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 man and nature in tandem, 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.

The occurrence of ozone holes in the polar regions is due to the influence of a number of factors. The concentration of ozone decreases as a result of exposure to substances of natural and anthropogenic origin, as well as due to a lack of solar radiation during the polar winter. The main anthropogenic factor causing the occurrence of ozone holes in the polar regions is due to the influence of a number of factors. The concentration of ozone decreases as a result of exposure to substances of natural and anthropogenic origin, as well as due to a lack of solar radiation during the polar winter. The main anthropogenic factor causing a decrease in ozone concentration is the release of chlorine- and bromine-containing freons. In addition, extremely low temperatures in the polar regions cause the formation of so-called polar stratospheric clouds, which, in combination with polar vortices, act as catalysts in the ozone decay reaction, that is, they simply kill ozone.

Sources of destruction

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 a “hole” was blamed on the chemical industry, which produces substances containing freons that contribute to the destruction of ozone (from deodorants to refrigeration units). There is no consensus on the question of how much a person is guilty of the formation of “ozone holes”. On the one hand - yes, of course, 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 “environmental protection” at the state level and forcibly introducing a new technological revolution, which is more economically weak 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, 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. 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 N 2 O 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 N 2 O 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. A temperature equal to 6000 0 C is set within a few seconds after a nuclear explosion. This is the energy of the fireball. In a strongly heated atmosphere, such transformations of chemical substances take place, which either do not occur under normal conditions, or proceed very slowly. As for ozone, its disappearance, the most dangerous for it are the oxides of nitrogen formed during these transformations. So, 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. Their further fate is 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.

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, it is formed in the following reactions:

N 2 + O + M \u003d N 2 O + M,

2NH 3 + 2O 2 \u003d N 2 O \u003d 3H 2.

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 indicates that it is a source of ozone destruction.

Conclusion: Sources of destruction are: freons, high-altitude aircraft, mineral fertilizers, nuclear explosions, fuel combustion.

There are many hypotheses trying to explain the decline in ozone concentration. The reasons for its fluctuations in the Earth's atmosphere are related to:

• · with dynamic processes occurring in the Earth's atmosphere (internal gravitational waves, Azores anticyclone, etc.);
• With the influence of the Sun (fluctuations in its activity);
• · with volcanism as a consequence of geological processes (outflow of freons from volcanoes involved in the destruction of the ozone layer, variations in the Earth's magnetic field, etc.);
• · with natural processes occurring in the upper shells of the Earth, including the activity of nitrogen-producing microorganisms, sea currents (the El Niño phenomenon), forest fires, etc.;
• · with the anthropogenic factor associated with human economic activity, when significant volumes of ozone-depleting compounds are produced into the atmosphere.

In recent decades, the impact of anthropogenic factors has increased dramatically, which led to the emergence of environmental problems that were unexpectedly turned into global ones by people themselves: the greenhouse effect, acid rain, deforestation, desertification of territories, pollution of the environment with harmful substances, reduction of the biological diversity of the planet.

Some scientists believe that it was human economic activity that largely increased the share of the halogen pathway of stratospheric ozone decay, which provoked the emergence of ozone holes.

The Montreal Protocol of 1987 banned the production of refrigerants, which in the past half century allowed food to be preserved and thereby not only made life more comfortable for people, but also saved the lives of many millions of people suffering from food shortages. As cheap refrigerants were banned, underdeveloped countries were unable to purchase expensive refrigerators. Therefore, they cannot store their agricultural products. Expensive imported equipment, developed in the countries of the initiators of the "fight against ozone holes", brings them considerable income. The prohibition of refrigerants contributed to the increase in mortality in the poorest countries.

Today we can say with confidence that there is no strictly scientifically proven evidence of the destructive effect of artificially created chlorofluorocarbon molecules on the planet's ozone layer. But in the scientific community, the point of view prevails, according to which, in the second half of the 20th century, the reason for the decrease in the thickness of the ozone layer is the anthropogenic factor, which, in the form of the release of chlorine- and bromine-containing freons, led to a significant thinning of the ozone layer.

Freons are fluorine-containing derivatives of saturated hydrocarbons (mainly methane and ethane) used as refrigerants in refrigerators. In addition to fluorine atoms, freon molecules usually contain chlorine atoms, less often bromine atoms. More than 40 different freons are known. Most of them are produced by the industry.

Freon 22 (Freon 22) - refers to substances of the 4th hazard class. Under the action of temperatures above 400°C, it can decompose with the formation of highly toxic products: tetrafluoroethylene (hazard class 4), hydrogen chloride (hazard class 2), hydrogen fluoride (hazard class 1).

Thus, the obtained data strengthened the conclusion of many (but not all!) researchers that the observed loss of ozone in middle and high latitudes is mainly due to anthropogenic chlorine- and bromine-containing compounds.

