1 Man and climate.

2 Introduction.

Relationship between energy consumption, economic activity and income in atmosphere.

Energy consumption and carbon dioxide emissions.

3 carbon in nature.

Isotopes of carbon.

4 Carbon in the atmosphere.

Atmospheric carbon dioxide.

Soil carbon.

5 Forecasts of carbon dioxide concentration in the atmosphere for the future. Main conclusions.

6 Bibliography.

Introduction.

Human activity has already reached a level of development at which its influence on nature becomes global. Natural systems - the atmosphere, land, ocean - as well as life on the planet as a whole are subject to these influences. It is known that over the past century, the content of certain gas components in the atmosphere has increased, such as carbon dioxide (), nitrous oxide (), methane () and tropospheric ozone (). In addition, other gases that are not natural components of the global ecosystem also entered the atmosphere. The main ones are fluorochlorohydrocarbons. These gaseous impurities absorb and emit radiation and therefore are able to influence the Earth's climate. All these gases together can be called greenhouse gases.

The notion that the climate could change as a result of the release of carbon dioxide into the atmosphere did not appear now. Arrhenius pointed out that the burning of fossil fuels could lead to an increase in atmospheric concentration and thereby change the radiation balance of the Earth. We now know approximately how much has been released into the atmosphere through the burning of fossil fuels and changes in land use (deforestation and expansion of agricultural land), and we can attribute the observed increase in atmospheric concentrations to human activities.

The mechanism of climate change is the so-called greenhouse effect. While it is transparent to solar short-wave radiation, this gas absorbs long-wave radiation leaving the earth's surface and radiates the absorbed energy in all directions. As a result of this effect, an increase in atmospheric concentration leads to heating of the Earth's surface and lower atmosphere. The continued rise in atmospheric concentrations can lead to global climate change, so predicting future carbon dioxide concentrations is an important task.

The release of carbon dioxide into the atmosphere

as a result of industrial

emissions.

The main anthropogenic source of emissions is the combustion of all kinds of carbonaceous fuels. Currently economic development usually associated with the growth of industrialization. Historically, economic recovery has depended on the availability of affordable energy sources and the amount of fossil fuels burned. Data on the development of the economy and energy for most countries for the period 1860-1973. They testify not only to economic growth, but also to the growth of energy consumption. However, one is not a consequence of the other. Since 1973, in many countries there has been a decrease in specific energy costs with an increase in real energy prices. A recent study of industrial energy use in the United States showed that since 1920 the ratio of primary energy costs to the economic equivalent of goods produced has steadily decreased. More efficient use of energy is achieved as a result of improvements in industrial technology, vehicles and building design. In addition, in a number of industrialized countries there have been shifts in the structure of the economy, expressed in the transition from the development of raw materials and processing industries to the expansion of industries that produce the final product.

The minimum level of energy consumption per capita currently required to meet the needs of medicine, education and recreation varies significantly from region to region and country to country. In many developing countries, a significant increase in per capita consumption of high-quality fuels is essential for achieving a higher standard of living. It now seems likely that the continuation economic growth and the achievement of the desired standard of living are not related to the level of energy consumption per capita, but this process is not yet well understood.

It can be assumed that before the middle of the next century, the economies of most countries will be able to adjust to higher energy prices, reducing the need for labor and other types of resources, as well as increasing the speed of processing and transmitting information, or perhaps changing the structure of the economic balance between the production of goods. and provision of services. Thus, from the choice of an energy development strategy with one or another share of the use of coal or nuclear fuel in energy system will directly depend on the rate of industrial emissions.

Energy consumption and emissions

carbon dioxide.

Energy is not produced for the sake of energy production itself. In industrialized countries, most of the energy generated comes from industry, transportation, heating and cooling buildings. Many recent studies have shown that the current level of energy consumption in industrialized countries can be significantly reduced through the use of energy-saving technologies. It was calculated that if the United States switched, in the production of consumer goods and in the service sector, to the least energy-intensive technologies at the same volume of production, then the amount entering the atmosphere would decrease by 25%. The resulting reduction in global emissions would be 7%. A similar effect would take place in other industrialized countries. A further reduction in the rate of entry into the atmosphere can be achieved by changing the structure of the economy as a result of the introduction of more effective methods production of goods and improvements in the provision of services to the population.

carbon in nature.

