, and 0.02 percent (a very small share) is rivers, swamps and lakes. The mass or volume of the hydrosphere is constantly changing, which is associated with the melting of glaciers and the departure of significant areas of land under water.

The volume of the water shell is 1.5 billion cubic kilometers. The mass will constantly increase, given the number of volcanic eruptions and earthquakes. Most of the hydrosphere is made up of oceans that form the World Ocean. This is the largest and saltiest body of water on Earth, in which the percentage of salinity reaches 35%.

According to the chemical composition, the waters of the oceans contain all the known elements that are located in the periodic table. The total part of sodium, chlorine, oxygen and hydrogen reaches almost 96%. The oceanic crust consists of basalt and sedimentary layers.

The hydrosphere also includes groundwater, which also differs in chemical composition. Sometimes the salt concentration reaches 600%, and they contain gases and derivatives. The most important of these are oxygen and carbon dioxide, which are consumed by plants in the ocean during the process of photosynthesis. It is necessary for the formation of limestone rocks, corals, shells.

Of great importance for the hydrosphere are fresh waters, part of which in the total volume of the shell is almost 3%, of which 2.15% are stored in glaciers. All components of the hydrosphere are interconnected, being in large or small turns, which allows the water to undergo a process of complete renewal.

The boundaries of the hydrosphere

The waters of the World Ocean cover an area of ​​71% of the Earth, where the average depth is 3800 meters, and the maximum depth is 11022 meters. On the land surface are the so-called continental waters, which provide all the vital activity of the biosphere, water supply, watering and irrigation.

The hydrosphere has a lower and an upper boundary. The lower one runs along the so-called Mohorovichic surface - earth's crust at the bottom of the ocean. The upper boundary is located in the uppermost layers of the atmosphere.

Functions of the hydrosphere

Water on Earth is essential for people and nature. It manifests itself in the following signs:

• First, water is important source minerals and raw materials, since people use water more than coal and oil;
• Second, it provides links between ecological systems;
• Thirdly, it acts as a mechanism that transfers bioenergetic ecological cycles of global importance;
• Fourth, it is part of all living beings that live on Earth.

Water becomes for many organisms the medium of origin, and then further development and formation. Without water, the development of land, landscapes, karst and slope rocks is impossible. In addition, the hydrosphere facilitates the transport of chemicals.

• Water vapor acts as a filter against the penetration of radiation rays from the Sun to the Earth;
• Water vapor on land helps regulate temperature and climate;
• The constant dynamics of the movement of ocean waters is maintained;
• A stable and normal circulation is ensured throughout the planet.

• Each part of the hydrosphere is involved in the processes that take place in the Earth's geosphere, which include water in the atmosphere, on land and underground. In the atmosphere itself, in the form of steam, there is more than 12 trillion tons of water. Steam is restored and renewed, thanks to condensation and sublimation, turning into clouds, fog. In this case, a significant amount of energy is released.
• Waters located underground and on land are divided into mineral and thermal, which is used in balneology. In addition, these properties have a recreational effect on both humans and nature.

If you answer the question of what the hydrosphere is rather superficially, then we can say that this is the water shell of our planet. It has its own complex structure, composition, is distinguished by many features and characteristics.

It is also impossible to deny its critical importance for all living things, from microorganisms to humans. After all, it is not for nothing that it is believed that life itself is possible only where there is water.

In a broad sense, the Earth's hydrosphere is understood as the entire supply of water on the planet in any of its form and state of aggregation, both on the surface and under the ground. This includes fresh salty water and even the liquid that is contained in living organisms.

Since about 70% of the planet's surface, that is, most of it, is occupied by the hydrosphere, it is not surprising that for ease of study it is divided into many groups and subgroups. For example, there are groups such as the World Ocean, continental waters, groundwater, which are divided into smaller components.

The boundaries of all these zones are rather arbitrary, but necessary for greater simplicity and systematization of the study of this most important component of nature.

What is the hydrosphere

As mentioned above, the concept of the hydrosphere refers to the totality of liquid on the Earth in all its states of aggregation, on the surface and underground, as well as inside all living organisms.

This also includes atmospheric moisture, which forms clouds and is involved in a host of important processes. Therefore, this broad concept should not be confused with simply water located in the World Ocean or continental rivers and lakes.