But according to other ideas, the formation of "ozone holes" is largely a natural, periodic process, not exclusively associated with the harmful effects of human civilization. Not many people share this point of view today, not only because of their lack of arguments, but because it turned out to be more profitable to follow in the wake of “global utopias”. Many scientists, in the absence of funds for scientific research, have become and are becoming victims of grants to substantiate the ideas of "global environmental chauvinism" and the guilt of progress in this.

As G. Kruchenitsky, A. Khrgian, Russia's leading expert on ozone, points out, he was practically the first to draw attention to the fact that the formation and disappearance of ozone holes in the northern hemisphere correlates with atmospheric-dynamic rather than chemical processes. The ozone content can change by several tens of percent within two to three days. That is, the point is not in ozone-depleting substances, but in the dynamics of the atmosphere itself.

E. Borisenkov, a prominent specialist in the field of atmospheric studies, based on the processing of data from nine Western European stations over twenty-three years, established a correlation between 11-year cycles of solar activity and ozone changes in the Earth's atmosphere.

The causes of ozone holes are mostly associated with anthropogenic sources of compounds penetrating into the stratospheric layer of the Earth's atmosphere. However, there is one catch. It consists in the fact that the main sources of ozone-depleting compounds are not located in the polar (southern and northern) latitudes, but are concentrated closer to the equator and are almost entirely located in the northern hemisphere. While the most frequent phenomena of the occurrence of thinning of the ozone layer (the actual appearance of ozone holes) are observed in Antarctica (southern hemisphere) and less often in the Arctic zone.

That is, the sources of ozone-depleting compounds must be rapidly and well mixed in the Earth's atmosphere. At the same time, they quickly leave the lower layers of the atmosphere, where their reactions with the participation of ozone should also be observed. In fairness, it should be noted that there is much less ozone in the troposphere than in the stratosphere. In addition, the "lifetime" of these compounds can reach several years. Therefore, they can reach the stratosphere under conditions of dominant vertical movements of air masses and heat. But here comes the difficulty. Since the main movements associated with heat and mass transfer (heat + transferred air mass) are carried out precisely in the troposphere. And since the air temperature already at an altitude of 11-10 km is constant and is about - 50 ° C, this heat and mass transfer from the tropospheric layer to the stratospheric one should be slowed down. And the participation of anthropogenic sources that destroy the ozone layer may not be as significant as it is believed so far.

The next fact that can reduce the role of the anthropogenic factor in the destruction of the Earth's ozone layer is the appearance of ozone holes, mostly in spring or winter. But this, firstly, contradicts the assumption about the possibility of rapid mixing of ozone-depleting compounds in the Earth's atmosphere and their penetration into the stratospheric layer of high ozone concentration. Secondly, the anthropogenic source of ozone-depleting compounds is a permanent one. Consequently, it is difficult to explain the reason for the appearance of ozone holes in spring and winter, and even in polar latitudes, by an anthropogenic cause. On the other hand, the presence of polar winters and the natural decrease in solar radiation in winter satisfactorily explain the natural cause of the occurrence of ozone holes over Antarctica and the Arctic. For example, ozone concentrations in the Earth's atmosphere in summer vary from 0 to 0.07%, and in winter from 0 to 0.02%.

In Antarctica and the Arctic, the mechanism of ozone depletion is fundamentally different from higher latitudes. Here, the conversion of inactive forms of halogen-containing substances into oxides mainly occurs. The reaction takes place on the surface of particles of polar stratospheric clouds. As a result, almost all ozone is destroyed in reactions with halogens. At the same time, chlorine is responsible for 40-50% and bromine is about 20-40%.

With the advent of the polar summer, the amount of ozone increases and again reaches its previous norm. That is, fluctuations in ozone concentration over the Antarctic are seasonal. Everyone recognizes this. But if, nevertheless, earlier supporters of anthropogenic sources of ozone-depleting compounds were inclined to assert that during the year there was a steady decrease in ozone concentration, then later this dynamics turned out to be the opposite. The ozone holes began to shrink. Although, in their opinion, the restoration of the ozone layer should take several decades. Since it was believed that a huge volume of freons from anthropogenic sources had accumulated in the atmosphere, which had a lifetime of tens, and even hundreds of years. Therefore, the tightening of the ozone hole should not be expected before 2048. As you can see, this prediction did not come true. On the other hand, efforts to reduce freon production volumes were made cardinal.

organism ultraviolet ozone marine

It is no secret that our planet Earth is unique in the solar system as it is the only planet where life exists. And including the origin of life on Earth was possible thanks to a special protective ball of ozone that covers our planet at an altitude of 20-50 km. What is ozone and why is it needed? The word "ozone" itself is translated from Greek as "smelling", because it is its smell that we can feel after. Ozone is a blue gas, consisting of triatomic molecules, in fact, such an even more concentrated oxygen. The value of ozone is enormous, since it is he who protects the Earth from the harmful effects of ultraviolet rays coming from the Sun. Unfortunately, we humans do not appreciate what was created by nature (or God) over billions of years, and one of the results of human destructive activity was the appearance of ozone holes, which we will talk about in today's article.

