Biological and geological cycles of matter. Substance cycles

geological circuit substances has the greatest speed in the horizontal direction between land and sea. The meaning of a 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 with 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 land and the process begins again.

Great geological cycle of matter. Under the influence of denudation processes, the destruction of rocks and sedimentation occur. Sedimentary rocks are formed. In areas of stable subsidence (usually the ocean floor), the substance of the geographic envelope enters the deep layers of the Earth. Further, under the influence of temperature and pressure, metamorphic processes take place, as a result of which rocks are formed, the substance moves closer to the center of the Earth. Magmatism occurs in the bowels of the Earth at very high temperatures: rocks melt, rise in the form of magma along faults to the earth's surface and pour out to the surface during eruptions. Thus, the circulation of matter is carried out. The geological cycle is complicated if the exchange of matter with outer space is taken into account. The great geological cycle is not closed in the sense that some particle of matter that has fallen into the bowels of the Earth will not necessarily come to the surface, and vice versa, a particle rising during an eruption could never have been on the earth's surface before.

The main energy sources of natural processes on Earth

Solar radiation is the main source of energy on Earth. Its power is characterized by the solar constant - the amount of energy passing through the area of ​​a unit area, perpendicular to the sun's rays. At a distance of one astronomical unit (that is, in the orbit of the Earth), 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 support many natural processes - heating the earth, ocean, atmosphere, air movement. wt. Direct solar heating or energy conversion using photovoltaic cells can be used to generate electricity (solar power plants) or perform other useful work. In the distant past, the energy stored in oil and other fossil fuels was also obtained through photosynthesis.

This huge 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 go back.

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

18. Energy transformations of biotic and abiotic origin

There is no waste in a functioning natural ecosystem. All organisms, living or dead, are potentially food for other organisms: a caterpillar eats leaves, a thrush eats caterpillars, a hawk can eat a thrush. When the plants, caterpillar, thrush and hawk die, they in turn are processed by decomposers.

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

organisms 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 the 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 the energy is lost, and 10% is transferred to the next level.

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

Energetics of the landscape sphere of the Earth:

1) solar energy: thermal, radiant

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

3) the energy of tidal currents

4) tectonic energy

5) energy assimilation during photosynthesis

The 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 mantle degassing processes: water continuously flows from the mantle. water has been found even at great depths.

The seas are losing due to evaporation more water than obtained with precipitation, on land - the situation is reversed. Water continuously circulates around the globe, while its total 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 the salt water of the seas and oceans, and the smaller part is fresh water lakes, rivers, glaciers, groundwater and water vapour.

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

There are several types of water cycles in nature:

A large, or world, 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: during evaporation, salt sea ​​water turns into fresh, and polluted - is purified.

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

Intracontinental circulation - water that has evaporated above the land surface again falls on land in the form of precipitation.

In the end, the precipitation in the process of movement again reaches the oceans.

Transfer speed various kinds water varies over a wide range, so the periods of flow, and the periods of water renewal are also different. They vary from a few hours to several tens of millennia. Atmospheric moisture, which is formed by the evaporation of water from the oceans, seas and land and exists in the form of clouds, is updated on average after eight days.

The waters that make up living organisms are restored within a few hours. This is the most active form 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.

The complete renewal of the waters of the World Ocean occurs in about 2,700 years.

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

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

The earth is tilted to the plane of the ecliptic by 23.5 degrees.

The beams travel at different angles. radiation balance. It is important not only how much one gains, but also how much one loses, and how much remains, taking into account the albedo.

Atmospheric Action Centers

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

Causes: 1) heterogeneity of the Earth;

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

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

4) F Coriolis

This causes OCA.

Atmospheric Action Centers:

● permanent- in them high or low pressure exists all year round:

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

2. on one subtropical band elevated. pressure in the North. and Yuzh. hemispheres; several migrate in summer to higher subtropics. latitudes, in winter - to lower ones; break up into a number of oceanic. anticyclones: in the North. hemispheres - Azores anticyclone (especially in summer) and Hawaiian; in South - South Indian, South Pacific and South Atlantic;

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

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

● seasonal- are 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 the land creates favorable conditions for the formation of lower areas here. pressure, winter hypothermia - for areas of increased. pressure. All in. hemisphere to winter areas increased. pressures include the Asian (Siberian) with a center in Mongolia and the Canadian maxima, in the South - Australian, South American and South African maxima. Summer areas lower pressure: in Sev. hemispheres - South Asian (or Western Asian) and North American lows, in the South. - Australian, South American and South African lows).