Such a name for this part of the geosphere was given to it in the old days - from the Greek "hydro" means water. Every literate person should know its main parts, understand the importance of this education not only for living, but also for inanimate nature.

Features of the composition of the hydrosphere are studied at school, but many by the beginning of adulthood have time to forget all this successfully, so it will be useful to update knowledge on this issue in your head.

Speaking in numbers, the mass of all liquid on the planet in all its forms is equal to 1.46 * 10 21 kilograms. The volume is 1.4 billion cubic centimeters. The largest percentage of the total volume of the hydrosphere falls on the oceans - about 95%.

The composition of the hydrosphere

It includes the following:

1. The world's oceans, which account for approximately 95% of the total volume.
2. Groundwater below the surface of the earth, which receives 4.5% of the total volume.
3. Next in size are glaciers, which in last years are melting at a faster rate. Their contribution to the total supply of liquid on the planet is 1.65%.
4. The remaining parts of the composition are soils, rivers, as well as atmospheric vapor, which is concentrated in its lower layers.

These groups are divided into smaller subgroups, but they are of interest to researchers and scientists, and not ordinary inquisitive citizens.

Origin of the hydrosphere

The origin of the World Ocean, as well as other parts of the hydrosphere, is still a mystery that specialists and researchers are struggling with.

On this moment There are two main hypotheses for its origin:

1. The hypothesis of a "cold" beginning, which says that at the beginning of time there was some primary cold dust cloud, which constantly heated up and changed its state of aggregation. As a result, it turned into the liquid known to everyone today.
2. The hot start hypothesis puts forward another theory. This scheme says that initially the Earth was a mixture of chemical elements heated to enormous temperatures. Gradually cooling, it was divided into gas, liquid, which eventually became the prototypes of the atmosphere and hydrosphere.

It is difficult to say unequivocally which theory is correct. Scientists are making efforts to give a definitive answer, but so far the truth is still far away.

It is worth noting: recent geochemical studies indicate that the formation of water and the hydrosphere is the result of a process of so-called degassing of the planet's shell.

The importance of the hydrosphere for humans and its role in the life of the Earth

The structure and study of the water shell is quite multifaceted, not without problems and contradictions, but, despite this, one cannot fail to recognize the importance of the hydrosphere for all life on Earth.

Without liquid, it is impossible to imagine the existence of not only humans or animals, but in general any form of life, including even the smallest bacteria and microorganisms.

That is why the search for life on other planets is now reduced to the search for water in some form there. This event is the first prerequisite for continuing the search.

Our life consists of many nuances, but water plays a key role in it. Biologists say that approximately 70% of the human body consists of water and various solutions based on it.

It is this form of existence that makes it possible to implement the necessary metabolic functions, to carry out the processes required by a living organism.

Water performs a transport function and delivers oxygen and micronutrients to all organs of our body, so its role in the life of all living things cannot be exaggerated.

As for the whole Earth in general, here too water acts the most important factor for all living things. It is she who makes up most of the atmosphere, participates in the formation of climate, gives precipitation, affects crop yields and many other issues.

It is enough to disturb the water balance at least in one part of the world, as everyone feels it: people, animals, animals, soil, groundwater, etc.

The hydrosphere is full amazing facts It is simply impossible to list all of them. This also applies to information about oceans, seas and rivers, and about lakes, currents operating in the ocean, existing glaciers and much more. Even school geography begins to acquaint us with such data, but they turn out to be very incomplete.

Lake Baikal

Let's pay attention to such interesting facts:

1. The largest and deepest river on the planet is Amazon, which is located in South America. It accounts for about 15% of all river water on Earth.
2. The largest number of lakes is found in Sweden.
3. If the water is too salty, then life cannot exist in it. A striking example is the Dead Sea in Israel.
4. 20% stock of all fresh water on the planet contains the deepest lake Baikal in Russia.
5. Ecological monuments from the hydrosphere are complemented by Lake Synevyr, in which even at a depth of 20 meters or more you can see the bottom and small pebbles on it.

Dangerous phenomena in the hydrosphere

Although the hydrosphere makes up the bulk of all life on the planet, people are not yet able to develop a careful attitude to water. Many factors lead to the fact that the structure is gradually changing, becoming less acceptable for normal life.