What are ozone holes?

To begin with, let's define the very concept of the "ozone hole", what it is. The fact is that many people mistakenly imagine the ozone hole as a kind of gap in the atmosphere of our planet, a place in which the ozone ball is completely absent. In fact, this is not entirely true, it is not that it is completely absent, just the concentration of ozone at the site of the ozone hole is several times lower than it should be. As a result, it is easier for ultraviolet rays to reach the surface of the planet, and to have their destructive effect precisely in the places of ozone holes.

Where are the ozone holes located?

Well, in this case, the question of the location of the ozone holes will be natural. The first ozone hole in history was discovered in 1985 over Antarctica, according to scientists, the diameter of this ozone hole was 1000 km. Moreover, this ozone hole has a very strange behavior: it appears every time in August and disappears by the beginning of winter to reappear in August.

A little later, another ozone hole, though smaller, was discovered already above the Arctic. In our time, many small ozone holes have been found in different places, but the ozone hole over Antarctica occupies the palm in size.

Photo of the ozone hole over Antarctica.

How are ozone holes formed?

The fact is that at the poles, due to the low temperature there, stratospheric clouds are formed containing ice crystals. When these clouds come into contact with molecular chlorine entering the atmosphere, a whole series of ozone molecules occurs, the result of which is the destruction of ozone molecules, there is a reduction in its amount in the atmosphere. And as a result, an ozone hole is formed.

Causes of ozone holes

What are the causes of ozone holes? There are several reasons for this phenomenon, and the most important of them is environmental pollution. Many factories, factories, flue gas thermal power plants emit into the atmosphere, including the ill-fated chlorine, and it, already entering into chemical reactions, makes a boom in the atmosphere.

Also, the appearance of ozone holes to a large extent contributed to nuclear tests conducted in the last century. During nuclear explosions, nitrogen oxides enter the atmosphere, which, entering into chemical reactions with ozone, also destroy it.

Airplanes flying in the clouds also contribute to the formation of ozone holes, since each of their flights is accompanied by the release of the same nitrogen oxide into the atmosphere, which is detrimental to our protective ozone balloon.

Consequences of ozone holes

The consequences of the expansion of the ozone holes, of course, are not the most rosy - due to increased ultraviolet radiation, the number of people with skin cancer may increase. In addition, the general immunity of a person falls, which leads to many other diseases. However, not only people can suffer from enhanced ultraviolet radiation passing through the ozone hole, but also, for example, inhabitants of the upper layers of the ocean: shrimps, crabs, algae. Why are ozone holes dangerous for them? All the same problems with immunity.

How to deal with ozone holes

The solution to the problem of ozone holes, scientists have proposed the following:

• Start regulating the release of ozone-destroying chemical elements into the atmosphere.
• Start to restore the amount of ozone by piecework in place of ozone holes. To do this in such a way, with the help of aircraft at an altitude of 12-30 km, spray piece ozone in the atmosphere. The disadvantage of this method is the need for significant economic costs, and, alas, it is impossible to spray a significant amount of ozone into the atmosphere at a time with modern technologies.

Ozone holes, video

And in conclusion, an interesting documentary about ozone holes.

These and other recent scientific findings reinforced the conclusion of previous assessments that the body 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.

Original text (English)

These and other recent scientific findings strengthen the conclusion of the previous assessment that the weight of scientific evidence suggests that the observed middle- and high-latitude ozone losses are largely due to anthropogenic chlorine and bromine 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.

To determine the boundaries of the ozone hole, a minimum level of ozone in the atmosphere of 220 Dobson units was chosen.

The area of ​​the ozone hole over the Antarctic averaged 22.8 million square kilometers in 2018 (in 2010-2017, the average annual values ​​ranged from 17.4 to 25.6 million square kilometers, in 2000-2009 - from 12.0 to 26 .6 million square kilometers, in 1990-1999 - from 18.8 to 25.9 million square kilometers).

Story [ | ]

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: (English), (English), (English), who published a corresponding article in the journal Nature. Every August it appeared, and in December - January it ceased to exist. Numerous mini-ozone holes exist over the Northern Hemisphere in the Arctic in autumn and winter. The area of ​​such a hole does not exceed 2 million km², its lifetime is up to 7 days.

