Consequences of ozone holes in the atmosphere. Encounter with ozone in everyday life

The ozone layer is a wide atmospheric belt extending from 10 to 50 km above the Earth's surface. Chemically, ozone is a molecule consisting of three oxygen atoms (an oxygen molecule contains two atoms). The concentration of ozone in the atmosphere is very low, and small changes in the amount of ozone lead to large changes in the intensity of ultraviolet, reaching earth's surface. Unlike ordinary oxygen, ozone is unstable, it easily transforms into a diatomic, stable form of oxygen. Ozone is a much stronger oxidizing agent than oxygen, and this makes it capable of killing bacteria and inhibiting plant growth and development. However, due to its low normal conditions concentrations in the surface layers of air, these features of it practically do not affect the state of living systems.

Much more important is its other property, which makes this gas absolutely necessary for all life on land. This property is the ability of ozone to absorb the hard (shortwave) ultraviolet (UV) radiation from the Sun. Hard UV quanta have enough energy to break some chemical bonds, so it is referred to as ionizing radiation. Like other radiation of this kind, X-ray and gamma radiation, it causes numerous disturbances in the cells of living organisms. Ozone is formed under the influence of high-energy solar radiation, which stimulates the reaction between O2 and free oxygen atoms. Under the influence of moderate radiation, it decays, absorbing the energy of this radiation. Thus, this cyclical process "eats" the dangerous ultraviolet.

Ozone molecules, like oxygen, are electrically neutral, i.e. carry no electrical charge. Therefore, the Earth's magnetic field itself does not affect the distribution of ozone in the atmosphere. The upper layer of the atmosphere - the ionosphere, almost coincides with the ozone layer.

In the polar regions where lines of force magnetic field The earth closes on its surface, the distortion of the ionosphere is very significant. The number of ions, including ionized oxygen, in the upper layers of the atmosphere of the polar zones is reduced. But main reason low ozone content in the region of the poles - low intensity of solar radiation, which falls even during the polar day at small angles to the horizon, and during the polar night is completely absent. The area of polar "holes" in ozone layer is a reliable measure of changes in total atmospheric ozone.

The ozone content in the atmosphere fluctuates due to many natural causes. Periodic fluctuations associated with cycles of solar activity; many components of volcanic gases are capable of destroying ozone, so an increase in volcanic activity leads to a decrease in its concentration. Thanks to the high, hurricane speeds air currents in the stratosphere, ozone-depleting substances are carried over large areas. Not only ozone depleters are transported, but also ozone itself, so ozone concentration disturbances quickly spread over large areas, and local small “holes” in the ozone shield, caused, for example, by a rocket launch, are relatively quickly drawn in. Only in the polar regions is the air inactive, as a result of which the disappearance of ozone there is not compensated by its drift from other latitudes, and the polar "ozone holes", especially at the South Pole, are very stable.

Sources of destruction of the ozone layer. Among the depleters of the ozone layer are:

1) Freons.

Ozone is destroyed under the influence of chlorine compounds known as freons, which, also being destroyed under the influence of solar radiation, release chlorine, which “tear off” the “third” atom from the ozone molecules. Chlorine does not form compounds, but serves as a “rupture” catalyst. Thus, one chlorine atom is able to "destroy" a lot of ozone. It is believed that chlorine compounds are able to remain in the atmosphere from 50 to 1500 years (depending on the composition of the substance) of the Earth. Observations of the planet's ozone layer have been carried out by Antarctic expeditions since the mid-1950s.

The ozone hole over Antarctica, which increases in spring and decreases in autumn, was discovered in 1985. The discovery of meteorologists caused a chain of consequences of an economic nature. The fact is that the existence of the “hole” was blamed chemical industry, which produces substances containing freons that contribute to the destruction of ozone (from deodorants to refrigeration units).

In the question of how much a person is guilty of the formation of "ozone holes" - consensus no.

On the one hand, yes, definitely guilty. The production of ozone-depleting compounds should be minimized or, better yet, stopped altogether. That is, to abandon the whole sector of industry, with a turnover of many billions of dollars. And if you do not refuse, then transfer it to a “safe” track, which also costs money.