Among the many chemical elements without which life on Earth is impossible, carbon is the main one. Chemical transformations of organic substances are associated with the ability of the carbon atom to form long covalent chains and rings. The biogeochemical cycle of carbon is, of course, very complex, since it includes not only the functioning of all forms of life on Earth, but also the transfer of inorganic substances both between different carbon reservoirs and within them. The main reservoirs of carbon are the atmosphere, continental biomass, including soils, the hydrosphere with marine biota, and the lithosphere. During the last two centuries in the atmosphere-biosphere-hydrosphere system there have been changes in carbon fluxes, the intensity of which is approximately an order of magnitude higher than the intensity of the geological processes of the transfer of this element. For this reason, one should confine oneself to the analysis of interactions within this system, including soils.

Basic chemical compounds and reactions.

More than a million carbon compounds are known, thousands of which are involved in biological processes. Carbon atoms can be in one of nine possible oxidation states: from +IV to -IV. The most common phenomenon is complete oxidation, i.e. +IV, and can serve as examples of such compounds. Over 99% of the carbon in the atmosphere is in the form of carbon dioxide. About 97% of carbon in the oceans exists in dissolved form (), and in the lithosphere - in the form of minerals. An example of a +II oxidation state is a small gaseous component of the atmosphere, which oxidizes rather quickly to . Elemental carbon is present in the atmosphere in small amounts in the form of graphite and diamond, and in the soil in the form of charcoal. The assimilation of carbon during photosynthesis leads to the formation of reduced carbon, which is present in biota, the dead organic matter of the soil, in the upper layers of sedimentary rocks in the form of coal, oil and gas buried at great depths, and in the lithosphere in the form of dispersed underoxidized carbon. Some gaseous compounds containing incompletely oxidized carbon, in particular methane, enter the atmosphere during the reduction of substances that occurs in anaerobic processes. Although several different gaseous compounds are formed during bacterial decomposition, they are rapidly oxidized, and it can be considered that enters the system. An exception is methane, as it also contributes to the greenhouse effect. The oceans contain a significant amount of dissolved organic carbon compounds, the processes of oxidation of which are not yet well known.

Isotopes of carbon.

There are seven known isotopes of carbon in nature, of which essential role play three. Two of them - and - are stable, and one is radioactive with a half-life of 5730 years. The need to study various carbon isotopes is due to the fact that the transfer rates of carbon compounds and the equilibrium conditions in chemical reactions depend on which carbon isotopes these compounds contain. For this reason, a different distribution of stable carbon isotopes is observed in nature. The distribution of the isotope, on the one hand, depends on its formation in nuclear reactions involving neutrons and nitrogen atoms in the atmosphere, and on the other, on radioactive decay.

Carbon in the atmosphere.

Careful measurements of atmospheric content were begun in 1957 by Killing at the Mauna Loa Observatory. Regular measurements of atmospheric content are also carried out at a number of other stations. From the analysis of observations, it can be concluded that the annual course of concentration is mainly due to seasonal changes in the cycle of photosynthesis and destruction of plants on land; it is also influenced, albeit to a lesser extent, by the annual variation in ocean surface temperature, on which solubility in seawater depends. Third, and probably least an important factor is the annual rate of photosynthesis in the ocean. Average for each given year the content in the atmosphere is slightly higher in the northern hemisphere, since the sources of anthropogenic input are located mainly in the northern hemisphere. In addition, small interannual variations in the content are observed, which are probably determined by the features of the general circulation of the atmosphere. From the available data on the change in concentration in the atmosphere, the data on the regular increase in the atmospheric content observed over the past 25 years are of primary importance. Earlier measurements of the content of atmospheric carbon dioxide (beginning from the middle of the last century) were, as a rule, insufficiently complete. Air samples were taken without the necessary thoroughness and no estimation of the error of the results was made. By analyzing the composition of air bubbles from glacial cores, it became possible to obtain data for the period from 1750 to 1960. It was also found that the values ​​of atmospheric concentrations for the 1950s, determined by analyzing the air inclusions of glaciers, are in good agreement with the data of the Mauna Loa observatory. The concentration during the years 1750-1800 turned out to be close to 280 million, after which it began to slowly increase and by 1984 amounted to 3431 million.