The centers of action of the atmosphere are inherent in 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 transfer and its causes

The main features of planetary heat transfer. The solar energy absorbed by the surface of the globe is then spent on evaporation and heat transfer by turbulent flows. Evaporation takes on average around the planet about 80%, and turbulent heat transfer - the remaining 20% ​​of the total heat.

The processes of heat transfer and changes with the geographical latitude of its components in the ocean and on land are very unique. All the heat absorbed by the 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 in low latitudes, heat is accumulated, from where it is transported by currents to high latitudes, where its expenditure exceeds its intake. Thus, the deficiency 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 heat transfer consumables, 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 time is spent in the autumn-winter period. In the waters of the World Ocean, over the long history of the Earth, a huge amount of heat equal to 7.6 * 10^21 kcal has accumulated. 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 the waters of the World Ocean.

Despite the fact that the share of solar energy used for turbulent heat exchange between the Earth's surface and air is relatively small, it is the main source of heating of the near-surface part of the atmosphere. The intensity of this heat transfer 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 latitudes of both hemispheres), the air is heated mainly from the land, which is unable to accumulate solar energy and gives off all the heat it receives to the atmosphere. Due to turbulent heat transfer, the air shell receives from 20 to 40 kcal/cm^2 per year, and in areas with low moisture (Sahara, Arabia, etc.) even more than 60 kcal/cm^2. Waters in these latitudes accumulate heat, giving the air in the process of turbulent heat exchange only 5-10 kcal/cm^2 per year or less. Only in certain areas (a limited area) the water turns out to be colder on average per year and therefore receives heat from the air (in the equatorial zone, in the northwest of the Indian Ocean, as well as off the western coast of Africa and South America).

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A large geological cycle involves sedimentary rocks deep into the earth's crust, for a long time turning off the elements contained in them from the system. biological cycle. During geological history the 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 biospheric cycle.

A large geological cycle occurs over hundreds of thousands or millions of years. It consists in the following: rocks are destroyed, weathered and eventually washed away by water flows into the oceans. Here they are deposited on the bottom, forming sedimentary rocks, and only partially return to land with organisms removed from the water by humans or other animals.

At the heart of a large geological cycle is the process of transferring mineral compounds from one place to another on a planetary scale without the participation of living matter.

In addition to the small circulation, there is a large, geological circulation. Some substances enter the deep layers of the Earth (through the bottom sediments of the seas or in another way), where slow transformations occur with the formation of various compounds, mineral and organic. The processes of the geological cycle are supported mainly by the internal energy of the Earth, its active core. The same energy contributes to the release of substances to the surface of the Earth. Thus, a large circulation of substances closes. It takes millions of years.

Concerning the speed and intensity of the large geological circulation of substances, it is currently impossible to give any accurate data, there are only approximate estimates, and then only for the exogenous component general cycle, i.e. without taking into account the influx of matter from the mantle into the earth's crust.

This carbon takes part in a large geological cycle. This carbon, in the process of a small biotic cycle, maintains the gas balance of the biosphere and life in general.

Solid runoff of some rivers of the world.

The contribution of biospheric and technospheric components to the large geological cycle of the Earth's substances is very significant: there is a constantly progressive growth of technospheric components due to the expansion of the sphere of human production activity.

Since the main technobio-geochemical flow on the earth's surface is directed within the framework of a large geological circulation of substances for 70% of the land into the ocean and for 30% - into closed drainless depressions, but always from higher to lower elevations, as a result of the action of gravitational forces, respectively, differentiation of the matter of the earth's crust from high to low elevations, from land to ocean. Reverse flows (atmospheric transport, human activity, tectonic movements, volcanism, migration of organisms) to some extent complicate this general downward movement of matter, creating local migration cycles, but do not change it in general.

The circulation of water between land and ocean through the atmosphere refers to a large geological cycle. Water evaporates from the surface of the oceans and is either transferred to land, where it falls in the form of precipitation, which again returns to the ocean in the form of surface and underground runoff, or falls in the form of precipitation to the surface of the ocean. More than 500 thousand km3 of water participate in the water cycle on Earth every year. 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 decays and is restored in 2 million years.

According to his formulation, the biological cycle of substances develops on part of the trajectory of a large, geological cycle of substances in nature.

The transport of matter by surface and groundwater- this is the main factor in terms of geochemical differentiation of the land of the globe, but not the only one, and if we talk about the large geological circulation of substances on the earth's surface as a whole, then it is very essential role flows also play, in particular, oceanic and atmospheric transport.

