Geological circulation substances have the highest speed in the horizontal direction between land and sea. The meaning of the large circulation is that rocks are subject to destruction, weathering, and weathering products, including water-soluble nutrients, are carried by water flows into the World Ocean with the formation of marine strata and return to land only partially, for example, with precipitation or organisms extracted from water by humans. Then, over a long period of time, slow geotectonic changes occur - the movement of continents, the rise and fall of the seabed, volcanic eruptions, etc., as a result of which the formed strata return to the land and the process begins again.

Big geological cycle substances. Under the influence of denudation processes, rock destruction and sedimentation occur. Sedimentary rocks are formed. In areas of stable subsidence (usually the ocean floor), the material of the geographic shell enters the deep layers of the Earth. Further, under the influence of temperature and pressure, metamorphic processes occur, as a result of which rocks are formed, the substance moves closer to the center of the Earth. In the depths of the Earth, under conditions of very high temperatures, magmatism occurs: rocks melt, rise in the form of magma along faults to the earth's surface and spill out to the surface during eruptions. Thus, the cycle of matter occurs. The geological cycle becomes more complicated if we take into account the exchange of matter with outer space. The great geological cycle is not closed in the sense that some particle of matter that falls into the bowels of the Earth does not necessarily come to the surface, and vice versa, a particle rising during an eruption may never have been on the earth's surface before

The main sources of energy for natural processes on Earth

Radiation from the Sun is the main source of energy on Earth. Its power is characterized by the solar constant - the amount of energy passing through a unit area area perpendicular to the sun's rays. At a distance of one astronomical unit (that is, in Earth's orbit), this constant is approximately 1370 W/m².

Living organisms use the energy of the Sun (photosynthesis) and the energy of chemical bonds (chemosynthesis). This energy can be used in various natural and artificial processes. A third of all energy is reflected by the atmosphere, 0.02% is used by plants for photosynthesis, and the rest is used to maintain many natural processes - heating the earth, ocean, atmosphere, air movement. wt. Direct heating by the sun's rays or energy conversion using photocells can be used to generate electricity (solar power plants) or perform other useful work. In the distant past, energy stored in oil and other types of fossil fuels was also obtained through photosynthesis.

This enormous energy leads to global warming, because after it has passed through natural processes it is radiated back and the atmosphere does not allow it to escape back.

2. Internal energy of the Earth; manifestation – volcanoes, hot springs

18. Energy transformations of biotic and abiotic origin

In a functioning natural ecosystem, waste does not exist. All organisms, living or dead, are potentially food for other organisms: a caterpillar eats foliage, a thrush eats caterpillars, a hawk can eat a blackbird. When plants, caterpillars, thrushes and hawks die, they are in turn processed by decomposers.

All organisms that use the same type of food belong to the same trophic level.

Organisms in natural ecosystems are involved in a complex network of many interconnected food chains. Such a network is called food web.

Pyramids of energy flows: With each transition from one trophic level to another within a food chain or network, work is done and thermal energy is released into the environment, and the amount of energy High Quality, used by organisms of the next trophic level, decreases.

10% rule: When moving from one trophic level to another, 90% of energy is lost and 10% is transferred to the next level.

The longer the food chain, the more useful energy is lost. Therefore, the length of the food chain usually does not exceed 4 - 5 links.

Energy of the Earth's landscape sphere:

1) solar energy: thermal, radiant

2) the flow of thermal energy from the bowels of the Earth

3) tidal current energy

4) tectonic energy

5) energy assimilation during photosynthesis

Water cycle in nature

The water cycle in nature is the process of cyclic movement of water in the earth's biosphere. It consists of evaporation, condensation and precipitation (atmospheric precipitation partially evaporates, partially forms temporary and permanent drains and reservoirs, partially seeps into the ground and forms groundwater), as well as the processes of degassing of the mantle: water continuously flows from the mantle. water has been found even at great depths.

The seas lose more water due to evaporation than they receive through precipitation; on land the situation is the opposite. Water continuously circulates on the globe, while its total quantity remains unchanged.

75% of the Earth's surface is covered with water. The water shell of the Earth is the hydrosphere. Most of it is salt water from seas and oceans, and a smaller part is fresh water from lakes, rivers, glaciers, groundwater and water vapor.

On earth, water exists in three states of aggregation: liquid, solid and gaseous. Without water, living organisms cannot exist. In any organism, water is the medium in which chemical reactions occur, without which living organisms cannot live. Water is the most valuable and essential substance for the life of living organisms.

There are several types of water cycles in nature:

The Great, or Global, Cycle - water vapor formed above the surface of the oceans is carried by winds to the continents, falls there in the form of precipitation and returns to the ocean in the form of runoff. In this process, the quality of water changes: with evaporation, salty sea water turns into fresh water, and polluted water is purified.

Small, or oceanic, cycle - water vapor formed above the surface of the ocean condenses and falls as precipitation back into the ocean.

The intracontinental cycle - water that has evaporated over the land surface again falls on land in the form of precipitation.

In the end, the sediments in the process of movement again reach the World Ocean.

The rate of transfer of different types of water varies widely, and the periods of flow and periods of water renewal are also different. They vary from several hours to several tens of thousands of years. Atmospheric moisture, which is formed by the evaporation of water from the oceans, seas and land and exists in the form of clouds, is renewed on average every eight days.

The waters that make up living organisms are restored within a few hours. This is the most active form of water exchange. The period of renewal of water reserves in mountain glaciers is about 1,600 years, in the glaciers of polar countries it is much longer - about 9,700 years.

Complete renewal of the waters of the World Ocean occurs in approximately 2,700 years.

Effects of interaction between solar radiation, moving and rotating earth.

In this matter, seasonal variability should be considered: winter/summer. Describe that due to the rotation and movement of the Earth, solar radiation arrives unevenly, which means climatic conditions change with latitude.

The Earth is inclined to the ecliptic plane by 23.5 degrees.

The rays pass at different angles. Radiation balance. It is important not only how much it receives, but also how much it loses, and how much remains, taking into account the albedo.

Centers of action of the atmosphere

Large areas of persistent high or low pressure, associated with the general circulation of the atmosphere – centers of atmospheric action. They determine the dominant direction of winds and serve as centers for the formation of geographical types of air masses. On synoptic maps they are expressed as closed lines - isobars.

Causes: 1) heterogeneity of the Earth;

2) difference in physical properties of land and water (heat capacity)

3) difference in surface albedo (R/Q): water – 6%, eq. forests – 10-12%, broad forests – 18%, meadow – 22-23%, snow – 92%;

4) Coriolis F

This causes OCA.

Centers of action of the atmosphere:

● permanent– they have high or low pressure all year round:

1. equatorial low band pressure, the axis of which migrates somewhat from the equator following the Sun towards the summer hemisphere - Equatorial depression (reasons: a large number of Q and oceans);

2. along one subtropical strip of elevation. pressure in the North and Yuzh. hemispheres; a few migrate in summer to higher subtropical areas. latitudes, in winter - to lower ones; break up into a series of oceanic anticyclones: in the North. hemispheres - Azores anticyclone (especially in summer) and Hawaiian; in the South - South Indian, South Pacific and South Atlantic;

3. areas of decline. pressure over the oceans in high latitudes of temperate zones: in the North. hemispheres - Icelandic (especially in winter) and Aleutian minimums, in the South - a continuous ring of low pressure surrounding Antarctica (50 0 S);

4. areas of increased pressure over the Arctic (especially in winter) and Antarctica - anticyclones;

● seasonal– can be traced as areas of high or low pressure during one season, changing in another season to the center of action of the atmosphere of the opposite sign. Their existence is associated with a sharp change during the year in the temperature of the land surface in relation to the temperature of the surface of the oceans; summer overheating of sushi creates favorable conditions to form areas of depression here. pressure, winter hypothermia - for areas of higher pressure. All in. hemispheres to higher winter areas. pressures include the Asian (Siberian) centered in Mongolia and the Canadian highs, and the South Australian, South American and South African highs. Summer low areas pressure: in North hemispheres - South Asian (or Western Asian) and North American minimums, in the South. - Australian, South American and South African lows).

The centers of action of the atmosphere are characterized by a certain type of weather. Therefore, the air here relatively quickly acquires the properties of the underlying surface - hot and humid in the Equatorial Depression, cold and dry in the Mongolian Anticyclone, cool and humid in the Icelandic Low, etc.

Planetary heat exchange and its causes

Main features of planetary heat exchange. Solar energy absorbed by the surface globe, is then spent on evaporation and heat transfer by turbulent flows. On average, about 80% of the entire planet goes to evaporation, and the remaining 20% ​​of the total heat goes to turbulent heat exchange.

