Unified global biogeochemical cycle of elements.

6.1. The water cycle

The water cycle- one of the main components of the abiotic circulation of substances, includes the transition of water from liquid to gaseous and solid states and back (Fig. 9). It has all the main features of other cycles - it is also approximately balanced on the scale of the entire globe and is driven by energy. The water cycle is the most significant cycle on Earth in terms of mass transfer and energy consumption. Every second, 16.5 million m3 of water is involved in it and more than 40 billion MW of solar energy is spent on this.

Rice. 9. The water cycle in nature

The main processes that ensure the water cycle are: infiltration, evaporation, runoff:

1. Infiltration - evaporation - transpiration: water is absorbed by the soil, retained as capillary water, and then returned to the atmosphere, evaporating from the surface of the earth, or absorbed by plants and released as vapor during transpiration;

2. Surface and subsurface flow: water becomes part of surface water. Groundwater movement: Water enters and moves through the ground, feeding wells and springs, before reentering the surface water system.

Thus, the water cycle can be represented in the form of two energy paths: the upper path (evaporation) is driven by solar energy, the lower path (precipitation) gives energy to lakes, rivers, wetlands, other ecosystems and directly to humans, for example, at hydroelectric power stations. Human activities have a huge impact on the global water cycle, which can change weather and climate. As a result of covering the earth's surface with materials impervious to water, building irrigation systems, compacting arable land, destroying forests, etc., the flow of water into the ocean increases and the replenishment of groundwater is reduced. In many dry areas, these reservoirs are pumped out by humans faster than they are filled. In Russia, 3,367 groundwater deposits have been explored for water supply and land irrigation. The exploitable reserves of explored deposits are 28.5 km 3 /year. The degree of development of these reserves in the Russian Federation is no more than 33%, and 1,610 deposits are in operation.

The peculiarity of the cycle is that more water evaporates from the ocean (approximately 3.8 10 14 tons) than it returns with precipitation (approximately 3.4 10 14 tons). On land, on the contrary, more precipitation falls (approximately 1.0 10 14 t) than evaporates (in total about 0.6 10 14 t). Because more water evaporates from the ocean than is returned, much of the sediment used by terrestrial ecosystems, including agroecosystems that produce human food, consists of water evaporating from the sea. Excess water from land flows into lakes and rivers, and from there back into the ocean. According to existing estimates, fresh water bodies (lakes and rivers) contain 0.25 10 14 tons of water, and the annual flow is 0.2 10 14 tons. Thus, the turnover time of fresh water is approximately one year. The difference between the amount of precipitation falling on land per year (1.0 10 14 t) and runoff (0.2 10 14 t) is 0.8 10 14 t, which evaporates and enters subsoil aquifers. Surface runoff partially replenishes groundwater reservoirs and is itself replenished from them.

Atmospheric precipitation is the main link in moisture circulation and largely determines the hydrological regime of land ecosystems. Their distribution throughout the territory, especially in the mountains, is uneven, which is due to the characteristics of atmospheric processes and the underlying surface. For example, for the forest-tundra open forests of the Putorana forest-growing province of Central Siberia, the annual precipitation amount is 617 mm, for the northern taiga forests of the Lower Tunguska forest-growing district - 548, and for the southern taiga forests of the Angara region it decreases to 465 mm (Table 2).

table 2

Evapotranspiration of forest ecosystems of the Yenisei meridian

District, province	Growing stock, m 3 /ha *	Precipitation, mm **	Evaporation, mm ***
			intercepted precipitation
Tundra forests
Putorana forest province
Northern taiga
Turukhansky forest vegetation district
Southern taiga
Priangarsky forest district

* – Vedrova et al. (from the book Forest Ecosystems of the Yenisei Meridian, 2002);

**, *** – Burenina and others (ibid.).

Evaporation has one of the leading places. With the advent of life on Earth, the water cycle became relatively complex, since the physical phenomenon of turning water into steam was supplemented by the process of biological evaporation associated with the life of plants and animals - transpiration. Along with precipitation and runoff, evapotranspiration, which includes the evaporation of intercepted precipitation, transpiration of moisture by plants and subcanopy evaporation, is the main expenditure item of the water balance, especially in forest ecosystems. For example, in a tropical rain forest the amount of water evaporated by plants reaches 7000 m3/km2 per year, while in a savannah at the same latitude and altitude from the same area it does not exceed 3000 m3/km2 per year.

