From oxygen under the influence of ultraviolet rays. The Earth's atmosphere has an ozone layer at an altitude of about 25 kilometers: a layer of this gas densely surrounds our planet, protecting it from high concentrations of ultraviolet radiation. If not for this gas, intense radiation could kill all life on Earth.
The ozone layer is quite thin, it cannot completely protect the planet from the penetration of radiation, which has a detrimental effect on the state and causes diseases. But long time it was enough to protect the Earth from danger.
In the 1980s, it was discovered that there are areas in the ozone layer where the content of this gas is greatly reduced - the so-called ozone holes. The first hole was discovered over Antarctica by British scientists, they were amazed at the scale of the phenomenon - a section with a diameter of more than a thousand kilometers had almost no protective layer and was subjected to stronger ultraviolet radiation.
Later, other ozone holes were found, smaller in size, but no less dangerous.
Reasons for the formation of ozone holes
The mechanism of formation of the ozone layer in the Earth's atmosphere is quite complex, and various reasons can lead to its violation. At first, scientists offered many versions: both the influence of particles formed during atomic explosions, and the impact of the eruption of the El Chicon volcano, even opinions were expressed about the activities of aliens.
The reasons for the depletion of the ozone layer can be the lack of solar radiation, the formation of stratospheric clouds, polar vortices, but most often the concentration of this gas falls due to its reactions with various substances, which can be both natural and anthropogenic. Molecules are destroyed under the influence of hydrogen, oxygen, chlorine, organic compounds. So far, scientists cannot unequivocally say whether the formation of ozone holes is mainly caused by human activity, or whether it is natural.
It has been proven that freons released during the operation of many devices cause ozone losses in middle and high latitudes, but they do not affect the formation of polar ozone holes.
It is likely that the combination of many, both human and natural factors, led to the formation of ozone holes. On the one hand, volcanic activity has increased, on the other hand, people have begun to seriously influence nature - the ozone layer can not only from the release of freon, but also from a collision with failed satellites. Due to the decrease in the number of erupting volcanoes since the end of the 20th century and the restriction of the use of freons, the situation has begun to improve slightly: scientists recently recorded a small hole over Antarctica. A more detailed study of ozone depletion will make it possible to prevent the appearance of these areas.
The earth is arranged in such a way that its unique ecosystem is preserved. These purposes are served by the layers of the atmosphere, which cover the planet from the penetration of ultraviolet rays, radiation, and space debris. In nature, everything is perfect, and interference in its structure leads to various cataclysms and violation of the established order. At the end of the 20th century, a clear problem emerged that affects all of humanity. The ozone hole formed in the Antarctic region and attracted the attention of scientists from all over the world. The critical situation of ecology was aggravated by another serious problem.
It was found that in the ozone layer surrounding the earth's surface, a gap was formed, more than a thousand kilometers in size. Through it, radiation enters, adversely affecting people, animals and vegetation. Ozone holes and thinning of the gas envelope were later discovered in several more places, causing a stir in public circles.
The essence of the problem
Ozone is formed from oxygen, which is affected by ultraviolet rays. Due to this reaction, the planet is shrouded in a layer of gas through which radiation cannot enter. This layer is located at an altitude of 25-50 kilometers above the surface. The thickness of the ozone is not very large, but it is quite enough for all life to exist on the planet.
What is the ozone hole, learned in the 80s of the last century. This sensational discovery was made by British scientists. In places of ozone destruction, gas is not completely absent, its concentration decreases to a critical level of 30%. The gap formed in the stratosphere layer passes ultraviolet rays to the ground, which can burn living organisms.
The first such hole was discovered in 1985. Its location is Antarctica. The peak time when the ozone hole expanded was August, and by winter the gas condensed and practically closed the hole in the stratospheric layer. Critical points in height are located at a distance of 19 kilometers from the ground.