The processes of heat exchange and changes in the geographical latitude of its components in the ocean and on land are very unique. All the heat absorbed by land in spring and summer is completely lost in autumn and winter; with a balanced annual heat budget, it therefore turns out to be equal to zero everywhere.

In the World Ocean, due to the high heat capacity of water and its mobility, heat accumulates in low latitudes, from where it is transferred by currents to high latitudes, where its consumption exceeds its supply. In this way, the deficit created in the heat exchange of water with air is covered.

In the equatorial zone of the World Ocean, with a large amount of absorbed solar radiation and reduced energy consumption, the annual heat budget has maximum positive values. With distance from the equator, the positive annual heat budget decreases due to an increase in the consumption components of heat exchange, mainly evaporation. With the transition from the tropics to temperate latitudes, the heat budget becomes negative.

Within the land, all the heat received in the spring-summer period is spent in the autumn-winter period. Over the long history of the Earth, the waters of the World Ocean have accumulated a huge amount of heat equal to 7.6 * 10^21 kcal. The accumulation of such a large mass is explained by the high heat capacity of water and its intense mixing, during which a rather complex redistribution of heat occurs in the thickness of the oceanosphere. The heat capacity of the entire atmosphere is 4 times less than that of a ten-meter layer of water in the World Ocean.

Despite the fact that the share of solar energy going to turbulent heat exchange between the Earth's surface and the air is relatively small, it is the main source of heating the near-surface part of the atmosphere. The intensity of this heat exchange depends on the temperature difference between the air and the underlying surface (water or land). In the low latitudes of the planet (from the equator to approximately the fortieth latitude of both hemispheres), the air is heated mainly by land, which is unable to accumulate solar energy and gives up all the heat it receives to the atmosphere. Due to turbulent heat exchange, the air shell receives from 20 to 40 kcal/cm^2 per year, and in areas with low humidity (Sahara, Arabia, etc.) - even more than 60 kcal/cm^2. The waters in these latitudes accumulate heat, releasing only 5-10 kcal/cm^2 per year or less to the air in the process of turbulent heat exchange. Only in certain areas (limited area) is the water colder on average per year and therefore receives heat from the air (in the equatorial zone, in the northwest Indian Ocean, as well as off the west coast of Africa and South America).

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 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 gas composition 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 when 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 in a 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 energy degradation, 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 substances necessary for life from the environment 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 diagram:

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 this case, energy and matter are transferred 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 geographical envelope, and the part of inert elements is very small.

Scattered elements characterized by a predominance of free atoms. They enter into 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 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 integral part all proteins. The general ratio of fixed nitrogen, as an element that makes up organic matter, to nitrogen in nature is 1:100000. 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 in which these salts are formed? Here are some of them:

In the biosphere, nitrogen fixation is carried out by several groups of animals. aerobic 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 passed 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 their 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.

Large (geological) and small (biogeochemical) cycle of substances

All substances on our planet are in the process of circulation. Solar energy causes two cycles of substances on Earth:

Large (geological or abiotic);

Small (biotic, biogenic or biological).

Cycles of matter and flows of cosmic energy create the stability of the biosphere. The cycle of solid matter and water that occurs as a result of the action of abiotic factors (inanimate nature) is called the great geological cycle. During a large geological cycle (lasting millions of years), rocks are destroyed, weathered, substances dissolve and enter the World Ocean; geotectonic changes, continental subsidence, and seabed uplift occur. The water cycle time in glaciers is 8,000 years, in rivers - 11 days. It is the great cycle that supplies living organisms with nutrients and largely determines the conditions of their existence.

The large geological cycle in the biosphere is characterized by two important points: oxygen carbon geological

• a) is carried out throughout the entire geological development of the Earth;
• b) is a modern planetary process that takes a leading part in the further development of the biosphere.

On modern stage During the development of mankind, as a result of the large cycle, pollutants are also transported over long distances - oxides of sulfur and nitrogen, dust, radioactive impurities. The areas of temperate latitudes of the Northern Hemisphere were the most contaminated.

Small, biogenic or biological cycle of substances occurs in solid, liquid and gaseous phases with the participation of living organisms. The biological cycle, as opposed to the geological cycle, requires less energy. The small cycle is part of a large one, occurs at the level of biogeocenoses (within ecosystems) and consists in the fact that soil nutrients, water, and carbon accumulate in plant matter and are spent on building the body. Decay products of organic matter decompose into mineral components. The small cycle is not closed, which is associated with the flow of substances and energy into the ecosystem from the outside and with the release of some of them into the biosphere cycle.

Many chemical elements and their compounds are involved in the large and small cycles, but the most important of them are those that determine the current stage of development of the biosphere, associated with human economic activity. These include the cycles of carbon, sulfur and nitrogen (their oxides are the main pollutants of the atmosphere), as well as phosphorus (phosphates are the main pollutant of continental waters). Almost all pollutants are harmful and are classified as xenobiotics. Currently great importance have cycles of xenobiotics - toxic elements - mercury (a food pollutant) and lead (a component of gasoline). In addition, many substances of anthropogenic origin (DDT, pesticides, radionuclides, etc.) that cause harm to biota and human health come from the large cycle to the small one.

The essence of the biological cycle lies in the occurrence of two opposite but interconnected processes - the creation of organic matter and its destruction by living matter.

Unlike the large gyre, the small gyre has a different duration: seasonal, annual, perennial and secular small gyres are distinguished. The cycling of chemicals from the inorganic environment through vegetation and animals back into the inorganic environment using solar energy from chemical reactions is called the biogeochemical cycle.

The present and future of our planet depends on the participation of living organisms in the functioning of the biosphere. In the cycle of substances, living matter, or biomass, performs biogeochemical functions: gas, concentration, redox and biochemical.

The biological cycle occurs with the participation of living organisms and consists in the reproduction of organic matter from inorganic and the decomposition of this organic to inorganic through the food trophic chain. The intensity of production and destruction processes in the biological cycle depends on the amount of heat and moisture. For example, the low rate of decomposition of organic matter in polar regions depends on heat deficiency.

An important indicator of the intensity of the biological cycle is the rate of circulation of chemical elements. The intensity is characterized by an index equal to the ratio of the mass of forest litter to litter. The higher the index, the lower the intensity of the circulation.

Index in coniferous forests - 10 - 17; broad-leaved 3 - 4; savanna no more than 0.2; in tropical rainforests no more than 0.1, i.e. Here the biological cycle is most intense.

The flow of elements (nitrogen, phosphorus, sulfur) through microorganisms is an order of magnitude higher than through plants and animals. The biological cycle is not completely reversible; it is closely related to the biogeochemical cycle. Chemical elements circulate in the biosphere along various pathways of the biological cycle:

• - are absorbed by living matter and charged with energy;
• - leave living matter, releasing energy into the external environment.

These cycles are of two types: the cycle of gaseous substances; sedimentary cycle (reserve in the earth's crust).

The gyres themselves consist of two parts:

• - reserve fund (this is the part of the substance not associated with living organisms);
• - mobile (exchange) fund (a smaller part of the substance associated with direct exchange between organisms and their immediate environment).

Gyres are divided into:

• - gyres gas type with a reserve fund in the earth's crust (carbon, oxygen, nitrogen cycles) - capable of rapid self-regulation;
• - sedimentary cycles with a reserve fund in the earth's crust (cycles of phosphorus, calcium, iron, etc.) are more inert, the bulk of the substance is in a form “inaccessible” to living organisms.

Gyres can also be divided into:

• - closed (the cycle of gaseous substances, for example, oxygen, carbon and nitrogen - a reserve in the atmosphere and hydrosphere of the ocean, so the shortage is quickly compensated);
• - open-ended (creating a reserve fund in the earth's crust, for example, phosphorus - therefore losses are poorly compensated, i.e. a deficit is created).

The energy basis for the existence of biological cycles on Earth and their initial link is the process of photosynthesis. Each new cycle is not an exact repetition of the previous one. For example, during the evolution of the biosphere, some of the processes were irreversible, resulting in the formation and accumulation of biogenic sediments, an increase in the amount of oxygen in the atmosphere, changes in the quantitative ratios of isotopes of a number of elements, etc.

The circulation of substances is usually called biogeochemical cycles. The main biogeochemical (biosphere) cycles of substances: water cycle, oxygen cycle, nitrogen cycle (participation of nitrogen-fixing bacteria), carbon cycle (participation of aerobic bacteria; annually about 130 tons of carbon are discharged into the geological cycle), phosphorus cycle (participation of soil bacteria; annually in 14 million tons of phosphorus are washed out of the oceans), the sulfur cycle, the cycle of metal cations.

The water cycle

The water cycle is a closed cycle that can occur, as mentioned above, even in the absence of life, but living organisms modify it.