Soil carbon.

According to various estimates, the total carbon content is about

GS. The main uncertainty of the existing estimates is due to the insufficient completeness of information on the areas and carbon content in the planet's peatlands.

The slower process of carbon decomposition in soils of cold climatic zones leads to a higher concentration of soil carbon (per unit surface area) in boreal forests and grassy communities of mid-latitudes compared to tropical ecosystems. However, just not a large number of(a few percent or even less) of detritus entering the soil reservoir annually remains in them for a long time. Most of the dead organic matter oxidizes within a few years. In chernozems, about 98% of litter carbon has a turnover time of about 5 months, and 2% of litter carbon remains in the soil for an average of 500-1000 years. This feature The soil-forming process is also manifested in the fact that the age of soils in the middle latitudes, determined by the radioisotope method, ranges from several hundred to a thousand years or more. However, the rate of decomposition of organic matter during the transformation of land occupied by natural vegetation into agricultural land is completely different. For example, it has been argued that 50% of the organic carbon in soils used in agriculture North America, could be lost due to acidification, since these soils began to be exploited before the beginning of the last century or at the very beginning of it.

Changes in carbon content in

continental ecosystems.

Over the past 200 years, significant changes have occurred in continental ecosystems as a result of increasing anthropogenic impact. When lands occupied by forests and herbaceous communities turn into agricultural land, organic matter, i.e. living matter of plants and dead organic matter of soils are oxidized and released into the atmosphere in the form of . Some elemental carbon may also be buried in the soil as charcoal (as a by-product of forest burning) and thus removed from the rapid turnover in the carbon cycle. The carbon content in various components of ecosystems varies, since the restoration and destruction of organic matter depend on the geographic latitude and type of vegetation.

Numerous studies have been carried out to resolve the current uncertainty in estimating changes in carbon stocks in continental ecosystems. Based on the data from these studies, it can be concluded that the atmospheric entry from 1860 to 1980 was C and that in 1980 the biotic carbon emission was C/year. In addition, the influence of increasing atmospheric concentrations and emissions of pollutants, such as and , on the intensity of photosynthesis and destruction of organic matter in continental ecosystems is possible. Apparently, the intensity of photosynthesis increases with increasing concentration in the atmosphere. It is most likely that this growth is characteristic of agricultural crops, and in natural continental ecosystems, an increase in the efficiency of water use could lead to an acceleration in the formation of organic matter.

Predictions of carbon dioxide concentration

gas in the atmosphere for the future.

Main conclusions.

Over the past decades, a large number of models of the global carbon cycle have been created, which it does not seem appropriate to consider in this paper due to the fact that they are sufficiently complex and voluminous. Let us briefly consider their main conclusions. Various scenarios used to predict future atmospheric abundances produced similar results. The following is an attempt to summarize our current knowledge and assumptions regarding the problem of anthropogenic change in atmospheric concentrations.

From 1860 to 1984, the atmosphere received d. Due to the burning of fossil fuels, the emission rate is currently (according to 1984 data) equal to g. C / year.

· During the same time period, atmospheric releases from deforestation and land-use change amounted to g. C, the intensity of this income is currently equal to C/year.

· Since the middle of the last century, the concentration in the atmosphere has increased from up to a million in 1984.

· The main characteristics of the global carbon cycle are well understood. It has become possible to create quantitative models that can be used as the basis for forecasting the growth of concentration in the atmosphere when certain emission scenarios are used.

· The uncertainties in the projections of likely future concentration changes derived from the emissions scenarios are significantly smaller and much smaller than the uncertainties in the emissions scenarios themselves.

If the intensity of emissions into the atmosphere over the next four decades remains constant or increases very slowly (no more than 0.5% per year) and in the more distant future also grows very slowly, then by the end of the 21st century, the atmospheric concentration will be about 440 million ., i.e. no more than 60% higher than the pre-industrial level.

· If the intensity of emissions over the next four decades will increase by an average of 1-2% per year, i.e. just as it has increased from 1973 to the present, and in the more distant future the rate of its growth will slow down, a doubling of the content in the atmosphere compared to pre-industrial levels will occur by the end of the 21st century.