The point of view of skeptics: human influence on atmospheric processes, for all its destructiveness on a local level, on a planetary scale is negligible. The anti-freon campaign of the “greens” has a completely transparent economic and political background: with its help, large American corporations (DuPont, for example) stifle their foreign competitors by imposing agreements on the “protection environment"at the state level and forcibly introducing a new technological revolution, which economically weaker states are not able to withstand.

2) High-altitude aircraft.

The destruction of the ozone layer is facilitated not only by freons released into the atmosphere and entering the stratosphere. Nitrogen oxides are also involved in the destruction of the ozone layer, which are formed during nuclear explosions. But nitrogen oxides are also formed in combustion chambers turbojet engines high-altitude aircraft. Nitrogen oxides are formed from the nitrogen and oxygen that are there. The rate of formation of nitrogen oxides is the greater, the higher the temperature, i.e., the greater the engine power.

Not only is the engine power of an aircraft important, but also the altitude at which it flies and releases ozone-destroying nitrogen oxides. The higher the oxide or nitrous oxide is formed, the more destructive it is for ozone.

The total amount of nitrogen oxide released into the atmosphere per year is estimated at 1 billion tons. About a third of this amount is emitted by aircraft above the average tropopause level (11 km). As for aircraft, the most harmful emissions are military aircraft, the number of which is in the tens of thousands. They fly mainly at the heights of the ozone layer.

3) Mineral fertilizers.

Ozone in the stratosphere can also decrease due to the fact that nitrous oxide N2O enters the stratosphere, which is formed during the denitrification of nitrogen bound by soil bacteria. The same denitrification of bound nitrogen is also carried out by microorganisms in the upper layer of the oceans and seas. The process of denitrification is directly related to the amount of bound nitrogen in the soil. Thus, one can be sure that with an increase in the amount of mineral fertilizers applied to the soil, the amount of nitrous oxide N2O formed will also increase to the same extent. Further, nitrogen oxides are formed from nitrous oxide, which lead to the destruction of stratospheric ozone.

4) Nuclear explosions.

Nuclear explosions release a lot of energy in the form of heat. The temperature equal to 60,000 K is set within a few seconds after a nuclear explosion. This is the energy of the fireball. In a very hot atmosphere, such transformations take place chemical substances, which under normal conditions either do not occur, or proceed very slowly. As for ozone, its disappearance, the most dangerous for it are the oxides of nitrogen formed during these transformations. Thus, during the period from 1952 to 1971, as a result of nuclear explosions, about 3 million tons of nitrogen oxides were formed in the atmosphere. Further fate They are as follows: as a result of the mixing of the atmosphere, they fall to different heights, including into the atmosphere. There they enter into chemical reactions with the participation of ozone, leading to its destruction. ozone hole stratosphere ecosystem

5) Fuel combustion.

Nitrous oxide is also found in flue gases from power plants. Actually, the fact that nitrogen oxide and dioxide are present in combustion products has been known for a long time. But these higher oxides do not affect ozone. They, of course, pollute the atmosphere, contribute to the formation of smog in it, but are quickly removed from the troposphere. Nitrous oxide, as already mentioned, is dangerous for ozone. At low temperatures Ah, it is formed in the following reactions:

N2 + O + M = N2O + M,

2NH3 + 2O2 =N2O = 3H2.

The scale of this phenomenon is very significant. In this way, approximately 3 million tons of nitrous oxide are formed in the atmosphere every year! This figure suggests that this source of ozone depletion is significant.

Ozone hole over Antarctica

A significant decrease in total ozone over Antarctica was first reported in 1985 by the British Antarctic Survey based on analysis of data from the Halle Bay Ozone Station (76 degrees S). Ozone depletion has also been observed by this service in the Argentine Islands (65 degrees S).

From August 28 to September 29, 1987, 13 flights of the laboratory aircraft over the Antarctic were performed. The experiment made it possible to register the origin of the ozone hole. Its dimensions were obtained. Studies have shown that the greatest decrease in the amount of ozone took place at altitudes of 14 - 19 km. Here the devices are registered the largest number aerosols (aerosol layers). It turned out that the more aerosols there are at a given altitude, the less ozone there is. Aircraft - the laboratory registered a decrease in ozone equal to 50%. Below 14 km. ozone changes were insignificant.

Already by the beginning of October 1985, the ozone hole (the minimum amount of ozone) covers pressure levels from 100 to 25 hPa, and in December the range of heights at which it is observed expands.