The second ozone hole appeared over the Arctic. Its dimensions were much smaller, but otherwise there was a striking resemblance. Critical heights and time of disappearance coincided. Currently, ozone holes appear in different places.
How does the thinning of the ozone layer occur?
Scientists attribute the emergence of a problem with the thinning of the ozone layer to natural phenomena occurring at the poles of the globe. According to their theory, during the long polar nights, the sun's rays do not reach the earth, and ozone cannot be formed from oxygen. In this regard, clouds with a high content of chlorine are formed. It is he who destroys the gas so necessary to protect the planet.
The earth was going through a period of volcanic activity. It also had a detrimental effect on the thickness of the ozone layer. Emissions into the atmosphere of combustion products destroyed the already thin layer of the stratosphere. The release of freons into the air is another reason for the thinning of the protective layer of the earth.
The ozone hole disappears as soon as the sun begins to shine and interact with oxygen. Due to air currents, the gas rises and fills the resulting void. This theory proves that ozone circulation is constant and inevitable.
Other causes of ozone holes
Despite the fact that chemical processes play a dominant role in the formation of ozone holes, human impact on nature creates the main prerequisites. Naturally occurring chlorine atoms are not the only substances harmful to ozone. The gas is also destroyed by the action of hydrogen, bromine and oxygen. The reasons for the appearance of these compounds in the air lie in human activities on the planet. The preconditions are:
- operation of plants and factories;
- lack of treatment facilities;
- atmospheric emissions from thermal power plants;
Nuclear explosions had a detrimental effect on the integrity of the atmosphere. Their consequences still affect the ecology of the planet. At the time of the explosion, a huge amount of nitrogen oxides is formed, which, rising, destroy the gas that protects the earth from radiation. Over 20 years of testing, more than three million tons of this substance have entered the atmosphere.
Jet planes have a devastating effect on the ozone layer. When fuel is burned in turbines, nitrogen oxides are thrown out, they directly enter the atmosphere and destroy gas molecules. Currently, out of a million tons of emissions of this substance, a third is accounted for by aircraft.
It would seem that mineral fertilizers are harmless and useful, but in fact they also adversely affect the atmosphere. When interacting with bacteria, they are processed into nitrous oxide, and then, under the influence of chemical reactions, change their shape and become oxides.
Thus, the ozone hole is a product not only of natural phenomena, but also. Rough decisions can lead to unexpected results.
Why is the disappearance of the ozone layer around the planet dangerous?
The sun is the source of heat and light for everything on the planet. Animals, plants and man flourish thanks to its life-giving rays. This was noted by the people of the ancient world, who considered the Sun-God to be the main idol. But the luminary can also cause the death of life on the planet.
Through the ozone holes formed under the influence of the tandem of man and nature, solar radiation can fall on the earth and incinerate everything that was once grown. The detrimental effects on humans are obvious. Scientists have found that if the protective gas or its layer becomes thinner by one percent, then seven thousand more cancer patients will appear on earth. First of all, the skin of people will suffer, and then other organs.
The consequences of the formation of ozone holes affect not only humanity. Vegetation suffers, as well as wildlife and inhabitants of the deep sea. Their mass extinction is a direct consequence of the processes taking place on the sun and in the atmosphere.
Ways to solve the problem
The reasons for the appearance of ozone holes in the atmosphere are varied, but come down to one essential fact: thoughtless human activity and new technological solutions. Freons that enter the atmosphere and destroy its protective layer are a product of the combustion of various chemicals.
To stop these processes, fundamentally new scientific developments are needed that will make it possible to produce, heat, work out and fly without the use of nitrogen, fluorine and bromine, as well as their derivatives.
The emergence of the problem is associated with careless production and agricultural activities. It's time to think:
- on the installation of treatment facilities on smoking chimneys;
- on the replacement of chemical fertilizers with organic ones;
- on the transition of transport to electricity.
