Before talking about the problem of ozone layer destruction, it is worth understanding what the ozone layer (screen) is and why its depletion is dangerous for the environment?
Ozone layer- one of the uppermost layers of the atmosphere of our planet. Despite its insignificant thickness (it is often compared to one book page in relation to an entire library), it protects the flora and fauna of the Earth from harmful short-wave ultraviolet rays emanating from the Sun. But this does not mean that it completely reflects the sun's rays; it attenuates radiation by about 6,500 times, making them relatively harmless.
Without the ozone layer, many important microorganisms for the ecosystem would be destroyed, flora and fauna would be subject to mutation, and the vision of animals and humans would be greatly affected.
It is noteworthy that ozone itself is also a dangerous substance, which in large quantities negatively affects human health. It contributes to destructive processes in human lungs, premature aging of tissues, etc. But its share in the atmosphere is extremely small, it is about 0.0001%. The smell of ozone can be heard after a severe thunderstorm.
Depletion of the ozone layer is the formation ozone holes through which ultraviolet radiation penetrates.
Causes of ozone layer depletion
Human activity greatly affects the depletion of the ozone layer and the appearance of holes in it. For example, they are formed when rockets are launched. Airplanes flying at an altitude of 12-16 also contribute to the destruction of the layer. Including the greenhouse effect, mass cattle breeding, industrial emissions of harmful substances, etc.
Release of freons into the atmosphere. If we talk about substances that contribute to the destruction of the ozone layer, then freons are the most “effective” of them. Freons- these are gases that do not enter into any chemical reactions at the surface of the planet. For a long time they were used in aerosol sprays, but have now gained popularity in industrial production.
Rising to the upper layers of the atmosphere, freon enters into a chemical reaction, converting ozone into oxygen, thus splitting the ozone shield.
Depletion of the ozone layer: ways to solve the problem
Since the reasons for the formation of ozone holes lie in man's inattention to nature, the way to solve the problem is obvious - switching to a more environmentally friendly lifestyle.
If it is possible to reduce the number of vehicles using gasoline as fuel at the global level, and instead increase the production of electric cars; reduce the area of livestock farms; solve the problem of the greenhouse effect; install cleaning technologies on the territory of factories that pollute the air with their waste, then, of course, the problem of holes in the ozone screen will be solved.
However, the problem of ozone layer depletion is not the only global environmental problem. You can read about other dangers that seriously threaten our planet.
the new era of active space exploration, namelyspace rocket launches . The substances that make up the expiring jet stream (which propels the rocket) intensively destroy ozone. Thus, at the launch site of the launch vehicle, a large “hole” appears in the ozone layer, which, as it turns out, takes a very long time to heal. And every year there are more and more such “holes drilled in the atmosphere.” Which inevitably leads to the depletion of the Earth's ozone layer.
The second reason for the destruction of the Earth's ozone layer is
intensive development of high-altitude aviation(aircraft flying at altitudes above 12 km). The combustion products of these cars also destroy ozone molecules, leading to the depletion of the Earth's ozone layer. Ozone-active components of exhaust gases are nitrogen oxides and, to a lesser extent, carbon monoxide. Scientists have analyzed ways to reduce nitrogen oxide in jet fuel combustion products. However, to date, research results are disappointing. Reducing nitrogen oxide, which destroys stratospheric ozone, is impossible either by modernizing existing engines or by switching to “environmentally friendly” fuels (liquefied natural gas and liquefied or compressed hydrogen). Reducing the emission of substances that destroy the Earth's ozone layer will only be possible with the creation of fundamentally new engines. But this is still a long way off...
The third reason for the destruction of the Earth's ozone layer is
use of nitrogen fertilizers in agriculture. As they decompose, they release nitrogen oxides, which rise into the stratosphere and... destroy ozone molecules, causing depletion of the Earth's ozone layer, of course.