Mechanism of Education[ | ]

As a result of the absence of solar radiation, ozone is not formed during the polar nights. No ultraviolet - no ozone. Having a large mass, ozone molecules descend to the Earth's surface and are destroyed, as they are unstable at normal pressure.

Rowland and Molina suggested that chlorine atoms could cause the destruction of large amounts of ozone in the stratosphere. Their findings were based on similar work by Paul Joseph Crutzen and Harold Johnstone, who showed that nitric oxide (II) (NO) can accelerate ozone depletion.

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, which 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 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 that contribute 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 fluorobromofreons, which emit chlorine and bromine atoms). Unlike, for example, hydrofluorofreons, which decompose to fluorine atoms, which, in turn, quickly react with water, forming stable hydrogen fluoride. Thus, fluorine does not participate in ozone decay reactions. Iodine also does not destroy stratospheric ozone, since iodine-containing organic matter is almost completely consumed even in the troposphere. The main reactions that contribute to the destruction of ozone are given in the article about the ozone layer.

Effects [ | ]

The weakening of the ozone layer increases the flow of ultraviolet solar radiation penetrating into ocean waters, which leads to an increase in mortality among marine animals and plants.

Restoration of the ozone layer[ | ]

Although mankind has taken measures to limit 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. According to Professor Susan Solomon, between 2000 and 2015, the ozone hole over Antarctica shrank by about the size of India. According to NASA, in 2000 the average annual area of ​​the ozone hole over Antarctica was 24.8 million square kilometers, in 2015 - 25.6 million square kilometers.

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 conspiracy theorists. Some of them are listed below.

The ozone hole over Antarctica has been around for a long time[ | ]

Systematic scientific observations of the ozone layer of Antarctica have been carried out since the 20s of the XX century, but only in the second half of the 70s was the formation of a “stable” Antarctic ozone hole discovered, and its rapid development (increase in size and decrease in the average concentration of ozone within the boundaries of the hole ) in the 1980s and 1990s caused panic fears that the point of no return in the degree of destructive anthropogenic impact on the ozone layer had already been passed.

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. At the same time, it should be noted that 80% of chlorine is of anthropogenic origin (for more details about the contribution of various cycles, see the article on the ozone layer). That is, human intervention greatly increases the contribution of the chlorine cycle. And if there was a tendency to increase the production of freons before the entry into force of the Montreal Protocol (10% per year), from 30 to 50% of the total ozone loss in 2050 would be due to exposure to freons. 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 position[ | ]

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 a July 16, 1975 article in Chemical Week that the ozone depletion theory was science fiction, nonsense that made no sense. In addition to DuPont, a number of companies around the world have produced and continue to produce various types of freons royalty-free.

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 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 processes of vertical mass transfer, convection and turbulence completely mix the atmosphere below the turbopause much faster. Therefore, even such heavy gases as inert or freons are evenly distributed in the atmosphere, including reaching the stratosphere. Experimental measurements of their concentrations in the atmosphere confirm this; Measurements also show that it takes about five years for 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 argon and carbon dioxide would form a layer several tens of meters thick on the Earth's surface, which would make the Earth's surface uninhabitable. 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. 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[ | ]

Sources of chlorine in the stratosphere

There is an opinion that natural sources of halogens, such as volcanoes or 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 Mount Pinatubo 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[ | ]

Dynamics of changes in the size of the ozone hole and ozone concentration in Antarctica by years

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. 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. Being highly volatile molecular compounds, they reach the upper atmosphere relatively easily.

The Antarctic "ozone hole" itself does not exist year-round. It appears in late winter - early spring (August-September) and manifests itself in a noticeable decrease in the average ozone concentration within a vast geographical area. The reasons why the ozone hole forms in Antarctica are related to the peculiarities of the local climate. The low temperatures of the Antarctic winter lead to the formation of the polar vortex. The air inside this vortex moves mainly along closed paths around the South Pole and weakly mixes with air from other latitudes. At this time, the polar region is not illuminated by the Sun, and in the absence of ultraviolet radiation, ozone is not formed, but, accumulated before, is destroyed (both as a result of interactions with other substances and particles, and spontaneously, since ozone molecules are unstable). With the advent of the polar day, the amount of ozone gradually increases and again reaches the normal level. That is, fluctuations in ozone concentration over the Antarctic are seasonal.

But if we trace the dynamics of changes in the ozone concentration and the size of the ozone hole averaged over each year over the past decades, then there is a pronounced trend towards a decrease in the average ozone concentration within a huge geographical area.

Sources and notes[ | ]

1. Scientific Assessment of Ozone Depletion: 2006(English) . Retrieved December 13, 2007. Archived from the original on February 16, 2012.
2. "Knowledge is power" Science news: 27.12.99 (Russian). Retrieved July 3, 2007. Archived from the original on February 16, 2012.