Geological and biological cycle of substances in nature. Great encyclopedia of oil and gas

All substances on the planet are in the process of circulation. Solar energy causes two cycles of substances on Earth: large (geological, biosphere) And small (biological).

The large cycle of substances in the biosphere is characterized by two important points: it occurs throughout the entire geological development of the Earth and represents a modern planetary process that takes a leading part in further development biosphere.

The geological cycle is associated with the formation and destruction of rocks and the subsequent movement of destruction products - clastic material and chemical elements. The thermal properties of the surface of land and water played and continue to play a significant role in these processes: absorption and reflection of solar rays, thermal conductivity and heat capacity. The unstable hydrothermal regime of the Earth's surface, together with the planetary atmospheric circulation system, determined the geological circulation of substances, which at the initial stage of the Earth's development, along with endogenous processes, was associated with the formation of continents, oceans and modern geospheres. With the formation of the biosphere, the waste products of organisms were included in the large cycle. The geological cycle supplies living organisms with nutrients and largely determines the conditions of their existence.

Main chemical elements lithosphere: oxygen, silicon, aluminum, iron, magnesium, sodium, potassium and others - participate in a large cycle, passing from the deep parts of the upper mantle to the surface of the lithosphere. Igneous rock, which arose during the crystallization of magma, arriving on the surface of the lithosphere from the depths of the Earth, undergoes decomposition and weathering in the biosphere. Weathering products enter a mobile state, are carried by water and wind to low areas of the relief, enter rivers, the ocean and form thick layers of sedimentary rocks, which over time, plunging to depth in areas with increased temperature and pressure, undergo metamorphosis, i.e. "remelted". During this melting, a new metamorphic rock appears, entering the upper horizons earth's crust and again entering the cycle of substances (rice.).

Easily mobile substances - gases and natural waters that make up the atmosphere and hydrosphere of the planet - undergo the most intense and rapid circulation. The lithosphere material cycles much more slowly. In general, each cycle of any chemical element is part of the general large cycle of substances on Earth, and they are all closely interconnected. The living matter of the biosphere in this cycle performs a tremendous job of redistributing chemical elements that continuously circulate in the biosphere, passing from the external environment into organisms and again into the external environment.

Small, or biological, cycle of substances- This

circulation of substances between plants, animals, fungi, microorganisms and soil. The essence of the biological cycle lies in the occurrence of two opposite but interconnected processes - the creation of organic substances and their destruction. First stage the emergence of organic substances is due to photosynthesis of green plants, i.e., the formation of living matter from carbon dioxide, water and simple mineral compounds using solar energy. Plants (producers) extract molecules of sulfur, phosphorus, calcium, potassium, magnesium, manganese, silicon, aluminum, zinc, copper and other elements from the soil in solution. Herbivorous animals (consumers of the first order) absorb compounds of these elements in the form of food of plant origin. Predators (II-order consumers) feed on herbivores, consuming food of a more complex composition, including proteins, fats, amino acids and other substances. In the process of destruction of organic substances of dead plants and animal remains by microorganisms (decomposers), simple mineral compounds enter the soil and aquatic environment, available for assimilation by plants, and the next round of the biological cycle begins (Fig. 33).

The emergence and development of the noosphere

Evolution organic world on Earth went through several stages. The first is associated with the emergence of the biological cycle of substances in the biosphere. The second was accompanied by the formation of multicellular organisms. These two stages are called biogenesis. The third stage is associated with the emergence of human society, under the influence of which modern conditions There is an evolution of the biosphere and its transformation into the sphere of reason - noosphere (from the Greek - mind, - ball). Noosphere is a new state of the biosphere, when intelligent human activity becomes the main factor determining its development. The term “noosphere” was introduced by E. Leroy. V.I. Vernadsky deepened and developed the doctrine of the noosphere. He wrote: “The noosphere is a new geological phenomenon on our planet. In it, man becomes a major geological force.” V.I. Vernadsky identified the necessary prerequisites for the creation of the noosphere: 1. Humanity has become a single whole. 2. The possibility of instant exchange of information. 3. Real equality of people. 4. Growth of the general standard of living. 5. Use of new types of energy. 6. Elimination of wars from the life of society. The creation of these prerequisites becomes possible as a result of the explosion of scientific thought in the twentieth century.

Topic – 6. Nature – man: a systematic approach. Purpose of the lecture: To form a holistic understanding of the systemic postulates of ecology.

Main questions: 1. The concept of the system and complex biosystems. 2. Features of biological systems. 3. System postulates: the law of universal connection, B. Commoner’s environmental laws, Law large numbers, Le Chatelier's principle, the Law of feedback in nature and the law of constancy of the amount of living matter. 4. Models of interactions in systems " nature - man" and "man-economy-biota-environment".