Vegetation in general plays a significant role in water evaporation, thereby influencing the climate of regions. The rate of evapotranspiration depends on the radiation balance and different vegetation productivity. As can be seen from table. 2, with an increase in above-ground phytomass due to greater evaporation of intercepted sediments and transpiration moisture consumption, total evaporation increases.

In addition, higher vegetation performs a water protection and water regulation function that is very important for terrestrial ecosystems: it mitigates floods, retaining moisture in the soils and preventing them from drying out and erosion. For example, when deforestation occurs, in some cases the likelihood of flooding and swamping of the territory increases, in others, the stopping process of transpiration can lead to a “drying” of the climate. Deforestation negatively impacts groundwater, reducing the area's ability to retain rainfall. In some places, forests help replenish aquifers, although in most cases forests actually drain them.

Table 3

Proportion of fresh and salt water on Earth

The total water reserves on Earth are estimated at approximately 1.5 to 2.5 billion km 3 . Salt water makes up about 97% of the volume of the water mass; the World Ocean accounts for 96.5% (Table 3). The volume of fresh water, according to various estimates, is 35–37 million km 3, or 2.5–2.7% of the total water reserves on Earth. Most of the fresh water (68–70%) is concentrated in glaciers and snow cover (according to Reimers, 1990).

Previous

1. Global water cycle.

2. Global carbon cycle.

3. Oxygen cycle.

4. Types of photosynthesis and producing organisms.

5. Types of catabolism and destructive organisms.

6. Overall balance of production and decomposition processes.

Global water cycle.

Globally, the water and CO 2 cycles are probably the most important biogeochemical cycles for humanity. Both are characterized by small but highly mobile funds in the atmosphere, highly sensitive to disturbances caused by human activity and which can influence weather and climate.

Although water is involved in the chemical reactions that make up photosynthesis, most of the water flow through an ecosystem is due to evaporation, transpiration (evaporation from plants), and precipitation.

The water cycle, or hydrological cycle, like any other cycle, is driven by energy. The absorption of light energy by liquid water represents the main point at which the energy source is coupled to the water cycle. It is estimated that about a third of all solar energy reaching the Earth is spent on driving the water cycle.

More than 90% of the earth's water is bound in the rocks that form the earth's crust and in sediments (ice and snow) on the earth's surface. This water enters the hydrological cycle occurring in the ecosystem very rarely: only during volcanic emissions of water vapor. Thus, the large reserves of water present in the earth's crust make a very insignificant contribution to the movement of water near the Earth's surface, forming the basis of the reserve fund of this cycle.

The amount of water in the atmosphere is small (about 3%). The water contained in the air as vapor at any given moment corresponds to an average layer of 2.5 cm thick, evenly distributed over the surface of the Earth. The amount of precipitation that falls per year averages 65 cm, which is 25 times more than the amount of moisture contained in the atmosphere at any given moment. Consequently, water vapor constantly contained in the atmosphere, the so-called atmospheric fund, cycles 25 times annually. Accordingly, the time of water transfer in the atmosphere is on average two weeks.

Particular attention should be paid to the following aspects of the water cycle:

1. The sea loses more water due to evaporation than it receives through precipitation; on land the situation is opposite. That. Much of the sediment that supports terrestrial ecosystems, including most agroecosystems, consists of water evaporated from the sea.

2. An important, if not the main role of plant transpiration in the total evapotranspiration (evaporation) from land. The effect that vegetation has on water movement is best revealed when the vegetation is removed. Thus, the experimental cutting down of all trees in small river basins increases the flow of water into the rivers draining the cleared areas by more than 200%. Under normal conditions, this excess would be released directly into the atmosphere in the form of water vapor.

3. Although surface runoff replenishes groundwater reservoirs and is itself replenished from them, these quantities have an inverse relationship. As a result of human activities (covering the earth's surface with materials impervious to water, creating reservoirs on rivers, building irrigation systems, compacting arable lands, clearing forests, etc.), runoff increases and the replenishment of such an important groundwater fund is reduced. In many dry areas, groundwater reservoirs are now being pumped out by humans faster than they are being replenished by nature.

Water dispersed in the atmosphere, buried in the earth's crust, or constituting the hydrosphere itself plays an exceptional role in the functioning of the entire geographic envelope as a dynamic system in continuous motion.