Soda, volcano, Venus, refrigerator - what do they have in common? Carbon dioxide. We have collected for you the most interesting information about one of the most important chemical compounds on Earth.

What is carbon dioxide

Carbon dioxide is known mainly in its gaseous state, i. as carbon dioxide with the simple chemical formula CO2. In this form, it exists under normal conditions - at atmospheric pressure and "normal" temperatures. But at high blood pressure, over 5,850 kPa (such, for example, the pressure at a sea depth of about 600 m), this gas turns into a liquid. And with strong cooling (minus 78.5 ° C), it crystallizes and becomes the so-called dry ice, which is widely used in trade for storing frozen foods in refrigerators.

Liquid carbon dioxide and dry ice are produced and used in human activities, but these forms are unstable and break down easily.

But gaseous carbon dioxide is ubiquitous: it is released during the respiration of animals and plants and is an important part of the chemical composition of the atmosphere and ocean.

Properties of carbon dioxide

Carbon dioxide CO2 is colorless and odorless. Under normal conditions, it has no taste. However, when inhaling high concentrations of carbon dioxide, a sour taste can be felt in the mouth, caused by the fact that carbon dioxide dissolves on mucous membranes and in saliva, forming a weak solution of carbonic acid.

By the way, it is the ability of carbon dioxide to dissolve in water that is used to make sparkling waters. Bubbles of lemonade - the same carbon dioxide. The first apparatus for saturating water with CO2 was invented as early as 1770, and already in 1783 the enterprising Swiss Jacob Schwepp began industrial production soda (the Schweppes brand name still exists).

Carbon dioxide is 1.5 times heavier than air, so it tends to “settle” in its lower layers if the room is poorly ventilated. The “dog cave” effect is known, where CO2 is released directly from the ground and accumulates at a height of about half a meter. An adult, getting into such a cave, at the height of his height does not feel an excess of carbon dioxide, but dogs find themselves right in a thick layer of carbon dioxide and are poisoned.

CO2 does not support combustion, so it is used in fire extinguishers and fire suppression systems. The trick with extinguishing a burning candle with the contents of an allegedly empty glass (but in fact with carbon dioxide) is based precisely on this property of carbon dioxide.

Carbon dioxide in nature: natural sources

Carbon dioxide is produced in nature from various sources:

• Breathing of animals and plants.
  Every schoolchild knows that plants absorb carbon dioxide CO2 from the air and use it in photosynthesis. Some housewives try with abundance indoor plants atone for shortcomings. However, plants not only absorb but also release carbon dioxide in the absence of light as part of the respiration process. Therefore, the jungle in a poorly ventilated bedroom is not very a good idea: CO2 levels will rise even more at night.
• Volcanic activity.
  Carbon dioxide is part of volcanic gases. In areas with high volcanic activity, CO2 can be released directly from the ground - from cracks and faults called mofet. The concentration of carbon dioxide in mofet valleys is so high that many small animals die when they get there.
• decomposition of organic matter.
  Carbon dioxide is formed during combustion and decay of organic matter. Volumetric natural emissions of carbon dioxide accompany forest fires.

Carbon dioxide is "stored" in nature in the form of carbon compounds in minerals: coal, oil, peat, limestone. Huge reserves of CO2 are found in dissolved form in the world's oceans.

The release of carbon dioxide from an open reservoir can lead to a limnological catastrophe, as happened, for example, in 1984 and 1986. in lakes Manun and Nyos in Cameroon. Both lakes were formed on the site of volcanic craters - now they are extinct, but in the depths, volcanic magma still emits carbon dioxide, which rises to the waters of the lakes and dissolves in them. As a result of a number of climatic and geological processes, the concentration of carbon dioxide in the waters exceeded the critical value. A huge amount of carbon dioxide was released into the atmosphere, which, like an avalanche, descended along the mountain slopes. About 1,800 people became victims of limnological disasters on the Cameroonian lakes.

Artificial sources of carbon dioxide

The main anthropogenic sources of carbon dioxide are:

• industrial emissions associated with combustion processes;
• automobile transport.

Despite the fact that the share of environmentally friendly transport in the world is growing, the vast majority of the world's population will not soon be able (or willing) to switch to new cars.