The fourth reason for the destruction of the Earth's ozone layer is
widespread use of freons in human economic activity(as sprayers, in the refrigeration industry). At the surface of the earth, these gases are practically harmless, since they do not enter into any chemical reactions. But, once in the stratosphere, freons, under the influence of solar radiation, enter into photochemical reactions, releasing atomic chlorine. And one chlorine atom, as mentioned above, during its long life is capable of destroying up to one hundred thousand ozone molecules. Here's one warrior in the field. And the amount of freons in the atmosphere is growing year by year, increasing by about 8-9% annually.
We looked at the reasons for the destruction of the Earth's ozone layer. To sum it up sadly: human activity is destroying the planet. It's time to move on to the next point of this article. What threatens us with the depletion of the Earth's ozone layer?
Consequences of destruction and depletion of the Earth's ozone layer.
Depletion of the ozone layer increases the flow of solar radiation to Earth.
According to doctors, every percentage of ozone lost on a planetary scale causes:
up to 150 thousand additional cases of blindness due to cataracts,
the number of skin cancers increases by 2.6 percent,
The number of diseases caused by a weakened human immune system is significantly increasing.
But it's not just people who suffer. Ultraviolet radiation is also extremely harmful to plankton, fry, shrimp, crabs, algae living on the surface of the ocean, and other organisms of the biosphere.
The problem of ozone layer depletion was discovered a long time ago, but by the 1980s, scientists sounded the alarm. If ozone is significantly reduced in the atmosphere, the earth will lose its normal temperature regime and stop cooling. As a result, a huge number of documents and agreements were signed in various countries to reduce the production of freons. In addition, a replacement for freon was invented - propane-butane. According to its technical parameters, this substance has high performance and can be used where freons are used.
Today, the problem of ozone layer destruction is very relevant. Despite this, the use of technologies using freons continues. At the moment, people are thinking about how to reduce the amount of freon emissions and are looking for substitutes to preserve and restore the ozone layer.
20. Acid rain: causes, mechanisms of occurrence, impact on flora and fauna, buildings.
Acid rain is usually called any precipitation (rain, snow, hail) containing any amount of acid. The presence of acids leads to a decrease in pH levels. Hydrogen index (pH) is a value that reflects the concentration of hydrogen ions in solutions. The lower the pH level, the more hydrogen ions in the solution, the more acidic the environment.
For rainwater, the average pH value is 5.6. When the pH of precipitation is less than 5.6, it is referred to as acid rain. Compounds that lead to a decrease in the pH level of sediments are oxides of sulfur, nitrogen, hydrogen chloride and volatile organic compounds (VOCs).
Causes of acid rain
Acid rain By the nature of their origin, there are two types: natural (arising as a result of the activity of nature itself) and anthropogenic (caused by human activity).
Natural acid rain
There are few natural causes of acid rain:
microorganism activity, volcanic activity, lightning discharges, combustion of wood and other biomass.
Anthropogenic acid rain
The main cause of acid rain is air pollution. If about thirty years ago industrial enterprises and thermal power plants were named as global reasons causing the appearance of compounds in the atmosphere that “oxidize” rain, today this list has been supplemented by road transport.
Thermal power plants and metallurgical enterprises “donate” about 255 million tons of sulfur and nitrogen oxides to nature.
Solid fuel rockets have also made and are making a significant contribution: the launch of one Shuttle complex results in the release of more than 200 tons of hydrogen chloride and about 90 tons of nitrogen oxides into the atmosphere.
Anthropogenic sources of sulfur oxides are enterprises producing sulfuric acid and refining oil.
Exhaust gases from motor vehicles account for 40% of nitrogen oxides entering the atmosphere.
The main source of VOCs in the atmosphere, of course, are chemical industries, oil storage facilities, gas stations and gas stations, as well as various solvents used both in industry and in everyday life.
The final result is as follows: human activity supplies the atmosphere with more than 60% of sulfur compounds, about 40-50% of nitrogen compounds and 100% of volatile organic compounds.
Oxides entering the atmosphere react with water molecules, forming acids. Sulfur oxides, when released into the air, form sulfuric acid, and nitrogen oxides form nitric acid. One should also take into account the fact that the atmosphere above large cities always contains particles of iron and manganese, which act as catalysts for reactions. Since there is a water cycle in nature, water in the form of precipitation sooner or later falls on the earth. Acid also gets in with the water.