The water cycle is a continuous process of moisture circulation, covering the atmosphere, hydrosphere, lithosphere and biosphere. It occurs according to a conventional scheme: precipitation, surface and underground runoff, infiltration, evaporation, transfer of water vapor in the atmosphere, its condensation, repeated precipitation. The driving force behind the global water cycle is solar energy, which causes evaporation from the surface of the oceans and land. The main source of moisture entering the atmosphere (85%) is the surface of the World Ocean, and about 14% comes from the land surface. During the cycle, water can move from one state of aggregation to another. There are water cycles in the atmosphere, between the atmosphere and the Earth's surface, between the Earth's surface and the interior of the lithosphere, within the interior of the lithosphere, and in the hydrosphere.

This is how S. Kalesnik describes the water cycle in nature: “Evaporation of water from the surface of the ocean, condensation of water vapor in the atmosphere and precipitation on the surface of the ocean form a small cycle. But when water vapor is carried onto land by air currents, the water cycle becomes more complex. Part of the precipitation that falls on the surface of the land evaporates and enters back into the atmosphere, while the other part flows through surface and underground routes into depressions of the relief and feeds rivers and standing reservoirs. The process of water evaporation and precipitation on land can be repeated many times, but in the end, moisture brought to land by air currents from the ocean returns to the ocean again by river and underground runoff, completing its large cycle.”.

The water cycle is not confined to Earth. Molecules of water vapor, raised into high layers of the atmosphere, undergoing photodissociation under the influence of ultraviolet rays of the Sun, disintegrate into oxygen and hydrogen atoms. Due to high temperatures in the thermosphere, the speed of hydrogen particles exceeds cosmic speed, and it leaves the atmosphere into interplanetary space - the site. Obviously, the escape of one hydrogen atom means for the Earth the loss of one molecule of water. In turn, Space supplies the Earth with water, which is contained in meteorite matter and icy comets. According to some estimates, about 80 m3 of moisture enters the Earth per day this way, i.e. 25 - 30 thousand tons annually.

In the natural water cycle, three main parts can be distinguished: continental, oceanic and atmospheric.

Continental link of the water cycle

Getting to the surface of the land in the form of precipitation, water either seeps into the soil (infiltration) or flows along the surface, forming surface and river runoff, and then enters lakes, seas and oceans.

Global volume of water cycle per day, km 3

Part of the water evaporates, and evaporation occurs both directly from the surface of the soil, reservoirs and above-ground plant organs, and from the soil, weathering crust and rocks after rising through capillaries to the surface. Part of the moisture that seeps into the soil moves in the form of intrasoil runoff, as well as ground and underground waters. Ground and underground waters sometimes reach the earth's surface on slopes, in places where aquifers have pinched out, and also in river beds. Part of the groundwater replenishes the water reserves of deep underground horizons and thereby leaves active water exchange for a long time.

Glaciers are a specific element of the continental part of the water cycle. The mass of glaciers on Earth has experienced great fluctuations throughout geological history. Several times, large continental glaciations occurred on the planet, when huge masses of water were withdrawn from the ocean and concentrated in the form of ice sheets on land (mainly in the circumpolar regions). During such periods, the level of the World Ocean dropped by 100 m or more. On the contrary, during interglacial periods; glaciers disappeared almost completely, which led to an increase; ocean level.

Oceanic part of the water cycle

The ocean is heated mainly from above due to the absorption of solar radiation and thermal counter-radiation of the atmosphere. The geothermal flow going to the ocean floor from the earth's interior is small and does not have a significant effect on the thermal regime of the ocean, except for its deepest zone. The heating of ocean water from above imparts hydrostatic stability to it (the warming upper layers have a lower density than the underlying colder ones), as a result of which vertical movements in the ocean are less pronounced than in the atmosphere. This is also facilitated by the higher density of water compared to air.

The totality of water movements in the ocean consists of movements and cycles of various spatial and temporal scales. The periods of movements range from a few seconds to hundreds of years, and the spatial (horizontal and vertical) scales range from a few millimeters to thousands of kilometers. In addition to sea currents that make up the general circulation of the oceanosphere, the oceanic link also involves turbulent phenomena, surface and internal waves, tidal phenomena (level fluctuations and tidal currents), meanders and eddies, upwelling and downwelling phenomena that transfer water energy horizontally and vertically directions.