Ecological system- the main object of ecology. Ecology is systemic in its essence and in its theoretical form is close to the general theory of systems. According to the general theory of systems, a system is a real or conceivable collection of parts, the integral properties of which are determined by the interaction between the parts (elements) of the system. In real life, a system is defined as a collection of objects united by some form of regular interaction or interdependence to perform given function. In the material there are certain hierarchies - ordered sequences of spatio-temporal subordination and complication of systems. Present all the diversity of our world in the form of three successively emerged hierarchies. This is the main, natural, physico-chemical-biological (F, X, B) hierarchy and two secondary hierarchies that arose on its basis, the social (S) and technical (T) hierarchies. The existence of the latter in total feedback influences the main hierarchy in a certain way. Combining systems from different hierarchies leads to “mixed” classes of systems. Thus, the combination of systems from the physicochemical part of the hierarchy (F, X - “environment”) with living systems of the biological part of the hierarchy (B - “biota”) leads to a mixed class of systems called environmental. A combination of systems from hierarchies C

(“man”) and T (“technology”) leads to the class of economic, or technical and economic, systems

Rice. . Hierarchies of material systems:

F, X - physical and chemical, B - biological, S - social, T - technical

It should be clear that the impact of human society on nature, mediated by technology and technology (technogenesis), shown in the diagram, applies to the entire hierarchy of natural systems: the lower branch - to the abiotic environment, the upper - to the biota of the biosphere. Below we will consider the connection between the environmental and technical and economic aspects of this interaction.

All systems have some general properties:

1. Each system has a specific structure, determined by the form of spatiotemporal connections or interactions between elements of the system. Structural ordering in itself does not determine the organization of the system. The system can be called organized, if its existence is either necessary to maintain some functional (performing a certain job) structure, or, on the contrary, depends on the activity of such a structure.

2. According to principle of necessary diversity the system cannot consist of identical elements devoid of individuality. The lower limit of diversity is at least two elements (proton and electron, protein and nucleic acid, “he” and “she”), the upper limit is infinity. Diversity is the most important information characteristic of the system. It differs from the number of varieties of elements and can be measured. 3. The properties of a system cannot be understood only on the basis of the properties of its parts. It is the interaction between the elements that is decisive. It is impossible to judge its operation by looking at individual parts of a machine before assembly. By studying separately some forms of fungi and algae, it is impossible to predict the existence of their symbiosis in the form of a lichen. The combined effect of two or more different factors on the body is almost always different from the sum of their separate effects. The degree of irreducibility of the properties of a system to the sum of the properties of the individual elements of which it consists determines emergence systems.

4. Isolating a system divides its world into two parts - the system itself and its environment. Depending on the presence (absence) of exchange of matter, energy and information with the environment, the following are fundamentally possible: isolated systems (no exchange is possible); closed systems (metabolism is impossible); open systems (exchange of matter and energy is possible). The exchange of energy determines the exchange of information. In living nature there are only open dynamic systems, between the internal elements of which and the elements of the environment there are transfers of matter, energy and information. Any living system - from a virus to the biosphere - is an open dynamic system.

5. The predominance of internal interactions in the system over external ones and the lability of the system in relation to external factors
actions determine it self-preservation ability thanks to the qualities of organization, endurance and stability. External influence on the system, exceeding the strength and flexibility of its internal interactions, leads to irreversible changes
and the death of the system. The stability of a dynamic system is maintained by the external cyclic work it continuously performs. This requires the flow and transformation of energy into this. topic. Probability of achievement main goal system - self-preservation (including through self-reproduction) is defined as its potential effectiveness.

6. The action of a system in time is called its behavior. Caused external factor behavior change is referred to as reaction system, and a change in the system’s reaction associated with a change in structure and aimed at stabilizing behavior is. device, or adaptation. Consolidation of adaptive changes in the structure and connections of the system over time, in which its potential efficiency increases, is considered as development, or evolution, systems. The emergence and existence of all material systems in nature is due to evolution. Dynamic systems evolve in the direction from more probable to less probable organization, i.e. development follows the path of increasing complexity of organization and formation of subsystems in the structure of the system. In nature, all forms of system behavior - from elementary reaction before global evolution - significantly nonlinear. An important feature of evolution complex systems is
unevenness, lack of monotony. Periods of gradual accumulation of minor changes are sometimes interrupted by sharp qualitative leaps that significantly change the properties of the system. They are usually associated with the so-called bifurcation points- bifurcation, splitting of the previous path of evolution. The choice of one or another continuation of the path at the bifurcation point depends on a lot, up to the emergence and prosperity of a new world of particles, substances, organisms, societies, or, conversely, the death of the system. Even for decisive systems, the result of the choice is often unpredictable, and the choice itself at the bifurcation point can be determined by a random impulse. Any real system can be represented in the form of some material resemblance or symbolic image, i.e. respectively analog or sign model of the system. Modeling is inevitably accompanied by some simplification and formalization of the relationships in the system. This formalization can be
implemented in the form of logical (cause-and-effect) and/or mathematical (functional) relationships. As the complexity of systems increases, they acquire new emergent qualities. At the same time, the qualities are preserved simple systems. Therefore, the overall variety of system qualities increases as it becomes more complex (Fig. 2.2).

Rice. 2.2. Patterns of changes in the properties of system hierarchies with an increase in their level (according to Fleishman, 1982):

1 - diversity, 2 - stability, 3 - emergence, 4 - complexity, 5 - non-identity, 6 - prevalence

In order of increasing activity in relation to external influences, the qualities of the system can be ordered in the following sequence: 1 - stability, 2 - reliability due to awareness of the environment (noise immunity), 3 - controllability, 4 - self-organization. In this series, each subsequent quality makes sense if the previous one is present.