Consequences of acid rain
Oxidation of water resources. Rivers and lakes are the most sensitive. Fish die. Despite the fact that some species of fish can withstand slight acidification of water, they also die due to the loss of food resources. In those lakes where the pH level was less than 5.1, not a single fish was caught. This is explained not only by the fact that adult fish die - at a pH of 5.0, most cannot hatch fry from the eggs, as a result of which there is a reduction in the numerical and species composition of fish populations.
Harmful effects on vegetation. Acid rain affects vegetation directly and indirectly. The direct impact occurs in high mountain areas, where tree crowns are literally immersed in acidic clouds. Excessively acidic water destroys leaves and weakens plants. Indirect impact occurs due to a decrease in the level of nutrients in the soil and, as a result, an increase in the proportion of toxic substances.
Destruction of human creations. Building facades, cultural and architectural monuments, pipelines, cars - everything is exposed to acid rain. Many studies have been conducted, and they all say one thing: acid rain exposure has increased significantly over the past three decades. As a result, not only marble sculptures and stained glass windows of ancient buildings are under threat, but also leather and paper products of historical value.
Human health. Acid rain itself does not have a direct impact on human health - if you get caught in such rain or swim in a reservoir with acidified water, you do not risk anything. Compounds that form in the atmosphere due to the entry of sulfur and nitrogen oxides into it pose a threat to health. The resulting sulfates are transported by air currents over considerable distances, are inhaled by many people, and, as studies show, provoke the development of bronchitis and asthma. Another point is that a person eats the gifts of nature; not all suppliers can guarantee the normal composition of food products.
21. Smog: types, mechanism of formation
Smog is a mixture of smoke, fog and some pollutants.
Ozone is a type of oxygen that is found in the stratosphere, approximately 12-50 kilometers above the ground. The highest concentration of this substance is at a distance of approximately 23 kilometers from the surface. Ozone was discovered in 1873 by the German scientist Schönbein. Subsequently, this modification of oxygen was found in the ground and upper layers of the atmosphere. In general, ozone consists of triatomic oxygen molecules. Under normal conditions, it is a blue gas with a characteristic aroma. Under various factors, ozone turns into an indigo-colored liquid. When it becomes hard, it takes on a dark blue hue.
The value of the ozone layer lies in the fact that it acts as a kind of filter, absorbing a certain amount of ultraviolet rays. It protects the biosphere and people from direct solar radiation.
Causes of ozone depletion
For many centuries, people did not suspect the existence of ozone, but their activities had a detrimental effect on the state of the atmosphere. At the moment, scientists are talking about such a problem as ozone holes. Depletion of oxygen modification occurs for a variety of reasons:
- launching rockets and satellites into space;
- operation of air transport at an altitude of 12-16 kilometers;
- emissions of freons into the air.
Major ozone layer depleters
The biggest enemies of the oxygen modification layer are hydrogen compounds and chlorine. This is due to the decomposition of freons, which are used as atomizers. At a certain temperature, they are able to boil and increase in volume, which is important for the manufacture of various aerosols. Freons are often used for freezing equipment, refrigerators and cooling units. When freons rise into the air, chlorine is split off under atmospheric conditions, which in turn converts ozone into oxygen.
The problem of ozone layer depletion was discovered a long time ago, but by the 1980s, scientists sounded the alarm. If ozone is significantly reduced in the atmosphere, the earth will lose its normal temperature regime and stop cooling. As a result, a huge number of documents and agreements were signed in various countries to reduce the production of freons. In addition, a replacement for freon was invented - propane-butane. According to their own technical parameters this substance has high performance and can be used where freons are used.
Today, the problem of ozone layer destruction is very relevant. Despite this, the use of technologies using freons continues. At the moment, people are thinking about how to reduce the amount of freon emissions and are looking for substitutes to preserve and restore the ozone layer.