Here are the main problems that are observed today:

1. Water resources are constantly polluted. This is facilitated by the chemical industry, the accumulation of garbage and waste, radioactive, thermal and organic pollution.
2. Only 2% of the world's supply is drinking water. Already now in Israel and other countries people are faced with its deficit and the need to save. If you use purified water or recycled water, then there is a risk of serious infections, diseases and even death.
3. Many kilometers of drifting debris are observed in the ocean. There is so much of it there that since 2018, the governments of many countries have nevertheless decided to take up the catch and processing of waste. Objects for recycling are not yet very common, so there are difficulties with this issue.

The properties of water in its various states have not yet been fully studied. This is a unique substance that serves the main life and gives us the opportunity to exist. It is necessary to treat the hydrosphere very carefully and carefully, to do everything possible to keep the water around us clean.

This term was first used by a geologist from Austria Eduard Suess, author of the famous trilogy "The Face of the Earth", written in 1883-1909. It was he who defined the hydrosphere as a discontinuous shell of the Earth, located between the atmosphere and the lithosphere.

General characteristics of the Earth's hydrosphere

More than 70% of the earth's surface is covered with water. The total volume of the hydrosphere is about one and a half billion cubic kilometers, of which more than 95% is in the World Ocean.

The hydrosphere is in close interaction with other geospheres. Most sedimentary rocks form at the junction of the hydrosphere and lithosphere. The hydrosphere inhabited by living beings is also part of the biosphere.

Possessing high thermal conductivity, the hydrosphere plays an important role in ensuring the temperature balance of the planet, transferring heat from its depths to the periphery.

The boundaries of the Earth's hydrosphere

At present, the concept of the hydrosphere includes not only the space between the atmosphere and the lithosphere. This term has acquired a much broader meaning and now its boundaries are determined by the limits of the distribution of water as a chemical compound.

Thus, the upper boundary of the hydrosphere is a height of 8-18 km, where water molecules begin to decompose under the influence of ultraviolet radiation. The lower boundary is considered to be a depth of 6-14 km below the earth's surface and 10 km below the ocean floor. It is at this depth that decomposition and synthesis of water occur under the influence of high temperatures.

The chemical composition of the Earth's hydrosphere

The water of natural reservoirs is a solution of salts of various concentrations. Since the main constituent element of the hydrosphere is the World Ocean, then the average chemical composition its close to sea water. But if we consider each element of the hydrosphere separately, then a large heterogeneity of its chemical composition is revealed.

Most in sea water contains oxygen - about 85.7%. Further in descending order are hydrogen H (10.8%), chlorine Cl (1.98%) and sodium Na (1.03%). In quantitative terms, the upper layers of the ocean contain more than 140 trillion tons of carbon dioxide and 8 trillion tons of oxygen. In general, the ocean contains all known elements, but their concentration is very low. At the same time, their total content in water is huge and amounts to millions or billions of tons. For example, gold contains 6 million tons, and silver - 5 billion. Methods for extracting these metals from ocean water have already been patented.

The average concentration of salts in sea water is 35 g/l. An interesting feature sea ​​water is the constancy of the ratio between the main components of the main salt composition of water.

Chemical composition of atmospheric waters do not have a high salt content. Their concentration averages 50 mg/l.

Chemical composition of groundwater the most varied. Salt concentration here varies from 0.05 to 400 g/kg.

No less varied and chemical composition of surface and ground waters, in many respects it is determined by the climatic zone. But the composition of rocks, soil and vegetation is also of no small importance.

The chemical composition of surface waters is classified according to several indicators. Let's give an example of classification by hydrochemical index.

• 1. The content of macrocomponents - the main compounds contained in water. Namely compounds of potassium, sodium, magnesium and calcium.
• 2. The level of concentration of dissolved gases in water - oxygen, nitrogen, hydrogen sulfide, ammonia and methane.
• 3. Inorganic forms of biogenic elements - the products of vital activity of organisms. These include mainly inorganic compounds nitrogen and phosphorus. Biogenic elements in water can contain from zero to ten mg/l.
• 4. Organic forms of biogenic elements. They are responsible for the color and smell of water. This group includes almost all classes organic compounds.
• 5. Trace elements, i.e. all known metals. Their content in natural water is very low.
• 6. Bacteria and microorganisms.