Concerning the speed and intensity of the large geological circulation of substances, it is currently impossible to give any exact data, there are only approximate estimates, and then only for the exogenous component of the general cycle, i.e. without taking into account the influx of matter from the mantle into the earth's crust. The exogenous component of the large geological circulation of substances is the constantly ongoing process of denudation of the earth's surface.

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Geological cycle (large cycle of substances in nature) - the cycle of substances, driving force which are exogenous and endogenous geological processes.

Geological circulation - the circulation of substances, the driving force of which is exogenous and endogenous geological processes.

The boundaries of the geological cycle are much wider than the boundaries of the biosphere, its amplitude captures the layers of the earth's crust far beyond the biosphere. And, most importantly, living organisms play a secondary role in the processes of this cycle.

Thus, the geological circulation of substances proceeds without the participation of living organisms and redistributes matter between the biosphere and the deeper layers of the Earth.

The most important role in the large cycle of the geological cycle is played by small cycles of matter, both biospheric and technospheric, once in which the substance is switched off for a long time from the large geochemical flow, transforming in endless cycles of synthesis and decomposition.

The most important role in the large cycle of the geological circulation is played by small cycles of matter, both biospheric and technospheric, once in which, the substance is switched off for a long time from the large geochemical flow, transforming in endless cycles of synthesis and decomposition.

This carbon takes part in the slow geological cycle.

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, a person is 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 land animals. The areas of cultivated plants are approaching the areas of natural biogeocenoses, and many cultural ecosystems, in terms of their productivity, continuously increased by man, are significantly superior to natural ones.

The most extensive in time and space is the so-called geological cycle of matter.

There are 2 types of circulation of substances in nature: a large or geological cycle of substances between land and ocean; small or biological - between soil and plants.

The water extracted by the plant from the soil in the vapor state enters the atmosphere, then, cooling, condenses and again returns to the soil or ocean as precipitation. The geological water cycle provides mechanical redistribution, sedimentation, accumulation of solid sediments on land and at the bottom of water bodies, as well as in the process of mechanical destruction of soils and rocks. However, the chemical function of water is carried out with the participation of living organisms or their metabolic products. Natural waters, like soils, are a complex bio-inert substance.

The geochemical activity of man is becoming comparable in scale with biological and geological processes. In the geological cycle, the link of denudation sharply increases.

The factor that leaves the main imprint on the general character and biological. At the same time, the geological water cycle is constantly striving to wash all these elements out of the strata of dry land into the ocean basin. Therefore, the preservation of plant food elements within the land requires their conversion to an absolutely water-insoluble form. This requirement is met by a living organic.

Small (biological) circulation

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

Table 4.1

Comparison of the biosphere with other geospheres of the Earth

*Living matter in terms of live weight

4.4.1. Functions of the biosphere

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

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

concentration function. Passing through their body large volumes of air and natural solutions, living organisms carry out biogenic migration (movement chemical substances) and concentration of chemical elements and their compounds. This refers 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 certain metal ores, the accumulation of iron-manganese nodules, on the ocean floor, etc. The early stages of biological evolution took place in aquatic environment. Organisms have learned to extract the substances they need from a dilute aqueous solution, multiplying their concentration in their bodies many times over.

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

Information function of the living matter of the biosphere. It was with the advent of the first primitive living beings that active (“live”) information appeared on the planet, which differs from the “dead” information, which is a simple reflection of the structure. Organisms turned out to be able to receive information by connecting the 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 an advanced evolution in nature and has become the most important ecological system-forming factor. The total stock of biota genetic information is estimated at 1015 bits. The total power of the flow of molecular information associated with the 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 is carried out between all components of the biosphere (ie, between soil, air, water, animals, microorganisms, etc.). It occurs with the obligatory participation of living organisms.

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

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

4.4.3. Energy cycle. Energy transformation in the biosphere

An ecosystem can be described as a collection of living organisms continuously exchanging 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 and is not created anew, it only changes from one form to another.

The second law of thermodynamics states that entropy can only increase in a closed system. With regard to energy in ecosystems, the following formulation is convenient: the processes associated with the transformation of energy can occur spontaneously only if the energy passes from a concentrated form to a diffuse one, that is, it degrades. A measure of the amount of energy that becomes unavailable for use, or otherwise a measure of the change in order that occurs when energy is degraded, is entropy. The higher the order of the system, the lower its entropy.

In other words, living matter receives and transforms the energy of the cosmos, the sun into the energy of terrestrial processes (chemical, mechanical, thermal, electrical). It involves this energy and inorganic matter in the continuous circulation 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 important environmental indicators (homeostasis) are the most ordered systems and are characterized by the lowest entropy.

