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

The ozone hole- local drop in ozone concentration in the ozone layer of the Earth.

According to the theory generally accepted in the scientific community, in the second half of the 20th century, the ever-increasing impact of the anthropogenic factor in the form of the release of chlorine- and bromine-containing freons led to a significant thinning of the ozone layer. This and other recent scientific evidence reinforced the conclusion of previous assessments that the weight in favor of scientific evidence suggests that the observed loss of ozone at mid and high latitudes is mainly due to anthropogenic chlorine and bromine compounds.

First of all, the massive occurrence of ozone holes hits people themselves. There is such a huge number of cancer patients on Earth today. It is not only harmful genetically modified foods that are to blame for this, since they just do not cause skin cancers so actively. BUT main reason cancerous growths on human skin is precisely the lack of good protection from solar ultraviolet radiation, the protection that ozone is supposed to provide. It was the ozone layer that for millennia and even millions of years retained harmful ultraviolet radiation, entering into a chemical reaction with it. This made it possible for life to spread throughout the planet. Now, many species of animals are dying out, and people have begun to live much less, and this is largely due to the lack of normal protection from sunlight, as a result of which they have become very harmful to humans - especially in summer. Ultraviolet penetrates into the water and causes the destruction of the living organisms that make up the plankton living in it, resulting in a lack of food for fish and mammals that are endangered. - Global warming, which manifests itself in a significant change in climatic conditions in various areas Earth, this phenomenon is also called the greenhouse effect, as it leads to the melting of glaciers and a general breakdown of the climate, for example, the transition of winter to hot summers without transitional seasons. Plants that are most sensitive to the harmful effects of ultraviolet radiation get impaired chlorophyll formation, which can lead to the extinction of some plant species.

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The heart of the problem Ozone is formed from oxygen, which is affected by ultra-violet 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.

Locations of ozone holes 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 reasons for the appearance 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 prerequisites are: the functioning 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. Thus, the ozone hole is a product not only of natural phenomena, but also of human impact on the environment. 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 has been noted by other people. ancient world who considered the sun-God to be the main idol. But the luminary can also cause the death of life on the planet. Through the ozone holes formed under the influence of the tandem of man and nature, solar radiation can fall on the earth and incinerate everything that was once grown. The detrimental effects on humans are obvious. Scientists have found that if the protective gas or its layer becomes thinner by one percent, then seven thousand more cancer patients will appear on earth. First of all, the skin of people will suffer, and then other organs. The consequences of the formation of ozone holes affect not only humanity. Vegetation suffers, as well as wildlife and inhabitants of the deep sea. Their mass extinction is a direct consequence of the processes taking place on the sun and in the atmosphere.

Ways to solve the problem The reasons for the appearance of ozone holes in the atmosphere are diverse, 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 chemical substances. 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: about installing 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. Consequences of negligent and inattentive attitude to environment are already making themselves known. In order not to aggravate the situation even more, it is necessary to deal with the problem at the global level.

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Presentation by a student of grade 11 "A" of school No. 835 Anna Kuptsova on the topic: "Myths and reality of ozone holes"

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The modern oxygen atmosphere of the Earth is a unique phenomenon among the planets of the solar system, and this feature is associated with the presence of life on our planet. The problem of ecology for people is undoubtedly the most important now. The destruction of the Earth's ozone layer points to the reality of an ecological catastrophe. Today we often hear about ozone holes. But what is it? How do ozone holes appear? What do they influence? There are a lot of answers to these questions, but which ones are really true, and which ones are just a myth? Let's try to figure this out.

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Ozone and the Atmosphere Ozone is a blue gas with a characteristic odor and a very strong oxidizing agent. Molecular formula of ozone is O3. It is heavier than oxygen and our habitual air. Atmospheric ozone plays an important role for all life on the planet. Forming an ozone layer in the stratosphere, it protects plants and animals from harsh ultraviolet radiation. Therefore, the problem of the formation of ozone holes is of particular importance.

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Ozone holes Ozone holes are a local drop in the concentration of ozone in the ozone layer of the Earth. Due to the formation of ozone holes, the flow of solar radiation to the Earth increases and causes an increase in the number of skin cancers in people. Plants and animals also suffer from increased levels of radiation.

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An ozone hole with a diameter of over 1000 km was first discovered in 1985 in the southern hemisphere over Antarctica by a group of British scientists ((J. Shanklin, J. Farman, B. Gardiner), who published a corresponding article in the journal Nature. Every August it appeared, by December or ceasing to exist in January, another smaller hole was forming over the Northern Hemisphere in the Arctic. this stage development of mankind, world scientists have proved that on Earth there is a huge number of ozone holes. But the most dangerous and largest is located above the Antarctic. What causes ozone holes? There are several hypotheses. Let's look at the popular versions of the occurrence of ozone holes and check if they are actually true?