The composition of surface waters also contains insoluble substances - sand, clay, silt, carbonates, bicarbonates, sulfates, chlorides, humus, plankton, etc. Their content varies from a few pieces to tens of thousands per liter of water, and sizes - from coarse to colloidal.

As a result of human activity, toxic pollutants have also appeared in the composition of natural waters. These include heavy metals, petroleum products, organochlorine compounds, phenols, etc.

Parts of the Earth's hydrosphere

The hydrosphere includes atmospheric, surface and ground water. Each of these groups is divided into subgroups. The quantitative ratio of the types of hydrosphere waters is given in Table 1.

Note: Dear visitors, hyphens in long words in the table are set for the convenience of mobile users - otherwise the words will not wrap and the table will not fit on the screen. Thanks for understanding!

Table 1. Parts of the Earth's hydrosphere

parts of the hydrosphere. Scheme.

Fresh water, occupying only a small percentage in the total composition of the planet's hydrosphere, plays an important role in human life.

About 75% of all fresh water on Earth is contained in the glaciers of the polar zones, in snow and permafrost. This water comes together under the name cryosphere. If all the ice in the cryosphere melted, the ocean level would rise by 64 meters. Recently, scientists have been anxiously monitoring the Arctic and Antarctic ice shelves. In the last few years alone, two glaciers have collapsed that have remained motionless for the past ten thousand years. More about it

20% of all fresh water reserves are groundwater and amount to 85 thousand km³.

5 to 10 years

Seasonal snow cover

2 to 6 months

soil crust

1 to 2 months

from 17 to 19 days

Lecture 3

The hydrosphere is the water shell of the earth.

Pollution of the hydrosphere.

Sources of pollution of the hydrosphere.

Water quality control methods.

Water protection measures.

Cleaning methods Wastewater.

The hydrosphere is the water shell of the Earth.

Hydrosphere- the water shell of the Earth, including all waters in liquid, solid and gaseous states.

The hydrosphere includes the waters of the oceans, seas, groundwater and land surface waters. Some water is found in the atmosphere and in living organisms.

Water occupies the predominant part of the Earth's biosphere (71% of the total area of ​​the earth's surface).

The hydrosphere already 4 billion years ago was represented by the following three components: terrestrial (World Ocean, river, soil, lake waters, glaciers), underground (waters of the lithosphere), air (vaporous water of the atmosphere). The hydrosphere includes the following types of water (in brackets, the share of the total volume of water in the hydrosphere,%, according to M.I. Lvovich, 1974):

World Ocean (94.0);

groundwater (4.3);

glaciers (1.7);

land waters (lakes, river waters, soil moisture) (0.03);

atmospheric vapors (0.001).

Water is a part of living matter as an essential component (70–99%). Essentially, living matter is water solution"living" molecules. It is water that keeps them alive. Terrestrial life originated in the aquatic environment, and therefore it can be considered a derivative of water.

Fundamental properties of water:

1. First property hydrosphere - unity and ubiquity"(in the words of V. I. Vernadsky) natural waters. All waters are interconnected and represent a single whole. This unity of natural waters is determined by:

a) easy transition of water from one phase state to another. Three states are known within the limits of terrestrial temperatures: liquid, solid, and vapor. The plasma state of water exists at high temperatures and pressures in the deep parts of the bowels;

b) the constant presence of gas components in the water. Natural water is an aqueous solution (gas, suspended solids, minerals).

2. Second property hydrosphere is determined special structure of the water molecule. The structure and properties of water provide the most favorable conditions for the development of life on Earth. We know from physics that all bodies expand when heated and contract when cooled. Water behaves differently. If it contracted when it turned into ice (cooling), the ice would be heavier than water and sink to the bottom of rivers and lakes. The rivers would be frozen to the bottom, and life in these reservoirs would be impossible. Ice is an insulator that keeps the water below the ice from freezing, which protects all underwater life. If it were not for this property, then the Earth would turn into an ice-bound planet.

The special structure of the water molecule provides manifold structure it when changing external factors (temperature, pressure, chemical composition). In winter, we had to observe the diversity and beauty of ice patterns on the windows, snowflakes, frost on the trees. Just as no two drops of water are exactly alike, so no two types of water are identical in structure.