The cycle is based on the principle: evapotranspiration is compensated by precipitation. For the planet as a whole, evaporation and precipitation balance each other. At the same time, more water evaporates from the ocean than returns with precipitation. On land, on the contrary, more precipitation falls, but the excess flows into lakes and rivers, and from there again into the ocean. The moisture balance between continents and oceans is maintained by river flow.

Thus, the global hydrological cycle has four main flows: precipitation, evaporation, moisture transfer, and transpiration.

Water, the most abundant substance in the biosphere, not only serves as a habitat for many organisms, but is also an integral part of the body of all living beings. Despite the enormous importance of water in all life processes occurring in the biosphere, living matter does not play a decisive role in the large water cycle on the globe. The driving force of this cycle is the energy of the sun, which is spent on the evaporation of water from the surface of water basins or land. Evaporated moisture condenses in the atmosphere in the form of clouds carried by the wind; When clouds cool, precipitation occurs.

The total amount of free unbound water (the proportion of oceans and seas containing liquid salt water) accounts for 86 to 98%. The rest of the water (fresh water) is stored in the polar caps and glaciers and forms water basins and its groundwater. Precipitation falling on the surface of land covered with vegetation is partially retained by the leaf surface and subsequently evaporates into the atmosphere. Moisture that reaches the soil may join surface runoff or be absorbed by the soil. Having been completely absorbed by the soil (this depends on the type of soil, the characteristics of the rocks and vegetation cover), excess sediment can seep deeper into the groundwater. If the amount of precipitation exceeds the moisture holding capacity of the upper layers of the soil, surface runoff begins, the speed of which depends on the condition of the soil, the steepness of the slope, the duration of precipitation and the nature of vegetation (vegetation can protect the soil from water erosion). Water retained in the soil can evaporate from its surface or, after being absorbed by plant roots, transpirate (evaporate) into the atmosphere through the leaves.

The transpiration flow of water (soil - plant roots - leaves - atmosphere) is the main path of water through living matter in its large cycle on our planet.

Carbon cycle

The entire diversity of organic substances, biochemical processes and life forms on Earth depends on the properties and characteristics of carbon. The carbon content in most living organisms is about 45% of their dry biomass. All living matter on the planet participates in the cycle of organic matter and all carbon on the Earth, which continuously arises, changes, dies, decomposes, and in this sequence carbon is transferred from one organic matter to the construction of another along the food chain. In addition, all living things breathe, releasing carbon dioxide.

Carbon cycle on land. The carbon cycle is maintained by photosynthesis by land plants and ocean phytoplankton. By absorbing carbon dioxide (fixing inorganic carbon), plants use the energy of sunlight to convert it into organic compounds- creating your own biomass. At night, plants, like all living things, breathe, releasing carbon dioxide.

Dead plants, corpses and animal excrement serve as food for numerous heterotrophic organisms (animals, saprophytic plants, fungi, microorganisms). All these organisms live mainly in the soil and in the process of life they create their own biomass, which includes organic carbon. They also release carbon dioxide, creating “soil respiration.” Often dead organic matter does not completely decompose and humus (humus) accumulates in soils, which plays an important role in soil fertility. The degree of mineralization and humification of organic substances depends on many factors: humidity, temperature, physical properties soil, composition of organic residues, etc. Under the influence of bacteria and fungi, humus can decompose into carbon dioxide and mineral compounds.

Carbon cycle in the World Ocean. The carbon cycle in the ocean is different from the cycle on land. The ocean is the weak link of organisms at higher trophic levels, and therefore all links of the carbon cycle. The time it takes for carbon to pass through the trophic link of the ocean is short, and the amount of carbon dioxide released is insignificant.

The ocean acts as the main regulator of carbon dioxide in the atmosphere. There is an intense exchange of carbon dioxide between the ocean and the atmosphere. Ocean waters have a high dissolving capacity and buffer capacity. A system consisting of carbonic acid and its salts (carbonates) is a kind of carbon dioxide depot, connected to the atmosphere through CO diffusion? from water to atmosphere and back.

In the ocean during the day, phytoplankton photosynthesis occurs intensively, while free carbon dioxide is intensively consumed, carbonates serve as an additional source of its formation. At night, when the free acid content increases due to the respiration of animals and plants, a significant part of it again enters into the composition of carbonates. The processes taking place go in the following directions: living matter? SO?? N?SO?? Sa(NSO?)?? CaCO?.

In nature, a certain amount of organic matter does not undergo mineralization as a result of a lack of oxygen, high acidity of the environment, specific burial conditions, etc. Some carbon leaves the biological cycle in the form of inorganic (limestone, chalk, corals) and organic (shale, oil, coal) deposits.

Human activities are making significant changes to the carbon cycle on our planet. Landscapes, types of vegetation, biocenoses and their food chains change, huge areas of land surface are drained or irrigated, soil fertility improves (or worsens), fertilizers and pesticides are introduced, etc. The most dangerous is the release of carbon dioxide into the atmosphere as a result of fuel combustion. At the same time, the rate of carbon circulation increases and its cycle shortens.

Oxygen cycle

Oxygen is prerequisite existence of life on Earth. It is included in almost all biological compounds, participates in biochemical reactions of oxidation of organic substances, providing energy for all life processes of organisms in the biosphere. Oxygen ensures the respiration of animals, plants and microorganisms in the atmosphere, soil, water, and participates in chemical oxidation reactions occurring in rocks, soils, silts, and aquifers.

The main branches of the oxygen cycle:

• - the formation of free oxygen during photosynthesis and its absorption during the respiration of living organisms (plants, animals, microorganisms in the atmosphere, soil, water);
• - formation of an ozone screen;
• - creation of redox zoning;
• - oxidation of carbon monoxide during volcanic eruptions, accumulation of sulfate sedimentary rocks, oxygen consumption in human activity, etc.; Molecular oxygen of photosynthesis is involved everywhere.

Nitrogen cycle

Nitrogen is part of the biologically important organic substances of all living organisms: proteins, nucleic acids, lipoproteins, enzymes, chlorophyll, etc. Despite the nitrogen content (79%) in the air, it is deficient for living organisms.

Nitrogen in the biosphere is in a gaseous form (N2) inaccessible to organisms - it is chemically little active, so it cannot be directly used by higher plants (and most lower plants) and the animal world. Plants absorb nitrogen from the soil in the form of ammonium ions or nitrate ions, i.e. so-called fixed nitrogen.

There are atmospheric, industrial and biological nitrogen fixation.

Atmospheric fixation occurs when the atmosphere is ionized by cosmic rays and during strong electrical discharges during thunderstorms, while nitrogen and ammonia oxides are formed from molecular nitrogen in the air, which, thanks to atmospheric precipitation, are converted into ammonium, nitrite, and nitrate nitrogen and enter the soil and water basins.

Industrial fixation occurs as a result of human economic activity. The atmosphere is polluted with nitrogen compounds by factories that produce nitrogen compounds. Hot emissions from thermal power plants, factories, spacecraft, and supersonic aircraft oxidize air nitrogen. Nitrogen oxides, interacting with water vapor from air and precipitation, return to the ground and enter the soil in ionic form.

Biological fixation plays a major role in the nitrogen cycle. It is carried out by soil bacteria:

• - nitrogen-fixing bacteria (and blue-green algae);
• - microorganisms living in symbiosis with higher plants (nodule bacteria);
• - ammonifying;
• - nitrifying;
• - denitrifying.

Free-living nitrogen-fixing aerobic (existing in the presence of oxygen) bacteria (Azotobacter) in the soil are capable of fixing atmospheric molecular nitrogen using the energy obtained from the oxidation of soil organic matter during respiration, ultimately binding it with hydrogen and introducing it in the form of an amino group (- NH2) into the amino acid composition of its body. Molecular nitrogen is also capable of fixing some anaerobic (living in the absence of oxygen) bacteria that exist in the soil (Clostridium). As they die, both microorganisms enrich the soil with organic nitrogen.

Blue-green algae, which are especially important for the soils of rice fields, are also capable of biological fixation of molecular nitrogen.

The most effective biological fixation of atmospheric nitrogen occurs in bacteria living in symbiosis in the nodules of leguminous plants (nodule bacteria).

These bacteria (Rizobium) use the energy of the host plant to fix nitrogen, while at the same time supplying the host's terrestrial organs with nitrogen compounds available to it.

By assimilating nitrogen compounds from the soil in nitrate and ammonium forms, plants build the necessary nitrogen-containing compounds of their body (nitrate nitrogen is pre-reduced in plant cells). Producing plants supply nitrogenous substances to the entire animal world and humanity. Dead plants are used, according to the trophic chain, as bioreducers.

Ammonifying microorganisms decompose organic substances containing nitrogen (amino acids, urea) to form ammonia. Some of the organic nitrogen in the soil is not mineralized, but is converted into humus substances, bitumen and components of sedimentary rocks.