In accordance with the zonal distribution of solar energy over the surface of the planet, in the ocean and atmosphere, genetically interconnected circulation systems are created, formed by similar water and air masses. The most important mechanical factor in the occurrence of oceanic circulation is wind friction on the surface of the water, due to which the ocean receives mechanical energy from the atmosphere. The wind causes drift currents, which cause water to flow in some areas and surge in others, resulting in gradient currents.

The formation of currents is also facilitated by thermohaline factors: the receipt and release of heat, precipitation, evaporation, and the influx of water from the continents affect the temperature and salinity of the water, and thereby its density. Denser layers sink, which leads to vertical mixing and then to horizontal transport (advection).

One of the characteristic features of the circulation of surface waters of the World Ocean is the system of cycles of individual elements. The figure shows that sea currents form circulation systems in each ocean. The exception is the Antarctic Circumpolar Current (Western Wind Current, or Great Eastern Drift), which forms a continuous flow of water around the globe in the mid-latitudes of the Southern Hemisphere, which has no analogue in the Northern Hemisphere.

Surface currents of the World Ocean: central gyre of the North Pacific Ocean: 1 - Kuroshio; 2 - North Pacific; 3 - Californian; 4 - Northern Passatnoye; central gyre of the South Pacific: 5 - East Australian; 6 - Western Winds (part of the Antarctic Circumpolar Current); 7 - Humboldt (Peruvian); 8 - South Passatnoe; central gyre of the North Atlantic: 9 - Gulf Stream; 10 - North Atlantic; 11 - Canary; 12 - Northern Passatnoe; central gyre of the South Atlantic: 13 - Brazilian; 14 - Western Winds (part of the Antarctic Circumpolar Current); 15 - Benguela; 16- South Passatnoye; central gyre of the Indian Ocean: 17 - Cape Agulhas; 18 - Western Winds (part of the Antarctic Circumpolar Current); 19 - Western Australian; 20 - South Passatnoe; subarctic gyre of the northern part of the Pacific Ocean: 21 - Alaskan; 22 - Alaskan Stream; 23 - Slope current of the Bering Sea; 24 - Kamchatsky; 25 - Oyashio; subtropical North Atlantic gyre: 26 - Irminger; 27 - East Greenland; 28 - Labrador; other circulation elements: 29 - Inter-trade wind countercurrent; 30 - Somali Current.

The circulation of surface waters almost completely repeats the main wind systems that have developed in one or another region of the World Ocean, however, it is impossible to explain the circulation of the ocean only by processes in the atmosphere, since there are other sources, including those of extraterrestrial origin (Moon, Sun).

If you calculate the gain and loss of water due to surface currents, you will find an imbalance: in some areas more water flows in than it leaves, in others - vice versa. The answer should be sought in the vertical exchange that connects surface currents with deep ones. At depth, the system of currents differs from the surface one, and in many cases deep countercurrents are observed, directed in the direction opposite to the distribution of surface waters. For example, the Cromwell Current in the Pacific Ocean at a depth of 100-400 m moves from west to east under the surface South Trade Wind Current, the Lomonosov Current in the Atlantic Ocean also passes under the South Trade Wind Current from west to east. However, in surface systems, surface countercurrents are formed that delimit flows of one direction (for example, the inter-trade countercurrents of the Pacific and Atlantic oceans).

At specific moments in time, the current fields that make up the oceanic link will differ from the average picture. Like rivers, they can bizarrely change directions (meander) or form eddies, like air or channel flows.

The ocean has great thermal and dynamic inertia and its response to the influence of the atmosphere is delayed. The ocean is a kind of “memory device” that stores “imprints” of the atmosphere for some previous period.

Atmospheric link of the water cycle

Moisture enters the atmosphere through evaporation. Every year, 577·1012 m3 of water evaporates from the earth's surface, and 505·1012 m3 of this water evaporates from the surface of the ocean. 80% of the radiation budget is spent on evaporation. The same amount of energy is released when moisture condenses in the atmosphere at the cloud level, and water vapor, moving hundreds and thousands of kilometers, also transfers a large amount of heat. The release of latent heat of vaporization into the atmosphere during condensation is the most important energy source of atmospheric processes. This is why water vapor is called the "primary fuel of the atmosphere."

The exchange of air containing moisture between the equator and the poles is achieved mainly due to the horizontal transfer of air masses. Vertical movements are not excluded, but their speed is much less than the speed of horizontal ones.