Active deforestation for industrial purposes also leads to an increase in the concentration of carbon dioxide CO2 in the air.

CO2 is one of the end products of metabolism (the breakdown of glucose and fats). It is secreted in the tissues and carried by hemoglobin to the lungs, through which it is exhaled. In the air exhaled by a person, there is about 4.5% carbon dioxide (45,000 ppm) - 60-110 times more than in the inhaled air.

Carbon dioxide plays an important role in the regulation of blood supply and respiration. An increase in the level of CO2 in the blood causes the capillaries to expand, allowing more blood to pass through, which delivers oxygen to the tissues and removes carbon dioxide.

The respiratory system is also stimulated by an increase in carbon dioxide, and not by a lack of oxygen, as it might seem. In fact, the lack of oxygen is not felt by the body for a long time, and it is quite possible that in rarefied air a person will lose consciousness before he feels a lack of air. The stimulating property of CO2 is used in artificial respiration devices: there, carbon dioxide is mixed with oxygen to "start" the respiratory system.

Carbon dioxide and us: why is CO2 dangerous?

Carbon dioxide is needed human body just like oxygen. But just like with oxygen, an excess of carbon dioxide harms our well-being.

A high concentration of CO2 in the air leads to intoxication of the body and causes a state of hypercapnia. With hypercapnia, a person experiences difficulty breathing, nausea, headache and may even lose consciousness. If the carbon dioxide content does not decrease, then the turn comes - oxygen starvation. The fact is that both carbon dioxide and oxygen move around the body on the same "transport" - hemoglobin. Normally, they "travel" together, attaching to different places on the hemoglobin molecule. However, an increased concentration of carbon dioxide in the blood reduces the ability of oxygen to bind to hemoglobin. The amount of oxygen in the blood decreases and hypoxia occurs.

Such unhealthy consequences for the body occur when inhaling air with a CO2 content of more than 5,000 ppm (this can be the air in mines, for example). In fairness, in ordinary life we ​​practically do not encounter such air. However, even a much lower concentration of carbon dioxide is not good for health.

According to the findings of some, already 1,000 ppm CO2 causes fatigue and headache in half of the subjects. Many people begin to feel closeness and discomfort even earlier. With a further increase in the concentration of carbon dioxide to 1,500 - 2,500 ppm, the brain is "lazy" to take the initiative, process information and make decisions.

And if the level of 5,000 ppm is almost impossible in Everyday life, then 1,000 and even 2,500 ppm can easily be part of the reality of modern man. Ours showed that in sparsely ventilated classrooms, CO2 levels stay above 1,500 ppm most of the time, and sometimes jump above 2,000 ppm. There is every reason to believe that the situation is similar in many offices and even apartments.

Physiologists consider 800 ppm as a safe level of carbon dioxide for human well-being.

Another study found a connection between CO2 levels and oxidative stress: the higher the level of carbon dioxide, the more we suffer from, which destroys the cells of our body.

Carbon dioxide in the earth's atmosphere

In the atmosphere of our planet, there is only about 0.04% CO2 (this is approximately 400 ppm), and more recently it was even less: carbon dioxide crossed the mark of 400 ppm only in the fall of 2016. Scientists attribute the rise in the level of CO2 in the atmosphere to industrialization: in the middle of the 18th century, on the eve of the industrial revolution, it was only about 270 ppm.

It seems that the Earth has crossed a significant threshold against the backdrop of global warming.

Usually in September, the levels of carbon dioxide (CO2) in the atmosphere are at their lowest. This concentration is the benchmark against which fluctuations in greenhouse gas levels are measured over the next year. But in September of this year, CO2 levels remain high, at about 400 ppm, and many scientists believe that in our lifetime, the concentration of greenhouse gases will not fall below this threshold.

The earth has been steadily accumulating CO2 in the atmosphere since the industrial revolution, but levels of 400 ppm are creating a new normal that has not been seen on our planet for millions of years.

“Our planet’s atmosphere last had CO2 levels of 400 ppm about three and a half million years ago, and the climate at that time was very different from today,” an associate professor at the School of Marine and Atmospheric Science told the Christian Science Monitor in an email. phenomena at the State University of New York at Stony Brook David Black.