3. Third property hydrosphere is expressed in its geologically eternal mobility. The movement of water is very diverse and manifests itself in numerous cycles. The main movement of water is the geological cycle of matter. Every second, under the influence of solar heat, millions of cubic meters of water rise up and form clouds. The wind sets the clouds in motion. Under the right conditions, moisture falls in the form of rain or snow. Raindrops have a favorable size for everything earthly and fall quietly, softly. Are all life-friendly coincidences accidental? Thus, water is involved in a kind of cycles of matter and energy. This system was established on Earth with the advent of free water and continues to this day.

Why is there movement? Movement can occur under the action of: a) gravity; b) solar (thermal) energy; c) molecular motion with a change in the phase state.

4. Fourth property hydrosphere is determined by high chemical activity of water. Under the conditions of the earth's crust, there are no natural bodies that would not dissolve to some extent in natural waters. Water in the biosphere acts as a universal solvent, because, interacting with all substances, as a rule, it does not enter into chemical reactions. This ensures the exchange of substances between land and ocean, organisms and the environment.

The most important abiotic factors of the aquatic environment are the following:

1. Density and viscosity.

The density of water is 800 times and the viscosity is about 55 times that of air.

2. Heat capacity.

Water has a high heat capacity, so the ocean is the main receiver and accumulator of solar energy.

3. Mobility.

The constant movement of water masses contributes to maintaining the relative homogeneity of physical and chemical properties.

4. Temperature stratification.

A change in water temperature is observed along the depth of the water body.

5. Periodic (annual, daily, seasonal) temperature changes

The lowest water temperature is considered to be - 2 ° C, the highest + 35-37 ° C. The dynamics of fluctuations in water temperature is less than that of air.

6. Transparency and turbidity of water.

Determines the light regime under the water surface. The photosynthesis of green bacteria, phytoplankton, higher plants, and, consequently, the accumulation of organic matter, depends on transparency (and its opposite characteristic - turbidity).

Turbidity and transparency depend on the content of substances suspended in water, including those entering water bodies along with industrial discharges. In this regard, the transparency and content of suspended solids are the most important characteristics of natural and waste waters that are subject to control at an industrial enterprise.

7. Salinity of water.

According to the degree of salinity, all water bodies are conventionally divided into

fresh with salinity less than 0.50/00,

brackish water - salinity ranges from 0.5 - 16 0 / 00,

salty - more than 16 0 / 00.

The salinity of oceanic water bodies is 32 - 38 0 / 00,

Salt lakes have the highest salt content, where the concentration of electrolytes reaches 370 0/00.

Main difference sea ​​water from river salt is that the vast majority of sea salt is chlorides, and in river water dominated carbonic salts. A person uses only fresh water for life support. Of the total water resources on the ground at share of fresh water account for no more than 3%.

8. Dissolved oxygen and carbon dioxide.

Excessive consumption of oxygen for the respiration of living organisms and for the oxidation of organic and minerals leads to the impoverishment of the living population up to the impossibility of habitation in such water of aerobic organisms.

9. Hydrogen ion concentration (pH).

All hydrobionts have adapted to a certain pH level: some prefer an acidic environment, others prefer an alkaline environment, and still others prefer a neutral one. Changes in these characteristics can lead to the death of hydrobionts.

The hydrosphere is the discontinuous water shell of the earth. What is included in its composition? How is it distributed on our planet? Why is life unthinkable without it?

Hydrosphere is one of the geological shells of our planet. It includes oceans, seas, all land water bodies (rivers, lakes, swamps and reservoirs), groundwater, glaciers and snow cover. The main component of the hydrosphere is water.

Often the hydrosphere is considered as a global open system, which occupies 75% of the surface the globe. The hydrosphere contains 1.5 billion km 3 of water, 96% of which falls on the share of the World Ocean. In underground and soil waters, rivers, lakes, swamps, reservoirs and glaciers, water reserves are measured in millions of km 3. There is much less water in the atmosphere, and its volume does not exceed 15 thousand km 3.

