Why are there ozone holes in Antarctica?

Ozone is distributed in the atmosphere from the ground to the height of 70km. The maximum concentration is at the height of 24km in mid-latitude, and gradually decreases towards the polar region, and the minimum concentration is at the height of polar region 17km. From the late 1950s to 1970s, it was found that the concentration of ozone was decreasing. During the period of 1985, the British Antarctic expedition discovered the ozone hole at 60 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, destroys the ecological environment and affects the normal survival of human beings and other biological organisms. Regarding the formation of ozone hole, the dominant hypothesis in the world is the hypothesis of human activity chemistry: chlorofluoroalkanes (such as refrigerants, foaming agents, cleaning agents, etc. ) is widely used by human beings and is not easy to decompose in the troposphere. After entering the stratosphere, it is irradiated by strong ultraviolet rays and decomposes to generate chlorine free radicals, which react with ozone to reduce the concentration of ozone, thus causing serious damage to the ozone layer. Therefore, in 1987, the Montreal agreement on restricting the production and use of chlorofluorocarbons and other substances was signed worldwide. There is also the theory of solar activity, which holds that the hole in the Antarctic ozone layer is a natural phenomenon. The cause of ozone hole needs further study. The area of Antarctic ozone hole formed in 2008 has reached 27 million square kilometers by the second week of September, while the area of ozone hole in 2007 was only 25 million square kilometers. In 2000, 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 2008 will break this record. Scientists believe that the small area of the ozone hole 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 scientist, said that the shrinking of the ozone hole over Antarctica last year should be regarded as an individual phenomenon in the historical record. 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. Scientists first discovered in 1985 that in September and October of 1984, the ozone concentration in the ozone layer over Antarctica was 40% lower than that in the mid-1970s, which could not completely block too much ultraviolet rays, resulting in a "hole" in this special life protection circle, threatening the survival of Antarctic marine phytoplankton. 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 decreased by 25-30% compared with that in the 1960s. However, the ozone hole over Antarctica is still expanding, with the largest area reaching 25 million Km2 in1September 1998. Why is there a hole in the ozone layer? Many scientists believe that it is the result of using freon as refrigerant. Freon consists of carbon, chlorine and fluorine. After chloride ions are released into the atmosphere, ozone molecules can be destroyed repeatedly and remain unchanged. Therefore, even if the amount is small, ozone molecules can be reduced to form "holes". Recently, scientists in China suggested that it is not enough to rely solely on the action of Freon. The particle flow of solar wind is concentrated to the geomagnetic pole under the action of geomagnetic field, where ozone molecules are destroyed, which is the main reason. (Yang Xuexiang, 1999) In any case, artificially discharging chloride ions into the atmosphere is a harmful behavior. In the 1970s, British scientists discovered for the first time through observation that the ozone content in the atmosphere over the South Pole of the Earth began to decrease gradually, especially in September-65438+1October every year (equivalent to spring in the southern hemisphere). Further detection by the American satellite Yuyun 7 shows that the area where ozone is reduced is located over the Antarctic, which is oval, and the area of 1985 is almost the same as the entire land area of the United States. It's like the sky is falling. Scientists call this phenomenon the Antarctic ozone hole. The discovery of the Antarctic ozone hole is deeply disturbing, which shows that the ozone layer around the earth is in crisis. So scientists set up a research center in Antarctica to further study the destruction of the ozone layer. 1989, scientists visited the arctic and found that the ozone layer over the arctic was also seriously damaged, but the degree was not as good as that of the Antarctic. Ozone is one of the trace gases in the atmosphere, mainly concentrated in the stratosphere at a height of 20-25 kilometers, that is, the ozone layer of the atmosphere. The ozone layer plays an extremely important role in protecting life on the earth and regulating the earth's climate. However, in recent years, due to the increasing number of planes operating in the stratosphere, human activities have produced some trace gases such as NO. However, chlorofluorocarbons (CFCs) entered the stratosphere, which destroyed the ozone layer and caused an "ozone hole" over Antarctica. The substance that causes the reduction and loss of ozone in the atmosphere is mainly a large amount of NO emitted by supersonic aircraft in the stratosphere. And chlorofluorocarbons (CFCs) produced and used in large quantities by human beings, such as CFCl3 (Freon-1 1), CF2Cl2 (Freon-12) and so on. During the period of 1973, the global output of these two fluoride ions reached 4.8 million, most of which entered the lower atmosphere and then 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.

Edit the reason for the ozone hole in this paragraph.

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

Interpretation of university chemistry laws and regulations

According to the explanation of atmospheric chemical process, some atmospheric chemical reaction can occur in the ozone layer, which decomposes ozone (O3) containing three oxygen atoms into molecular oxygen (O2) and atomic oxygen (O), thus destroying the ozone layer.

Explanation of the influence of solar activity

According to the explanation of the influence of solar activity, it is considered that before and after the peak of solar activity (that is, the intense period of solar activity), cosmic rays are obviously enhanced, which makes the two-electron nitrides (such as NO2) and O3 react chemically with the ozone hole over Antarctica.