Ammonia (in the form of ammonium ion) can enter root system plants, or used in nitrification processes.

Nitrifying microorganisms are chemosynthetics; they use the energy of the oxidation of ammonia to nitrates and nitrites to nitrates to ensure all life processes. Using this energy, nitrifiers reduce carbon dioxide and build organic matter in their bodies. Ammonia oxidation during nitrification proceeds through the following reactions:

NH? + 3O? ? 2HNO? + 2H?O + 600 kJ (148 kcal).

HNO? +O? ? 2HNO? + 198 kJ (48 kcal).

Nitrates formed during nitrification processes again enter the biological cycle, are absorbed from the soil by plant roots or after entering with water runoff into water basins - phytoplankton and phytobenthos.

Along with organisms that fix atmospheric nitrogen and nitrify it, there are microorganisms in the biosphere that are capable of reducing nitrates or nitrites to molecular nitrogen. Such microorganisms, called denitrifiers, when there is a lack of free oxygen in waters or soil, use nitrate oxygen to oxidize organic substances:

C?H??O?(glucose) + 24KNO? ? 24KHCO? + 6CO? +12N? + 18H?O + energy

The energy released in this case serves as the basis for all the life activity of denitrifying microorganisms.

Thus, living substances play an exceptional role in all parts of the cycle.

Currently, industrial fixation of atmospheric nitrogen by humans plays an increasingly important role in the nitrogen balance of soils and, consequently, in the entire nitrogen cycle in the biosphere.

Phosphorus cycle

The phosphorus cycle is simpler. While the reservoir of nitrogen is the air, the reservoir of phosphorus is the rocks from which it is released by erosion.

Carbon, oxygen, hydrogen and nitrogen migrate more easily and quickly in the atmosphere, since they are in gaseous form, forming gaseous compounds in biological cycles. For all other elements, except for sulfur necessary for the existence of living matter, the formation of gaseous compounds in biological cycles is uncharacteristic. These elements migrate mainly in the form of ions and molecules dissolved in water.

Phosphorus, assimilated by plants in the form of orthophosphoric acid ions, takes a large part in the life of all living organisms. It is part of ADP, ATP, DNA, RNA and other compounds.

The phosphorus cycle in the biosphere is not closed. In terrestrial biogeocenoses, phosphorus, after being absorbed by plants from the soil through the food chain, again enters the soil in the form of phosphates. The main amount of phosphorus is reabsorbed by the root system of plants. Phosphorus can be partially washed out with rainwater runoff from the soil into water basins.

In natural biogeocenoses there is often a lack of phosphorus, and in an alkaline and oxidized environment it is usually found in the form of insoluble compounds.

Lithosphere rocks contain large amounts of phosphates. Some of them gradually pass into the soil, some are developed by humans for the production of phosphate fertilizers, and most of them are leached and washed into the hydrosphere. There they are used by phytoplankton and associated organisms located at different trophic levels of complex food chains.

In the World Ocean, the loss of phosphates from the biological cycle occurs due to the deposition of plant and animal remains at great depths. Since phosphorus moves mainly from the lithosphere to the hydrosphere with water, it migrates to the lithosphere biologically (eating fish by seabirds, using benthic algae and fishmeal as fertilizer, etc.).

Of all the elements of plant mineral nutrition, phosphorus can be considered deficient.

Sulfur cycle

For living organisms, sulfur is of great importance, because it is part of sulfur-containing amino acids (cystine, cysteine, methionine, etc.). Being part of proteins, sulfur-containing amino acids maintain the necessary three-dimensional structure of protein molecules.

Sulfur is absorbed by plants from the soil only in oxidized form, in the form of an ion. In plants, sulfur is reduced and is included in amino acids in the form of sulfhydryl (-SH) and disulfide (-S-S-) groups.

Animals assimilate only reduced sulfur found in organic matter. After the death of plant and animal organisms, sulfur returns to the soil, where, as a result of the activity of numerous forms of microorganisms, it undergoes transformations.

Under aerobic conditions, some microorganisms oxidize organic sulfur to sulfates. Sulfate ions, being absorbed by plant roots, are again included in the biological cycle. Some sulfates may be included in water migration and removed from the soil. In soils rich in humic substances, a significant amount of sulfur is found in organic compounds, which prevents its leaching.

Under anaerobic conditions, the decomposition of organic sulfur compounds produces hydrogen sulfide. If sulfates and organic substances are in an oxygen-free environment, the activity of sulfate-reducing bacteria is activated. They use the oxygen of sulfates to oxidize organic substances and thus obtain the energy necessary for their existence.

Sulfate-reducing bacteria are common in groundwater, mud, and stagnant seawater. Hydrogen sulfide is a poison for most living organisms, so its accumulation in water-filled soil, lakes, estuaries, etc. significantly reduces or even completely stops life processes. This phenomenon is observed in the Black Sea at a depth below 200 m from its surface.

Thus, to create a favorable environment, it is necessary to oxidize hydrogen sulfide to sulfate ions, which will destroy harmful effect hydrogen sulfide, sulfur will turn into a form accessible to plants - in the form of sulfate salts. This role is performed in nature by a special group of sulfur bacteria (colorless, green, purple) and thionic bacteria.

Colorless sulfur bacteria are chemosynthetics: they use the energy obtained from the oxidation of hydrogen sulfide by oxygen to elemental sulfur and its further oxidation to sulfates.

Colored sulfur bacteria are photosynthetic organisms that use hydrogen sulfide as a hydrogen donor to reduce carbon dioxide.

The resulting elemental sulfur in green sulfur bacteria is released from the cells, and in purple bacteria it accumulates inside the cells.

The overall reaction of this process is photoreduction:

CO?+ 2H?S light? (CH?O)+ H?O +2S.

Thionic bacteria oxidize elemental sulfur and its various reduced compounds to sulfates using free oxygen, returning it back to the main stream of the biological cycle.

In the processes of the biological cycle, where the transformation of sulfur occurs, living organisms, especially microorganisms, play a huge role.

The main reservoir of sulfur on our planet is the World Ocean, since sulfate ions continuously flow into it from the soil. Part of the sulfur from the ocean returns to land through the atmosphere according to the scheme hydrogen sulfide - its oxidation to sulfur dioxide - dissolution of the latter in rainwater with the formation of sulfuric acid and sulfates - return of sulfur with precipitation to the soil cover of the Earth.

Cycle of inorganic cations

In addition to the basic elements that make up living organisms (carbon, oxygen, hydrogen, phosphorus and sulfur), many other macro- and microelements - inorganic cations - are vitally important. In water basins, plants receive the metal cations they need directly from the environment. On land, the main source of inorganic cations is the soil, which received them during the destruction of parent rocks. In plants, cations absorbed by root systems move to leaves and other organs; some of them (magnesium, iron, copper and a number of others) are part of biologically important molecules (chlorophyll, enzymes); others staying in free form, participate in maintaining the necessary colloidal properties of cell protoplasm and perform other various functions.

When living organisms die, inorganic cations return to the soil during the mineralization of organic substances. The loss of these components from the soil occurs as a result of leaching and removal of metal cations with rainwater, rejection and removal of organic matter by humans during the cultivation of agricultural plants, cutting down forests, mowing grass for livestock feed, etc.

Rational use of mineral fertilizers, soil reclamation, application organic fertilizers, proper agricultural technology will help restore and maintain the balance of inorganic cations in the biocenoses of the biosphere.

Anthropogenic cycle: cycle of xenobiotics (mercury, lead, chromium)

Humanity is part of nature and can only exist in constant interaction with it.

There are similarities and contradictions between the natural and anthropogenic cycle of substances and energy occurring in the biosphere.

The natural (biogeochemical) cycle of life has the following features:

• - the use of solar energy as a source of life and all its manifestations based on thermodynamic laws;
• - it is carried out without waste, i.e. all products of its vital activity are mineralized and again included in the next cycle of the circulation of substances. At the same time, waste, depreciated thermal energy is removed outside the biosphere. During the biogeochemical cycle of substances, waste is formed, i.e. reserves in the form of coal, oil, gas and other mineral resources. Unlike the waste-free natural cycle, the anthropogenic cycle is accompanied by increasing waste every year.

There is nothing useless or harmful in nature; even volcanic eruptions have benefits, since volcanic gases enter the air necessary elements(eg nitrogen).

There is a law of global closure of the biogeochemical cycle in the biosphere, which operates at all stages of its development, as well as the rule of increasing closure of the biogeochemical cycle during succession.

Huge role on biogeochemical cycle a person renders, but in the opposite direction. Man disrupts the existing cycles of substances, and this manifests his geological power - destructive in relation to the biosphere. As a result anthropogenic activities the degree of closedness of biogeochemical cycles decreases.