In many experiments, not only the amount of ozone and other small components of the atmosphere was measured, but also the temperature. The closest relationship was established between the amount of ozone in the stratosphere and the air temperature there. It turned out that the nature of the change in the amount of ozone is closely related to the thermal regime of the stratosphere over Antarctica.

The formation and development of the ozone hole in Antarctica was observed by British scientists in 1987. In the spring, the total ozone content decreased by 25%.

American researchers took measurements in Antarctica in winter and in early spring 1987 of ozone and other small constituents of the atmosphere (HCl, HF, NO, NO2, HNO3, ClONO2, N2O, CH4) using a special spectrometer. The data from these measurements made it possible to delineate an area around the South Pole in which the amount of ozone is reduced. It turned out that this region coincides almost exactly with the extreme polar stratospheric vortex. When passing through the edge of the vortex, the amount of not only ozone changed dramatically, but also other small components that affect the destruction of ozone. Within the ozone hole (or, in other words, the polar stratospheric vortex), the concentrations of HCl, NO2, and nitric acid were significantly lower than outside the vortex. This takes place because chlorins during the cold polar night destroy ozone in the corresponding reactions, acting as catalysts in them. It is in the catalytic cycle with the participation of chlorine that the main decrease in the concentration of ozone occurs (at least 80% of this decrease).

These reactions take place on the surface of the particles that make up the polar stratospheric clouds. So than more area this surface, i.e., the more particles of stratospheric clouds, and hence the clouds themselves, the faster the ozone eventually decays, which means the more efficiently the ozone hole is formed.

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MINISTRY OF TRANSPORT OF THE RUSSIAN FEDERATION

FGOUVPO ULYANOVSK HIGHER AVIATION SCHOOL

CIVIL AVIATION (INSTITUTE)

FACULTY FLIGHT OPERATION AND AIR TRAFFIC CONTROL

DEPARTMENT PASOP

ESSAY

on the topic:Ozone holes: causesandeffects

Completed by: Bazarov M.A.

Head: Morozova M.M.

Ulyanovsk 2012

Introduction

1. Reasons

2. Consequences

3. Geographic location

4. The role of civil and military aviation in the formation of ozone holes

5. Ways to solve problems

Conclusion

Introduction

With the rise of human civilization, new factor influencing the fate of wildlife. He has attained great strength in this century and especially in recent times. 5 billion of our contemporaries have the same impact on nature in terms of scale that people of the Stone Age could have if their number was 50 billion people, and the amount of energy released by the earth received from the sun.

Since the emergence of a highly industrialized society, the dangerous human intervention in nature has increased dramatically, the scope of this interference has expanded, it has become more diverse and now threatens to become a global danger to humanity.

The consumption of non-renewable raw materials is increasing, more and more arable land is leaving the economy, as cities and factories are built on them. The Earth's biosphere is currently undergoing increasing anthropogenic impact. At the same time, several of the most significant processes can be distinguished, none of which improves the state of the airspace of our planet.

Progresses and accumulation carbon dioxide in the atmosphere. Further development this process will reinforce the undesirable upward trend average annual temperature on the planet.

As a result, a dilemma arose before society: either thoughtlessly roll towards its inevitable death in an impending ecological catastrophe, or consciously turn the mighty forces of science and technology created by the genius of man from a weapon previously turned against nature and man himself, into a tool for their protection and prosperity, into a tool rational environmental management.

A real threat of a global ecological crisis, understood by the entire population of the planet, hangs over the world, and the real hope for its prevention lies in continuous environmental education and enlightenment of people.

The World Health Organization has determined that human health is 20% dependent on heredity, 20% on the state of the environment, 50% on lifestyle and 10% on medicine. In a number of regions of Russia, by 2005, the following dynamics of factors affecting human health is expected: the role of ecology will increase to 40%, the effect of the genetic factor will increase to 30%, the ability to maintain health due to lifestyle will decrease to 25%, and the role of medicine will decrease to 5%. .

Characterizing state of the art ecology, as critical, one can single out the main causes that lead to an ecological catastrophe: pollution, poisoning of the environment, depletion of the atmosphere with oxygen, ozone holes.

