9.3.1.4. Ozone layer hole

Ozone layer

The ozone layer (O₃) is in the stratosphere, about 25 km high, and acts as a filter for ultraviolet rays, preventing them from reaching the earth's surface and damaging the health of living beings.

The ozone layer began to thin out when, starting in the 1970s, CFCs (chlorofluorocarbons) began to be released from aerosols, solvents, refrigerants, and fertilizers. CFCs, by the action of solar radiation, release chlorine and bromine in the stratosphere, which react with ozone and decompose it. This caused that in the 80s, in the Antarctic area (South Pole) it decreased significantly, originating the well-known hole in the ozone layer. It is not really a hole, but a decrease in the thickness of the ozone layer.

In the 90s the emission of CFCs was banned and you can already see how it is increasing its thickness again.

Why does the ozone hole occur in Antarctica?

The depletion of the ozone layer is produced by the presence in the stratosphere of CFCs (chlorofluorocarbons) and nitrogen oxides. Chlorine from CFCs reacts with ozone (O₃) to form chlorine oxides, capturing oxygen atoms, and preventing the ozone layer from regenerating.

Cl + O₃ → Cl₂O + O₂

The special atmospheric conditions of Antarctica have favored the ozone layer to decrease its thickness by more than 50%, allowing the entry of ultraviolet radiation. This ultraviolet radiation is the cause of some diseases in humans (such as skin cancer, visual problems, deficiencies in the immune system, etc.), and mutations in animals and plants.

The hole in the ozone layer becomes larger in September, when the temperature is very low (southern hemisphere) and sunlight begins to appear over the horizon (south pole), when chemical reactions begin to destroy ozone. In October, this ozone destruction stops, and the hole shrinks. From October to December, the hole moves towards mid-latitudes.

Evolution and solutions

Since the 1990s, the use of CFCs and other chemicals that damage the ozone layer has been discontinued and, until seven years later, a decrease in CFCs in the troposphere could not be observed. Although there is already an improvement and the ozone layer is gaining thickness, due to the long life that CFCs have in the atmosphere, it is believed that it will not reach its natural situation until the year 2070.

Cartoons about the hole in the Ozone layer: Ozzy Ozone (part 1 and part 2).

Answer in your notebook

9.4.- What is the cause of the depletion of the ozone layer?