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The purpose of my project is to create a presentation that arouses interest in the problem of the occurrence of ozone holes.

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Ozone hole myths Myth 1: Ozone only depletes over Antarctica In the 1980s. Observations have shown that a slow but steady decrease in the concentration of stratospheric ozone occurs over the Antarctic from year to year. This phenomenon was called the "ozone hole" and began to be closely studied. It is not true that ozone levels are only destroyed over Antarctica. It also falls in the entire atmosphere. This is shown by the results of long-term measurements of the ozone concentration in different parts of the planet. You can look at the graph of ozone over Arosa in Switzerland. Thus, we can conclude that ozone is being destroyed not only over Antarctica, but also over the entire planet.

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Myth 2. Freons are the main destroyers of ozone* This statement is true for middle and high latitudes. In the rest, the chlorine cycle is responsible for only 15-25% of ozone loss in the stratosphere. It should be noted that 80% of chlorine is of anthropogenic origin. That is, human intervention greatly increases the contribution of the chlorine cycle. And if there was a trend to increase the production of freons before the entry into force of the Montreal Protocol, 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 the freons emitted at human activity, shifted this equilibrium in the direction of decreasing 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%. Thus, we can conclude that not only freons are the destroyer of ozone. * Freon is a chemical element with chlorine. It is found in aerosols and chemical installations. It is known that one Freon atom can destroy a million ozone molecules and turn them into ordinary oxygen.

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Myth 3. CFCs are too heavy to reach the stratosphere It is sometimes argued that CFC molecules, which are much heavier than nitrogen and oxygen (in molecular weight), cannot reach the stratosphere in significant quantities. However, atmospheric gases are not stratified or sorted by weight, but are mixed completely as a result of vertical mass transfer, convection and turbulence. Therefore, heavy inert gases, freons and other pollutants of both natural and anthropogenic origin are evenly distributed in the atmosphere, reaching, among other things, the stratosphere. Experimental measurements of gas concentrations in the atmosphere confirm this. Conducted studies show: in order for freons that have fallen as a result of leaks or technological processes into the surface layer of atmospheric air, reached the stratosphere, it takes about five years. 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 surface, which would make the Earth uninhabitable. In reality, both krypton with an atomic mass of 84 and helium with an atomic mass of 4 have the same relative concentration, both near the earth's surface and at an altitude of 100 km. Of course, all of the above is only true for gases that are relatively stable, like freons or inert gases. The concentration of substances that enter into reactions and are subjected to various physical influences (for example, those that dissolve in water) depends on the height.

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Myth 4. The ozone hole must be above the sources of freon 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. Therefore, they easily reach the upper atmosphere. The Antarctic "ozone hole" does not exist permanently. It appears in late winter - early spring. The reasons why the ozone hole forms in Antarctica are related to the 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 mostly in closed paths around the South Pole. At this time, the polar region is not illuminated by the Sun, and ozone does not occur there. With the advent of summer, the amount of ozone increases and again reaches its previous norm. That is, fluctuations in ozone concentration over the Antarctic are seasonal. However, if we trace the dynamics of changes in the ozone concentration and the size of the ozone hole averaged over the course of the year over the past decades, then there is a strictly defined trend towards a decrease in the ozone concentration. Thus, we can conclude that the ozone hole is located not only above the freon sources.

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Myth 5. The main sources of halogens are natural, not anthropogenic factors It is believed that natural sources of halogens, such as volcanoes or oceans, are more significant for the process of ozone depletion than man-made ones. 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.

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So, having considered the above hypotheses, we can conclude that the ozone layer is being destroyed not only over the surface of Antarctica, but over the entire planet. The reason for the occurrence of ozone holes are not only freons, but also other factors.

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It has been established that the ozone content is influenced by nitrogen-containing air pollutants, which appear both as a result of natural processes and as a result of anthropogenic pollution. So, NO is formed in internal combustion engines. Accordingly, the launch of rockets and supersonic aircraft leads to the destruction of the ozone layer. The source of NO in the stratosphere is also the gas N2O, which is stable in the troposphere and decays in the stratosphere under the action of hard UV radiation.