Quite a lot has been done over the past sixteen years, since 2000. Scientists managed to achieve amazing results: the size of the ozone hole over Antarctica has decreased by an area equal to the territory of India.
The consequences of negligent and inattentive attitude to the environment are already making themselves felt. In order not to aggravate the situation even more, it is necessary to deal with the problem at the global level.
Introduction
An ozone hole with a diameter of over 1000 km was first discovered in 1985 in the Southern Hemisphere by a group of British scientists in Antarctica. Every August it appeared, by December or January it ceased to exist. Another smaller hole was forming over the Northern Hemisphere in the Arctic.
The ozone hole- local drop in the concentration of ozone in the ozone layer of the Earth. According to the generally accepted theory in the scientific community, in the second half of the 20th century, the ever-increasing impact of anthropogenic factor in the form of the release of chlorine- and bromine-containing freons led to a significant thinning of the ozone layer, see for example the report of the World Meteorological Organization:
These and other recent scientific findings reinforced the conclusion of previous assessments that the weight in favor of scientific evidence suggests that the observed loss of ozone at mid and high latitudes is mainly due to anthropogenic chlorine- and bromine-containing compounds.
According to another hypothesis, the process of formation of "ozone holes" can be largely natural and is not associated solely with the harmful effects of human civilization.
Mechanism of education
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 of anthropogenic and natural origin, the absence of solar radiation during the polar winter, a particularly stable polar vortex that prevents the penetration of ozone from subpolar latitudes, and the formation polar stratospheric clouds (PSC), whose surface particles catalyze ozone decay reactions. These factors are especially typical for 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 of chlorine bromine), inorganic (hydrochloride nitrogen monoxide) and organic compounds of methane, fluorochlorine and fluorine bromine, which release chlorine and bromine atoms). Unlike, for example, hydrofluorofreons, which decompose to fluorine atoms, which, in turn, quickly react with a vault 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 substances are almost completely consumed even in the troposphere. The main reactions that contribute to the destruction of ozone are given in the article proozone layer.
Effects
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.
Restoration of the ozone layer
Although mankind has taken measures to limit the emissions of chlorine- and bromine-containing freons by switching to other substances, such as fluorine-containing freons , the process of restoring the ozone layer will take several decades. First of all, this is due to the huge volume of freons already accumulated in the atmosphere, which have a lifetime of tens and even hundreds of years. Therefore, the tightening of the ozone hole should not be expected before 2048.
Misconceptions about the ozone hole
There are several widespread myths about the formation of ozone holes. Despite their unscientific nature, they often appear in the media - sometimes out of ignorance, sometimes supported by supporters conspiracy theories. Some of them are listed below.
Freons are the main destroyers of ozone.
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. It should be noted that 80% of chlorine is of anthropogenic origin. (for more details about the contribution of various cycles, see Art. ozone layer). That is, human intervention greatly increases the contribution of the chlorine cycle. And given the tendency to increase the production of freons before the entry into force Montreal Protocol(10% per year) 30 to 50% of total ozone loss in 2050 would be due to CFC exposure. Before human intervention, the processes of ozone formation and its destruction were in equilibrium. But freons emitted by human activity have shifted this balance towards a decrease in ozone concentration. As for the polar ozone holes, the situation is completely different. The mechanism of ozone destruction is fundamentally different from higher latitudes, the key stage is the conversion of inactive forms of halogen-containing substances into oxides, which occurs on the surface of particles of polar stratospheric clouds. And as a result, almost all ozone is destroyed in reactions with halogens, chlorine is responsible for 40-50% and bromine is about 20-40%.
DuPont initiated a ban on old and transition to new types of freons because their patent was expiring
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. The DuPont chairman wrote in an article in Chemical Week on July 16, 1975, that the theory of ozone depletion was science fiction, nonsense that made no sense. In addition to DuPont, a number of companies around the world have produced and are producing various types of freons without deduction of royalties.