Should be, make odd electron nitride (such as NO3) increase, O3 into O2;

Atmospheric dynamic interpretation

According to the explanation of atmospheric dynamics, in early spring, at the end of the polar night, solar radiation heats the air, leading to upward movement, and air with low tropospheric ozone concentration enters 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 by atmospheric circulation (16 km ~ 30 km), it is easy to form free chloride ions due to the irradiation of solar ultraviolet rays. 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. It turns out that ozone is concentrated in the atmosphere 20 km to 30 km from the ground, which is called the ozone layer. When solar radiation passes through this atmosphere, a large amount of ozone absorbs ultraviolet radiation with shorter wavelength (0.20 micron to 0.30 micron 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, short-wave ultraviolet rays are the most lethal, which can kill cells and destroy genetic materials in biological cells, such as chromosomes and deoxyribonucleic acid. In severe cases, it will lead to genetic diseases, mutants and human skin cancer. Strong ultraviolet rays can also penetrate the ocean from 10 m to 30 m, reducing the primary productivity of marine phytoplankton by about three quarters and inhibiting the growth of zooplankton. Once people understand the harm and the causes of the ozone hole, it is believed that new theories and methods will be put forward to predict and prevent the evolution of the ozone hole. It is unevenly distributed in all parts of the ozone layer. The three polar regions in the world, namely, the Antarctic, the Arctic and the Qinghai-Tibet Plateau, have a cold climate and a poor ozone layer. The ozone content in the ozone layer is reduced somewhere, which is equivalent to opening a skylight on the roof. If it is reduced to more than 50% of the normal value, people vividly say it is an ozone hole. The ozone hole can be described by three-dimensional structure, that is, the area, depth and duration of the ozone hole. Antarctic ozone hole On September 3, 2000, the ozone hole over Antarctica reached 2,830 square kilometers, more than twice the area of China and three times the territory of the United States. This is the largest ozone hole observed so far. The blue water droplets covering the South Pole in the picture are the ozone holes observed by satellites. Antarctica is a very cold area, covered with ice and snow all year round, surrounded by oceans. 1985, the British scientist Farmer and others found at the Harry Bay Observatory in Antarctica that the ozone concentration over Antarctica decreased by about 30% 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 ozone hole have been expanding.

Edit the harm of ozone hole in this paragraph.

10 has been studied by scientists for many years; Every reduction of ozone in the atmosphere is 1%. 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 cataracts, immune system defects, developmental retardation and other diseases. Now people living in Cape Helena, the southern tip of Chile near Antarctica, have suffered greatly. As long as you go out of the house, you should apply sunscreen and sunglasses on the skin that clothes can't cover, otherwise your skin will turn 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 rabbits there are all blind, and hunters can easily pick up 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 living things on earth, and mankind will 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 the survival of mankind. 1987, major industrialized countries signed the Montreal convention, demanding that the use of chemicals harmful to the ozone layer be phased out. Now, a healthier third-generation refrigerant has appeared, which is ammonia. Ammonia is a natural 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 make the global climate warm. But ozone is different from other greenhouse gases, it is produced by natural factors (ultraviolet rays in solar radiation are produced by photochemical action of oxygen molecules in the upper atmosphere), not 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 practical observations will have the following effects.

Impact on human health

1. Skin cancer increased: ozone decreased 1%, and skin cancer patients increased by 4%-6%, mainly melanoma cancer. 2. Damage the eyes and increase the number of cataract patients. 3. Immunity is weakened and patients with infectious diseases are increased.

Impact on ecology

1. The output and quality of agricultural products decreased. The sensitivity of 200 crops to the increase of ultraviolet radiation was tested. The results showed that two thirds 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 decrease 1% and soybean yield will decrease 1%. 2. Reduce fishery production. Ultraviolet radiation can kill single-celled marine plankton at a water depth of 10 meter. Experiments show that ozone reduction 10% and ultraviolet radiation increase by 20% will kill all eel larvae living in the water depth of 10 meter 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.