The purpose of this work was to summarize the literature data on the causes and consequences of the destruction of the ozone layer, as well as ways to solve the problem of the formation of “ozone holes”.

ozone layer hole ecological

1. The reasons

Ozone hole - a local drop in the concentration of ozone in the ozone layer of the Earth. According to the theory generally accepted in the scientific community, in the second half of the 20th century, the ever-increasing impact of the anthropogenic factor in the form of the release of chlorine- and bromine-containing freons led to a significant thinning of the ozone layer.

According to another hypothesis, the process of formation of "ozone holes" can be largely natural and is not associated exclusively with harmful effects human civilization.

An ozone hole with a diameter of over 1000 km was first discovered in 1985, in the Southern Hemisphere, over Antarctica, by a group of British scientists: J. Shanklin (English), J. Farman (English), B. Gardiner (English), who published the corresponding article in the journal Nature. Every August it appeared, and in December-January it ceased to exist. Another hole was forming over the Northern Hemisphere in the Arctic, but smaller. At this stage in the development of mankind, world scientists have proved that there are a huge number of ozone holes on Earth. But the most dangerous and largest is located above the Antarctic.

A combination of factors leads to a decrease in the concentration of ozone in the atmosphere, the main of which is the death of ozone molecules in reactions with various substances anthropogenic and natural origin, lack of solar radiation during the polar winter, a particularly stable polar vortex, which prevents the penetration of ozone from subpolar latitudes, and the formation of polar stratospheric clouds (PSC), the surface of whose particles catalyze ozone decay reactions. These factors are especially characteristic of the Antarctic, in the Arctic the polar vortex is much weaker due to the lack of a continental surface, the temperature is several degrees higher than in the Antarctic, and PSOs are less common, and they also tend to break up in early autumn. Being reactive, ozone molecules can react with many inorganic and organic compounds. The main substances contributing to the destruction of ozone molecules are simple substances(hydrogen, oxygen atoms, chlorine, bromine), inorganic (hydrogen chloride, nitrogen monoxide) and organic compounds(methane, fluorochlorine and fluorobromfreons, which emit chlorine and bromine atoms). Unlike, for example, hydrofluorofreons, which decompose to fluorine atoms, which, in turn, quickly react with water to form stable hydrogen fluoride. Thus, fluorine does not participate in ozone decay reactions. Iodine also does not destroy stratospheric ozone, since iodine-containing organic matter almost completely consumed in the troposphere. The main reactions that contribute to the destruction of ozone are given in the article about the ozone layer.

Chlorine "eats" both ozone and atomic oxygen due to rather fast reactions:

O3 + Cl = O2 + ClO

СlO + O = Cl + O2

Moreover, the last reaction leads to the regeneration of active chlorine. Chlorine is thus not even consumed, destroying the ozone layer.

In summer and spring, the concentration of ozone increases. It is always higher over the polar regions than over the equatorial ones. In addition, it changes according to an 11-year cycle, coinciding with the cycle of solar activity. All this was already well known in the 1980s. Observations have shown that a slow but steady decrease in the concentration of stratospheric ozone occurs over the Antarctic from year to year. This phenomenon is called " the ozone hole” (although no hole in own meaning this word, of course, was not).

Later, in the 90s of the last century, the same decrease began to occur over the Arctic. The phenomenon of the Antarctic "ozone hole" is not yet clear: whether the "hole" arose as a result of anthropogenic pollution of the atmosphere, or whether it is a natural geoastrophysical process.

Among the versions of the formation of ozone holes are:

the influence of particles emitted in atomic explosions;

flights of rockets and high-altitude aircraft;

reactions with ozone of certain substances produced by chemical plants. These are primarily chlorinated hydrocarbons and especially freons - chlorofluorocarbons, or hydrocarbons, in which all or most of hydrogen atoms are replaced by fluorine and chlorine atoms.

Chlorofluorocarbons are widely used in modern household and industrial refrigerators (therefore they are called “freons”), in aerosol cans, as dry cleaning agents, for extinguishing fires in transport, as foaming agents, for the synthesis of polymers. The world production of these substances has reached almost 1.5 million tons/year.

Being highly volatile and fairly resistant to chemical attack, chlorofluorocarbons after use enter the atmosphere and can stay in it for up to 75 years, reaching the height of the ozone layer. Here under the action sunlight they decompose, releasing atomic chlorine, which serves as the main “disturber” in the ozone layer.

