Presentation "Ozone holes" (grade 5) in geography - project, report. Myths and reality of ozone holes Presentation about ozone holes

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Contents: Introduction Definition of the ozone hole History Mechanism of formation Consequences Restoration of the ozone layer Misconceptions about the ozone hole The transition to ozone-saving technologies is not only environmentally, but also economically justified The main sources of halogens Ozone is destroyed only over Antarctica Conclusion References to used literature Ozone holes

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* Introduction A real threat of a global ecological crisis is looming over the world, understood by the entire population of the planet, and the real hope for its prevention lies in the continuous environmental education and educating people. Characterizing state of the art ecology, as critical, one can single out the main causes that lead to an ecological catastrophe: pollution, poisoning of the environment, depletion of the atmosphere with oxygen, ozone holes. The purpose of this work was to summarize the literature data on the causes and consequences of the destruction of the ozone layer, as well as ways to solve the problem of the formation of “ozone holes”. Ozone holes

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* Ozone hole The ozone hole is a local drop in the concentration of ozone 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. According to another hypothesis, the process of formation of "ozone holes" is largely natural and not associated solely with the harmful effects of human civilization. Freons are haloalkanes, fluorine-containing derivatives of saturated hydrocarbons (mainly methane and ethane), used as refrigerants in refrigeration machines (for example, in air conditioners). 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. Ozone holes

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The first threat on Earth An ozone hole with a diameter of more than 1000 km was first discovered in 1985 in the Southern Hemisphere over Antarctica by a group of British scientists. Every August it appeared, by December or January it ceased to exist. Ozone Holes Another smaller hole was forming over the Northern Hemisphere in the Arctic.

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The mechanism of formation A combination of factors leads to a decrease in the concentration of ozone in the atmosphere, the main of which is the death of ozone molecules in reactions with various substances of anthropogenic and natural origin, the absence of solar radiation during the polar winter, a particularly stable polar vortex that prevents the penetration of ozone from subpolar latitudes, and the formation of polar stratospheric clouds (PSCs), whose surface particles catalyze ozone decay reactions. Ozone holes

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Consequences The weakening of the ozone layer increases the flow of solar radiation to the earth and causes an increase in the number of skin cancers in people. Plants and animals also suffer from increased levels of radiation. Ozone holes

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Recovery 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 already accumulated ozone holes in the atmosphere of freons, which have a lifetime of tens and even hundreds of years. Therefore, the tightening of the ozone hole should not be expected before 2048.

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* Misconceptions about the ozone hole The transition to ozone-saving technologies is not only environmentally, but also economically justified The main sources of halogens Ozone is destroyed only over Antarctica Ozone holes

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* The transition to ozone-saving technologies is not only environmentally, but also economically justified Russian Federation assumed all the obligations of the USSR, and since 2000, in accordance with the Montreal Protocol, the production of ozone-depleting substances in Russia has been stopped. Ozone holes Since, due to a number of economic, political and financial reasons, Russia did not have time to develop and implement its own alternative technologies, this led to the almost complete elimination of Russian production aerosols and refrigeration equipment.

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* Fortunately, most of the industrial refrigeration units in Russia operate on ammonia, namely: 70% of refrigeration units for vegetable and fruit storage, 60% - in the meat industry, 50% - in confectionery production, 80% - in the production of beer and beverages. Although ammonia is a highly toxic, flammable and explosive substance, it does not lead to the destruction of ozone. Ozone holes

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* Major sources of halogens It is believed that natural sources of halogens, such as volcanoes or the 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 and are washed out of the atmosphere, falling as rain on the ground. Ozone holes

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* 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 ozone destruction reactions. 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. Ozone holes

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* Ozone only breaks down over Antarctica This is not true, ozone levels are also falling in the entire atmosphere. This is shown by the results of long-term measurements of the ozone concentration in different parts of the planet. You can look at the graph of ozone over Arosa in Switzerland on the left. Ozone holes

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Objectives: - to deepen and expand knowledge on the state of the location of ozone holes on the territory of the globe; - identify the causes of the ozone hole over Antarctica; - to give the concept of "greenhouse effect"; - identify the causes of the greenhouse effect. The work was completed by: Goncharova Daria Nesterova Sofya Druzhinina Evgeniya Sochneva Tatiana Consultants: Zabara T.G. Popova N.I. website

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OZONE HOLES IN ANTARCTICA

The first such “hole” was discovered over Antarctica in 1978. First, it was studied from Earth satellites, then from ground stations, and in 1985 British scientists published a sensational report that every year in October the amount of atmospheric ozone over Antarctica decreases by 40 50%, and sometimes drops to zero. At the same time, the dimensions of the “hole” range from 5 million to 20 million kmg (p). In the first half of the 1990s, international studies in Antarctica were continued. it was especially pronounced in 1992. A second similar "hole" was discovered over the Arctic. Although it turned out to be not so extensive and, in fact, consisting of several "holes" of smaller area, intensity and duration, it can pose a much greater danger to the population of the northern latitudes of Eurasia, than a huge "ozone hole" over deserted Antarctica. In the mid-1980s, the ozone content began to decrease over the territory of the middle latitudes of the Northern Hemisphere. At the end of 1994, a huge ozone anomaly arose over the territory of foreign Europe, Russia, and the USA. In early 1995 In the spring of 1997, an anomalously low ozone content over the Arctic and a significant part of Eastern Siberia. The diameter of this "ozone hole" was approximately 3000 km.

