Where are the ozone holes found? Reasons for the formation of the “ozone hole”

The ozone layer was first studied by scientists at the British Antarctic Stations in 1957. Ozone has been considered as a possible indicator of long-term changes in the atmosphere. In 1985, the annual depletion of the ozone layer and the formation of ozone holes were announced in the journal Nature.

What is the ozone hole and why does it occur?

Ozone is produced in large quantities in the stratosphere above the tropics, where UV radiation is strongest. It then circulates to earth's atmosphere towards the poles. The amount of ozone varies depending on the location, season and daily climatic conditions. The decrease in the concentration of ozone in the atmosphere, which is observed at the poles of the Earth, is called the ozone hole.

The thinner it gets ozone layer, topics larger size ozone holes. There are 3 main reasons for their formation:

Natural redistribution of ozone concentration in the atmosphere. The maximum amount of ozone is found at the equator, decreasing towards the poles, forming areas with a reduced concentration of this element.
Technogenic factor . CFCs contained in aerosol cans and refrigerants are emitted into the atmosphere by human activities. The resulting chemical reactions in the atmosphere destroy the ozone molecules. This thins the ozone layer and reduces its ability to absorb ultraviolet light.
Global climate warming. The temperature at the earth's surface is constantly rising, while the upper layers of the stratosphere are cooling. This is accompanied by the formation of mother-of-pearl clouds, in which ozone destruction reactions occur.

Consequences of expanding ozone holes

The existence of life on Earth is possible only due to the presence of the ozone layer. It effectively protects the planet from the penetration of harmful UV radiation, which is highly reactive.

When exposed to ultraviolet radiation, DNA is damaged. This can lead to unwanted mutations in living organisms.
UV rays penetrate even through water and cause the death of plant cells and microorganisms that serve as food for more developed animals. As a result, their numbers are decreasing.
In humans, excess UV radiation can cause skin cancer. (A 1% decrease in ozone increases the incidence of skin cancer by 5%).
Direct contact of ultraviolet light with the retina of the eye provokes the formation of cataracts. This affects the quality of vision and can cause blindness.

In 1987, an international agreement was drawn up - the Montreal Protocol - to regulate the emission of harmful gases into the atmosphere that destroy ozone molecules. Following the protocol helps to gradually reduce the depletion of the ozone layer in the atmosphere and prevent the expansion of ozone holes.

Earth is undoubtedly the most unique planet in our solar system. It is the only planet adapted for life. But we do not always appreciate it and believe that we are not able to change and disrupt what has been created over billions of years. In the entire history of existence, our planet has never received such loads that man gave it.

There is an ozone layer on our planet, which is so necessary for our life. It protects us from the effects ultraviolet rays emanating from the sun. Without him, life on this planet would not be possible.

Ozone is a blue gas with a characteristic odor. Each of us knows this pungent smell, which is especially audible after rain. No wonder ozone in Greek means "smelling". It is formed at a height of up to 50 km from the surface of the earth. But most of it is located at 22 - 24 km.

Causes of ozone holes

In the early 1970s, scientists began to notice a decrease in the ozone layer. The reason for this is the entry into the upper layers of the stratosphere of ozone-depleting substances used in industry, the launch of rockets, and many other factors. These are mainly chlorine and bromine molecules. Chlorofluorocarbons and other substances released by man reach the stratosphere, where, under the influence of sunlight, they decompose into chlorine and burn ozone molecules. It has been proven that one molecule of chlorine can burn 100,000 molecules of ozone. And it keeps in the atmosphere from 75 to 111 years!

As a result of falling ozone, ozone holes occur in the atmosphere. The first was discovered in the early 80s in the Arctic. Its diameter was not very large, and the fall in ozone was 9 percent.

The ozone hole in the Arctic

An ozone hole is a large drop in the percentage of ozone in certain places in the atmosphere. The very word "hole" makes us understand this without further explanation.

In the spring of 1985, in Antarctica, over the station Halle Bay, the ozone content dropped by 40%. The hole turned out to be huge and has already moved beyond the boundaries of Antarctica. In height, its layer reaches up to 24 km. In 2008, it was estimated that its size is already more than 26 million km2. It stunned the whole world. Is it clear? that our atmosphere is in greater danger than we thought. Since 1971, the ozone layer has fallen by 7% worldwide. As a result, ultraviolet radiation from the Sun, which is biologically dangerous, began to fall on our planet.

