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 for a 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. Thanks 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.
In recent years, scientists have noted with increasing alarm the depletion of the ozone layer of the atmosphere, which is a protective screen against ultraviolet radiation. The danger lies in the fact that ultraviolet radiation is detrimental to living organisms.
Under the action of ultraviolet radiation, oxygen molecules break down into free atoms, which in turn can join other oxygen molecules to form ozone. Free oxygen atoms can also react with ozone molecules to form two oxygen molecules. Thus, an equilibrium is established and maintained between oxygen and ozone.
However, freon-type pollution catalyzes (accelerates) the process of ozone decomposition, breaking the balance between it and oxygen in the direction of reducing the ozone concentration.
Given the danger looming over the planet, the international community has taken the first step towards solving this problem. An international agreement was signed, according to which the production of freons in the world by 1999. Should be reduced by about 50%.
Ozone
Ozone (O3) is an aggressive gas with a strong oxidizing effect. Translated from Greek, ozon means "smelling", as it has a sharp, pungent odor. This smell can be felt after a thunderstorm.
Ozone is formed in the atmosphere when high-energy short-wave ultraviolet rays and electrical discharges act on oxygen. The high energy splits oxygen into individual atoms, which bind with molecular oxygen to form ozone.
Ozone molecules are very unstable and easily decompose, so this reaction is reversible.
The ecological role of ozone is twofold.
Formed near the Earth's surface as a component of photochemical smog, ozone is extremely harmful because it has strong oxidizing properties and irritates the mucous membranes of the eyes and respiratory tract. At the Earth's surface, ozone is formed during lightning discharges and as a result of photochemical reactions between nitrogen oxides and volatile hydrocarbons released from car exhaust gases. In addition to ozone, as a result of these reactions, a number of aggressive substances are formed. They are also strong oxidizers, have an irritant effect, some of them are carcinogenic. The combination of these substances is called photochemical smog.
Formed in the upper stratosphere, ozone forms the ozone layer, which protects the Earth's organisms from the action of short-wave ultraviolet rays. Up to 98% of the energy of short-wave ultraviolet rays of the Sun is spent on ozone synthesis reactions, due to which they do not reach the Earth's surface and do not have a detrimental effect on the body. For this, the ozone layer is called the "protective shield" of the Earth. Without it, life could not exist on the surface of the Earth.
The formation of the ozone layer became possible when the concentration of oxygen in the atmosphere reached 1% of the current level. The appearance of the ozone layer allowed life to reach land, whereas before life could only exist in the ocean.
The ozone layer (ozonosphere) covers the entire globe and is located at altitudes from 10 to 50 km with a maximum ozone concentration at an altitude of 20-25 km. The saturation of the atmosphere with ozone is constantly changing in any part of the planet, reaching a maximum in the spring in the subpolar region.
The ozone layer performs two important functions in the atmosphere:
- Protects organisms from the harmful effects of ultraviolet rays that cause sunburn, skin cancer, cataracts (clouding of the lens of the eye), weakening of the immune system;
- It forms the stratosphere - a layer of the atmosphere in which the temperature increases with height, which limits the processes of weather formation to the troposphere: the upper heated layers of the atmosphere prevent the rise of colder surface air. If it were not for the ozone layer, then the temperature of the atmosphere would gradually decrease with height and the temperature regime of the Earth would be completely different.
Ozone depletion
In the mid 1960s. scientists came to the conclusion that there are factors that destroy ozone in the atmosphere. Such factors are free radicals from water vapor and nitrogen oxides released into the stratosphere with the exhaust of supersonic aircraft and coming from the lower layers of the troposphere.
In 1973, American chemists F. Rowland and M. Molina found that ozone is destroyed by chlorofluorocarbons, known as freons. For this discovery F. Rowland and M. Molina in 1996. was awarded the Nobel Prize.
In 1984 a group of American scientists led by D. Farman published data from research conducted in Antarctica. They showed that during the spring of 1983 the ozone content over Antarctica dropped to 40%. According to D. Farman, "the sky over Antarctica was literally empty, and it was terrible" (Roun Sh., 1993).
The decrease in ozone concentration over Antarctica has been called the "ozone hole". At present, the dimensions of the “hole” are almost equal to the area of this mainland.
The sharp decrease in the concentration of ozone over Antarctica is explained by several reasons:
- The formation of ozone is possible only in the presence of ultraviolet rays, it does not occur during the polar night;
- Low temperatures contribute to the formation of ice stratospheric clouds over Antarctica, on the particles of which the reactions of ozone destruction are accelerated;
- The circulation of air masses over Antarctica has some features: in spring, ascending eddy currents form over it, sucking air into this area from the troposphere with a low ozone content and preventing the inflow of ozone-rich air from middle latitudes.