Fighting methods
Since 1985, measures have been taken to protect the ozone layer. The first step was the introduction of restrictions on the emission of freons. Next, the government approved the Vienna Convention, the provisions of which were aimed at protecting the ozone layer and consisted of the following points:
- representatives different countries adopted an agreement on cooperation regarding the study of processes and substances that affect the ozone layer and provoke its changes;
- systematic observations of the state of the ozone layer;
- creation of technologies and unique substances that help minimize damage;
- cooperation in various areas of development of measures and their application, as well as control of activities that provoke the appearance of ozone holes;
- transfer of technologies and acquired knowledge.
Over the past decades, protocols have been signed according to which the production of chlorofluorocarbons should be reduced, and in some cases completely stopped.
The most problematic was the use of ozone-friendly products in the production of refrigeration equipment. During this period, a real “freon crisis” began. In addition, the developments required significant financial investments, which could not but upset entrepreneurs. Fortunately, a solution was found and manufacturers began to use other substances in aerosols instead of freons (hydrocarbon propellant such as butane or propane). Today, it is common to use installations that can use endothermic chemical reactions that absorb heat.
It is also possible to clear the atmosphere of freon content (as physicists say) using a nuclear power plant power unit, the power of which must be at least 10 GW. This design will serve as an excellent source of energy. After all, it is known that the Sun is capable of producing about 5-6 tons of ozone in just one second. By increasing this indicator with the help of power units, it is possible to achieve a balance between the destruction and production of ozone.
Many scientists consider it advisable to create an “ozone factory” that will improve the condition of the ozone layer.
In addition to this project, there are many others, including obtaining ozone artificially in the stratosphere or producing ozone in the atmosphere. The main disadvantage of all ideas and proposals is their high cost. Large financial losses push projects into the background and some of them remain unimplemented.
Five-minute video about protecting the ozone layer
The sun's molecular oxygen) dissociates into atoms, which then combine with other O2 molecules to form ozone (O3). The relatively high concentration of ozone (about 8 ml/m³) absorbs dangerous ultraviolet rays and protects everything living on land from harmful radiation
Stages of ozone layer destruction:
1) Emissions: as a result of human activity, as well as as a result of natural processes on Earth, gases containing halogens (bromine and chlorine) are emitted (released), i.e. substances that destroy the ozone layer.
2) Accumulation (emitted gases containing halogens accumulate (accumulate) in the lower atmospheric layers, and under the influence of wind, as well as air flows, move to regions that are not in direct proximity to the sources of such gas emissions).
3) Movement (accumulated gases containing halogens move into the stratosphere with the help of air flows).
4) Transformation (most of the gases containing halogens are exposed to ultraviolet radiation The sun in the stratosphere is converted into easily reacting halogen gases, as a result of which the destruction of the ozone layer occurs relatively more actively in the polar regions of the globe).
5) Chemical reactions (easily reacting halogen gases cause the destruction of stratospheric ozone; a factor promoting reactions is polar stratospheric clouds).
6) Removal (under the influence of air currents, easily reacting halogen gases return to the troposphere, where, due to the humidity and rain present in the clouds, they are separated, and thus completely removed from the atmosphere).
Reasons for OS destruction:
Firstly , are launches of space rockets. Burning fuel “burns” large holes in the ozone layer. It was once assumed that these “holes” were closing. It turned out not. They have been around for quite a long time. Secondly , airplanes flying at altitudes of 12-15 km. The steam and other substances they emit destroy ozone. But at the same time, planes flying below 12 km give an increase in ozone. In cities it is one of the components of photochemical smog . Third - nitrogen oxides. They are ejected by the same airplanes, but most of them are released from the soil surface, especially during the decomposition of nitrogen fertilizers.
Consequences:
This negatively affects not only all living beings: people, animals, plants, tropical forests, but also on objects. For example, if the ozone layer becomes too thin, the rubber used on the farm will last much less. Aquatic organisms living in the upper layers of water will cease to exist. The fauna of the Amazon jungle with pythons and parrots will finally die. Fishing catches and agricultural yields will be significantly reduced. Undoubtedly, the destruction of the ozone layer will affect people. Humanity will become sick twice as often because the immune system will weaken significantly. Your risk of developing skin cancer and cataracts will increase.