“In particular, in the Arctic (north of the 60th latitude) it was much warmer than today, and the sea level on the planet was 5-27 meters higher than the current one,” Black noted.

“Then it took millions of years for the atmosphere to reach 400 ppm CO2. And for it to fall to 280 millionths (such an indicator was on the eve of the industrial revolution), it took another millions of years. Climatologists are very worried that people have done in just a few centuries what nature has done in millions of years, with most of these changes occurring in the last 50-60 years.

The global concentration of CO2 has been periodically rising above 400 ppm for several years now; but during the summer growing season, a significant part of the carbon dioxide in the atmosphere is absorbed by photosynthesis, and therefore CO2 levels are below this mark most of the year.

Context

Greenhouse Madness

Wprost 12/15/2015

The world is ill-prepared for global warming

The Globe And Mail 05/09/2016

Climate catastrophe in Europe

02.05.2016

It's time for the climate

Project Syndicate 04/26/2016

Toxic climate

Die Welt 01/18/2016
But due to human activities (primarily due to the combustion of fossil fuels), more CO2 is emitted into the atmosphere, and the annual minimum was getting closer and closer to the mark of 400 ppm. Scientists fear that this year the planet has reached the point of no return.

“Is it possible that in October 2016 the monthly figure was lower than in September, dropping below 400 millionths? Practically not,” wrote the director of the program from the Institute of Oceanography. Skrips Ralph Keeling.

There have been cases in the past when CO2 levels fell below the previous September values, but they are extremely rare. According to scientists, even if the world is right from tomorrow will completely stop emitting carbon dioxide into the atmosphere, its concentration will remain above 400 ppm for several more years.

“In the best case (under such a scenario), stabilization can be expected in the near future, and therefore the level of CO2 is unlikely to change much. But in 10 years or so, it will start to decline, NASA chief climate scientist Gavin Schmidt told Climate Central. “In my opinion, we will no longer see a monthly figure below 400 ppm.”

Although the rise in atmospheric CO2 concentrations is cause for concern, it should be noted that the 400 ppm mark itself is more of a route marker than a hard indicator that portends a climate apocalypse to the world.

“People like rounded numbers,” says Damon Matthews, an environmental professor at Concordia University in Montreal. “It is also very symbolic that, in parallel with the increase in CO2, global temperatures have risen by one degree above pre-industrial levels.”

Of course, these indicators are mostly symbolic, but they are a real illustration of the trajectory followed by the earth's climate.

"CO2 concentration is somewhat reversible because plants absorb carbon dioxide," notes Dr. Matthews. “But the temperature that occurs on the basis of such changes, in the absence of human efforts, is irreversible.”

Carbon dioxide in the form of a greenhouse gas not only contributes to global warming, but also negatively affects the state of the world's oceans due to its acidification. When carbon dioxide dissolves in large volumes in water, some of it turns into carbon dioxide, which reacts with water molecules to produce hydrogen ions, which makes the ocean more acidic. This in turn leads to coral bleaching and interferes with the life cycle of small organisms, which also negatively affects larger organisms further down the food chain.

The news of the 400 ppm threshold comes as world leaders have taken a series of steps towards ratifying the Paris Agreement on climate change, which aims to systematically reduce carbon emissions worldwide starting in 2020.

The countries that ratify the agreement have a lot of work to do.

“In order to reduce atmospheric CO2 on a time scale of several centuries, we need to not only use and develop non-carbon energy sources; we also need to physically, chemically and biologically remove CO2 from the atmosphere,” says Black. “There is a technology for removing atmospheric CO2, but it is not yet applicable on the scale of the existing problem.”

The composition and structure of the atmosphere.

The atmosphere is the gaseous envelope of the Earth. The vertical extent of the atmosphere is more than three earth radii (the average radius is 6371 km) and the mass is 5.157 x 10 15 tons, which is approximately one millionth of the mass of the Earth.

The division of the atmosphere into layers in the vertical direction is based on the following:

Compound atmospheric air,

Physical and chemical processes;

Altitude temperature distribution;

Interaction of the atmosphere with the underlying surface.

