Ozone is distributed in the atmosphere from the ground to the altitude of 7km, and its maximum concentration is at the altitude of 24km in the mid-latitude, and gradually decreases towards the polar regions, and its minimum concentration is at the altitude of 17km in the polar regions. From the late 195s to the 197s, it was found that the concentration of ozone was decreasing. In 1985, the British Antarctic expedition observed the ozone hole at 6 south latitude, which attracted great attention from all countries in the world. The reduction of ozone concentration in the ozone layer increases the amount of ultraviolet radiation from the sun on the earth's surface, which damages the ecological environment and affects the normal survival of human beings and other biological organisms. About the formation of ozone hole, the dominant hypothesis in the world is the hypothesis of human activity chemistry: chlorofluoroalkane chemicals (such as refrigerants, foaming agents, cleaning agents, etc.) widely used by human beings are not easy to decompose in the troposphere, and when they enter the stratosphere, they are irradiated by strong ultraviolet rays and decompose to produce chlorine free radicals, which react chemically with ozone, reducing the concentration of ozone, thus causing serious damage to the ozone layer. Therefore, in 1987, the Montreal Agreement on limited production and use of chlorofluorocarbons and other substances was signed worldwide. In addition, there is the theory of solar activity, which holds that the hole in Antarctic ozone layer is a natural phenomenon. The cause of ozone hole needs further study. The area of the Antarctic ozone hole formed in 28 has reached 27 million square kilometers by the second week of September, while the area of the ozone hole in 27 was only 25 million square kilometers. In 2, the ozone hole area over Antarctica reached a record 28 million square kilometers, equivalent to 4 Australia. Scientists don't know whether the ozone hole area in 28 will break this record. Scientists believe that the small ozone hole area last year was mainly due to the climate, rather than the reduction of chemical gas emissions that destroyed the ozone layer. Alan Roger, a British Antarctic expedition scientist, said that the shrinking of the ozone hole over Antarctica last year should be regarded as an individual phenomenon in historical records. Therefore, the hole area of the ozone layer may be further expanded. Ozone in the atmosphere can't make ends meet, and its concentration decreases. In 1985, scientists first discovered that in September and October of 1984, the concentration of ozone in the ozone layer over Antarctica was 4% lower than that in the mid-197s, which could not fully block excessive ultraviolet rays, resulting in a "hole" in this special life-protecting circle, threatening the survival of phytoplankton in the Antarctic ocean. According to the report of the World Meteorological Organization, it was found in 1994 that the ozone content in the stratosphere over the Arctic region also decreased, and in some months it was 25-3% lower than that in the 196s. However, the hole in the ozone layer over Antarctica is still expanding. In September 1998, it set a historical record with the largest area of 25 million Km2. Why does the ozone layer have a "hole"? Many scientists believe that it is the result of using freon as refrigerant and other aspects. Freon is composed of carbon, chlorine and fluorine. After chloride ions are released into the atmosphere, they can repeatedly destroy ozone molecules and remain the same. Therefore, even though the amount is very small, ozone molecules can be reduced to form "holes". Chinese scientists have recently proposed that the function of Freon alone is not enough, and the particle flow from the solar wind is concentrated to the geomagnetic poles under the action of the geomagnetic field, and the ozone molecules there are destroyed, which is the main reason. (Yang Xuexiang, 1999) In any case, artificially sending chloride ions into the atmosphere is a harmful behavior. In the 197s, British scientists first discovered through observation that the ozone content in the atmosphere over the South Pole of the Earth began to decrease gradually, especially in September-October every year (which is equivalent to spring in the southern hemisphere). Further detection by the American satellite Yunyu 7 shows that the area where ozone is reduced is located over the South Pole, which is oval, and in 1985 it was similar to the whole land area of the United States. It's as if the sky had collapsed. Scientists call this phenomenon the Antarctic ozone hole. The discovery of the Antarctic ozone hole is deeply disturbing, which shows that the ozone layer surrounding the earth is in crisis. So scientists set up a research center in Antarctica to further study the destruction of the ozone layer. In 1989, scientists went to the North Pole for investigation and study, and found that the ozone layer over the North Pole had also been seriously damaged, but the degree was less than that of the South Pole. Ozone is one of the trace gases in the atmosphere, which is mainly concentrated in the stratosphere at a height of 2-25km, that is, the ozone layer of the atmosphere. The ozone layer plays an extremely important role in protecting the life on the earth and regulating the climate of the earth. However, in recent years, due to the increasing number of aircraft operating in the stratosphere, some trace gases such as NO are produced by human activities. And chlorofluorocarbons (CFCs) enter the stratosphere, so that the ozone layer is destroyed and an "ozone hole" appears over Antarctica. The substances that lead to the reduction and depletion of ozone in the atmosphere are mainly a large number of NO emitted by supersonic aircraft in the stratosphere. And chlorofluorocarbon compounds (Freon) produced and used in large quantities by human beings, such as CFCl3 (Freon -11) and CF2Cl2 (Freon -12). In 1973, the global output of these two freons reached 4.8 million, and most of them entered the lower atmosphere and then entered the ozone layer. Freon is stable in the troposphere, but after entering the ozone layer, it is easy to react with ozone and consume ozone, thus reducing the ozone concentration in the ozone layer.

editing the causes of ozone hole in this paragraph

There are three explanations for the formation of Antarctic ozone hole, namely, atmospheric chemical process explanation, solar activity influence and atmospheric dynamics explanation.