Par Difficulty the structure of the system is determined by the number P its elements and number T

connections between them. If in any system the number of particular discrete states is studied, then the complexity of the system WITH is determined by the logarithm of the number of connections:

C=lgm.(2.1)

Systems are conventionally classified by complexity in the following way: 1) systems with up to a thousand states (O <С < 3), относятся к simple; 2) systems with up to a million states (3< С < 6), являют собой complex systems; 3) systems with the number of states over a million (C > 6) are identified as very complex.

All real natural biosystems are very complex. Even in the structure of a single virus, the number of biologically significant molecular states exceeds the latter value.

Before the emergence of the biosphere, there were three cycles of matter on Earth: mineral cycle - movement of igneous products from the depths to the surface and back; gas cycle - circulation of air masses periodically heated by the Sun,The water cycle - evaporation of water and its transfer by air masses, precipitation (rain, snow). These three cycles are united by a single term - geological (abiotic) cycle. With the advent of life, the gas, mineral and water cycles were supplemented by biotic (biogenic) cycle - the cycle of chemical elements carried out by the vital activity of organisms. Together with the geological one, a single biogeochemical cycle substances on Earth.

Geological cycle.

About half reaching the Earth's surface solar energy is spent on evaporation of water, weathering of rocks, dissolution of minerals, movement of air masses and with them water vapor, dust, and solid weathering particles.

The movement of water and wind leads to soil erosion, movement, redistribution and accumulation of mechanical and chemical precipitation in the hydrosphere and lithosphere. This cycle is still happening today.

Of great interest The water cycle. Approximately 3.8 10 14 tons of water evaporate from the hydrosphere in one year, and only 3.4 10 14 tons of water returns with precipitation to the water shell of the Earth. The missing part falls onto land. In total, about 1 10 14 tons of precipitation falls on land, and approximately 0.6 10 14 tons of water evaporate. Excess water formed in the lithosphere flows into lakes and rivers, and then into the World Ocean (Fig. 2.4). Surface runoff is approximately 0.2 10 14 tons, the remaining 0.2 10 14 tons of water enters subsoil aquifers, from where water flows into rivers, lakes and the ocean, and also replenishes reservoirs groundwater.

biotic cycle. It is based on the processes of synthesis of organic substances with their subsequent destruction into the original minerals. The processes of synthesis and destruction of organic substances are the foundation of the existence of living matter and the main feature of the functioning of the biosphere.

The life activity of any organism is impossible without metabolism with the environment. In the process of metabolism, the body consumes and assimilates necessary substances and releases waste products; the size of our planet is not infinite, and ultimately everything useful substance would be recycled into useless waste. However, in the process of evolution, an excellent solution was found: in addition to organisms that can build living matter from non-living matter, other organisms appeared that decomposed this complex organic matter into initial minerals, ready for new use. “The only way to give a limited quantity the properties of infinity,” wrote V.R. Williams, is to make it rotate along a closed curve."

The mechanism of interaction between living and inanimate nature consists of the involvement of inanimate matter in the realm of life. After a series of transformations of inanimate matter in living organisms, it returns to its previous original state. Such a cycle is possible due to the fact that living organisms contain the same chemical elements as inanimate nature.

How does this cycle happen? V.I. Vernadsky substantiated that the main converter of energy coming from space (mainly solar) is the green matter of plants. Only they are capable of synthesizing primary organic compounds under the influence of solar energy. The scientist calculated that total area The surface of the green matter of plants that absorbs energy, depending on the time of year, ranges from 0.86 to 4.2% of the surface area of ​​the Sun. At the same time, the surface area of ​​the Earth

Animals whose food is plants or other animals synthesize new organic compounds in their bodies.

The remains of animals and plants serve as food for worms, fungi and microorganisms, which ultimately convert them into the original minerals, releasing carbon dioxide. These minerals again serve as the initial raw materials for the creation of primary organic compounds plants. Thus the circle closes and a new movement of atoms begins.

However, the cycle of substances is not completely closed. Some of the atoms come out of the cycle, are fixed and organized by new forms of living organisms and the products of their vital activity. Penetrating into the lithosphere, hydrosphere and troposphere, living organisms have produced and are producing enormous geochemical work on the movement and redistribution of existing substances and the creation of new ones. This is the essence of the progressive development of the biosphere, since this expands the scope of biogeochemical cycles and strengthens the biosphere. As V.I. Vernadsky noted, in the biosphere there is a constant biogenic movement of atoms in the form of “vortices”.

Unlike the geological one, the biotic cycle is characterized by insignificant energy consumption. As already noted, about 1% of solar energy reaching the Earth's surface is spent on the creation of primary organic matter. This energy is sufficient for the functioning of the most complex biogeochemical processes on the planet.

The basis for self-sustaining life on Earth is biogeochemical cycles. All chemical elements used in the life processes of organisms undergo constant movements, moving from living bodies to compounds of inanimate nature and back. The possibility of reusing the same atoms makes life on Earth almost eternal, provided there is a constant supply of the required amount of energy.

Types of substance cycles. The Earth's biosphere is characterized by a certain cycle of substances and the flow of energy. Cycle of substances – repeated participation of substances in processes occurring in the atmosphere, hydrosphere and lithosphere, including those layers that are part of the Earth's biosphere. The circulation of substances occurs with a continuous supply (flow) of the external energy of the Sun and the internal energy of the Earth.

Depending on the driving force, with a certain degree of convention, within the cycle of substances one can distinguish geological, biological and anthropogenic cycles. Before the emergence of man on Earth, only the first two were realized.