Economic link of the water cycle

The idea of ​​unlimited fresh water supplies on Earth has been thoroughly revised. The main consumers of water (usually fresh) are agriculture, industry and the population. In agriculture, the largest (over 2·10 12 m 3) amount of water is spent on irrigation, and 80% of it irrevocably leaves the river network in the composition of chemical compounds or through evaporation. The total water intake for industrial needs is 0.7·10 12 m 3 /year, of which 5-10% is irrevocably withdrawn to support technological processes. About 0.2·10 12 m 3 /year is used for the needs of the population, and a sixth of the water does not return to the river network - site. It should be taken into account that wastewater for almost any neutralization must be diluted with clean water, which currently consumes approximately 40% of all the world's quality water resources.

In relation to river flow, these volumes are small. However, in the most densely populated areas of Western and Central Asia, Africa, and in some industrial regions of Russia, there is already a noticeable shortage of water resources, which is even increasing. To make up for it, they resort to artificial territorial redistribution of runoff and land reclamation, which in turn not only creates numerous environmental problems, but is also not always economically justified.

The role of water in the processes occurring in the biosphere is enormous. Without water, metabolism in living organisms is impossible. With the advent of life on Earth, the water cycle became relatively complex, since the simple phenomenon of physiological evaporation was supplemented by the more complex process of biological evaporation (transpiration), associated with the life of plants and animals.

Briefly, the water cycle in nature can be described as follows. Water reaches the Earth's surface in the form of precipitation, which is formed mainly from water vapor entering the atmosphere as a result of physical evaporation and evaporation of water by plants. One part of this water evaporates directly from the surface of water bodies or indirectly through plants and animals, while the other feeds groundwater (Figure 1.13).

The nature of evaporation depends on many factors. Thus, significantly more water evaporates from a unit area in a forest area than from the surface of a water body. With a decrease in vegetation cover, transpiration also decreases, and, consequently, the amount of precipitation.

The flow of water in the hydrological cycle is determined by evaporation, not precipitation. The atmosphere's ability to hold water vapor is limited. An increase in evaporation rates leads to a corresponding increase in precipitation. The water contained in the air in the form of vapor at any moment corresponds to an average layer 2.5 cm thick, evenly distributed over the surface of the Earth. The amount of precipitation that falls per year averages 65 cm. Consequently, water vapor from the atmospheric front circulates approximately 25 times annually (once every two weeks).

The water content in water bodies and soil is hundreds of times greater than in the atmosphere, but it flows through the first two funds at the same speed. The average time of transport of water in its liquid phase across the Earth's surface is about 3650 years, 10,000 times longer than the time of its transport in the atmosphere. Humans in the process of economic activity have a strong impact on the basis of the hydrological cycle - water evaporation.

Pollution of water bodies and, first of all, seas and oceans with petroleum products sharply worsens the process of physical evaporation, and a decrease in forest area - transpiration. This cannot but affect the nature of the water cycle in nature.

Figure 1.13 - Water cycle

Global cycles of vitally important nutrients break up in the biosphere into many small cycles confined to the local habitats of various biological communities. They can be more or less complex and to varying degrees sensitive to various types of external influences. But nature has decreed that under natural conditions these biochemical cycles are “exemplary waste-free technologies.” Cycling covers 98-99% of nutrients and only 1-2% goes not even to waste, but to the geological reserve (Figure 1.14).

1.8 Fundamentals of biosphere sustainability

The stability of ecosystems and their entire biosphere depends on many factors (Figure 1.15), the essence of the most important of which is as follows:

Figure 1.15- Factors of biosphere stability

1. The biosphere uses external energy sources: solar energy and the heating energy of the earth’s interior to streamline its organization, effectively use free energy, without causing environmental pollution. The constant use of a certain amount of energy and its dissipation in the form of heat has created an evolutionarily established heat balance in the biosphere.

Biocenoses are characterized by the law (principle) of “energy conductivity”: the through flow of energy, passing through the trophic levels of the biocenosis, is constantly extinguished.

In 1942, R. Lindeman formulated the law of the energy pyramid or the law (rule) of 10%, according to which on average about 10% moves from one trophic level of the ecological pyramid to another higher level (“on the ladder” producer - consumer - decomposer). energy received at the previous level of the ecological pyramid.

2. The biosphere uses substances (mainly light nutrients) mainly in the form of cycles. Biogeochemical cycles of elements have been worked out evolutionarily and do not lead to the accumulation of waste.