Explanation of university chemical regulations

Explanation of atmospheric chemical process, it is believed that some atmospheric chemical reaction can occur in the ozone layer, which decomposes ozone (O3) with three oxygen atoms into molecular oxygen (O2) and atomic oxygen (O), thus destroying the ozone layer;

explanation of the influence of solar activity

explanation of the influence of solar activity, it is considered that when the peak year of solar activity (that is, the period of intense solar activity) is around, cosmic rays are obviously enhanced, which makes two-electron nitrides (such as NO2) and O3 chemically react against the ozone hole over Antarctica, which makes odd electron nitrides (such as NO3) increase and O3 transform into O2;

explanation of atmospheric dynamics

The explanation of atmospheric dynamics holds that in early spring, at the end of the polar night, the air is heated by solar radiation, resulting in upward movement, and the air with low tropospheric ozone concentration is input into the stratosphere, which reduces the stratospheric ozone content and is prone to ozone holes. It is generally believed that among human factors, the extensive use of freon gas in industry is one of the main reasons for destroying the ozone layer. Usually, freon is a relatively stable substance. However, when it is brought to the stratosphere (16 km ~ 3 km) by atmospheric circulation, it is easy to form free chloride ions due to the irradiation of ultraviolet rays from the sun. These chloride ions are very active and easily react with ozone, changing ozone (O3) into oxygen molecules (O2) and oxygen atoms (O), thus reducing the total amount of ozone and forming ozone holes. Originally, in the atmosphere 2 km ~ 3 km above the ground, ozone is concentrated, which is called the ozone layer. When solar radiation passes through this atmosphere, a large amount of ozone absorbs ultraviolet radiation with shorter wavelength (.2 μ m ~ .3 μ m band), which greatly weakens the ultraviolet intensity of solar radiation reaching the ground. However, if the ozone content in the ozone layer is greatly reduced, the ability to absorb solar ultraviolet radiation will be weakened, and the intensity of solar radiation reaching the ground will increase. Medically speaking, shorter-wave ultraviolet radiation has the greatest killing power, which can kill cells and destroy genetic materials in biological cells, such as chromosomes and deoxyribonucleic acid, etc., which will lead to genetic diseases of organisms, mutants and human skin cancer in severe cases. Strong ultraviolet rays can also penetrate the ocean for 1-3 meters, reducing the primary productivity of marine phytoplankton by about three quarters and inhibiting the growth of zooplankton. Once people understand the harm and formation reasons of ozone hole, it is believed that new theories and methods will be put forward to predict and prevent the evolution of ozone hole. It is unevenly distributed in all parts of the ozone layer. The climate in the three polar regions of the world, namely the Antarctic, the Arctic and the Qinghai-Tibet Plateau, is cold and the ozone layer is meager. The reduction of ozone content in the ozone layer somewhere is equivalent to opening a skylight on the roof. If it is reduced to more than 5% of the normal value, people vividly say that it is an ozone hole. The ozone hole can be described by a three-dimensional structure, namely the area, depth and duration of the ozone hole. Antarctic ozone hole On September 3rd, 2, the ozone hole area over Antarctica reached 2,83 square kilometers, more than twice the area of China, and equivalent to three times the territory of the United States. This is the largest ozone hole observed so far. In the picture, the blue water droplets covering the Antarctic are the ozone holes observed by satellites. The Antarctic is a very cold area, which is covered with ice and snow all year round and surrounded by the ocean. In 1985, British scientist farman and others discovered at Haley Bay Observatory in Antarctica that the ozone concentration over Antarctica would decrease by about 3% every spring from 1977 to 1984, and nearly 95% of the ozone was destroyed. Before 1985, the size and depth of the Antarctic ozone hole were about two years. In recent years, the depth and area of the ozone hole continue to expand.