The atmosphere of our planet is a mechanical mixture of various gases, including water vapor, as well as a certain amount of aerosols. The composition of dry air in the lower 100 km remains almost constant. Clean and dry air, in which there is no water vapor, dust and other impurities, is a mixture of gases, mainly nitrogen (78% of air volume) and oxygen (21%). A little less than one percent is argon, and in very small quantities there are many other gases - xenon, krypton, carbon dioxide, hydrogen, helium, etc. (Table 1.1).

Nitrogen, oxygen and other components of atmospheric air are always in the atmosphere in a gaseous state, since the critical temperatures, that is, the temperatures at which they can be in a liquid state, are much lower than the temperatures observed at the Earth's surface. The exception is carbon dioxide. However, for the transition to a liquid state, in addition to temperature, it is also necessary to reach a state of saturation. There is not much carbon dioxide in the atmosphere (0.03%) and it is in the form of individual molecules, evenly distributed among the molecules of other atmospheric gases. Over the past 60-70 years, its content has increased by 10-12%, under the influence of human activities.

More than others, the content of water vapor is subject to change, the concentration of which at the Earth's surface at high temperature can reach 4%. With an increase in altitude and a decrease in temperature, the content of water vapor decreases sharply (at a height of 1.5-2.0 km - by half and 10-15 times from the equator to the pole).

The mass of solid impurities over the past 70 years in the atmosphere of the northern hemisphere has increased by about 1.5 times.

The constancy of the gas composition of the air is ensured by intensive mixing of the lower layer of air.

Gas composition of the lower layers of dry air (without water vapor)

The role and importance of the main gases of atmospheric air

OXYGEN (O) vital for almost all the inhabitants of the planet. It is an active gas. It participates in chemical reactions with other atmospheric gases. Oxygen actively absorbs radiant energy, especially very short wavelengths less than 2.4 μm. Under the influence of solar ultraviolet radiation (X< 03 µm), the oxygen molecule breaks up into atoms. Atomic oxygen, combining with an oxygen molecule, forms a new substance - triatomic oxygen or ozone(Oz). Ozone is mostly found at high altitudes. There his role for the planet is exceptionally beneficial. At the surface of the Earth, ozone is formed during lightning discharges.

Unlike all other gases in the atmosphere, which have neither taste nor smell, ozone has a characteristic smell. Translated from Greek, the word "ozone" means "sharp smelling". After a thunderstorm, this smell is pleasant, it is perceived as the smell of freshness. In large quantities, ozone is a poisonous substance. In cities with a large number of cars, and therefore large emissions of automobile gases, ozone is formed under the action of sunlight in cloudless or slightly cloudy weather. The city is shrouded in a yellow-blue cloud, visibility is deteriorating. This is photochemical smog.

NITROGEN (N2) is a neutral gas, it does not react with other gases of the atmosphere, does not participate in the absorption of radiant energy.

Up to altitudes of 500 km, the atmosphere mainly consists of oxygen and nitrogen. At the same time, if nitrogen prevails in the lower layer of the atmosphere, then at high altitudes there is more oxygen than nitrogen.

ARGON (Ag) - a neutral gas, does not enter into a reaction, does not participate in the absorption and emission of radiant energy. Similarly - xenon, krypton and many other gases. Argon is a heavy substance, it is very scarce in the high layers of the atmosphere.

CARBON DIOXIDE (CO2) in the atmosphere is on average 0.03%. This gas is very necessary for plants and is actively absorbed by them. The actual amount in the air may vary somewhat. In industrial areas, its amount can increase up to 0.05%. In the countryside, above the forests, there are fewer fields. Over Antarctica, approximately 0.02% of carbon dioxide, i.e., almost Ouse less than the average amount in the atmosphere. The same amount and even less over the sea - 0.01 - 0.02%, since carbon dioxide is intensively absorbed by water.

In the layer of air that is directly adjacent to the earth's surface, the amount of carbon dioxide also experiences daily fluctuations.

More at night, less during the day. This is explained by the fact that during the daytime, carbon dioxide is absorbed by plants, but not at night. Plants of the planet during the year take about 550 billion tons of oxygen from the atmosphere and return about 400 billion tons of oxygen to it.