3. There is a huge diversity of species and biological communities in the biosphere. Competitive and predatory relationships between species contribute to the establishment of equilibrium between them. At the same time, there are practically no dominant species with excessive numbers, which protects the biosphere from severe danger from internal factors.

Species diversity is a factor in increasing the resistance of ecosystems to external factors. The gene pool of wild nature is an invaluable gift, the potential of which has so far been used only to a small extent.

4. Almost all patterns characteristic of living matter have adaptive significance. Biosystems are forced to adapt to continuously changing living conditions. In the ever-changing environment of life, each type of organism is adapted in its own way. This is expressed by the rule of ecological individuality: no two species are identical.

The ecological specificity of species is emphasized by the so-called axiom of adaptability: each species is adapted to a strictly defined set of existence conditions specific to it - an ecological niche.

5. Self-regulation or maintenance of population size depends on a combination of abiotic and biotic factors. Each population interacts with nature as an integral system.

Population maximum rule: the size of natural populations is limited by the depletion of food resources and breeding conditions, the insufficiency of these resources and the too short period of acceleration of population growth.

Any population has a strictly defined genetic, phenotic, sex-age and other structure. It cannot consist of fewer individuals than is necessary to ensure its resistance to environmental factors.

The principle of minimum size is not a constant for any species; it is strictly specific for each population. Going beyond the minimum threatens the population with death: it will no longer be able to regenerate itself.

The destruction of each of these factors can lead to a decrease in the stability of both individual ecosystems and the biosphere as a whole.

Related information.

As is known, all structural components of the biosphere are closely interconnected by complex biogeochemical cycles of migration of substances and energy. Processes of mutual exchange and interaction occur at different levels: between geospheres (atmosphere, hydro, lithosphere), between natural zones, individual landscapes, their morphological parts, etc. However, a single general process of exchange of matter and energy dominates everywhere, a process that gives rise to various phenomena scale - from atomic to planetary. Many elements, having gone through a chain of biological and chemical transformations, return to the composition of the same chemical compounds in which they were at the initial moment. At the same time, the main driving force in the functioning of both global and small (as well as local) cycles are living organisms themselves.
The role of biogeochemical cycles in the development of the biosphere is exceptionally great, since they ensure the repetition of the same organic forms with a limited volume of the initial substance participating in the cycles. Humanity can only be amazed at how wisely nature is structured, which itself tells the “unlucky Homo sapiens* how to organize the so-called waste-free production. Let us note, however, that in nature there are no completely closed cycles: any of them is simultaneously closed and open. An elementary example of a partial cycle is water that, having evaporated from the surface of the ocean, partially returns there.
There are complex relationships between individual small cycles, which ultimately leads to a constant redistribution of matter and energy between them, to the elimination of a kind of asymmetric phenomena in the development of cycles. Thus, in the lithosphere, oxygen and silicon appeared in excess in a bound state, in the atmosphere in a free state - nitrogen and oxygen, in the biosphere - hydrogen, oxygen and carbon. It should also be noted that the bulk of carbon was concentrated in sedimentary rocks of the lithosphere, where carbonates accumulated the bulk of carbon dioxide that entered the atmosphere with volcanic eruptions.
We must not forget that there is a very close connection between space and the Earth, which, with a certain degree of convention, should be considered within the framework of the global circulation (since, as already noted, it is not closed). From space, our planet receives radiant energy (solar and cosmic rays), corpuscles of the Sun and other stars, meteorite dust, etc. The role of solar energy is especially important. In turn, the Earth gives back some of the energy, dissipates hydrogen into space, etc.
Many scientists, starting with V.I. Vernadsky, considering the global biogeochemical cycle of elements in nature as one of the most important factors in maintaining dynamic equilibrium in nature, distinguished two stages in the process of its evolution: ancient and modern. There is reason to believe that at the ancient stage the cycle was different, however, due to the absence of many unknowns (names of elements, their mass, energy, etc.), it is almost impossible to simulate the cycles of past geological eras (“former biospheres”).
To this it should be added that the main part of living matter consists of C, O, H, N, the main sources of plant nutrition are CO2, NO and other minerals. Taking into account the importance of carbon, oxygen, hydrogen, nitrogen for the biosphere, as well as the specific role of phosphorus, we will briefly consider their global cycles, called “private” or “small”. (There are also local circulations associated with individual landscapes.)