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Skip navigation Biology and Geology 4th ESO Biology and Geology 4º ESO 1. The cell 1.1. Levels of organization of living beings 1.2. Cell theory 1.3. The cell 1.3.1. Prokaryotic cell 1.3.2. Eukaryotic cell 1.3.2.1. Common organelles 1.3.2.2. Organelles of the animal cell 1.3.2.3. Plant cell organelles 1.4. Cell nucleus 1.5. Vital functions of cells 1.6. Cellular cycle 1.6.1. Mitosis 1.6.1.1. Cytokinesis 1.6.2. Meiosis 1.6.2.1. Meiosis I. First meiotic division 1.6.2.2. Meiosis II. Second meiotic division 1.6.2.3. Result of meiosis 1.6.3. Differences between mitosis and meiosis 1.6.4. Biological importance of mitosis and meiosis 1.7. Bibliography 2. Genetic information 2.1. Nucleic acids 2.1.1. DNA 2.1.2. RNA 2.1.3. Control of protein synthesis 2.2. DNA and molecular genetics 2.3. Gene concept 2.4. Replication of DNA 2.5. DNA to RNA transcription 2.6. Genetic code 2.7. Translation of RNA to proteins 2.8. Mutations Relations with evolution 2.9. Biotechnology 2.10. Genetic engineering: techniques and applications 2.10.1. Cloning 2.10.2. Human Genome Project 2.11. Bioethics 2.12. Bibliography 3. Biological inheritance 3.1. The inheritance and transmission of characters 3.2. Introduction and development of Mendel's Laws 3.2.1. Mendel's First Law 3.2.2. Mendel's second law 3.2.3. Mendel's third law 3.3. Chromosomal basis of Mendel's Laws 3.3.1. Exceptions to Mendel's Laws 3.3.2. Chromosomal theory of heredity 3.3.3. Genetics concepts 3.3.4. Types of inheritance 3.4. Human genetics 3.4.1. Inheritance of blood groups 3.4.2. Sex inheritance 3.4.3. Sex-linked inheritance 3.4.4. Heredity influenced by sex 3.5. Genetics problems 3.5.1. Inheritance of a character (problems solved) 3.5.1.1. Albinism (problems solved) 3.5.1.2. Rh groups (problems solved) 3.5.1.3. Eye color (problems solved) 3.5.1.4. More inheritance problems of a character 3.5.1.5. More inheritance problems of a character 3.5.1.6. More inheritance problems of a character 3.5.1.7. More inheritance problems of a character 3.5.2. Two-character inheritance (problems solved) 3.5.2.1. More two-character genetic inheritance solved problems 2 3.5.2.2. More two-character genetic inheritance solved problems 3 3.5.2.3. More two-character genetic inheritance solved problems 4 3.5.2.4. More two-character genetic inheritance solved problems 5 3.5.3. Codominance and intermediate inheritance (problems solved) 3.5.3.1. More codominance and intermediate inheritance problems 2 3.5.4. Sex-linked inheritance (problems solved) 3.5.4.1. Color blindness or daltonism (problems solved) 3.5.4.1.1. More color blindness problems or daltonism 3.5.4.2. Hemophilia (problems solved) 3.5.4.3. Sex-linked inheritance (two characters) 3.5.4.4. More sex-linked inheritance problems 3.5.5. Sex-influenced inheritance (problems solved) 3.5.6. Multiple alleles (problems solved) 3.5.6.1 AB0 blood groups (problems solved) 3.5.6.1.1. More AB0 blood group problems solved 2 3.5.6.1.2. More AB0 blood group problems solved 3 3.5.7. Genealogical trees 3.5.7.1. Family Trees 2 3.5.7.2. Family Trees 3 3.6. Bibliography 4. Origin and evolution of living beings 4.1. Hypothesis about the origin of life on Earth 4.2. Evolution of living beings 4.3. Theories of evolution 4.3.1. Lamarck 4.3.2. Darwin and Wallace 4.3.3. Neo-Darwinism 4.3.4. Other evolutionary theories 4.4. Evidences of evolution 4.4.1. Anatomical evidence of evolution 4.4.2. Embryological evidence of evolution 4.4.3. Paleontological evidence of evolution 4.4.4. Biogeographic evidence of evolution 4.4.5. Biochemical evidence of evolution 4.5. Mechanisms of evolution 4.5.1. Genetic variability 4.5.2. Natural selection 4.5.3. Consequences of evolution 4.5.3.1. Adaptation of organisms 4.5.3.2. Speciation 4.5.3.3. Species diversification 4.6. Human evolution: process of hominization 4.6.1. Primates 4.6.2. Hominids 4.6.3. The human being 4.7. Bibliography 5. The history of the Earth 5.1. The origin of the Earth 5.2. Earth, a changing planet 5.3. Geological time: historical ideas about the age of the Earth 5.4. Dating methods 5.4.1. Relative dating 5.4.1.1. Geological history exercises - relative dating 5.4.2. Absolute dating 5.5. Fossils 5.5.1. Fossils in Aragon 5.6. Geological history of the Earth 5.6.1. Precambrian 5.6.2. Phanerozoic 5.6.2.1. Paleozoic 5.6.2.2. Mesozoic 5.6.2.3. Cenozoic 5.7. Bibliography 6. Structure and dynamics of the Earth 6.1. Earth study methods 6.1.1. Seismic discontinuities 6.2. Structure and composition of the Earth 6.2.1. Geochemical model 6.2.2. Dynamic model 6.3. Bibliography 7. Plate tectonics 7.1. From continental drift to plate tectonics 7.1.1. Wegener