Geological cycle ( great gyre substances in nature) – cycle of substances, the driving force of which is exogenous and endogenous geological processes.

Endogenous processes(processes of internal dynamics) occur under the influence of the internal energy of the Earth. This is the energy released as a result of radioactive decay, chemical reactions of the formation of minerals, crystallization of rocks, etc. Endogenous processes include: tectonic movements, earthquakes, magmatism, metamorphism. Exogenous processes(processes of external dynamics) occur under the influence of the external energy of the Sun. Exogenous processes include weathering of rocks and minerals, removal of destruction products from some areas of the earth's crust and their transfer to new areas, deposition and accumulation of destruction products with the formation of sedimentary rocks. Exogenous processes include the geological activity of the atmosphere, hydrosphere (rivers, temporary streams, groundwater, seas and oceans, lakes and swamps, ice), as well as living organisms and humans.

The largest landforms (continents and ocean basins) and large forms (mountains and plains) were formed due to endogenous processes, and medium and small landforms (river valleys, hills, ravines, dunes, etc.), superimposed on larger forms, are due to exogenous processes. Thus, endogenous and exogenous processes are opposite in their effects. The former lead to the formation of large relief forms, the latter – to their smoothing.

Igneous rocks are transformed into sedimentary rocks as a result of weathering. In moving zones of the earth's crust, they plunge deep into the Earth. There under the influence high temperatures and pressure, they melt and form magma, which, rising to the surface and solidifying, forms igneous rocks.

Thus, geological cycle substances flows without the participation of living organisms and carries out the redistribution of substances between the biosphere and the deeper layers of the Earth.

Biological (biogeochemical) cycle (small cycle of substances in the biosphere) – cycle of substances, the driving force of which is the activity of living organisms. In contrast to the large geological cycle, the small biogeochemical cycle of substances occurs within the biosphere. The main source of energy in the cycle is solar radiation, which generates photosynthesis. In an ecosystem, organic substances are synthesized by autotrophs from inorganic substances. They are then consumed by heterotrophs. As a result of release during vital activity or after the death of organisms (both autotrophs and heterotrophs), organic substances undergo mineralization, that is, transformation into inorganic substances. These inorganic substances can be reused for the synthesis of organic substances by autotrophs.

In biogeochemical cycles, two parts should be distinguished:

1) reserve fund – this is a part of a substance that is not associated with living organisms;

2) exchange fund – a significantly smaller part of a substance that is associated with direct exchange between organisms and their immediate environment. Depending on the location of the reserve fund, biogeochemical cycles can be divided into two types:

1) Gyres gas type with a reserve fund of substances in the atmosphere and hydrosphere (carbon, oxygen, nitrogen cycles).

2) Sedimentary gyres with a reserve fund in the earth’s crust (cycles of phosphorus, calcium, iron, etc.).

Gas-type circulations are more perfect, since they have a large exchange fund, and therefore are capable of rapid self-regulation. Sedimentary cycles are less perfect, they are more inert, since the bulk of the substance is contained in the reserve fund of the earth's crust in a form “inaccessible” to living organisms. Such cycles are easily disrupted by various kinds of influences, and part of the exchanged material leaves the cycle. It can return again to the cycle only as a result of geological processes or through extraction by living matter. However, extracting substances needed by living organisms from the earth’s crust is much more difficult than from the atmosphere.

The intensity of the biological cycle is primarily determined by temperature environment and amount of water. For example, biological cycle occurs more intensely in tropical rainforests than in the tundra.

With the advent of man, the anthropogenic circulation, or exchange, of substances arose. Anthropogenic cycle (exchange) – the cycle (metabolism) of substances, the driving force of which is human activity. There are two components in it: biological, associated with the functioning of man as a living organism, and technical, related to human economic activities (technogenic cycle).

Geological and biological cycles are largely closed, which cannot be said about the anthropogenic cycle. Therefore, they often talk not about the anthropogenic cycle, but about anthropogenic metabolism. The openness of the anthropogenic cycle of substances leads to natural resource depletion and pollution natural environment – the main reasons for all environmental problems humanity.

Cycles of basic nutrients and elements. Let us consider the cycles of the most significant substances and elements for living organisms. The water cycle refers to the large geological cycle, and the cycles of biogenic elements (carbon, oxygen, nitrogen, phosphorus, sulfur and other biogenic elements) refer to the small biogeochemical cycle.

The water cycle between land and ocean through the atmosphere refers to the great geological cycle. Water evaporates from the surface of the oceans and is either transported to land, where it falls as precipitation, which returns to the ocean in the form of surface and underground runoff, or falls as precipitation on the surface of the ocean. More than 500 thousand km 3 of water annually participates in the water cycle on Earth. The water cycle in general plays a major role in the formation natural conditions on our planet. Taking into account the transpiration of water by plants and its absorption in the biogeochemical cycle, the entire water supply on Earth disintegrates and is restored in 2 million years.

Carbon cycle. Producers capture carbon dioxide from the atmosphere and convert it into organic substances, consumers absorb carbon in the form of organic substances with the bodies of producers and consumers of lower orders, decomposers mineralize organic substances and return carbon to the atmosphere in the form of carbon dioxide. In the World Ocean, the carbon cycle is complicated by the fact that some of the carbon contained in dead organisms sinks to the bottom and accumulates in sedimentary rocks. This part of the carbon is excluded from the biological cycle and enters the geological cycle of substances.