4.4.4. The cycle of substances in 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 circulation of chemical elements between organisms and the environment.

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

some organisms consume minerals directly from the environment;

others use products processed and isolated first;

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

In the biosphere, the need for the coexistence of various organisms that can use each other's waste products is obvious. We see practically waste-free biological production.

The cycle of substances in living organisms can be conditionally 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, fats.

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

This process takes place only during the day and is accompanied by an increase in the mass of plants.

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 assimilated, and about 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 the thermodynamic process, according to the minimalist principle, does not dissipate, but rather accumulates.

By synthesizing the amino acids necessary for building proteins, plants can exist relatively independently of other living organisms. This manifests the autotrophy of plants (self-sufficiency in nutrition). At the same time, the green mass of plants and the oxygen formed in the process of photosynthesis are the basis for maintaining the life of the next group of living organisms - animals, microorganisms. This shows 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 energy.

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

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

Schematically, it can be described as follows. Plants absorb soil moisture through their roots. At the same time, mineral substances dissolved in water enter them, which are absorbed, and 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 circulation 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 BHCC, but only biogenic ones. Living organisms consist of them, these elements enter into numerous reactions and participate in the processes occurring in living organisms. In percentage terms, the total mass of the living matter of 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%).

Essence of biogenic migration of chemical elements.

Thus, in the biosphere there is a biogenic cycle of substances (ie, 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 opposite processes:

1. The formation of living matter from the elements of the environment due to solar energy.

2. The destruction of organic substances, accompanied by the release of energy. At the same time, elements of mineral substances repeatedly enter living organisms, thereby entering into the composition 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 not related to biogenic ones. Such elements are classified according to their weight fraction in organisms:

Macronutrients - components of at least 10-2% of the mass;

Trace elements - 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 biogenic elements among other chemical elements of the biosphere, let us consider the classification adopted in ecology. According to the activity shown in the processes occurring in the biosphere, all chemical elements are divided into 6 groups:

The noble gases are helium, neon, argon, krypton, xenon. Inert gases are not part of living organisms.

Noble metals - ruthenium, radium, palladium, osmium, iridium, platinum, gold. These metals almost do not create 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 carry out circulation in geographical envelope, and the part of inert elements is very small.

Scattered elements, characterized by the 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 of the earth's crust, and on the surface of 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.

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 tends to its maximum manifestation.

The evolution of species in the course of geological time, leading to the creation of sustainable forms of life, proceeds 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 us consider how some of these elements move in the biosphere.

The carbon cycle. The main participant in the biotic cycle is carbon as the basis of organic substances. Mostly carbon cycle occurs between living matter and carbon dioxide of the atmosphere in the process of photosynthesis. Herbivores get it with food, predators get it from herbivores. When breathing, rotting, 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 used up by green plants in 7-8 years. The rate of biological turnover of carbon through photosynthesis is 300 years. The oceans play an important role in regulating the content of CO2 in the atmosphere. If the CO2 content rises in the atmosphere, some of it dissolves in water, reacting with calcium carbonate.

The oxygen cycle.

Oxygen has a high chemical activity, enters into compounds with almost all elements of the earth's crust. It occurs 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.

The nitrogen cycle. Nitrogen is integral part all proteins. The total ratio of bound nitrogen, as an element constituting organic matter, to nitrogen in nature is 1:100,000. The chemical bond energy in the 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 takes place 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% of molecular nitrogen, but in this state it is not available to green plants. For their nutrition, plants can use only salts of nitric and nitrous acids. What are the ways of formation of these salts? Here are some of them:

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

Soil nitrogen-fixing bacteria are able to assimilate molecular nitrogen from the air. They enrich the soil with nitrogenous compounds, so their value is extremely high.

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

Under the action of bacteria, nitrogen is converted into nitrates, nitrites, ammonium compounds. In plants, nitrogen compounds take part in the synthesis of protein compounds, which are transferred 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 assimilated by living organisms, which, with its participation, synthesize a number of organic compounds and transfer them to various trophic levels.

Having finished their journey along the trophic chains, organic phosphates are decomposed by microbes and turn 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 products) of each life form are the breeding ground for other organisms.