The anthropogenic cycle is not limited to the energy of sunlight captured by the green plants of the planet. Humanity uses the energy of fuel, hydro and nuclear power plants.

It can be argued that anthropogenic activity at the present stage represents a huge destructive force for the biosphere.

The biosphere has a special property - significant resistance to pollutants. This stability is based on the natural ability of the various components natural environment to self-purification and self-healing. But not unlimited. A possible global crisis has necessitated the construction of a mathematical model of the biosphere as a single whole (the Gaia system) in order to obtain information about the possible state of the biosphere.

A xenobiotic is a substance foreign to living organisms that appears as a result of anthropogenic activities (pesticides, household chemicals and other pollutants) that can cause disruption of biotic processes, incl. disease or death of the body. Such pollutants do not undergo biodegradation, but accumulate in trophic chains.

Mercury is a very rare element. It is dispersed in the earth's crust and is found in concentrated form only in a few minerals, such as cinnabar. Mercury participates in the cycle of matter in the biosphere, migrating in a gaseous state and in aqueous solutions.

It enters the atmosphere from the hydrosphere during evaporation, when released from cinnabar, with volcanic gases and gases from thermal springs. Part of the gaseous mercury in the atmosphere turns into the solid phase and is removed from the air. The dropped mercury is absorbed by soils, especially clayey soils, water and rocks. Combustible minerals - oil and coal - contain up to 1 mg/kg of mercury. The water mass of the oceans contains approximately 1.6 billion tons, in bottom sediments - 500 billion tons, and in plankton - 2 million tons. River waters annually carry about 40 thousand tons from land, which is 10 times less than what enters the atmosphere during evaporation (400 thousand tons). About 100 thousand tons fall on the land surface annually.

Mercury has transformed from a natural component of the natural environment into one of the most dangerous man-made emissions into the biosphere for human health. It is widely used in the metallurgy, chemical, electrical, electronics, pulp and paper and pharmaceutical industries and is used for the production of explosives, varnishes and paints, as well as in medicine. Industrial effluents and atmospheric emissions, along with mercury mines, mercury production plants and thermal power plants (CHPs and boiler houses) using coal, oil and petroleum products, are the main sources of pollution of the biosphere with this toxic component. In addition, mercury is part of organomercury pesticides used in agriculture to treat seeds and protect crops from pests. It enters the human body with food (eggs, pickled grain, meat of animals and birds, milk, fish).

Mercury in water and river sediments

It has been established that about 80% of mercury entering natural water bodies is in dissolved form, which ultimately contributes to its distribution over long distances along with water flows. The pure element is non-toxic.

Mercury is often found in bottom silt water in relatively harmless concentrations. Inorganic mercury compounds are converted into toxic organic mercury compounds, such as methylmercury CH?Hg and ethylmercury C?H?Hg, by bacteria living in detritus and sediments, in the bottom mud of lakes and rivers, in the mucus covering the bodies of fish, and in fish stomach mucus. These compounds are easily soluble, mobile and very poisonous. The chemical basis for the aggressive action of mercury is its affinity with sulfur, in particular with the hydrogen sulfide group in proteins. These molecules bind to chromosomes and brain cells. Fish and shellfish can accumulate them to concentrations that are dangerous for humans who eat them, causing Minamata disease.

Metallic mercury and its inorganic compounds act mainly on the liver, kidneys and intestinal tract, but under normal conditions they are removed from the body relatively quickly and a dangerous amount for the human body does not have time to accumulate. Methylmercury and other alkyl mercury compounds are much more dangerous because accumulation occurs - the toxin enters the body faster than it is eliminated from the body, affecting the central nervous system.

Bottom sediments are an important characteristic of aquatic ecosystems. Accumulating heavy metals, radionuclides and highly toxic organic substances, bottom sediments, on the one hand, contribute to the self-purification of aquatic environments, and on the other hand, they represent a constant source of secondary pollution of water bodies. Bottom sediments are a promising object of analysis, reflecting a long-term pattern of pollution (especially in low-flow water bodies). Moreover, the accumulation of inorganic mercury in bottom sediments is observed especially at river mouths. A tense situation may arise when the adsorption capacity of sediments (silt, sediment) is exhausted. When the adsorption capacity is reached, heavy metals, incl. mercury will begin to enter the water.

It is known that under marine anaerobic conditions in sediments of dead algae, mercury attaches hydrogen and turns into volatile compounds.

With the participation of microorganisms, metallic mercury can be methylated in two stages:

CH?Hg+ ? (CH?)?Hg

Methylmercury appears in the environment almost exclusively through the methylation of inorganic mercury.

The biological half-life of mercury is long; for most tissues of the human body it is 70-80 days.

It is known that large fish, such as swordfish and tuna, are contaminated with mercury at the beginning of the food chain. It is not without interest to note that, to an even greater extent than in fish, mercury accumulates (accumulates) in oysters.

Mercury enters the human body through breathing, food and through the skin according to the following scheme:

Firstly, mercury is transformed. This element occurs naturally in several forms.

Metallic mercury, used in thermometers, and its inorganic salts (for example, chloride) are eliminated from the body relatively quickly.

Much more toxic are alkyl mercury compounds, in particular methyl and ethyl mercury. These compounds are eliminated from the body very slowly - only about 1% of the total amount per day. Although most of the mercury that enters natural waters is found in the form of inorganic compounds, in fish it always appears in the form of the much poisonous methylmercury. Bacteria in the bottom silt of lakes and rivers, in the mucus covering the bodies of fish, as well as in the mucus of fish stomachs are capable of converting inorganic mercury compounds into methylmercury.

Second, selective accumulation, or biological accumulation (concentration), increases mercury levels in fish and shellfish to levels many times higher than in bay waters. Fish and shellfish living in the river accumulate methylmercury to concentrations that are dangerous for humans who use them as food.

% of the world's fish catch contains mercury in quantities of no more than 0.5 mg/kg, and 95% contain less than 0.3 mg/kg. Almost all the mercury in fish is in the form of methylmercury.

Taking into account the different toxicity of mercury compounds for humans in food products, it is necessary to determine inorganic (total) and organically bound mercury. We only determine the total mercury content. According to medical and biological requirements, the mercury content in freshwater predatory fish is allowed to be 0.6 mg/kg, in sea fish - 0.4 mg/kg, in freshwater non-predatory fish only 0.3 mg/kg, and in tuna fish up to 0.7 mg/kg kg. In baby food products, the mercury content should not exceed 0.02 mg/kg in canned meat, 0.15 mg/kg in canned fish, and 0.01 mg/kg in others.

Lead is present in almost all components of the natural environment. The earth's crust contains 0.0016%. The natural level of lead in the atmosphere is 0.0005 mg/m3. Most of it is deposited with dust, approximately 40% falls with precipitation. Plants obtain lead from soil, water and atmospheric deposition, and animals receive lead from consuming plants and water. Metal enters the human body along with food, water and dust.

The main source of lead pollution in the biosphere are gasoline engines, the exhaust gases of which contain triethyl lead, thermal power enterprises coal burning, mining, metallurgical and chemical industry. Significant amounts of lead are introduced into the soil along with wastewater used as fertilizer. To extinguish the burning reactor of the Chernobyl nuclear power plant, lead was also used, which entered the air basin and was dispersed over vast areas. With increasing environmental pollution by lead, its deposition in bones, hair, and liver increases.

Chromium. The most dangerous is toxic chromium (6+), which is mobilized in acidic and alkaline soils, in fresh and sea waters. In sea water, chromium is 10 - 20% represented by the form Cr (3+), 25 - 40% - Cr (6+), 45 - 65% - organic form. In the pH range 5 - 7, Cr (3+) predominates, and at pH > 7, Cr (6+) predominates. It is known that Cr(6+) and organic chromium compounds do not coprecipitate with iron hydroxide in seawater.

Natural cycles of substances are practically closed. In natural ecosystems, matter and energy are used sparingly and the waste of some organisms serves an important condition the existence of others. The anthropogenic cycle of substances is accompanied by huge consumption natural resources and large amounts of waste causing environmental pollution. The creation of even the most advanced treatment facilities does not solve the problem, so it is necessary to develop low- and waste-free technologies that make the anthropogenic cycle as closed as possible. Theoretically, it is possible to create a waste-free technology, but low-waste technologies are real.

Adaptation to natural phenomena

Adaptations are various adaptations to the environment developed in organisms (from the simplest to the highest) in the process of evolution. The ability to adapt is one of the main properties of living things, ensuring the possibility of their existence.

The main factors developing the adaptation process include: heredity, variability, natural (and artificial) selection.

Tolerance may change if the body is exposed to different external conditions. Finding himself in such conditions, after some time he gets used to them, adapts to them (from the Latin adaptation - to adapt). The consequence of this is a change in the position of the physiological optimum.