Carbon dioxide is completely transparent to short-wavelength solar rays, but intensely absorbs the thermal infrared radiation of the Earth. Related to this is the problem of the greenhouse effect, about which discussions periodically flare up on the pages of the scientific press, and mainly in the mass media.

HELIUM (He) is a very light gas. It enters the atmosphere from the earth's crust as a result of the radioactive decay of thorium and uranium. Helium escapes into outer space. The rate of decrease of helium corresponds to the rate of its entry from the bowels of the Earth. From an altitude of 600 km to 16,000 km, our atmosphere consists mainly of helium. This is the "helium corona of the Earth" in the words of Vernadsky. Helium does not react with other atmospheric gases and does not participate in radiant heat transfer.

HYDROGEN (Hg) is an even lighter gas. There is very little of it near the Earth's surface. It rises to the upper atmosphere. In the thermosphere and exosphere, atomic hydrogen becomes the dominant component. Hydrogen is the topmost, most distant shell of our planet. Above 16,000 km to the upper boundary of the atmosphere, that is, up to altitudes of 30-40 thousand km, hydrogen predominates. Thus, the chemical composition of our atmosphere with height approaches the chemical composition of the Universe, in which hydrogen and helium are the most common elements. In the outermost, extremely rarefied part of the upper atmosphere, hydrogen and helium escape from the atmosphere. Their individual atoms have sufficiently high speeds for this.

The role of carbon dioxide in the atmosphere is very large * Carbon dioxide takes part in the formation of all living matter on the planet and, together with water and methane molecules, creates the so-called “greenhouse (greenhouse) effect” *

Carbon dioxide value ( CO 2 , dioxide or carbon dioxide) in the life of the biosphere consists primarily in maintaining the process of photosynthesis, which is carried out by plants *

Being greenhouse gas, carbon dioxide in the air affects the heat exchange of the planet with the surrounding space, effectively blocking the re-radiated heat at a number of frequencies, and thus participates in the formation of the planet's climate *

AT recent times there is an increase in the concentration of carbon dioxide in the air, which leads to a change in the Earth's climate.

Carbon (C) in the atmosphere is found mainly in the form of carbon dioxide (CO 2) and in a small amount in the form of methane (CH 4), carbon monoxide and other hydrocarbons.

For atmospheric gases, the concept of "gas lifetime" is used. This is the time during which the gas is completely renewed, i.e. the time it takes for as much gas to enter the atmosphere as it contains. So, for carbon dioxide this time is 3-5 years, for methane - 10-14 years. CO oxidizes to CO 2 within a few months.

In the biosphere, the importance of carbon is very high, since it is part of all living organisms. Within living beings, carbon is contained in a reduced form, and outside the biosphere, in an oxidized form. Thus, the chemical exchange of the life cycle is formed: CO 2 ↔ living matter.

Sources of carbon in the atmosphere.

Volcanoes are the source of primary carbon dioxide, during the eruption of which a huge amount of gases is released into the atmosphere. Part of this carbon dioxide arises from the thermal decomposition of ancient limestones in various metamorphic zones.

Carbon also enters the atmosphere in the form of methane as a result of anaerobic decomposition of organic residues. Methane under the influence of oxygen is quickly oxidized to carbon dioxide. The main suppliers of methane to the atmosphere are tropical forests and swamps.

In turn, atmospheric carbon dioxide is a source of carbon for other geospheres - the lithosphere, biosphere and hydrosphere.

Migration of CO 2 in the biosphere.

Migration of CO 2 proceeds in two ways:

In the first method, CO 2 is absorbed from the atmosphere during photosynthesis and participates in the formation of organic substances with subsequent burial in earth's crust in the form of minerals: peat, oil, oil shale.

In the second method, carbon is involved in the creation of carbonates in the hydrosphere. CO 2 goes into H 2 CO 3, HCO 3 -1, CO 3 -2. Then, with the participation of calcium (less often magnesium and iron), the precipitation of carbonates occurs in a biogenic and abiogenic way. Thick strata of limestones and dolomites appear. According to A.B. Ronov, the ratio of organic carbon (Corg) to carbonate carbon (Ccarb) in the history of the biosphere was 1:4.

How is the geochemical cycle of carbon carried out in nature and how carbon dioxide is returned back to the atmosphere