2. Effects

The ozone hole poses a danger to living organisms, since the ozone layer protects the Earth's surface from excessive doses. ultraviolet radiation Sun. The weakening of the ozone layer increases the flow of solar radiation to the earth and causes an increase in the number of skin cancers in people. Plants and animals also suffer from increased levels of radiation.

Ozone in the stratosphere protects the Earth from damaging ultraviolet, solar radiation. The destruction of the ozone layer will allow more solar radiation to reach the Earth's surface.

Every percent of stratospheric ozone lost results in a 1.5 to 2 percent increase in exposure to ultraviolet, solar radiation, according to the US Environmental Protection Agency. For humans, an increase in the intensity of ultraviolet radiation, primarily dangerous, is the effect of solar radiation on the skin and eyes.

Radiation with a wavelength in the spectrum from 280 to 320 nanometers - UV rays, which are partially blocked by ozone - can cause premature aging and an increase in skin cancers, as well as damage to plants and animals.

Radiation with a wavelength of more than 320 nanometers, the UV spectrum, is practically not absorbed by ozone and is actually necessary for a person to form vitamin D. UV radiation with a wavelength in the spectrum of 200 - 280 nanometers can cause serious consequences for biological organisms. However, the radiation of this spectrum is almost completely absorbed by ozone. Thus, the "Achilles' heel" of terrestrial life is the radiation of a rather narrow spectrum of UV waves with a length of 320 to 280 nanometers. With a reduction in wavelength, their ability to harm living organisms and DNA increases. Fortunately, the ability of ozone to absorb ultraviolet radiation increases in proportion to the reduction in the wavelength of radiation.

· Increasing incidence of skin cancer.

Suppression of the human immune system.

· Damage to the eyes.

Ultraviolet radiation can damage the cornea of the eye, the connective membrane of the eye, the lens and the retina of the eye. Ultraviolet radiation can cause photokeratosis (or snow blindness), similar to sunburn of the cornea or connective tissue of the eye. Increased human exposure to ultraviolet radiation due to ozone depletion will increase the number of people with cataracts, according to the authors of How to Save Our Skin. A cataract blocks the lens of the eye, reducing visual acuity and can cause blindness.

· Destruction of crops.

3. Geographic location

The thinning of the ozone layer began to be recorded in the 70s. It decreased especially significantly over Antarctica, which led to the appearance of the common expression “ozone hole”. Small holes are also fixed in the northern hemisphere - over the Arctic, in the region of the Plesetsk and Baikonur cosmodromes. In 1974, two scientists from the University of California, Mario Molina and Sherwood Rowland, hypothesized that freon gases used in the refrigeration and perfume industries are the main factor in the destruction of ozone. Less significant ozone-depleting factors are flights of rockets and supersonic aircraft.

The location of "ozone holes" tends to localize positive World magnetic anomalies. In the Southern Hemisphere, this is the Antarctic, and in the Northern Hemisphere, the East Siberian World Magnetic Anomaly. Moreover, the power of the Siberian anomaly is growing so strongly that even in Novosibirsk the vertical component of the geomagnetic field is growing annually by 30 gamma (nanotesla).

The loss of the ozone layer over the Arctic Basin was so significant this year that for the first time in the history of observations, one can speak of the emergence of an "ozone hole" similar to the Antarctic one. At altitudes above 20 km, ozone losses amounted to about 80%. Probable cause This phenomenon is called the unusually long persistence of relatively low temperatures in the stratosphere at these latitudes.

4. The role of the civil and military aviation in educationozone holes

The destruction of the ozone layer is facilitated not only by freons released into the atmosphere and entering the stratosphere. Nitrogen oxides, which are formed during nuclear explosions, are also involved in the destruction of the ozone layer. But nitrogen oxides are also formed in the combustion chambers of high-altitude aircraft turbojet engines. Nitrogen oxides are formed from the nitrogen and oxygen that are there. The rate of formation of nitrogen oxides is the greater, the higher the temperature, i.e., the greater the engine power.