The main reservoir of biologically bound carbon is forests; they contain up to 500 billion tons of this element, which is 2/3 of its reserve in the atmosphere. Human intervention in the carbon cycle (combustion of coal, oil, gas, dehumification) leads to an increase in the CO 2 content in the atmosphere and the development of the greenhouse effect.

The rate of CO 2 circulation, that is, the time during which all carbon dioxide in the atmosphere passes through living matter, is about 300 years.

Oxygen cycle. The oxygen cycle mainly occurs between the atmosphere and living organisms. Basically, free oxygen (0^) enters the atmosphere as a result of photosynthesis of green plants, and is consumed in the process of respiration by animals, plants and microorganisms and during the mineralization of organic residues. A small amount of oxygen is formed from water and ozone under the influence of ultraviolet radiation. A large amount of oxygen is consumed by oxidative processes in the earth’s crust, during volcanic eruptions, etc. The main share of oxygen is produced by land plants - almost 3/4, the rest - by photosynthetic organisms of the World Ocean. The speed of the cycle is about 2 thousand years.

It has been established that 23% of the oxygen produced during photosynthesis is annually consumed for industrial and domestic needs, and this figure is constantly increasing.

Nitrogen cycle. The supply of nitrogen (N 2) in the atmosphere is huge (78% of its volume). However, plants cannot absorb free nitrogen, but only in bound form, mainly in the form of NH 4 + or NO 3 –. Free nitrogen from the atmosphere is fixed by nitrogen-fixing bacteria and converted into forms available to plants. In plants, nitrogen is fixed in organic matter (in proteins, nucleic acids ah, etc.) and is transmitted along power circuits. After the death of living organisms, decomposers mineralize organic substances and convert them into ammonium compounds, nitrates, nitrites, as well as free nitrogen, which returns to the atmosphere.

Nitrates and nitrites are highly soluble in water and can migrate into groundwater and plants and be transmitted through food chains. If their quantity is excessively large, which is often observed when nitrogen fertilizers are used incorrectly, then water and food are polluted and cause human diseases.

Phosphorus cycle. The bulk of phosphorus is contained in rocks formed in past geological eras. Phosphorus is included in the biogeochemical cycle as a result of rock weathering processes. In terrestrial ecosystems, plants extract phosphorus from the soil (mainly in the form of PO 4 3–) and incorporate it into organic compounds (proteins, nucleic acids, phospholipids, etc.) or leave it in inorganic form. Phosphorus is then transferred through food chains. After the death of living organisms and with their excretions, phosphorus returns to the soil.

With improper use of phosphorus fertilizers, water and wind erosion of soils, large amounts of phosphorus are removed from the soil. On the one hand, this leads to excessive consumption of phosphorus fertilizers and depletion of reserves of phosphorus-containing ores (phosphorites, apatites, etc.). On the other hand, the entry of large quantities of biogenic elements such as phosphorus, nitrogen, sulfur, etc. from the soil into water bodies causes the rapid development of cyanobacteria and other aquatic plants (“blooming” of water) and eutrophication reservoirs. But most of the phosphorus is carried out to sea.

In aquatic ecosystems, phosphorus is absorbed by phytoplankton and passed along the food chain to seabirds. Their excrement either immediately ends up back into the sea, or first accumulates on the shore and then is washed into the sea anyway. From dying marine animals, especially fish, phosphorus again enters the sea and into the cycle, but some fish skeletons reach great depths, and the phosphorus contained in them again enters sedimentary rocks, that is, it is turned off from the biogeochemical cycle.

Sulfur cycle. The main reserve fund of sulfur is in sediments and soil, but unlike phosphorus there is a reserve fund in the atmosphere. the main role in the involvement of sulfur in the biogeochemical cycle belongs to microorganisms. Some of them are reducing agents, others are oxidizing agents.

In rocks, sulfur is found in the form of sulfides (FeS 2, etc.), in solutions - in the form of an ion (SO 4 2–), in the gaseous phase in the form of hydrogen sulfide (H 2 S) or sulfur dioxide (SO 2). In some organisms, sulfur accumulates in pure form and when they die off, deposits of native sulfur are formed at the bottom of the seas.

In terrestrial ecosystems, sulfur enters plants from the soil mainly in the form of sulfates. In living organisms, sulfur is contained in proteins, in the form of ions, etc. After the death of living organisms, part of the sulfur is reduced in the soil by microorganisms to H 2 S, the other part is oxidized to sulfates and is again included in the cycle. The resulting hydrogen sulfide evaporates into the atmosphere, where it is oxidized and returned to the soil with precipitation.

Human combustion of fossil fuels (especially coal), as well as emissions chemical industry, lead to the accumulation of sulfur dioxide (SO 2) in the atmosphere, which, reacting with water vapor, falls to the ground in the form of acid rain.

Biogeochemical cycles not as large-scale as geological ones and are largely subject to human influence. Economic activity violates their isolation, they become acyclical.

The large geological cycle of minerals and water occurs under the influence of a huge number of abiotic factors.

4.3.1. The circulation of substances in the large geological cycle.

According to the theory of lithospheric plates, the outer shell of the Earth consists of several very large blocks (plates). This theory assumes the existence of horizontal movements of powerful lithospheric plates, 100–150 km thick.