Consequences of ozone holes

Doctors believe that as a result of the decrease in ozone, the percentage of skin cancer and blindness due to cataracts has increased. Also, the human immunity decreases, which leads to various types other diseases. The inhabitants of the upper layers of the oceans suffer the most. These are shrimps, crabs, algae, plankton, etc.

An international agreement has now been signed by the United Nations to reduce the use of ozone-depleting substances. But even if you stop using them. it will take more than 100 years to close the holes.

Can the ozone holes be repaired?

To date, scientists have proposed one way to restore ozone using aircraft. To do this, it is necessary to release oxygen or artificially created ozone at an altitude of 12-30 kilometers above the Earth and disperse it with a special atomizer. So little by little the ozone holes can be filled. The disadvantage of this method is that it requires significant economic waste. In addition, it is impossible to release into the atmosphere at a time a large number of ozone. Also, the process of transporting ozone is complex and unsafe.

Myths about ozone holes

Since the problem of ozone holes remains open, several misconceptions have formed around it. Thus, the depletion of the ozone layer was sought to be turned into a fiction that is beneficial to industry, allegedly due to enrichment. On the contrary, all chlorofluorocarbon substances have been replaced with cheaper and safer components of natural origin.

Another false claim that supposedly ozone depleting freons are too heavy to reach the ozone layer. But in the atmosphere, all elements are mixed, and polluting components are able to reach the level of the stratosphere, in which the ozone layer is located.

You should not trust the statement that ozone is destroyed by halogens of natural origin, and not anthropogenic. This is not so, it is human activity that contributes to the release of various harmful substances that destroy the ozone layer. The consequences of the explosion of volcanoes and other natural disasters practically do not affect the state of ozone.

And the last myth is that ozone is destroyed only over Antarctica. In fact, ozone holes form everywhere in the atmosphere, causing the amount of ozone to decrease in general.

Forecasts for the future

Since the ozone holes have become, they have been closely monitored. AT recent times the situation was quite ambiguous. On the one hand, in many countries, small ozone holes appear and disappear, especially in industrialized areas, and on the other hand, there is a positive trend in the reduction of some large ozone holes.

In the course of observations, researchers recorded that the largest ozone hole hung over Antarctica, and it reached its maximum size in 2000. Since then, judging by the pictures taken by satellites, the hole has been gradually closing in. These statements are presented in the scientific journal Science. Environmentalists have calculated that its area has decreased by 4 million square meters. kilometers.

Studies show that gradually from year to year the amount of ozone in the stratosphere increases. This was facilitated by the signing of the Montreal Protocol in 1987. In accordance with this document, all countries are trying to reduce emissions into the atmosphere, reducing the amount of transport. China has been particularly successful in this regard. It regulates the emergence of new cars and there is the concept of a quota, that is, a certain number of car license plates can be registered per year. In addition, some progress has been made in improving the atmosphere, because gradually people are switching to alternative sources energy, there is a search for effective resources that would help save.

Since 1987, the problem of ozone holes has been raised more than once. This problem is devoted to many conferences and meetings of scientists. Issues are also discussed at meetings of state representatives. So in 2015, a conference was held in Paris, the purpose of which was to work out actions against climate change. This will also help reduce emissions into the atmosphere, which means that the ozone holes will gradually tighten. For example, scientists predict that by the end of the 21st century, the ozone hole over Antarctica will completely disappear.

Where are the ozone holes (VIDEO)

The occurrence of ozone holes in the polar regions is due to the influence of a number of factors. The concentration of ozone is reduced 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 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, 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 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, which are formed during nuclear explosions, are also involved in the destruction of the ozone layer. 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. Total Nitrogen oxide, which is 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. It's energy 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. 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. 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.

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, burning fuel.

OZONE HOLE - a gap in the ozonosphere (with a diameter of more than 1000 km), which arose over Antarctica and moved to the populated areas of Australia. Many do not understand why the ozone hole is formed in the Antarctic, when the main emissions of freons occur in the Northern Hemisphere. 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 led by George Farman.

The ozone hole is a local drop in the concentration of ozone in the ozone layer of the Earth. Another hole was forming over the Northern Hemisphere in the Arctic, but smaller. At this stage of human development, world scientists have proven that there are a huge number of ozone holes on Earth. But the most dangerous and largest is located over Antarctica.

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 with the help of spectroscopic measurements ultraviolet radiation to prove the existence of ozone in the layers of the atmosphere remote 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 matter almost completely consumed 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. 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 on south pole, found that during the Antarctic spring, the level of ozone in the atmosphere there is significantly below normal. Every year at the same time, the amount of ozone decreased - 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 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.