Freons are too heavy to reach 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. However, atmospheric gases are mixed completely, and are not stratified or sorted by weight. Estimates of the required time for diffusional separation of gases in the atmosphere require times of the order of thousands of years. Of course, this is not possible in a dynamic atmosphere. The vertical mass transfer processes of convection and turbulence completely mix the atmosphere below the turbopause much faster. Therefore, even such heavy gases as inert freons are evenly distributed in the atmosphere, reaching, among other things, the stratosphere. Experimental measurements of their concentrations in the atmosphere confirm this; Measurements also show that it takes about five years for the gases released on the Earth's surface to reach the stratosphere, see the second graph on the right. If the gases in the atmosphere did not mix, then such heavy gases from its composition as carbon dioxide would form a layer several tens of meters thick on the Earth's surface, which would make the Earth's surface uninhabitable. Fortunately, this is not the case. Ikrypton 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. Of course, all of the above is only true for gases that are relatively stable, like freons or inert gases. Substances that enter into reactions and are also subjected to various physical influences, say, dissolve in water, have a dependence of concentration on height.
The main sources of halogens are natural, not anthropogenic
It is believed that natural sources of halogens, such as volcanoes and oceans, are more significant for the process of ozone depletion than those produced by man. Without questioning the contribution of natural sources to the overall balance of halogens, it should be noted that they generally do not reach the stratosphere due to the fact that they are water-soluble (mainly chloride ions and hydrogen chloride) and are washed out of the atmosphere, falling as rain on the ground. Also, natural compounds are less stable than freons, for example, methyl chloride has an atmospheric lifetime of only about a year, compared to tens and hundreds of years for freons. Therefore, their contribution to the destruction of stratospheric ozone is rather small. Even the rare eruption of the Pinatubo volcano in June 1991 caused a drop in ozone levels not due to the released halogens, but due to the formation of a large mass of sulfuric acid aerosols, the surface of which catalyzed the reactions of ozone destruction. Fortunately, after three years, almost the entire mass of volcanic aerosols was removed from the atmosphere. Thus, volcanic eruptions are relatively short-term factors affecting the ozone layer, unlike freons, which have lifetimes of tens and hundreds of years.
The ozone hole must be above the freon sources
Many do not understand why the ozone hole is formed in the Antarctic, when the main emissions of freons occur in the Northern Hemisphere. The fact is that freons are well mixed in the troposphere and stratosphere. In view of 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. Therefore, they easily reach the upper atmosphere. The Antarctic "ozone hole" does not exist permanently. It appears in late winter - early spring. The reasons why the ozone hole forms in Antarctica are related to the local climate. The low temperatures of the Antarctic winter lead to the formation of the polar vortex. The air inside this vortex moves mostly in closed paths around the South Pole. At this time, the polar region is not illuminated by the Sun, and ozone does not occur there. With the advent of summer, the amount of ozone increases and again reaches its previous norm. That is, fluctuations in ozone concentration over the Antarctic are seasonal. However, if we trace the dynamics of changes in the ozone concentration and the size of the ozone hole averaged over the course of a year over the past decades, then there is a strictly defined trend towards a decrease in the ozone concentration.
Ozone only depletes over Antarctica
The evolution of the ozone layer over Arosa, Switzerland
This is not true, the ozone level is also falling in the entire atmosphere. This is shown by the results of long-term measurements of the ozone concentration in different parts of the planet. You can look at the graph of ozone over Arosa in Switzerland on the right.
Ozone (O 3 ) is formed in the atmosphere from oxygen during electrical discharges during thunderstorms and under the influence of ultraviolet radiation from the Sun in the stratosphere. The ozone layer (ozone screen, ozonosphere) is located in the atmosphere at an altitude of 10-50 km with a maximum concentration of ozone at an altitude of 20-25 km (it is thinner above the poles, like the entire atmosphere, and thicker above the equator). If the entire amount of ozone is collected under normal conditions (pressure 760 mm Hg and temperature 20 ° C), then the thickness of this layer will be only 2.5 - 3 mm.