Moreover, within the mid-ocean ridges, the so-called rift zone. Lithospheric plates rupture and move apart with the formation of young oceanic crust

This phenomenon is called ocean floor spreading. Thus, a flow of mineral substances rises from the depths of the mantle, forming young crystalline rocks.

In contrast to this process, in the zone of deep ocean trenches, one part of the continental crust is constantly being pushed onto another, which is accompanied by the immersion of the peripheral part of the plate into the mantle, i.e., part solid the earth's crust becomes part of the earth's mantle. The process occurring in deep ocean trenches is called subduction of oceanic crust.

The water cycle on the planet operates continuously and everywhere. Driving forces of the water cycle – thermal energy and gravity. Under the influence of heat, evaporation, condensation of water vapor and other processes occur, which consumes about 50% of the energy coming from the sun. Under the influence of gravity - the fall of raindrops, the flow of rivers, the movement of soil and groundwater. Often these reasons act together, for example, both thermal processes and gravity affect the atmospheric circulation of water.

4.3.2. Cycle of elements in inanimate nature

It is carried out in two ways: water and air migration. Air migrants include: oxygen, hydrogen, nitrogen, iodine.

Water migrants include those substances that migrate primarily in soils, surface and groundwater, mainly in the form of molecules and ions: sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, manganese, iron, cobalt, nickel, strontium , lead, etc. Air migrants are also part of the salts that migrate in water. However, air migration is more typical for them.

4.4 Small (biological) cycle

The mass of living matter in the biosphere is relatively small. If it is distributed over the earth's surface, the result is a layer of only 1.5 cm. Table 4.1 compares some quantitative characteristics of the biosphere and other geospheres of the Earth. The biosphere, making up less than 10-6 times the mass of the other shells of the planet, has incomparably greater diversity and renews its composition a million times faster.

Table 4.1

Comparison of the biosphere with other geospheres of the Earth

*Live matter based on live weight

4.4.1. Functions of the biosphere

Thanks to the biota of the biosphere, the predominant part of chemical transformations on the planet occurs. Hence the judgment of V.I. Vernadsky about the enormous transformative geological role of living matter. During organic evolution, living organisms passed through themselves, through their organs, tissues, cells, and blood, the entire atmosphere, the entire volume of the World Ocean, most of the soil mass, and a huge mass of mineral substances a thousand times (for different cycles from 103 to 105 times). And they not only missed it, but also modified the earth’s environment in accordance with their needs.

Thanks to their ability to transform solar energy into the energy of chemical bonds, plants and other organisms perform a number of fundamental biogeochemical functions on a planetary scale.

Gas function. Living things constantly exchange oxygen and carbon dioxide with the environment through the processes of photosynthesis and respiration. Plants played a decisive role in the change from a reducing environment to an oxidizing one in the geochemical evolution of the planet and in the formation of the gas composition of the modern atmosphere. Plants strictly control the concentrations of O2 and CO2, which are optimal for the totality of all modern living organisms.

Concentration function. By passing large volumes of air and natural solutions through their bodies, living organisms carry out biogenic migration (movement chemical substances) and concentration of chemical elements and their compounds. This relates to the biosynthesis of organic matter, the formation of coral islands, the construction of shells and skeletons, the appearance of sedimentary limestone strata, deposits of some metal ores, the accumulation of iron-manganese nodules on the ocean floor, etc. The early stages of biological evolution took place in the aquatic environment. Organisms have learned to extract the substances they need from a dilute aqueous solution, repeatedly increasing their concentration in their body.

The redox function of living matter is closely related to the biogenic migration of elements and the concentration of substances. Many substances in nature are stable and do not undergo oxidation under normal conditions, for example, molecular nitrogen is one of the most important biogenic elements. But living cells have such powerful catalysts - enzymes - that they are able to carry out many redox reactions millions of times faster than they can take place in an abiotic environment.

Information function of living matter of the biosphere. It was with the appearance of the first primitive living beings that active (“living”) information appeared on the planet, which differed from that “dead” information, which is a simple reflection of the structure. Organisms turned out to be capable of obtaining information by combining a flow of energy with an active molecular structure that plays the role of a program. The ability to perceive, store and process molecular information has undergone rapid evolution in nature and has become the most important ecological system-forming factor. The total supply of genetic information of the biota is estimated at 1015 bits. The total power of the flow of molecular information associated with metabolism and energy in all cells of the global biota reaches 1036 bit/s (Gorshkov et al., 1996).

4.4.2. Components of the biological cycle.

The biological cycle occurs between all components of the biosphere (i.e. between soil, air, water, animals, microorganisms, etc.). It occurs with the obligatory participation of living organisms.

Solar radiation reaching the biosphere carries energy of about 2.5 * 1024 J per year. Only 0.3% of it is directly converted during the process of photosynthesis into the energy of chemical bonds of organic substances, i.e. is involved in the biological cycle. And 0.1 - 0.2% of solar energy falling on the Earth turns out to be contained in pure primary production. The further fate of this energy is associated with the transfer of organic matter of food through cascades of trophic chains.

The biological cycle can be conditionally divided into interconnected components: the cycle of substances and the energy cycle.

4.4.3. Energy cycle. Transformation of energy in the biosphere

An ecosystem can be described as a collection of living organisms that continuously exchange energy, matter, and information. Energy can be defined as the ability to do work. The properties of energy, including the movement of energy in ecosystems, are described by the laws of thermodynamics.