international ozone layer protection day

1995 65438+1On October 23rd, the United Nations General Assembly adopted a resolution to designate September 16 every year as the International Day for the Protection of the Ozone Layer from1995. 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 6th, 1987. All States parties must take concrete actions to commemorate this special day in accordance with 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. Memorabilia1977 In April, the Governing Council of the United Nations Environment Programme held an international conference on "Assessing the Whole Ozone Layer" in Washington, D.C., USA. The meeting adopted the first "World Action Plan for the Ozone Layer". The plan includes monitoring ozone and solar radiation, assessing the impact of ozone depletion on human health, ecosystems and climate, and requesting the United Nations Environment Programme to set up an ozone coordination committee. 1980 Coordination Committee put forward the assessment conclusion that ozone depletion poses a serious threat to human beings and the earth's ecosystem. 198 1 year, the Governing Council of the United Nations Environment Programme set up a working group to draft a global convention for the protection of the ozone layer. After four years of efforts, the Vienna Convention for the Protection of the Ozone Layer, an international convention for the protection of the ozone layer, was adopted in April 1985 in Vienna, Austria. The Convention entered into force on September 1988. The convention only provides for the exchange of information and data about the ozone layer, but it is not binding on the provisions on controlling 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 (UNEP) adopted the Montreal Protocol on Substances that Deplete the Ozone Layer at the meetings in Montreal, Canada, on September 1987+06 and June 65438, 2006 after reviewing the statistical data of the production, use and trade of chlorofluorocarbons in various countries around the world. According to the Montreal Protocol, the member organizations 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 was frozen from 1 in July to 1986. From July 1 9931day, its consumption shall not exceed 80% of that of 1986; From 1 July 9981to 50% of the consumption of 1986. The investigation after the implementation of the Montreal Protocol shows that the control process and effect under the Protocol are not satisfactory. 1989 From March to May, the United Nations Environment Programme convened the London Conference for the Protection of the Ozone Layer and the first conference of the parties to the Convention and Protocol-Helsinki Conference, which further emphasized the urgency of protecting the ozone layer, and adopted the Helsinki Declaration for the Protection of the Ozone Layer on May 2, 1989, encouraging all countries that have not yet acceded to the Vienna Convention for the Protection of the Ozone Layer and the Montreal Protocol. Agree to phase out the production and use of controlled CFCs as far as possible but not later than 2000, taking due account of the special situation of developing countries; Control and reduce other ozone-depleting substances as soon as possible; Accelerate the research and development of alternative products and technologies; Promote developing countries to obtain relevant scientific information, research results and training, and seek to establish an appropriate financial mechanism to promote the transfer of technology and alternative equipment to developing countries at the lowest price. 1From June 20 to 29, 1990, the United Nations Environment Programme convened the second meeting of the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer in London. Ministers or senior officials of the environment of 53 of the 57 Parties participating in the Protocol and representatives of the European Community attended the meeting. In addition, representatives of 49 States not parties attended the meeting. The meeting also adopted a number of supplementary regulations, which revised and expanded the scope of control of substances harmful to the ozone layer, and expanded the controlled substances from the original two categories and eight categories to seven categories and hundreds. Require the parties to phase out freon and halon in 2000 or earlier; By 1995, carbon tetrachloride will be reduced by 85% and will be completely phased out by 2000; By 2000, trichloroethane will be reduced by 70%, and it will be completely eliminated before 2005. The meeting also put forward the requirement to oppose the uncontrolled use of hydrofluorocarbons (HCFCs), which is a "transitional substance" and was not involved in the protocol adopted at the first meeting (the potential danger of this substance to the ozone layer is much less than that of Freon). The second meeting of the Parties to the Montreal Protocol established the International Ozone Layer Protection Fund with an initial fund of 240 million US dollars for three years. This fund will be mainly used for research on freon substitutes in developing countries, personnel training and regional research, and should be geared to the overall development needs of developing countries. So far, more than 50 governments have ratified this treaty. The production and consumption of chlorofluorocarbons and other ozone-depleting substances have miraculously decreased by nearly 70%. The recovery of chlorofluorocarbons is widely used. In addition, ozone safety technology is now feasible and widely used. Monitoring shows that the growth rate of ozone-depleting substances in the atmosphere is gradually slowing down. The content of methyl bromide in the atmosphere has also decreased. However, the ozone layer is fragile, and only with the continuous support of all sectors of society, including consumers, can the struggle to protect the ozone layer finally win. The confirmation of the "International Day for the Protection of the Ozone Layer" on September 16 further demonstrates the international community's concern about ozone layer depletion and understanding of ozone layer protection. In order to strengthen the leadership of ozone layer protection, China established the National Leading Group for Ozone Layer Protection, which is composed of 18 ministries including the State Environmental Protection Agency. Under the organization and coordination of the leading group, the National Plan for the Elimination of Substances that Deplete the Ozone Layer in China was compiled, and it was approved by the State Council with the document 1993, which became the guiding document for China to carry out ozone layer protection. On this basis, the elimination strategies of eight industries, such as chemical industry and household refrigeration, have been formulated, and the guidelines, policies, plans and priority projects for eliminating ozone-depleting substances in various industries have been further clarified, which has strong operability. Based on the above two documents, China actively organized the application and implementation of the Montreal Multilateral Fund project. As of1June 1997, the Executive Committee of the Multilateral Fund has approved 2 10 projects in China with a total grant of US$ 6,543.8+5 billion. In order to cooperate with the implementation of the International Convention for the Protection of the Ozone Layer, the state is gradually formulating and adopting certain laws and measures to control the production and use of ozone-depleting substances, and to guide and encourage the production and application of substitutes and alternative technologies, such as production quotas, environmental labeling, tax price adjustment, import and export control, investment control and other policies. At present, some regulations have been introduced. In addition, China has also carried out activities such as propaganda, international cooperation and scientific research to protect the ozone layer, which has raised people's awareness of protecting the ozone layer and actively participated in actions to protect the earth's environment. Through these efforts, China has made remarkable progress in protecting the ozone layer. Many enterprises use multilateral funds or their own funds to change production. According to incomplete statistics, about 20,000 tons of ozone-depleting substances have been eliminated; Some substitute products have been put on the market, creating conditions for reducing or even eliminating ozone-depleting substances. A little too much! I'm sorry. I hope I can help you O(∩_∩)O~