Editing the harm of ozone hole in this paragraph

For more than 1 years, it has been studied by scientists; Every 1% reduction of ozone in the atmosphere. The ultraviolet rays irradiated to the ground will increase by 2%, and human skin cancer will increase by 3%. It will also be attacked by diseases such as cataracts, immune system defects and stunted development. Residents who now live in Helena Point, the southern tip of Chile, which is close to Antarctica, have suffered a lot. As long as they go out of their homes, they should apply sunscreen and sunglasses on the skin that clothes can't cover, otherwise their skin will become bright pink in half an hour, accompanied by itching and pain. Sheep often suffer from cataracts and are almost completely blind. It is said that the rabbits there are all blind, and hunters can easily pick up the rabbits' ears and take them home. The fresh fish caught in the river are also blind. By extension, if the ozone layer is completely destroyed, the ultraviolet rays of the sun will kill all terrestrial life, and human beings will also be "devastated", and the earth will become a barren land without any life. It can be seen that the hole in the ozone layer has threatened human survival. In 1987, major industrial countries signed the Montreal Convention, demanding that the use of chemicals harmful to the ozone layer be phased out. And now, a healthier third-generation refrigerant has appeared, which is ammonia. Ammonia is a naturally occurring substance, which is composed of hydrogen and nitrogen, and has little impact on the environment. Ozone is a kind of greenhouse gas, and its existence can warm the global climate. However, ozone is different from other greenhouse gases, which is produced by natural factors (ultraviolet rays in solar radiation are generated by photochemical action of oxygen molecules in the upper atmosphere) in nature, and is not produced by human activities. Ozone not only has an impact on climate change, thus affecting the environment and ecology, but also has a strong direct impact on human health. Inference from experiments and actual observations will have the following effects.

Impact on human health

1. Increase skin cancer: ozone decreases by 1%, and skin cancer patients increase by 4%-6%, mainly melanoma cancer. 2. Damage the eyes and increase the number of cataract patients. 3. Weaken immunity and increase patients with infectious diseases.

Impact on ecology

1. The output of agricultural products and their quality decline. The sensitivity of 2 crops to the increase of ultraviolet radiation was tested, and the results showed that 2/3 of them were affected, especially rice, wheat, cotton, soybean, fruit and cabbage, which were often eaten by human beings. It is estimated that ozone will be reduced by 1% and soybean production will be reduced by 1%. 2. Reduce fishery production. Ultraviolet radiation can kill single-celled marine plankton within 1 meters of water depth. Experiments show that a 1% reduction in ozone and a 2% increase in ultraviolet radiation will kill all young eels living in a water depth of 1 meters within 15 days. 3. Destroy forests. According to research, the main mechanism of ozone reduction affecting human health and ecosystem is that the increase of ultraviolet radiation will destroy ribonucleic acid (DNA), thus changing genetic information and destroying protein. In addition to affecting human health and ecology, the increase of ultraviolet radiation caused by ozone reduction will also have an impact on industrial production, such as accelerating the aging of plastics and other polymers.

Editing this paragraph: International Day for the Protection of the Ozone Layer

On January 23rd, 1995, the United Nations General Assembly passed a resolution to designate September 16th every year as the International Day for the Protection of the Ozone Layer from 1995. The United Nations General Assembly established the "International Day for the Protection of the Ozone Layer" to commemorate the Montreal Protocol on Substances that Deplete the Ozone Layer signed on September 16, 1987, and requested all contracting countries to take concrete actions to commemorate this special day according to the objectives of the Protocol and its amendments. Since 1976, the United Nations Environment Programme has held various international conferences and adopted a series of resolutions to protect the ozone layer. Especially in 1985, after the discovery of the obvious thinning of the ozone layer around the Antarctic, the so-called "Antarctic ozone hole" problem, the international call for protecting the ozone layer and protecting future generations of mankind became even louder. Memorabilia In April 1977, the Governing Council of the United Nations Environment Programme held an international conference on "Evaluating the Whole Ozone Layer" in Washington, D.C., USA, which was attended by 32 countries. The meeting adopted the first "World Plan for Action on the Ozone Layer". The plan includes monitoring ozone and solar radiation, evaluating the impact of ozone depletion on human health, ecosystems and climate, and requesting the United Nations Environment Programme to establish a coordinating committee on ozone issues. In 198, the Coordinating Committee put forward the evaluation conclusion that ozone depletion is a serious threat to human beings and the earth's ecosystem. In 1981, the Governing Council of the United Nations Environment Programme established a working group to draft a global convention for the protection of the ozone layer. After four years of hard work, the Vienna Convention for the Protection of the Ozone Layer, an international convention on the protection of the ozone layer, was adopted in April 1985 in Vienna, Austria. The Convention came into force in September 1988. This convention only provides for the exchange of information and data about the ozone layer, but it is not binding on the provisions on the control of ozone-depleting substances. On the basis of the Vienna Convention for the Protection of the Ozone Layer, in order to further control chlorofluorocarbons, the United Nations Environment Programme adopted the Montreal Protocol on Substances that Deplete the Ozone Layer at the Montreal Conference in Canada on September 16, 1987, after reviewing the statistics of the production, use and trade of chlorofluorocarbons in various countries around the world, and through consultations and discussions at several international conferences, which came into effect on January 1, 1989. According to the Montreal Protocol, each member organization participating in the treaty will freeze and reduce the production and consumption of five CFCs and three bromides according to the reduction schedule. Most of the consumption of five kinds of Freon has been frozen at the level of consumption in 1986 since July 1, 1989; From July 1, 1993, its consumption shall not exceed 8% of the consumption in 1986; From July 1, 1998, it was reduced to 5% of the consumption in 1986. The investigation after the implementation of Montreal Protocol shows that according to the discussion