The main reason for the decrease in the ozone concentration over Antarctica is the formation of stratospheric ice clouds above it, on the particles of which the processes of ozone destruction by chlorine are activated.
After the discovery of the "ozone hole" over Antarctica, scientific research was carried out to study the effect of ozone concentration in the atmosphere on biological objects. It was found that with a decrease in the ozone concentration by 1%, the degree of penetration of ultraviolet rays into the atmosphere increases by 1.5 - 2%. This contributes to an increase in the incidence of skin cancer, cataracts, a decrease in the immunity of organisms, etc.
The scientists concluded that increased doses of ultraviolet radiation reduce seed quality, plant resistance to drought, diseases, and reduce the production of Antarctic phytoplankton and the survival of fish fry, which can have a catastrophic effect on global fisheries. With a decrease in the ozone content in the atmosphere by 25%, phytoplankton production could decrease by 35%.
Since then, measurements have confirmed the widespread depletion of the ozone layer on almost the entire planet. For example, in Russia over the past ten years, the concentration of the ozone layer has decreased by 4-6% in winter and by 3% in summer.
Currently, the depletion of the ozone layer is recognized by all as a serious threat to global environmental security. A decrease in ozone concentration weakens the ability of the atmosphere to protect all life on Earth from the brutal ultraviolet radiation (UV - radiation). Living organisms are very vulnerable to ultraviolet radiation, because the energy of even one photon from these rays is enough to destroy the chemical bonds in most organic molecules. It is no coincidence that in areas with a low ozone content, sunburns are numerous, an increase in skin cancer, etc. . In addition to skin diseases, it is possible to develop eye diseases (cataracts, etc.), suppression of the immune system, etc.
It has also been established that under the influence of strong ultraviolet radiation, plants gradually lose their ability to photosynthesis, and disruption of the vital activity of plankton leads to a break in the trophic chains of the biota of aquatic ecosystems, etc.
Science has not yet fully established what are the main processes that violate the ozone layer. Both natural and anthropogenic origin of "ozone holes" is assumed. The latter, according to most scientists, is more likely and is associated with an increased content of chlorofluorocarbons (freons). Freons are widely used in industrial production and in everyday life (cooling units, solvents, sprayers, aerosol packages, etc.). Rising into the atmosphere, freons decompose with the release of chlorine oxide, which has a detrimental effect on ozone molecules.
According to the international environmental organization Greenpeace, the main suppliers of chlorofluorocarbons (freons) are the USA - 30.85%, Japan - 12.42%, Great Britain - 8.62% and Russia - 8.0%. The United States has punched a "hole" in the ozone layer with an area of 7 million square kilometers, Japan - 3 million square kilometers, which is 7 times larger than the area of Japan itself. Recently, factories have been built in the USA and in a number of Western countries for the production of new types of refrigerants (hydrochlorofluorocarbons) with a low potential for ozone depletion.
After assessing the volume of production of chlorofluorocarbons and their release into the atmosphere, scientists came to the conclusion that this leads to the inevitable destruction of the ozone layer.
International meetings have been held and a number of agreements have been signed on the issues of reducing chlorofluorocarbon emissions into the atmosphere. In 1989 At the International Conference in Helsinki, 81 countries reached an agreement to stop the production of all types of chlorofluorocarbons by the year 2000.
According to the protocol of the Montreal Conference (1990), later revised in London (1991) and Copenhagen (1992), it was envisaged to reduce chlorofluorocarbon emissions by 50% by 1998. According to Art. 56 of the Law of the Russian Federation on Environmental Protection, in accordance with international agreements, all organizations and enterprises are required to reduce and subsequently completely stop the production and use of ozone-depleting substances. The law provides for the following set of measures to protect the ozone layer:
- Organization of observations of changes in the ozone layer under the influence of economic activities and other processes;
- Compliance with the standards of maximum permissible emissions of substances that adversely affect the state of the ozone layer;
- Regulation of the production and use of chemicals that deplete the ozone layer.
In 1993, an Interdepartmental Commission was established in our country, whose task is to coordinate the activities of various organizations to fulfill international obligations to protect the ozone layer and stop the production of ozone-depleting substances by the year 2000. There is also an intensive development and implementation of measures to drastically reduce emissions of sulfur compounds, nitrogen oxides and other most dangerous air pollutants.