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Anthropogenic factors As a result of the movement of air masses from the leeward side of large cities, a multi-kilometer plume of pollution is formed. General air pollution is increasing, the source of which is automobile transport. The second largest source of anthropogenic organic pollutants is industrial production. Emissions from the chemical and petrochemical industries contain wide range of pollutants: components of the feedstock, intermediate, by-products and target products of synthesis. Thus, in the gas emissions of synthetic plants detergents contains alkanes, as well as carbonyl compounds, esters, carboxylic acids. Synthetic rubber plants pollute the air with parent monomers and solvents. Wood chemical industry enterprises emit aldehydes, ketones, alcohols and carboxylic acids, a lot of terpenes (hydrocarbon terpenes, the waste products of plants, the molecules of which are built from isoprene units). Pulp and paper mills throw away large quantities foul-smelling gaseous substances (odorants), such as methyl and dimethyl sulfides, dimethyl disulfides, as well as formaldehyde, alcohols and phenols. Public utilities of cities (residential and public buildings, heat and water supply enterprises, dry cleaners, landfills) are becoming a noticeable source of organic atmospheric pollutants. Although the contribution of this source to the total anthropogenic emission is small, the main amounts of dangerous long-lived pollutants (for example, dioxides) come from here, and therefore they participate in the formation of the global background of some organic ecotoxicants.

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According to recent studies, the ozone layer is leaking a natural phenomenon, which depends on the circulation of air and the intensity of the sun's rays, where there are fewer of them, gaps appear there, so holes most often appear at the poles.

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Thus, we can conclude that the ozone layer is depleted over the entire surface of the planet. The source of destruction is not only freons, but also harmful substances emitted industrial enterprises and transport.

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The consequences of ozone depletion could be dire, leading to more than 3 million deaths from skin cancer by 2030 and 19 million by 2060. The number of eye diseases (cataracts) could increase by 130 million by 2060; approximately 50% of these will be in developing countries. The number of these diseases is on the rise. In the United States, for 7 years, the number of cases of one of the most dangerous types of skin cancer (melanoma) has increased by 3-7%. crops, aquatic ecosystems, etc.

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The thinning of the ozone layer leads to the extinction of amphibians on the planet Back in the 1970s, scientists noticed a rapid decline in amphibian populations on our planet. For 40 years, scientists from all over the world have been studying this phenomenon, which is called the "Global amphibian extinction", but only now experts have come close to unraveling it ... As it turned out, it was in the 70s of the last century that the thinning of the ozone layer of our planet took place, caused by the rapid development of the industrial activity of mankind. Thus, most scientists agreed that the thinning of the Earth's ozone layer can dramatically reduce the survival rate of amphibian fry due to the increased dose of ultraviolet radiation they receive. Which leads to the extinction of amphibians on our planet. Scientists have confirmed their point of view even in laboratory research. So, scientists irradiated the tadpoles of a striped lake frog with artificial UV radiation. The first group of tadpoles received a standard dose of radiation, but the second received 5% more intense, which corresponds to the effect of thinning the ozone layer. After this exposure to UV radiation, the tadpoles were released into aquariums with a predator - freshwater shrimp. As it turned out, an increased dose of UV radiation shortens the life of tadpoles by about a quarter - tadpoles from the second group were caught and eaten much faster than those that received a standard dose of radiation. It turned out that an increased dose of UV radiation shortens the life of tadpoles by about a quarter.

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Whales and Dolphins Are Increasingly Sunburned Due to Ozone Layer Thinning and Increased Sun Activity the largest marine mammals increasingly suffering from sunburn. Researchers spent three years in the Gulf of California photographing and collecting skin samples from more than 150 individuals of three species of cetaceans: sperm whale, blue whale and fin whale.

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“The fact is that whales do not have hair, fur or feathers that could provide some protection, and besides, they are forced to rise to the surface in order to breathe,” explains study co-author Karina Acevedo-Whitehouse from the Zoological Society of London (UK). "Other animals can somehow adapt - hide in the shadows, for example - and whales don't have that option." Darker-skinned sperm whales and fin whales are comparatively better protected, but sperm whales spend more time on the surface of the ocean compared to blue whales and also become more and more "tanned". During the whale watching period, the number of bites and other skin lesions remained the same, and the prevalence of sunblisters increased significantly. This is especially true for blue whales.

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International Day for the Preservation of the Ozone Layer In 1994, the UN General Assembly proclaimed September 16 as the International Day for the Preservation of the Ozone Layer. The day is set to commemorate the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer. motto international day protection of the ozone layer became the words: "Save the sky: protect yourself - protect the ozone layer."

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UN experts said that the decrease in the ozone layer of the Earth has stopped. 300 scientists who have observed the behavior of the planet's ozone layer over the past four years claim that by the 1950s the ozone layer will be able to recover to the maximum thanks to the current ban on the use of chlorofluorocarbons (CFCs), which were previously used in aerosols, refrigerators and some types of foam. Scientists predict that by about 2050 the thickness of the ozone layer will return to the levels of the late 70s.