The total amount of nitrogen oxide emitted into the atmosphere per year is estimated at 1 billion tons. About a third of this amount is emitted by aircraft above the average tropopause level (11 km). As for aircraft, the most harmful emissions are military aircraft, the number of which is in the tens of thousands. They fly mainly at the heights of the ozone layer.

5. Problem Solving Ways

To start a global recovery, it is necessary to reduce the access to the atmosphere of all substances that destroy ozone very quickly and are stored there for a long time.

Also, we - all people should understand this and help nature turn on the process of restoring the ozone layer, we need new forest plantations, stop cutting down forests for other countries that for some reason do not want to cut down their own, but make money from our forests.

To restore the ozone layer, it needs to be fed. At first, for this purpose, it was supposed to create several ground-based ozone factories and "throw" ozone into the upper atmosphere on cargo planes. However, this project (probably it was the first project to "treat" the planet) was not implemented.

Another way is proposed by the Russian consortium "Interozone": to produce ozone directly in the atmosphere. In the near future, together with the German company Daza, it is planned to raise balloons with infrared lasers to a height of 15 km, with the help of which ozone can be obtained from diatomic oxygen.

If this experiment turns out to be successful, in the future it is supposed to use the experience of the Russian orbital station"Mir" and create several space platforms with energy sources and lasers at an altitude of 400 km. The laser beams will be directed towards central part the ozone layer and will constantly feed it. The source of energy can be solar panels. Astronauts on these platforms will only be required for periodic inspections and repairs.

Conclusion

The possibilities of human impact on nature are constantly growing and have already reached a level where it is possible to cause irreparable damage to the biosphere. This is not the first time a substance that for a long time Thought to be completely harmless, it actually turns out to be extremely dangerous. Twenty years ago, hardly anyone could have imagined that an ordinary aerosol can could pose a serious threat to the planet as a whole. Unfortunately, it is far from always possible to predict in time how this or that compound will affect the biosphere. However, in the case of CFCs, there was such a possibility: all chemical reactions describing the process of CFC ozone destruction are extremely simple and have been known for a long time. But even after the CFC problem was formulated in 1974, the only country that took any action to reduce the production of CFCs was the United States and these measures were completely insufficient. It took a strong enough demonstration of the dangers of CFCs for serious action to be taken on a global scale. It should be noted that even after the discovery of the ozone hole, the ratification of the Montreal Convention was at one time under threat. Perhaps the problem of CFCs will teach us to treat all substances that enter the biosphere as a result of human activities with great attention and caution.

The problem of historical and modern climate change turned out to be very complex and cannot be solved in the schemes of one-factor determinism. In addition, as the concentration of carbon dioxide increases, changes in the ozonosphere associated with the evolution of the geomagnetic field play an important role. The development and testing of new hypotheses is a necessary condition for understanding the patterns of the general circulation of the atmosphere and other geophysical processes affecting the biosphere.

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How do ozone holes appear? How to darn them?

Rowland and Molina suggested that chlorine atoms could cause the destruction of large amounts of ozone in the stratosphere. It is sometimes argued that since Freon molecules are much heavier than nitrogen and oxygen, they cannot reach the stratosphere in significant quantities. Therefore, even such heavy gases as inert or freons are evenly distributed in the atmosphere, reaching, among other things, the stratosphere.

Due to their low reactivity, they are practically not consumed in the lower layers of the atmosphere and have a lifetime of several years or even decades. At that time polar region is not illuminated by the Sun, and ozone does not form there.

The French physicists Charles Fabry and Henri Buisson were the discoverers of the ozone layer. In 1912, they succeeded in using spectroscopic measurements of ultraviolet radiation to prove the existence of ozone in the layers of the atmosphere distant from the Earth. In 1985, the Vienna Convention for the Protection of the Ozone Layer was adopted, and in 1987, the Montreal Protocol. Some of them are able to reach the earth's surface and diffuse into the atmosphere through cracks.

1992 was marked for scientists by the fact that already over the Northern Hemisphere in Antarctica another ozone hole was formed, with a much smaller diameter. And in 2008, the diameter of the first ozone phenomenon discovered in Antarctica reached its maximum record size - 27 million square kilometers. Since the ozone layer is designed to protect the surface of our planet from an excess of ultraviolet solar radiation, ozone holes can be considered a phenomenon that is really dangerous for living organisms.