The property of organisms to adapt to existence in a particular range environmental factor called ecological plasticity.

The wider the range of environmental factors within which a given organism can live, the greater its ecological plasticity. According to the degree of plasticity, two types of organisms are distinguished: stenobiont (stenoeca) and eurybiont (eurieca). Thus, stenobionts are ecologically non-plastic (for example, flounder lives only in salt water, and crucian carp only in fresh water), i.e. are not hardy, and eurybionts are ecologically plastic, i.e. more hardy (for example, three-spined stickleback can live in both fresh and salt waters).

Adaptations are multidimensional, since the organism must simultaneously comply with many different environmental factors.

There are three main ways of adaptation of organisms to environmental conditions: active; passive; avoidance of adverse effects.

The active path of adaptation is strengthening resistance, developing regulatory processes that allow all vital functions of the body to be carried out, despite deviations of the factor from the optimum. For example, warm-blooded animals maintain a constant body temperature - optimal for the biochemical processes occurring in it.

The passive path of adaptation is the subordination of the vital functions of organisms to changes in environmental factors. For example, under unfavorable environmental conditions, many organisms go into a state of suspended animation (hidden life), in which the metabolism in the body practically stops (state of winter dormancy, torpor of insects, hibernation, preservation of spores in the soil in the form of spores and seeds).

Avoidance of adverse effects - the development of adaptations, behavior of organisms (adaptation), which help to avoid unfavorable conditions. In this case, adaptations can be: morphological (the structure of the body changes: modification of the leaves of a cactus), physiological (the camel provides itself with moisture due to the oxidation of fat reserves), ethological (behavior changes: seasonal migrations of birds, hibernation in winter).

Living organisms are well adapted to periodic factors. Non-periodic factors can cause illness and even death of the body (for example, drugs, pesticides). However, with prolonged exposure to them, adaptation to them may also occur.

Organisms adapted to daily, seasonal, tidal rhythms, rhythms of solar activity, lunar phases and other strictly periodic phenomena. Thus, seasonal adaptation is distinguished as seasonality in nature and a state of winter dormancy.

Seasonality in nature. The leading significance for plants and animals in the adaptation of organisms is the annual variation of temperature. The period favorable for life, on average for our country, lasts about six months (spring, summer). Even before the arrival of stable frosts, a period of winter dormancy begins in nature.

State of winter dormancy. Winter dormancy is not just a cessation of development as a result of low temperatures, but a complex physiological adaptation, which occurs only at a certain stage of development. For example, the malaria mosquito and the urticaria butterfly overwinter in the adult insect stage, the cabbage moth in the pupal stage, and the gypsy moth in the egg stage.

Biorhythms. In the process of evolution, each species has developed a characteristic annual cycle of intensive growth and development, reproduction, preparation for winter and wintering. This phenomenon is called biological rhythm. Match every period life cycle with the appropriate time of year is crucial for the existence of the species.

The main factor in the regulation of seasonal cycles in most plants and animals is the change in day length.

Biorhythms are:

exogenous (external) rhythms (arise as a reaction to periodic changes in the environment (change of day and night, seasons, solar activity) endogenous (internal rhythms) are generated by the body itself

In turn, endogenous are divided into:

Physiological rhythms (heartbeat, breathing, work of endocrine glands, synthesis of DNA, RNA, proteins, work of enzymes, cell division, etc.)

Ecological rhythms (daily, annual, tidal, lunar, etc.)

The processes of DNA, RNA, protein synthesis, cell division, heartbeat, breathing, etc. have rhythm. External influences can shift the phases of these rhythms and change their amplitude.

Physiological rhythms vary depending on the state of the body, environmental rhythms are more stable and correspond to external rhythms. With endogenous rhythms, the body can orient itself in time and prepare in advance for upcoming environmental changes - this is the body’s biological clock. Many living organisms are characterized by circadian and circan rhythms.

Circadian rhythms (circadian) - repeating intensities and nature of biological processes and phenomena with a period of 20 to 28 hours. Circadian rhythms are associated with the activity of animals and plants during the day and, as a rule, depend on temperature and light intensity. For example, bats fly at dusk and rest during the day; many planktonic organisms stay near the surface of the water at night and descend into the depths during the day.

Seasonal biological rhythms are associated with the influence of light - photoperiod. The response of organisms to day length is called photoperiodism. Photoperiodism is a general, important adaptation that regulates seasonal phenomena in a wide variety of organisms. The study of photoperiodism in plants and animals has shown that the reaction of organisms to light is based on alternating periods of light and darkness of a certain duration during the day. The response of organisms (from single-celled organisms to humans) to the length of day and night shows that they are able to measure time, i.e. have some biological clock. Biological clocks, in addition to seasonal cycles, control many other biological phenomena and determine the correct daily rhythm of both the activity of entire organisms and processes occurring even at the cellular level, in particular, cell division.

A universal property of all living things, from viruses and microorganisms to higher plants and animals, is the ability to produce mutations - sudden, natural and artificially induced, inherited changes in genetic material, leading to changes in certain characteristics of the organism. Mutational variability does not meet environmental conditions and, as a rule, disrupts existing adaptations.

Many insects enter diapause (a long stop in development) at a certain stage of development, which should not be confused with a state of rest in unfavorable conditions. The reproduction of many marine animals is influenced by lunar rhythms.

Circanian (annual) rhythms are repeated changes in the intensity and nature of biological processes and phenomena with a period of 10 to 13 months.

Physical and psychological condition human also has a rhythmic character.

The disrupted rhythm of work and rest reduces performance and has an adverse effect on human health. A person’s condition in extreme conditions will depend on the degree of his preparedness for these conditions, since there is practically no time for adaptation and recovery.

The sulfur and phosphorus cycle is a typical sedimentary bio-geochemical cycle. 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 the extraction of biophilic components by living matter.[...]

The circulation of substances and the transformation of energy ensure the dynamic balance and stability of the biosphere as a whole and its individual parts. At the same time, in the general single cycle, the cycle of solid matter and water, which occurs as a result of the action of abiotic factors (large geological cycle), as well as the small biotic cycle of substances in the solid, liquid and gaseous phases, occurring with the participation of living organisms, are distinguished.[...]

Carbon cycle. Carbon is probably one of the most frequently mentioned chemical elements when considering geological, biological, and, in recent years, technical problems.[...]

The circulation of substances is the repeated participation of substances in processes occurring in the atmosphere, hydrosphere, lithosphere, including those layers that are part of the planet’s biosphere. In this case, two main cycles are distinguished: large (geological) and small (biogenic and biochemical).[...]

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 the depletion of natural resources and pollution of the natural environment - the main causes of all environmental problems of mankind.[...]

Cycles of basic nutrients and elements. Let's consider the cycles of the most significant substances and elements for living organisms (Fig. 3-8). The water cycle is a large geological one; and the cycles of biogenic elements (carbon, oxygen, nitrogen, phosphorus, sulfur and other biogenic elements) - to small biogeochemical.[...]

The circulation of water between land and ocean through the atmosphere is part of 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 km3 of water annually participates in the water cycle on Earth. The water cycle as a whole plays a major role in shaping the 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.[...]

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.[...]

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 the substances needed by living organisms from the earth’s crust is much more difficult than from the atmosphere.[...]

The geological cycle is clearly demonstrated by the example of the water cycle and atmospheric circulation. It is estimated that up to half of the energy received from the Sun is spent on the evaporation of water. Its evaporation from the Earth's surface is compensated by precipitation. At the same time, more water evaporates from the Ocean than is returned with precipitation, but on land the opposite happens - more precipitation falls than water evaporates. Its excess flows into rivers and lakes, and from there again into the Ocean. In the process of the geological cycle, it changes repeatedly state of aggregation water (liquid; solid - snow, ice; gaseous - vapor). Its greatest circulation is observed in the vapor state. Along with water, other minerals are transferred from one place to another in the geological cycle on a global scale. [...]

The water cycle. At the beginning of the section, its geological cycle was considered. Basically, it comes down to the processes of evaporation of water from the surface of the Earth and Ocean and precipitation on them. Within individual ecosystems, additional processes occur that complicate the large water cycle (interception, evapotranspiration and infiltration).[...]

Geological cycles. The relative positions and outlines of continents and the ocean floor are constantly changing. Within the upper shells of the Earth, there is a continuous gradual replacement of some rocks by others, called the large cycle of matter. Geological processes of formation and destruction of mountains are the greatest energy processes in the Earth's biosphere.[...]