Theoretically, the biosphere should always maintain a balance 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, cataclysms, not all biological products were assimilated and transformed. In these cases, surpluses of biological products were formed, which were conserved and deposited in the earth's crust, under the water column, sediments, and ended up in the permafrost zone. So deposits of coal, oil, gas, limestone were formed. It should be noted that they do not litter the biosphere. The energy of the Sun, accumulated in the process of photosynthesis, is concentrated in organic minerals. Now, by burning organic fossil fuels, a person releases this energy.

In order for the biosphere to continue to exist, so that its movement (development) does not stop, the cycle of biologically important substances must constantly occur on Earth. This transition of biologically important substances from link to link can be carried out only with a certain expenditure of energy, the source of which is the Sun.

Solar energy provides two cycles of matter on Earth:

- geological (abiotic), or large, circulation;

- biological (biotic), or small, circulation.

geological cycle most clearly manifested in the water cycle and atmospheric circulation.

Approximately 21 10 20 kJ of radiant energy comes to the Earth from the Sun every year. About half of it is spent on the evaporation of water. This is what creates the big cycle.

The water cycle in the biosphere is based on the fact that its total evaporation from the Earth's surface is compensated by precipitation. At the same time, more water evaporates from the ocean than returns with precipitation. On land, on the contrary, 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 water cycle, mineral compounds are transferred from one place to another on a planetary scale, and the state of aggregation of water also changes (liquid, solid - snow, ice; gaseous - vapor). Water circulates most intensively in the vapor state.

With the advent of living matter based on the circulation of the atmosphere, water, mineral compounds dissolved in it, i.e. on the basis of the abiotic, geological cycle, the cycle of organic matter, or small, arose, biological cycle.

As living matter develops, more and more elements are constantly extracted from the geological cycle and enter a new, biological cycle.

In contrast to the simple transfer-movement of mineral elements in a large (geological) cycle, in a small (biological) cycle, the most important moments are the synthesis and destruction of organic compounds. These two processes are in a certain ratio, which underlies life and is one of its main features.

In contrast to the geological cycle, the biological cycle has a lower energy. As is known, only 0.1-0.2% of the solar energy incident on the Earth is spent on the creation of organic matter (up to 50% on the geological cycle). Despite this, the energy involved in the biological cycle is expended on a huge amount of work to create primary production on Earth.

With the advent of living matter on Earth, chemical elements continuously circulate in the biosphere, passing from external environment into organisms and back to the environment.

Such a circulation of chemical elements along more or less closed paths, proceeding with the use of solar energy through living organisms, is called biogeochemical circulation (cycle).

The main biogeochemical cycles are the cycles of oxygen, carbon, nitrogen, phosphorus, sulfur, water and biogenic elements.

The carbon cycle.

On land, the carbon cycle begins with the fixation of carbon dioxide by plants through photosynthesis. Further, carbohydrates are formed from carbon dioxide and water and oxygen is released. At the same time, carbon is partially released during the respiration of plants as part of carbon dioxide. The carbon fixed in plants is consumed to some extent by animals. Animals also release carbon dioxide when they breathe. The obsolete animals and plants are decomposed by microorganisms, as a result of which the carbon of the dead organic matter is oxidized to carbon dioxide and re-enters the atmosphere.

A similar cycle of carbon occurs in the ocean.

The nitrogen cycle.

The nitrogen cycle, like other biogeochemical cycles, covers all areas of the biosphere. The nitrogen cycle is associated with its conversion into nitrates due to the activity of nitrogen-fixing and nitrifying bacteria. Nitrates are absorbed by plants from soil or water. Plants are eaten by animals. In the end, the reducers again convert nitrogen into a gaseous form and return it to the atmosphere.

In modern conditions, a man intervened in the nitrogen cycle, who, growing nitrogen-fixing legumes on vast areas, artificially binds natural nitrogen. It is believed that agriculture and industry provide almost 60% more fixed nitrogen than natural terrestrial ecosystems.

A similar nitrogen cycle is also observed in the aquatic environment.

Phosphorus cycle.

Unlike carbon and nitrogen, phosphorus compounds are found in rocks that are eroded and release phosphates. Most of them end up in the seas and oceans and partly can be returned to land again through marine food chains ending in fish-eating birds. Some of the phosphates end up in the soil and are taken up by plant roots. The absorption of phosphorus by plants depends on the acidity of the soil solution: as the acidity increases, practically insoluble phosphates in water are converted into highly soluble phosphoric acid. The plants are then eaten by animals.

The main links of biogeochemical cycles are various organisms, the variety of forms of which determines the intensity of the cycles and the involvement of almost all elements of the earth's crust in them.

In general, each circulation of any chemical element is a part of the general grandiose circulation of substances on Earth, i.e. they are closely related.