The first law of thermodynamics or the law of conservation of energy states that energy does not disappear or be created anew, it only passes from one form to another.

The second law of thermodynamics states that closed system entropy can only increase. In relation to energy in ecosystems, the following formulation is convenient: processes associated with the transformation of energy can occur spontaneously only under the condition that the energy passes from a concentrated form to a dispersed one, that is, it degrades. The measure of the amount of energy that becomes unavailable for use, or otherwise the measure of the change in order that occurs during the degradation of energy, is entropy. The higher the order of the system, the lower its entropy.

In other words, living matter receives and transforms the energy of space and the sun into the energy of earthly processes (chemical, mechanical, thermal, electrical). Involves this energy and inorganic matter into the continuous cycle of substances in the biosphere. The flow of energy in the biosphere has one direction - from the Sun through plants (autotrophs) to animals (heterotrophs). Natural untouched ecosystems in a stable state with constant critical environmental indicators (homeostasis) are the most ordered systems and are characterized by the lowest entropy.

4.4.4. Cycle of substances in living nature

The formation of living matter and its decomposition are two sides of a single process, which is called the biological cycle of chemical elements. Life is the cycle of chemical elements between organisms and the environment.

The reason for the cycle is the limited number of elements from which the bodies of organisms are built. Each organism extracts from the environment substances necessary for life and returns unused ones. Wherein:

Some organisms consume minerals directly from the environment;

others use processed and isolated products first;

third - second, etc., until the substances return to the environment in their original state.

In the biosphere, there is an obvious need for the coexistence of various organisms capable of using each other’s waste products. We see virtually waste-free biological production.

The circulation of substances in living organisms can be roughly reduced to four processes:

1. Photosynthesis. As a result of photosynthesis, plants absorb and accumulate solar energy and synthesize organic substances - primary biological products - and oxygen from inorganic substances. Primary biological products are very diverse - they contain carbohydrates (glucose), starch, fiber, proteins, and fats.

The photosynthesis scheme for the simplest carbohydrate (glucose) has the following scheme:

This process occurs only during the day and is accompanied by an increase in plant mass.

On Earth, about 100 billion tons of organic matter are formed annually as a result of photosynthesis, about 200 billion tons of carbon dioxide are absorbed, and approximately 145 billion tons of oxygen are released.

Photosynthesis plays a decisive role in ensuring the existence of life on Earth. Its global significance is explained by the fact that photosynthesis is the only process during which energy in a thermodynamic process, in accordance with the minimalist principle, is not dissipated, but rather accumulates.

By synthesizing the amino acids necessary for the construction of proteins, plants can exist relatively independently of other living organisms. This manifests the autotrophy of plants (independence in nutrition). At the same time, the green mass of plants and the oxygen produced during photosynthesis are the basis for supporting the life of the next group of living organisms - animals, microorganisms. This demonstrates the heterotrophy of this group of organisms.

2. Breathing. The process is the reverse of photosynthesis. Occurs in all living cells. During respiration, organic matter is oxidized by oxygen, resulting in the formation of carbon dioxide, water and the release of energy.

3. Food (trophic) connections between autotrophic and heterotrophic organisms. IN in this case there is a transfer of energy and matter along the links of the food chain, which we discussed in more detail earlier.

4. The process of transpiration. One of the most important processes in the biological cycle.

It can be schematically described as follows. Plants absorb soil moisture through their roots. At the same time, they receive minerals dissolved in water, which are absorbed, and the moisture evaporates more or less intensively depending on environmental conditions.

4.4.5. Biogeochemical cycles

Geological and biological cycles are connected - they exist as a single process, giving rise to the circulation of substances, the so-called biogeochemical cycles (BGCC). This cycle of elements is due to the synthesis and decay of organic substances in the ecosystem (Fig. 4.1). Not all elements of the biosphere are involved in the BGCC, but only biogenic ones. Living organisms are composed of them; these elements enter into numerous reactions and participate in processes occurring in living organisms. In percentage terms, the total mass of living matter in the biosphere consists of the following main biogenic elements: oxygen - 70%, carbon - 18%, hydrogen - 10.5%, calcium - 0.5%, potassium - 0.3%, nitrogen - 0, 3% (oxygen, hydrogen, nitrogen, carbon are present in all landscapes and are the basis of living organisms - 98%).

The essence of biogenic migration of chemical elements.

Thus, in the biosphere there is a biogenic cycle of substances (i.e. a cycle caused by the vital activity of organisms) and a unidirectional flow of energy. Biogenic migration of chemical elements is determined mainly by two opposing processes:

1. Formation of living matter from environmental elements due to solar energy.

2. Destruction of organic substances, accompanied by the release of energy. In this case, elements of mineral substances repeatedly enter living organisms, thereby becoming part of complex organic compounds, forms, and then, when the latter are destroyed, they again acquire a mineral form.

There are elements that are part of living organisms, but are not classified as biogenic. Such elements are classified according to their weight fraction in organisms:

Macroelements – constituting at least 10-2% of the mass;

Microelements – components from 9*10-3 to 1*10-3% of the mass;

Ultramicroelements – less than 9*10-6% of the mass;

To determine the place of nutrients among other chemical elements of the biosphere, let us consider the classification accepted in ecology. According to their activity in processes occurring in the biosphere, all chemical elements are divided into 6 groups:

Noble gases - helium, neon, argon, krypton, xenon. Inert gases are not part of living organisms.