Significance of the ozone layer
The ozone screen delays the penetration to the earth's surface of the most severe UV radiation of the Sun, the deadly "B-band", which affects all living things. The reduction of the ozone layer leads to a sharp increase in oncological diseases (a decrease in the layer by 1% means an increase in ultraviolet radiation by 2% and leads to an increase in skin cancer by 5–6%), damage to the cornea of the eyes and blindness, the development of a mutation, a decrease in the productivity of some plant species , and with a strong reduction - to the destruction of all living things.
Excess UV radiation disrupts the body's immune defenses, contributing to the appearance of such diseases in humans as lupus (skin tuberculosis), erysipelas, smallpox, leishmaniasis, viral herpes, etc.
It has been established that a decrease in the ozone content in the atmosphere can contribute to an increase in the greenhouse effect more significantly than an increase in the concentration of carbon dioxide.
Excessive flux of UV radiation is detrimental to phyto- and zooplankton, larvae of many fish.
A bit of history
Ozone holes most often appear over the poles, where the thickness of the atmosphere is less, and they reach their greatest magnitudes over Antarctica (where it is colder). This phenomenon began to be noted back in the 70s of the twentieth century, but they reached a maximum in the mid-80s.
So, in October 1985, there were reports that the ozone concentration in the stratosphere over the English station Halley Bay (Antarctica) decreased by 40% of its minimum values, and over the Japanese station - by almost 2 times .. This phenomenon was named "ozone hole". Significant ozone holes over Antarctica arose, as a rule, in the spring of 1987, 1992, 1997, when a decrease in the total stratospheric ozone (TO) by 40-60% was recorded. In the spring of 1998, the ozone hole over Antarctica reached a record area - 26 million square meters. km (3 times the size of Australia). And at an altitude of 14-25 km, almost complete destruction of ozone occurred in the atmosphere.
Similar phenomena were noted in the Arctic (especially since the spring of 1986), but the size of the ozone hole here was almost 2 times smaller than over the Antarctic. In March 1995, the Arctic ozone layer was depleted by about 50%, with the formation of "mini-holes" over the northern regions of Canada and the Scandinavian Peninsula, the Scottish Isles (UK).
Ozone holes are noted not only over the poles. There are known cases when holes that spread to South America led to the blinding of livestock, mainly cattle. In the Kyrgyz Republic, an ozone hole was noted in May 1995 over high-mountainous regions. The size and duration (about 4-5 days) of its existence were insignificant, and it did not lead to any consequences.
Reasons for the formation of ozone holes
Numerous international expeditions to study ozone holes in Antarctica to the Arctic have established that, in addition to various natural factors, the presence of a significant amount of CFCs (freons) in the atmosphere is still the main one.
Freons (chlorofluorocarbons) - highly volatile, chemically inert substances near the earth's surface (synthesized in the 1930s), since the 1960s. began to be widely used as refrigerants (refrigerators, air conditioners, refrigerators), foaming agents for aerosols, etc. Freons, rising into the upper layers of the atmosphere, undergo photochemical decomposition, forming chlorine oxide, which intensively destroys ozone (each chlorine atom is capable of destroying 100,000 ozone molecules). The duration of stay of freons in the atmosphere is on average 50-200 years.
Protection measuresozone layer
In 1985, the Vienna Convention for the Protection of the Ozone Layer was adopted.
In 1987, in Montreal, representatives of 36 countries signed a Protocol under which they committed themselves to reduce the use and then eliminate the use in industry and in the home of ozone-depleting substances (ODS). After 10 years, the number of countries that have signed this Protocol has increased to 163.
In a number of countries, in order to protect the ozone layer, alternative ozone-safe substitutes for freons were obtained, in particular, firms in Germany, Italy, Switzerland, and Great Britain began to use the refrigerant - isobutane, which has zero ozone-depleting potential. In many countries, in the production of aerosols, they began to use environmentally friendly freon - a hydrocarbon propellant (80% of all aerosols produced in the world).