Water is the only chemical compound that exists in nature in both liquid and solid(ice), and gas (water vapor). Everyone is well aware that water under normal conditions is a colorless, odorless, transparent liquid. It has a number of amazing physical and chemical properties:

high surface tension (a significant capillary rise of water is associated with this property, which contributes to the nutrition of plants through root systems);
high boiling and freezing points;
specific enthalpies (heat content) of melting and evaporation are higher than those of most substances;
the density of water in the liquid phase is greater than the density of ice, so ice floats on the surface of the water, and reservoirs do not freeze to the bottom.

Water is an excellent solvent for many substances. Due to the high solubility of water, it contains almost all chemical elements of which are the most important for living organisms. The abundance of dissolved elements turns the aquatic environment into a kind of "witch's jelly", in which the most fantastic transformations of energy, matter and information are possible. Almost all biochemical processes that ensure the vital activity of organisms are reduced to reactions in aqueous solutions.

In a broad sense, the boundaries of the hydrosphere are determined by the boundaries of the distribution of water as a chemical compound. The upper detection limit for water is at an altitude of 8–18 km, where water molecules are decomposed by UV radiation. The lower boundary of the water shell is located at a depth of about 10 km below the ocean floor and 6–14 km below the earth's surface. According to the definition of V. I. Vernadsky, the lower boundary of the hydrosphere is that area of ​​the earth's crust where, at high temperatures (up to 1800 ° C), not only decomposition processes take place, but also the synthesis of water molecules.

From the point of view of ecology, the boundaries of the hydrosphere are defined more clearly and coincide with the boundaries of water bodies: marine and freshwater reservoirs and land streams.

The hydrosphere is a dynamically active shell. The horizontal transfer and mixing of water masses determines the constant redistribution of their properties, transmission over great distances and depths.

As already mentioned, about 96% of the volume of the hydrosphere falls on the share of the oceans. His main feature is conservatism and stability over time. Especially surprising is the preservation of the constancy of the salt composition of ocean water: the percentage of basic salts in it remains unchanged in any region of the ocean and at all depths, regardless of the degree of freshening.

The high heat capacity of water smooths out extreme temperatures, leads to the accumulation a large number heat, which creates favorable conditions for the development and spread of organisms throughout the water column.

The low variability of physical conditions in the World Ocean at one time contributed to the origin of life, and at present favors the maintenance of its greatest diversity. Of the 33 classes of plants known to biologists, 18 representatives are found in the hydrosphere, and 60 of the 63 classes of animals. We can assume that the hydrosphere, and in particular the World Ocean, are repositories of the species diversity of life.

It should be noted that the chemical composition of the blood of all animals (including humans) is similar in composition to sea water. Coming out of the "sea element" on land, living beings continue to maintain their familiar marine environment in their blood vessels. The functions of blood and sea water are basically the same. This is the transport of living cells, protein-carbohydrate complexes and dissolved gases.

Important properties of the oceanic environment, in addition to stability on a geological time scale, are also:

– continuity (unlike continental water bodies);
- continuous population and almost complete absence of lifeless zones;
– intensive circulation;
- the presence of ebbs and flows.

In the ocean, two main groups of habitats (biotopes) of plants and animals can be distinguished: these are coastal biotopes ( shelf zone) and open water biotopes ( pelagial).

Coastal biotopes have fairly pronounced, well-defined boundaries. Usually they are located along the shelf in belts (bands) parallel to the coastline, which replace each other as the depth increases.

In the pelagic part of the ocean, the structure of biotopes depends on the regime of currents and the characteristics of the circulation of water masses in each specific area. In the presence of stable connections of the entire water mass with the bottom (due to intensive hydrodynamic transfer), a single biotope is formed.

Much more often, however, a situation arises in the ocean when contrasting water masses, differing in physicochemical regime, are located one above the other like a layer cake. In this case, it is reasonable to consider them as separate biotopes. Common features pelagic biotopes are large and blurred boundaries.

How important are freshwater bodies and natural water in the Earth's hydrosphere?

The hydrosphere is formed by oceans, seas, land water bodies (rivers, lakes, swamps and reservoirs), as well as groundwater, glaciers and snow cover.

Compared to the ocean, fresh water covers a small portion of the Earth's surface; they account for only about 0.5% of the total volume of the hydrosphere. However, for humans, continental water bodies and streams play the same important role as oceanic ones.