Noble metals - ruthenium, radium, palladium, osmium, iridium, platinum, gold. These metals create almost no compounds in the earth's crust.

Cyclic or biogenic elements (they are also called migratory). This group of biogenic elements in the earth's crust accounts for 99.7% of the total mass, and the remaining 5 groups - 0.3%. Thus, the bulk of the elements are migrants who circulate in the geographic envelope, and the part of the inert elements is very small.

Scattered elements characterized by a predominance of free atoms. Join chemical reactions, but their compounds are rarely found in the earth's crust. They are divided into two subgroups. The first - rubidium, cesium, niobium, tantalum - create compounds in the depths of the earth's crust, and on the surface their minerals are destroyed. The second - iodine, bromine - react only on the surface.

Radioactive elements - polonium, radon, radium, uranium, neptunium, plutonium.

Rare earth elements - yttrium, samarium, europium, thulium, etc.

All year round, biochemical cycles set in motion about 480 billion tons of matter.

IN AND. Vernadsky formulated three biogeochemical principles that explain the essence of biogenic migration of chemical elements:

Biogenic migration of chemical elements in the biosphere always strives for its maximum manifestation.

The evolution of species over geological time, leading to the creation of stable forms of life, goes in a direction that enhances the biogenic migration of atoms.

Living matter is in continuous chemical exchange with its environment, which is a factor that recreates and maintains the biosphere.

Let's consider how some of these elements move in the biosphere.

Carbon cycle. The main participant in the biotic cycle is carbon as the basis of organic substances. The carbon cycle primarily occurs between living matter and atmospheric carbon dioxide through the process of photosynthesis. It is obtained from food by herbivores, and from herbivores by carnivores. During respiration and decay, carbon dioxide is partially returned to the atmosphere; the return occurs when organic minerals are burned.

In the absence of carbon return to the atmosphere, it would be consumed by green plants in 7-8 years. The rate of biological carbon turnover through photosynthesis is 300 years. The oceans play a large role in regulating the CO2 content in the atmosphere. If the CO2 content increases in the atmosphere, some of it dissolves in water, reacting with calcium carbonate.

Oxygen cycle.

Oxygen has high chemical activity and combines with almost all elements of the earth’s crust. It is found mainly in the form of compounds. Every fourth atom of living matter is an oxygen atom. Almost all of the molecular oxygen in the atmosphere originated and is maintained at a constant level due to the activity of green plants. Atmospheric oxygen, bound during respiration and released during photosynthesis, passes through all living organisms in 200 years.

Nitrogen cycle. Nitrogen is an integral part of all proteins. The general ratio of fixed nitrogen, as an element that makes up organic matter, to nitrogen in nature is 1:100,000. The chemical bond energy in a nitrogen molecule is very high. Therefore, the combination of nitrogen with other elements - oxygen, hydrogen (the process of nitrogen fixation) - requires a lot of energy. Industrial nitrogen fixation occurs in the presence of catalysts at a temperature of -500°C and a pressure of –300 atm.

As you know, the atmosphere contains more than 78% molecular nitrogen, but in this state it is not available to green plants. For their nutrition, plants can only use salts of nitric and nitrous acids. What are the ways these salts are formed? Here are some of them:

In the biosphere, nitrogen fixation is carried out by several groups of anaerobic bacteria and cyanobacteria at normal temperature and pressure due to the high efficiency of biocatalysis. It is believed that bacteria convert approximately 1 billion tons of nitrogen per year into a bound form (the global volume of industrial fixation is about 90 million tons).

Soil nitrogen-fixing bacteria are able to absorb molecular nitrogen from the air. They enrich the soil with nitrogen compounds, so their importance is extremely great.

As a result of the decomposition of nitrogen-containing compounds of organic substances of plant and animal origin.

Under the influence of bacteria, nitrogen turns into nitrates, nitrites, and ammonium compounds. In plants, nitrogen compounds take part in the synthesis of protein compounds, which are transmitted from organism to organism in food chains.

Phosphorus cycle. Another important element, without which protein synthesis is impossible, is phosphorus. The main sources are igneous rocks (apatites) and sedimentary rocks (phosphorites).

Inorganic phosphorus is involved in the cycle as a result of natural leaching processes. Phosphorus is absorbed by living organisms, which, with its participation, synthesize a number of organic compounds and transfer them to various trophic levels.

Having completed its journey through trophic chains, organic phosphates are decomposed by microbes and converted into mineral phosphates available to green plants.

In the process of biological circulation, which ensures the movement of matter and energy, there is no place for the accumulation of waste. The waste products (i.e., waste) of each life form provide a breeding ground for other organisms.

Theoretically, a balance should always be maintained in the biosphere between the production of biomass and its decomposition. However, in certain geological periods, the balance of the biological cycle was disturbed when, due to certain natural conditions and disasters, not all biological products were assimilated and transformed. In these cases, excess biological products were formed, which were preserved and deposited in the earth's crust, under the thickness of water, sediment, and ended up in the permafrost zone. This is how deposits of coal, oil, gas, and limestone were formed. It should be noted that they do not pollute the biosphere. Organic minerals concentrate the energy of the Sun, accumulated during the process of photosynthesis. Now, by burning organic combustible minerals, a person releases this energy.