CYCLE OF SUBSTANCES (on Earth) - repeatedly repeating processes of transformation and movement of substances in nature, which are more or less cyclical in nature. General K.v. consists of individual processes (the cycle of water, nitrogen, carbon and other substances and chemical elements), which are not completely reversible, since the substance is dissipated, removed, buried, changed in composition, etc. There are biological, biogeochemical , geological K.v., as well as the cycles of individual chemical elements (Fig. 15) and water. Human activity at the present stage of development mainly increases the intensity of coercion. and has an impact commensurate in power with the scale of natural planetary processes.[...]

BIOGEOCHEMICAL CYCLE is the movement and transformation of chemical elements through inert and organic nature with the active participation of living matter. Chemical elements circulate in the biosphere along various paths of the biological cycle: they are absorbed by living matter and charged with energy, then they leave living matter, releasing the accumulated energy into the external environment. Such more or less closed paths were called “biogeochemical cycles” by V.I. Vernadsky. These cycles can be divided into two main types: 1) the circulation of gaseous substances with a reserve fund in the atmosphere or hydrosphere (ocean) and 2) the sedimentary cycle with reserve fund in the earth's crust. Living matter plays an active role in all biogeochemical cycles. On this occasion, V.I. Vernadsky (1965, p. 127) wrote: “Living matter embraces and rearranges all chemical processes of the biosphere, its effective energy is enormous. matter is the most powerful geological force, growing with the passage of time.” The main cycles include the cycles of carbon, oxygen, nitrogen, phosphorus, sulfur and biogenic cations. Below we will consider, as an example, the main features of the cycle of typical biophilic elements (carbon, oxygen and phosphorus). , playing a significant role in the life of the biosphere.[...]

Geological cycle (large cycle of substances in nature) is a cycle of substances, the driving force of which is exogenous and endogenous geological processes.[...]

Due to geological changes in the face of the Earth, part of the substance of the biosphere may be excluded from this cycle. For example, biogenic sediments such as coal and oil are preserved in the thickness of the earth’s crust for many millennia, but in principle their re-inclusion in the biosphere cycle cannot be ruled out.[...]

Knowledge of the cycles of substances on Earth has great practical meaning, since they significantly influence human life and, at the same time, are influenced by humans. The consequences of these impacts have become comparable to the results of geological processes. New migration paths of elements emerge, new chemical compounds appear, and the rate of turnover of substances in the biosphere changes significantly.[...]

The large cycle of substances in nature (geological) is caused by the interaction of solar energy with the deep energy of the Earth and redistributes substances between the biosphere and the deeper horizons of the Earth. This circulation in the system “igneous rocks - sedimentary rocks - metamorphic rocks (transformed by temperature and pressure) - igneous rocks” occurs due to the processes of magmatism, metamorphism, lithogenesis and dynamics of the earth’s crust (Fig. 6.2). The symbol of the cycle of substances is a spiral: each new cycle of the cycle does not exactly repeat the old one, but introduces something new, which over time leads to very significant changes.[...]

The Great Geological Cycle draws sedimentary rocks deep into the earth's crust, permanently excluding the elements they contain from the biological circulation system. In the course of geological history, transformed sedimentary rocks, once again on the surface of the Earth, are gradually destroyed by the activity of living organisms, water and air and are again included in the biosphere cycle.[...]

Thus, the geological cycle of substances occurs without the participation of living organisms and redistributes substances between the biosphere and the deeper layers of the Earth.[...]

Thus, the geological cycle and circulation of rocks consists of: 1) weathering, 2) formation of sediments, 3) formation of sedimentary rocks, 4) metamorphism, 5) magmatization. The release of magma to the surface and the formation of igneous rocks repeats the entire cycle all over again. The complete cycle can be interrupted at various stages (3 or 4) if, as a result of tectonic uplifts and denudation, rocks reach the surface and undergo repeated weathering.[...]

The geological activity of bacteria is of enormous importance. Bacteria take an active part in the cycle of substances in nature. All organic compounds and a significant part of inorganic ones undergo significant changes. And this cycle of substances is the basis for the existence of life on Earth.[...]

In the hydrosphere, the suspension of the carbon cycle is associated with the inclusion of CO2 in the composition of CaCO3 (limestone, chalk, corals). In this version, carbon falls out of the cycle for entire geological epochs and is not included in the concept of the biosphere. However, the rise of organogenic rocks above sea level leads to the resumption of the carbon cycle due to the leaching of limestones and similar rocks by atmospheric precipitation, as well as by biogenic means - the influence of lichens and plant roots. [...]

The removal of part of the carbon from the natural cycle of the ecosystem and “reservation” in the form of fossil reserves of organic matter in the bowels of the Earth is an important feature of the process under consideration. In distant geological epochs, a significant part of photosynthesized organic matter was not used by either consumers or decomposers, but accumulated in the form of detritus. Later, layers of detritus were buried under layers of various mineral sediments, where under the influence of high temperatures and pressure over millions of years they turned into oil, coal and natural gas(depending on the source material, duration and conditions of stay in the ground). Similar processes are taking place today, but much less intensely. Their result is the formation of peat.[...]

BIOGEOCHEMICAL CYCLE [from gr. kyklos - circle], biogeochemical cycle - cyclical processes of exchange and transformation of a chemical element between the components of the biosphere (from an inorganic form through living matter again into inorganic). It is accomplished using predominantly solar energy (photosynthesis) and partly the energy of chemical reactions (chemosynthesis). See cycle of substances. Biological cycle of substances. Geological cycle of substances.[...]

All the noted and many other counter geological processes remaining “behind the scenes”, grandiose in their final results, are, firstly, interconnected and, secondly, are the main mechanism that ensures the development of the lithosphere, which continues to this day, its participation in the constant circulation and transformation of matter and energy, maintains the physical state of the lithosphere that we observe.[...]

All these planetary processes on Earth are closely intertwined, forming a common, global cycle of substances that redistributes the energy coming from the sun. It is carried out through a system of small circulations. Tectonic processes caused by volcanic activity and the movement of oceanic plates in the earth's crust are connected to large and small gyres. As a result, a large geological cycle of substances occurs on Earth.[...]

Soil is an integral component of terrestrial biogeocenoses. It carries out the conjugation (interaction) of large geological and small biological cycles of substances. Soil is a unique natural formation with a complex material composition. Soil matter is represented by four physical phases: solid (mineral and organic particles), liquid (soil solution), gaseous (soil air) and living (organisms). Soils are characterized by complex spatial organization and differentiation of signs, properties and processes.[...]

Thanks to the continuous functioning of the “atmosphere-soil-plants-animals-microorganisms” system, a bio-geochemical cycle of many chemical elements and their compounds has developed, covering land, atmosphere and inland waters. Its total characteristics are comparable to the total river flow of land, the total supply of matter from the upper mantle to the planet’s biosphere. That is why living matter on Earth has been a factor of geological significance for many millions of years.[...]

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

Of course, all non-renewable resources are also exhaustible. These include the vast majority of fossils: mining materials, ores, minerals that arose in the geological history of the Earth, as well as products of the ancient biosphere that fell out of the biotic cycle and were buried in the depths - fossil fuels and sedimentary carbonates. Some mineral resources are still slowly formed during geochemical processes in the subsoil, the depths of the ocean or on the surface of the earth's crust. With regard to mineral resources, the availability and quality of the resource is of great importance, as well as the quantitative relationship between unknown but estimated resources (77), estimated potential (77), actual explored (R) and operational (E) reserves, and usually N > P > R > E (Fig. 6.6).[...]

Study of the ocean as a physical and chemical system progressed much faster than its study as biological system. Hypotheses about the origin and geological history of the oceans, initially speculative, have become firmly established theoretical basis.[ ...]

Living organisms are, in general, a very powerful regulator of the flow of matter on the earth's surface, selectively retaining certain elements in the biological cycle. ’ Every year, 6-20 times more nitrogen is involved in the biological cycle than in the geological cycle, and phosphorus - 3-30 times; at the same time, sulfur, on the contrary, is involved 2-4 times more in the geological cycle than in the biological cycle (Table 4).[...]

A complex system feedback contributed not only to an increase in species differentiation, but also to the formation of certain natural complexes, having specificity depending on environmental conditions and the geological history of a particular part of the biosphere. Any collection in the biosphere of naturally interconnected organisms and inorganic components The environment in which the cycle of substances occurs is called an ecological system or ecosystem.[...]

Synthetic detergents (detergents, tensides). They constitute a large group of artificial surfactants that are produced all over the world in huge quantities. These substances enter the geological environment in large volumes with household wastewater. Most of them are not toxic, but synthetic detergents can destroy various ecosystems and disrupt the natural processes of the geochemical cycle of substances in soils and groundwater.[...]