At 20-50 kilometers above the Earth's surface, there is a layer of ozone in the atmosphere. Ozone is special shape oxygen. The ozone layer of the atmosphere is very thin. If all available atmospheric ozone evenly covers an area of 45 square kilometers, then a layer 0.3 centimeters thick will be obtained.

What is the ozone layer and why is its destruction harmful?

In 1978, based on data on the effect of freons on the ozone layer of the atmosphere, the government of the United States of America (USA) banned the production and sale of aerosols containing freons. True, aerosol manufacturers, and many scientists along with them, consider the theory of ozone depletion to be unconvincing. In 1985, British scientists made a startling discovery. They discovered a huge "hole" in the ozone layer over Antarctica. This hole, the size of the US, appears annually in the spring.

The area of the so-called ozone hole, which annually forms in the stratosphere over Antarctica, is 1.7 times the area of the mainland itself, the National Meteorological Administration of Japan said. The ozone "hole" is formed as a result of the destruction of the ozone layer by gases such as freon, and is formed every year between August and December.

Ozone holes - causes and consequences

It appeared every year in August and ceased to exist in December-January. Thus, fluorine does not participate in ozone decay reactions. Iodine also does not destroy stratospheric ozone, since iodine-containing organic substances are almost completely consumed even in the troposphere.

Halogenated hydrocarbons are also present in the gases of hydrothermal sources. So, solid particles that fell into the stratosphere back in 1991 during the eruption of Mount Pinatubo in the Philippine Islands still contribute to the formation of ozone holes. The ozone hole poses a danger to living organisms, since the ozone layer protects the Earth's surface from excessive doses of ultraviolet radiation from the Sun.

The history of the discovery of ozone holes in the atmosphere

The ozone "hole" (decrease in the concentration of ozone in the atmosphere) constantly exists over the Antarctic; increases in winter, by spring - to a maximum. And there can be no "complete restoration of the ozone layer". It should be noted that ozone is an unstable gas, its molecules decompose rather quickly. Continuous monitoring of the Antarctic ozone hole has been carried out since 1987; it was found that its dimensions are approximately stable - from 21 to 30 million square kilometers.

The ozone layer is located in the stratosphere at an altitude of approximately 25 kilometers from the earth's surface. And again, people are to blame for the appearance of ozone holes. No, of course they didn't tear up the ozone layer in the literal sense.

As a result of the absence of solar radiation, ozone is not formed during the polar nights. This statement is true for middle and high latitudes. In the rest, the chlorine cycle is responsible for only 15-25% of ozone loss in the stratosphere. DuPont, after the publication of data on the participation of freons in the destruction of stratospheric ozone, took this theory with hostility and spent millions of dollars on a press campaign to protect freons.

Experimental measurements of their concentrations in the atmosphere confirm this; But it's not. Both krypton with an atomic mass of 84 and helium with an atomic mass of 4 have the same relative concentration, which is near the surface, which is up to 100 km in height.

Occurring annually in August, this ozone hole disappeared from December to January. Unlike, for example, hydrofluorofreons, which decompose to fluorine atoms, which, in turn, quickly react with water to form stable hydrogen fluoride. The fact is that freons are well mixed in the troposphere and stratosphere. In the place of such interaction, the ozone layer is destroyed - it disappears. The ozone hole was first discovered in 1985 by a group of British scientists led by Joe Farman.

First of all, it should be clear that the ozone hole, contrary to its name, is not a hole in the atmosphere. The ozone molecule differs from the ordinary oxygen molecule in that it consists not of two, but of three oxygen atoms connected to each other. In the atmosphere, ozone is concentrated in the so-called ozone layer, at an altitude of about 30 km within the stratosphere. This layer absorbs ultraviolet rays emitted by the Sun, otherwise solar radiation could cause great harm to life on the surface of the Earth. Therefore, any threat to the ozone layer deserves the most serious attitude. In 1985, British scientists working at the South Pole discovered that during the Antarctic spring, the level of ozone in the atmosphere was significantly below normal. Every year at the same time, the amount of ozone decreased - sometimes more, sometimes less. Similar but less pronounced ozone holes have also appeared over north pole during the arctic spring.