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In 1985, scientists found that in September-October, the ozone content over Antarctica fell by 30-40%. This phenomenon is called the ozone hole. "The name " ozone hole" refers to a section in the atmosphere where the ozone content is significantly reduced compared to the usual content at this time of the year. In other words, the ozone screen here is very thin and transmits much more ultraviolet radiation than The ozone hole over Antarctica appears regularly in the Southern Hemisphere in the spring and gets bigger every year.It is currently three times the size of the US and its ozone is declining by 40-60% (depending on the year). In 1987 and 1994 it was almost four times lower than normal. Why did the first ozone hole form over Antarctica, and not somewhere else? After all, there are no plants or factories here, and it seemed The air in this area should be the cleanest, but there are no borders in the atmosphere, pollutants are carried by air currents around the world and often settle many thousands of kilometers from from the place where they were formed.

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Diagram showing the dynamics of the ozone hole. (According to the US NSP)

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Summary maps of world ozone and ultraviolet radiation.

The data show that from August 21 to August 31, 2004. areas with high concentration ozone (dark purple color) increased significantly. (Data from the Canadian Center for the Environment, 2005)

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Forecasts for the future

Nevertheless, Geir Braaten, an expert at the World Meteorological Organization, believes that this time the ozone hole will not be able to overcome the record figure of 28 million square meters two years ago. km. In his opinion, this season the area of the Antarctic ozone hole will fluctuate within the limits established in the period 2000-2003.

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In another polar region of the Earth - in the Arctic - the circumpolar vortex does not have such strength as over Antarctica, and ozone-saturated air masses throughout the winter regularly enter the Arctic atmosphere. Therefore, despite the fact that the concentration of chlorine compounds also increases here, ozone holes are distributed only locally. Over the territory of Russia, the decrease in the ozone content in the 1980s was episodic, but now entire regions have appeared where the ozone content drops by 15-20% at the end of winter and early spring. These are the West Siberian Plain and the Central Siberian Plateau, as well as the North-West of Russia. Launches also pose a threat to the ozone layer spaceships, as well as aircraft flights that occur just at the height of this layer. Rockets punch holes in it up to several hundred kilometers in diameter, which persist for several weeks and can move from place to place.

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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. On reality ecological disaster indicates the destruction of the Earth's ozone layer. Ozone - a triatomic form of oxygen, is formed in the upper atmosphere under the influence of hard (short-wavelength) ultraviolet radiation from the sun.

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The ozone layer is a wide atmospheric belt extending from 10 to 50 km above the Earth's surface. Chemically, ozone is a molecule consisting of three oxygen atoms (an oxygen molecule contains two atoms). The concentration of ozone in the atmosphere is very low, and small changes in the amount of ozone lead to large changes in the intensity of ultraviolet reaching the earth's surface. Unlike ordinary oxygen, ozone is unstable, it easily transforms into a diatomic, stable form of oxygen. Ozone is a much stronger oxidizing agent than oxygen, which makes it capable of killing bacteria and inhibiting plant growth and development. However, due to its low concentration in the surface layers of air under normal conditions, these features of it practically do not affect the state of living systems.

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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.

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In the polar zones, where the lines of force of the Earth's magnetic field are closed on its surface, the distortion of the ionosphere is very significant. The number of ions, including ionized oxygen, in the upper layers of the atmosphere of the polar zones is reduced. But the main reason for the low content of ozone in the region of the poles is the low intensity of solar radiation, which falls even during the polar day at small angles to the horizon, and during the polar night is completely absent. The area of polar "holes" in the ozone layer is a reliable indicator of change general content ozone in the atmosphere.

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The ozone content in the atmosphere fluctuates due to many natural causes. Periodic fluctuations are associated with cycles of solar activity; many components of volcanic gases are capable of destroying ozone, so an increase in volcanic activity leads to a decrease in its concentration. Due to the high hurricane speeds of air currents in the stratosphere, ozone-destroying substances are carried over large areas. Not only ozone depleters are transported, but also ozone itself, so ozone concentration disturbances quickly spread over large areas, and local small “holes” in the ozone shield, caused, for example, by a rocket launch, are relatively quickly drawn in. Only in the polar regions is the air inactive, as a result of which the disappearance of ozone there is not compensated by its drift from other latitudes, and the polar "ozone holes", especially at the South Pole, are very stable.

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Ozone hole - a local drop in the concentration of ozone 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-containing compounds.

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Being reactive, ozone molecules can react with many inorganic and organic compounds. The main substances contributing to the destruction of ozone molecules are simple substances (hydrogen, oxygen atoms, 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 substances are almost completely consumed even in the troposphere.

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First of all, the massive occurrence of ozone holes hits people themselves. On Earth today great amount cancer patients. It is not only harmful genetically modified foods that are to blame for this, since they just do not cause skin cancers so actively. And the main cause of cancers on human skin is precisely the lack of good protection from solar ultraviolet radiation, the protection that ozone should 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 against sun rays, 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, the result is 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 regions of the Earth, is the phenomenon is also called the greenhouse effect, as it leads to the melting of glaciers and a general disruption of the climate, such as the transition of winter into 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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Presentation "Ozone holes" (grade 5) in geography - project, report. Myths and reality of ozone holes Presentation about ozone holes

OZONE HOLES IN ANTARCTICA

Diagram showing the dynamics of the ozone hole. (According to the US NSP)

Summary maps of world ozone and ultraviolet radiation.

Forecasts for the future

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