The bulk of carbon is accumulated in carbonate sediments of the ocean floor (1.3 - 101 t), crystalline rocks (1.0 - 1016 t), in coal and oil (3.4 - 1015 t). It is this carbon that takes part in the slow geological cycle. Life on Earth and the gas balance of the atmosphere are supported by relatively small amounts of carbon contained in plant (5 10 t) and animal (5 109 t) tissues participating in the small (biogenic) cycle. However, at present, humans are intensively closing the cycle of substances, including carbon. For example, it is estimated that the total biomass of all domestic animals already exceeds the biomass of all wild terrestrial animals. The areas of cultivated plants are approaching the areas of natural biogeocenoses, and many cultural ecosystems are significantly superior to natural ones in their productivity, continuously increased by humans.[...]

When phosphate gets into water bodies with wastewater, it saturates and sometimes oversaturates them. ecological systems. Phosphorus under natural conditions returns back to land almost only with droppings and after the death of fish-eating birds. The vast majority of phosphates form bottom sediments, and the cycle enters its slowest phase. Only geological processes occurring over millions of years can actually raise oceanic phosphate deposits, after which phosphorus can be reintroduced into the described cycle. [...]

The values ​​characterizing the annual removal of sediments from each continent are given in Table. 17. It is easy to see that the greatest loss of soil is characteristic of Asia - the continent with the most ancient civilizations and the most extensive exploitation of the land. Although the rate of the process is variable, during periods of minimal geological activity the accumulation of dissolved minerals nutrients occurs in lowlands and oceans at the expense of elevated areas. In this case, local biological return mechanisms become especially important, thanks to which the loss of substances does not exceed their supply from the underlying rocks (this was discussed when considering the calcium cycle). In other words, the longer the vital elements remain in a given area, being used again and again by successive generations of organisms, the less new material will be required from the outside. Unfortunately, as we already noted in the section on phosphorus, man often upsets this balance, usually unintentionally, but simply because he does not fully understand the complexity of the symbiosis between life and inorganic matter that has developed over many millennia. For example, it is now assumed (though this has not yet been proven) that dams that prevent salmon from entering rivers to spawn lead to a decline in not only salmon numbers, but also endangered fish, game, and even a decline in timber production in some northern regions of the Western United States. When salmon spawn and die inland, they leave behind a supply of valuable nutrients returned from the sea. The removal of large masses of wood from the forest (without the minerals contained in it returning to the soil, unlike what happens in nature when fallen trees decompose) no doubt also impoverishes the uplands, usually in situations where the nutrient pool is lacking. that one is poor.[...]

The fifth function is the biogeochemical activity of mankind, covering an ever-increasing amount of matter in the earth’s crust for the needs of industry, transport, Agriculture. This function occupies a special place in the history of the globe and deserves careful attention and study. Thus, the entire living population of our planet - living matter - is in a constant cycle of biophilic chemical elements. The biological cycle of substances in the biosphere is associated with a large geological cycle (Fig. 12.20).[...]

Another process that drives carbon is the formation of hummus by saprophages and subsequent mineralization of the substance by fungi and bacteria. This is a very slow process, the speed of which is determined by the amount of oxygen, the chemical composition of the soil, and its temperature. With a lack of oxygen and high acidity, carbon accumulates in peat. Similar processes in distant geological epochs formed deposits of coal and oil, which stopped the process of the carbon cycle.[...]

As an example, consider the environment-forming role of a forest ecosystem. Forest products and biomass are reserves of organic matter and accumulated energy created during photosynthesis by plants. The rate of photosynthesis determines the rate of absorption of carbon dioxide and release of oxygen into the atmosphere. Thus, when 1 ton of plant products is formed, on average 1.5-1.8 tons of CO2 are absorbed and 1.2-1.4 tons of 02 are released. Biomass, including dead organic matter, is the main reservoir of biogenic carbon. Some of this organic matter is removed from the cycle by long time, forming geological deposits.[...]

Vladimir Ivanovich Vernadsky (1863-1945) - great Russian scientist, academician, founder of biogeochemistry and the study of the biosphere. He is rightfully considered one of the largest universalists in world science. Scientific interests of V.I. Vernadsky are extremely wide. He made significant contributions to mineralogy, geochemistry, radiogeology, crystallography; conducted the first studies of the patterns of composition, structure and migration of interacting elements and structures of the earth's crust, hydrosphere and atmosphere. In 1923, he formulated a theory about the leading role of living organisms in geochemical processes. In 1926, in the book “Biosphere” V.I. Vernadsky put forward a new concept of the biosphere and the role of living matter in the cosmic and terrestrial circulation of substances. Transformations of nature as a result of human activity are seen by V.I. Vernadsky as a powerful planetary process (“Scientific thought as a geological phenomenon”, 1936) and as the possibility of the biosphere growing into the noosphere - the sphere of the mind.

There are two main cycles of substances in nature: large (geological) and small (biogeochemical).

Geological - large cycle of substances(Appendix A), is caused by the interaction of solar energy with the deep energy of the Earth and carries out the redistribution of matter between the biosphere and the deeper horizons of the Earth. Sedimentary rocks, formed due to the weathering of igneous rocks, in mobile zones of the earth's crust are again immersed in a zone of high temperatures and pressures. There they melt and form magma - the source of new igneous rocks. After these rocks rise to the earth's surface and undergo weathering processes, they are again transformed into new sedimentary rocks. The symbol of the cycle of substances is spiral, not a circle. This means that the new cycle does not exactly repeat the old one, but introduces something new, which over time leads to very significant changes.

The Great Gyre is also a gyre water between land and ocean through the atmosphere. Moisture evaporated from the surface of the World Ocean is transferred to land, where it falls in the form of precipitation, which returns to the ocean in the form of surface and underground runoff.

The water cycle also follows a simpler scheme: evaporation of moisture from the surface of the ocean - condensation of water vapor - precipitation onto the same water surface of the ocean.

It is estimated that more than 500 thousand km3 of water annually participates in the water cycle on Earth. The water cycle as a whole plays a major role in shaping the natural conditions on our planet. Taking into account the transpiration of water by plants and its absorption in the biogeochemical cycle, the entire supply of water on Earth breaks down and is restored in 2 million years.

Small cycle of substances in the biosphere (biogeochemical) (Appendix B). Unlike the great cycle, it occurs only within the biosphere. Its essence is the formation of living matter from inorganic compounds during the process of photosynthesis and the transformation of organic matter during decomposition back into inorganic compounds. This cycle is the main one for the life of the biosphere, and it itself is the creation of life. By changing, being born and dying, living matter supports life on our planet, ensuring the biogeochemical cycle of substances. The main source of energy in the cycle is solar radiation, which generates photosynthesis. This energy is distributed rather unevenly across the surface of the globe. For example, at the equator the amount of heat per unit area is three times greater than on the Spitsbergen archipelago (80°N). In addition, it is lost by reflection, absorbed by the soil, and spent on water transpiration. As we have already noted, no more than 5% of all energy is spent on photosynthesis, but most often 2-3%.

In a number of ecosystems, the transfer of matter and energy occurs primarily through trophic chains.

This cycle is usually called biological. It assumes a closed cycle of substances that is repeatedly used by the trophic chain. It is found in aquatic ecosystems, especially plankton with its intensive metabolism, but not in terrestrial ecosystems, with the exception of tropical rainforests, where plant-to-plant transfer of nutrients can occur with roots on the soil surface.

However, on the scale of the entire biosphere, such a cycle is impossible. The biogeochemical cycle operates here, which is the exchange of macro- and microelements and simple inorganic substances with the substance of the atmosphere, hydrosphere and lithosphere.

Cycle of individual substances - V.I. Vernadsky called biogeochemical cycles. The main thing is that chemical elements absorbed by the organism subsequently leave it, going into the abiotic environment, then, after some time, they again enter the living organism. Such elements are called biophilic. These cycles and the circulation as a whole provide the most important functions of living matter in the biosphere. V. I. Vernadsky identifies five such functions:

- first function - gas - the main gases of the Earth's atmosphere, nitrogen and oxygen, of biogenic origin, like all underground gases - a product of the decomposition of dead organic matter;

- second function - concentration - organisms accumulate in their bodies many chemical elements, among which carbon comes first, among metals - calcium, silicon concentrators are diatoms, iodine - algae (kelp), phosphorus - the skeletons of vertebrates;

- third function - redox - organisms living in water bodies regulate the oxygen regime and create conditions for the dissolution or precipitation of a number of metals (V, Mn, Fe) and non-metals (S) with variable valence;

- fourth function - biochemical - reproduction, growth and movement in space ("spreading") of living matter;

- fifth function - human biogeochemical activity - covers the entire growing amount of substances in the earth's crust.

Consequently, it should be noted that there is only one process on Earth that does not waste, but, on the contrary, binds solar energy and even accumulates it - this is the creation of organic matter as a result of photosynthesis. The main planetary function of the cycle of substances on Earth lies in the binding and storage of solar energy.