First, continental reservoirs and streams are the main source of fresh water for domestic and industrial needs. Secondly, freshwater ecosystems are used by humans as convenient and cheap waste processing systems.

Natural freshwater biotopes can be divided into two classes: stagnant reservoirs(lakes, ponds, oxbow lakes) and flowing streams(rivers and streams). There are no sharp boundaries between these groups, and even more so within each of them.

In general, stagnant water bodies have low dynamic activity. They may develop stagnant zones characterized by oxygen deficiency.

The main feature of watercourses is the presence of a more or less pronounced current, which, as a rule, averages the distribution of the physical conditions of the aquatic environment.

Under the influence of directed anthropogenic impact, a third, very extensive class of biotopes with intermediate properties was formed in the hydrosphere. This - reservoirs, combining the features of reservoirs and streams.

Fresh water bodies differ from oceanic ones in a variety of conditions and a high degree of discreteness. The isolation of continental water bodies and streams from each other, the individuality of the hydrological regime, and the great dependence on the land environment create very significant differences between water bodies even in geographically close areas. Particularly variable are artificial reservoirs, some of which are subjected to heating (discharge warm waters), others to severe pollution, and others to periodic drying and freezing.

Fresh water on the planet is less than 3% of its total reserves, of which 75% is in the Arctic and Antarctic, 20% is groundwater, and only 1% is concentrated in rivers, lakes and clouds. For many regions, the problem of fresh water is one of the most important environmental problems.

Natural water is a solution of salts, organic matter and gases. Basically, natural water is formed as a result of rainfall, less often it has a deep origin, that is, it is a condensate of vapors rising from the bowels of the earth.

The chemical composition of lake, river and groundwater varies widely and depends on the composition of the rocks, soil cover and vegetation.

Currently, there are several classifications of the chemical composition of natural waters. For example, according to hydrochemical indicators in natural waters, the following important characteristics are determined:

1. The main compounds contained in water are called macrocomponents. These include compounds of potassium, sodium, magnesium, calcium. It should be noted that in ocean water, regardless of the absolute concentration, the ratio between the main components of the main salt composition always remains constant.

2. Concentration dissolved gases(oxygen, nitrogen, hydrogen sulfide, ammonia and methane) is determined by their partial pressure.

3. Biogenic elements(waste products of organisms) - mainly inorganic compounds of nitrogen and phosphorus. Their concentration in fresh water bodies varies over a very wide range: from traces to 10 mg/l. Biogenic elements also include silicon compounds found in water in the form of colloidal or dissolved forms, iron compounds, mainly in the form of colloidal iron hydroxides or organic complexes.

4. Dissolved organic matter(DOM), that is, organic forms of biogenic elements. This group includes practically all classes of organic compounds. This group includes substances that give water a smell and color.

5. Microelements. This group includes all metals, for example, copper, manganese. They are found in natural waters in very low concentrations.

6. Living biomass bacteria and microorganisms.

Surface natural waters are characterized by a high content of insoluble substances - in particular, organic compounds. In addition to sand and clay particles, they contain loess, silt, various carbonates, bicarbonates, sulfates, chlorides, hydroxides of aluminum, manganese and iron, high-molecular organic impurities of humus origin (sometimes in the form of organomineral complexes), plankton, etc. The content of suspended particles in surface water bodies varies from a few to tens of thousands per liter. The particle sizes of substances in suspension vary from coarse to colloidal.

Due to anthropogenic activity, another type of compounds can be introduced into the chemical composition of natural waters - this toxic pollutants: heavy metals, petroleum products, organochlorine compounds, synthetic surfactants (surfactants), phenols. When natural water is chlorinated, dioxins can also form in it.

In total, natural waters contain about 50 chemical elements in noticeable quantities.

The hydrosphere, like all other geospheres of the planet, has natural radioactive background. Its main sources are isotopes of potassium, uranium, thorium, protactinium and their decay products. For example, more than 90% of the total radioactivity of sea water is formed by isotopes of uranium, thorium and radium. The natural radioactivity of rainwater can sometimes reach a fairly high value, which, however, decreases quite rapidly with time. This is due to the presence in such water of short-lived decay products of the inert gas radon.

Natural water, which we use daily, is not a simple chemical compound. It is different in different regions, and its chemical composition depends on the combined action of many factors.