Even if the protocol is implemented by all countries, the problem of protecting people from UV radiation must continue to be addressed, since many of the chlorofluorocarbons can persist in the atmosphere for hundreds of years.
Currently, the ozone layer is being depleted at a rate of 0.5 - 0.7% per year.
Measures to reduce ozone depletion are:
- A global ban on the use of chlorofluorocarbons in areas where they can be replaced by other substances;
- Utilization of chlorofluorocarbons from used refrigerators and air conditioners;
- Complete ban on production of chlorofluorocarbons, gallons, chloroform and carbon tetrachloride.
However, the problem of ozone depletion is not limited to the damaging effects of CFCs and halons. Like all other biospheric processes, the concentration of ozone in the atmosphere depends on many factors, the relationship between all the mechanisms of its formation and destruction. In particular, the concentration of ozone is affected by:
- The intensity of ultraviolet radiation - depends on the activity of the Sun, which has 11 - year and longer cycles;
- The content of oxygen in the atmosphere depends on the production of O2 by plants. It is reduced by human deforestation, plowing of soils, in which the processes of decomposition of organic matter are accelerated, and the burning of fossil fuels;
- Volcanic eruptions - bring into the atmosphere huge amounts of dust that traps sunlight, oxides of nitrogen and sulfur;
- Atmospheric pollution by industrial emissions (nitrogen oxides, dust, sulfuric acid aerosols) - acid droplets are centers of water vapor condensation, and therefore the cause of cloud formation.
A number of scientists continue to insist on the natural origin of the "ozone hole". They see the reasons for its occurrence in the natural variability of the ozonosphere, the cyclic activity of the Sun, while others associate these processes with rifting and degassing of the Earth.
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 at the South Pole discovered that during the Antarctic spring, the level of ozone in the atmosphere was significantly below normal. Every year at the same time, the amount of ozone decreased - sometimes more, sometimes less. Similar but less pronounced ozone holes 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 + 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 eddies collapse, fresh air (containing new ozone) rushes into the area, and the hole disappears.
In 1987, the International Conference on the threat to the ozone layer was held in Montreal, and industrialized countries agreed to reduce, and eventually stop, the production of 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.
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[ | ]
- Scientific Assessment of Ozone Depletion: 2006(English) . Retrieved December 13, 2007. Archived from the original on February 16, 2012.
- "Knowledge is power" Science news: 27.12.99 (Russian). Retrieved July 3, 2007. Archived from the original on February 16, 2012.
About forty years ago, it was first discovered that the ozone layer in the earth's atmosphere began to deplete. The first to notice this were British scientists who worked at a research base in Antarctica. They found that over the Halley Bay station, the thickness of the ozone had almost halved! At that time, the possible causes of this phenomenon had not yet been studied, so all that remained for scientists to do was to observe the development of the situation. And the results did not please them at all - the ozone holes not only did not close, but even spread far beyond the South Pole. So there was information about a new global catastrophe.
What exactly are ozone holes?
Ozone is a gas that is produced from oxygen by ultraviolet radiation from the sun. It, in turn, prevents the passage of this radiation, the effect of which is detrimental to all living organisms. A layer of this gas is located at an altitude of about twenty kilometers above the surface and protects the planet from the negative effects of solar energy. Ozone holes are places where the thickness of the gas decreases for some reason. At this stage, it is still enough to delay the ultraviolet, but if humanity does nothing to change the situation, after some time the depletion of the ozone layer will lead to the fact that harmful radiation can freely penetrate the atmosphere, and then the existence of life on Earth will simply become impossible.
Why do ozone holes appear?
Space exploration
And yet, despite the wide variety of possible versions, the most probable of them remains anthropogenic. Indeed, in the middle of the last century, there were numerous launches of space rockets, each of which, taking off, left a "hole" in the atmosphere, breaking through the ozone layer. In just thirty years of space exploration, 30% of the protective barrier of the Earth, which was formed over four billion years, was destroyed!
Freon
Freon is a destructive substance for ozone, which is widely used both in everyday life and in industry. It was contained in almost all gas cartridges of the last century: in hair sprays, perfumes, deodorants, fire extinguishers. It was even in refrigerators and air conditioners! It is not surprising that every day more and more new ozone holes appeared, and the protective layer became thinner and thinner.
Solutions
To date, the problem remains acute and relevant. Numerous agreements have been adopted under which substances harmful to the ozone layer are prohibited from being used in production and industry. But this is not enough, because the question is not only to stop the destruction of ozone, but also to restore it. And this problem has not been solved yet.