In subsequent years, scientists figured out why the ozone hole appears. When the sun hides and the long polar night begins, there is a sharp drop in temperature, and high stratospheric clouds form, containing ice crystals. The appearance of these crystals causes a series of complex chemical reactions leading to the accumulation of molecular chlorine (the chlorine molecule consists of two connected chlorine atoms). When the sun appears and the Antarctic spring begins, under the influence of ultraviolet rays, intramolecular bonds are broken, and a stream of chlorine atoms rushes into the atmosphere. These atoms act as catalysts for the conversion of ozone into simple oxygen, proceeding according to the following double scheme:

Cl + O 3 -> ClO + O 2 and ClO + O -> Cl + O 2

As a result of these reactions, ozone molecules (O 3) are converted into oxygen molecules (O 2), while the original chlorine atoms remain in a free state and again participate in this process (each chlorine molecule destroys a million ozone molecules before they are removed from the atmosphere under other chemical reactions). As a result of this chain of transformations, ozone begins to disappear from the atmosphere over Antarctica, forming an ozone hole. However, soon, with warming, the Antarctic vortices are destroyed, Fresh air(containing new ozone) rushes into the area and the hole disappears.

In 1987, Montreal hosted international Conference, dedicated to the threat to the ozone layer, and industrial the developed countries agreed to reduce and eventually stop production chlorinated and fluorinated hydrocarbons (chlorofluorocarbons, CFCs) — chemicals that deplete the ozone layer. By 1992, the replacement of these substances with safe ones was so successful that a decision was made to eliminate them completely by 1996. Today, scientists believe that in fifty years the ozone layer will fully recover.

Recently, more and more often the public is concerned about environmental issues - protecting the environment, animals, reducing the amount of harmful and dangerous emissions. Surely everyone has also heard about what an ozone hole is, and that there are a lot of them in the modern stratosphere of the Earth. And there is.

Modern anthropogenic activity and technical development endanger the existence of animals and plants on Earth, as well as the very life of people.

The ozone layer is the protective shell of the blue planet, which is located in the stratosphere. Its height is about twenty-five kilometers from the earth's surface. And this layer is formed from oxygen, which, under the influence of solar radiation, undergoes chemical transformations. The local decrease in ozone concentration (in the common people this is the well-known "hole") is currently caused by many reasons. First of all, this, of course, is human activity (both industrial and everyday household). There are, however, opinions that the ozone layer is destroyed under the influence of exclusively natural phenomena not related to people.

Anthropogenic influence

Having understood what the ozone hole is, it is necessary to find out what kind of human activity contributes to its appearance. First of all, these are aerosols. Every day we use deodorants, hairsprays, eau de toilette with spray bottles and often do not think about the fact that this adversely affects the protective layer of the planet.

The fact is that the compounds that are present in the cans we are used to (including bromine and chlorine) readily react with oxygen atoms. Therefore, the ozone layer is destroyed, turning after such chemical reactions into completely useless (and often harmful) substances.

Destructive compounds for the ozone layer are also present in life-saving summer heat air conditioners and refrigeration equipment. The widespread industrial activity of man also weakens earthly defenses. It is oppressed by industrial water (some of the harmful substances evaporate over time), pollute the stratosphere and cars. The latter, as statistics show, is becoming more and more every year. negatively affects the ozone layer and

natural influence

Knowing what an ozone hole is, you must also have an idea of how many of them are above the surface of our planet. The answer is disappointing: there are many gaps in earthly protection. They are small and often do not represent a hole, but a very thin remaining layer of ozone. However, there are also two huge unprotected spaces. This is the Arctic and Antarctic ozone hole.

The stratosphere above the Earth's poles contains almost no protective layer at all. What is it connected with? There are no cars there industrial productions. It's all about natural influence, the second reason Polar vortices arise when warm and cold air flows collide. These gas formations contain nitric acid in large quantities, which, under the influence of very low temperatures, reacts with ozone.

Environmentalists began to sound the alarm only in the twentieth century. Destructive ones that make their way to the ground without bumping into an ozone barrier can cause skin cancer in humans, as well as the death of many animals and plants (primarily marine). So, international organizations almost all compounds that destroy the protective layer of our planet were banned. It is believed that even if humanity abruptly stops any negative impact on ozone in the stratosphere, the holes that currently exist will not disappear very soon. This is due to the fact that freons that have already made their way up are able to exist independently in the atmosphere for decades.