In the United States and Russia, research has already begun on active methods based on complex physicochemical processes that either reduce the rate of ozone destruction in the stratosphere or accelerate its formation. So, to tighten ozone holes over Antarctica, it is possible to use the method of injection (introduction) into the stratosphere of ethane (C 2 H b) or propane (C 3 H 8), which will bind atomic chlorine, which destroys ozone, into passive hydrogen chloride. There are also physical and chemical methods that accelerate the formation of ozone in the stratosphere, in particular methods of electromagnetic radiation, using electrical discharges (the ozonator principle) and laser radiation.
In addition, in order to prevent the release of CFCs from the many available cooling devices, methods for their disposal have been developed.
Ozone holes
It is known that the main part of natural ozone is concentrated in the stratosphere at an altitude of 15 to 50 km above the Earth's surface. The ozone layer begins at altitudes of about 8 km above the poles (or 17 km above the Equator) and extends upwards to altitudes of approximately 50 km. However, the density of ozone is very low, and if you compress it to the density that air has at the surface of the earth, then the thickness of the ozone layer will not exceed 3.5 mm. Ozone is formed when solar ultraviolet radiation bombards oxygen molecules.
Most of the ozone is in the five-kilometer layer at an altitude of 20 to 25 km, which is called the ozone layer.
protective role. Ozone absorbs part of the ultraviolet radiation of the Sun: moreover, its wide absorption band (wavelength 200-300 nm) includes radiation that is harmful to all life on Earth.
Reasons for the formation of the "ozone hole"
In summer and spring, ozone concentrations rise; over the polar regions it is always higher 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 was called the "ozone hole" (although, of course, there was no hole in the proper meaning of this word) and began to be carefully studied. Later, in the 1990s, 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.
At first it was assumed that ozone was affected by particles emitted in atomic explosions; tried to explain the change in ozone concentration by rocket flights and high-altitude aircraft. In the end, it was clearly established that the cause of the undesirable phenomenon is the reaction 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 the hydrogen atoms are replaced by fluorine and chlorine atoms.
It is assumed that due to the destructive effect of chlorine and similarly acting bromine, by the end of the 1990s. ozone concentration in the stratosphere decreased by 10%.
In 1985, British scientists released data showing that over the previous eight years, ozone holes had been found to increase each spring over the North and South Poles.
Scientists have proposed three theories to explain the causes of this phenomenon:
nitrogen oxides - compounds that form naturally in sunlight;
destruction of ozone by chlorine compounds.
First of all, it should be clear: 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. In this layer, the absorption of ultraviolet rays emitted by the Sun takes place - 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 was decreasing - sometimes more, sometimes less. Similar but less pronounced ozone holes also appeared over the 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 action 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 + O3 -> ClO + O2 and ClO + O -> Cl + O2
As a result of these reactions, ozone molecules (O3) are converted into oxygen molecules (O2), 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 by the action of others). 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 collapse, fresh air (containing new ozone) rushes into the area, and the hole disappears.
In 1987, the Montreal Protocol was adopted, according to which a list of the most dangerous chlorofluorocarbons was determined, and chlorofluorocarbon-producing countries pledged to reduce their release. In June 1990, in London, the Montreal Protocol was amended: by 1995, reduce the production of freons by half, and by 2000, stop it altogether.
It has been established that the ozone content is influenced by nitrogen-containing air pollutants, which appear both as a result of natural processes and as a result of anthropogenic pollution.
So, NO is formed in internal combustion engines. Accordingly, the launch of rockets and supersonic aircraft leads to the destruction of the ozone layer.
The source of NO in the stratosphere is also N2O gas, which is stable in the troposphere and decomposes in the stratosphere under the action of hard UV radiation.