continental drift 7.2. Plate Tectonics and its manifestations 7.2.1. Lithospheric plates 7.2.2. Oceanic ridges 7.2.2.1. Expansion of the ocean floor 7.2.3. Ocean trenches 7.2.4. Transforming faults 7.2.5. Formation of mountain ranges 7.3. The Wilson cycle 7.4. Rock deformation 7.4.1. Folds 7.4.2. Faults 7.4.3. Joints 7.4.4. Mixed structures 7.5. Bibliography 8. Ecosystems 8.1. Ecosystem structure 8.1.1. Types of ecosystems 8.1.1.1. Aquatic ecosystems 8.1.1.2. Terrestrial ecosystems 8.1.1.2.1. Urban ecosystems 8.2. Components of the ecosystem: community and biotope 8.2.1. Biotope 8.2.2. Biocenosis or community 8.3. Habitat and ecological niche 8.4. Limiting factors and adaptations 8.5. Tolerance limit 8.6. Trophic levels 8.7. Trophic relationships: chains and networks 8.8. Ecological pyramids 8.9. Self-regulation of the ecosystem, the population and the community 8.9.1. Intra and interspecific relationships 8.10. Matter cycle and energy flow 8.11. Biogeochemical cycles 8.11.1. Carbon cycle 8.11.2. Nitrogen cycle 8.11.3. Phosphorus cycle 8.12. Ecological successions 8.13. Bibliography 9. Resources and environmental impacts 9.1. Human activity and the environment 9.2. Natural resources and their types 9.3. Environmental impacts 9.3.1. Pollution of the atmosphere 9.3.1.1. Air pollutants 9.3.1.2. Acid rain 9.3.1.3. The smog 9.3.1.4. Ozone layer hole 9.3.1.5. Increased greenhouse effect 9.3.1.6. Climate change 9.3.2. Noise pollution 9.3.3. Light pollution 9.3.4. Water contamination 9.3.4.1. Water pollutants 9.3.4.2. Water eutrophication 9.3.4.3. Aquifer reduction 9.4. Soil 9.4.1. Soil contamination 9.5. Main environmental problems of Aragon 9.6. Overpopulation and its consequences 9.7. Waste and its management 9.8. Bibliography and student work « Previous \| Next » 9.3.1.4. Ozone layer hole Ozone layer The ozone layer (O₃) is in the stratosphere, about 25 km high, and acts as a filter for ultraviolet rays, preventing them from reaching the earth's surface and damaging the health of living beings. The ozone layer began to thin out when, starting in the 1970s, CFCs (chlorofluorocarbons) began to be released from aerosols, solvents, refrigerants, and fertilizers. CFCs, by the action of solar radiation, release chlorine and bromine in the stratosphere, which react with ozone and decompose it. This caused that in the 80s, in the Antarctic area (South Pole) it decreased significantly, originating the well-known hole in the ozone layer. It is not really a hole, but a decrease in the thickness of the ozone layer. In the 90s the emission of CFCs was banned and you can already see how it is increasing its thickness again. Why does the ozone hole occur in Antarctica? The depletion of the ozone layer is produced by the presence in the stratosphere of CFCs (chlorofluorocarbons) and nitrogen oxides. Chlorine from CFCs reacts with ozone (O₃) to form chlorine oxides, capturing oxygen atoms, and preventing the ozone layer from regenerating. Cl + O₃ → Cl₂O + O₂ The special atmospheric conditions of Antarctica have favored the ozone layer to decrease its thickness by more than 50%, allowing the entry of ultraviolet radiation. This ultraviolet radiation is the cause of some diseases in humans (such as skin cancer, visual problems, deficiencies in the immune system, etc.), and mutations in animals and plants. The hole in the ozone layer becomes larger in September, when the temperature is very low (southern hemisphere) and sunlight begins to appear over the horizon (south pole), when chemical reactions begin to destroy ozone. In October, this ozone destruction stops, and the hole shrinks. From October to December, the hole moves towards mid-latitudes. Evolution and solutions Since the 1990s, the use of CFCs and other chemicals that damage the ozone layer has been discontinued and, until seven years later, a decrease in CFCs in the troposphere could not be observed. Although there is already an improvement and the ozone layer is gaining thickness, due to the long life that CFCs have in the atmosphere, it is believed that it will not reach its natural situation until the year 2070. Cartoons about the hole in the Ozone layer: Ozzy Ozone (part 1 and part 2). Answer in your notebook 9.4.- What is the cause of the depletion of the ozone layer? Licensed under the Creative Commons Attribution Share Alike License 4.0 « Previous \| Next » You can ask, comment, contribute, get in touch with other users in the forum of this course. This course is translated from https://biologia-geologia.com/BG4/
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Ozone layer

Why does the ozone hole occur in Antarctica?

Evolution and solutions