Scientists suggest that a 1% decrease in the ozone layer will lead to the active spread of diseases. For example, cases of skin cancer will increase by 10 thousand times, and eye cataracts - by 100 thousand. A person’s tendency to develop diseases of the respiratory tract and lungs will increase rapidly.
Scientists are searching for ways to restore the ozone layer. Initially, for this purpose, it was proposed to create factories for the production of ozone, and then deliver it by plane into the atmosphere. Another option is to create balloons equipped with lasers, powered by solar panels, which will use oxygen to create ozone. The most realistic way out of this situation is is a reduction in deforestation and an increase in green spaces.
The ozone layer, despite its enormous importance for all living things, is a very fragile barrier to ultraviolet rays. Its integrity depends on a number of conditions, but nature nevertheless came to a balance in this matter, and for many millions of years the Earth’s ozone layer successfully coped with the mission entrusted to it. The processes of formation and destruction of the ozone layer were strictly balanced...
- ... Until man appeared on the planet and reached the current technical level in his development.
In the 70s twentieth century, it was proven that many substances actively used by humans in economic activity, can significantly reduce the level of ozone in the Earth's atmosphere.
Substances that destroy the Earth's ozone layer include fluorochlorocarbons - freons (gases used in aerosols and refrigerators, consisting of chlorine, fluorine and carbon atoms), combustion products during high-altitude aviation flights and rocket launches, i.e. substances whose molecules contain chlorine or bromine.
These substances, released into the atmosphere near the Earth's surface, reach the upper limit of the ozone layer in 10-20 years. There, under the influence of ultraviolet radiation, they decompose, forming chlorine and bromine, which, in turn, interact with stratospheric ozone, significantly reducing its amount.
- For example, one chlorine atom during its entire existence (74 - 111 years) can break up to 100,000 ozone molecules.
Thus, the share of the halogen decay pathway of stratospheric ozone presented in Table 1 has increased, which has led to the emergence ozone holes– local drops in ozone concentration in the Earth’s ozone layer.
Table 1. Contribution of various chemical families to ozone destruction at different altitudes:
Note: Dear visitors, hyphens in long words in the table are placed for the convenience of mobile users - otherwise the words will not be transferred and the table will not fit on the screen. Thanks for understanding!
Causes of destruction and depletion of the Earth's ozone layer.
Let us consider again in more detail the reasons for the destruction of the Earth's ozone layer. At the same time, we will not consider the natural decay of ozone molecules. We will focus on human economic activity.
The first reason for the destruction of the Earth's ozone layer —
the new era of active space exploration, namely space rocket launches. The substances that make up the expiring jet stream (which propels the rocket) intensively destroy ozone. Thus, at the launch site of the launch vehicle, a large “hole” appears in the ozone layer, which, as it turns out, takes a very long time to heal. And every year there are more and more such “holes drilled in the atmosphere.” Which inevitably leads to the depletion of the Earth's ozone layer.
The second reason for the destruction of the Earth's ozone layer —
intensive development of high-altitude aviation(aircraft flying at altitudes above 12 km). The combustion products of these cars also destroy ozone molecules, leading to the depletion of the Earth's ozone layer. Ozone-active components of exhaust gases are nitrogen oxides and, to a lesser extent, carbon monoxide. Scientists have analyzed ways to reduce nitrogen oxide in jet fuel combustion products. However, to date, research results are disappointing. Reducing nitrogen oxide, which destroys stratospheric ozone, is impossible either by modernizing existing engines or by switching to “environmentally friendly” fuels (liquefied natural gas and liquefied or compressed hydrogen). Reducing the emission of substances that destroy the Earth's ozone layer will only be possible with the creation of fundamentally new engines. But this is still a long way off...
The third reason for the destruction of the Earth's ozone layer is
use of nitrogen fertilizers in agriculture. As they decompose, they release nitrogen oxides, which rise into the stratosphere and... destroy ozone molecules, causing depletion of the Earth's ozone layer, of course.
The fourth reason for the destruction of the Earth's ozone layer —
widespread use of freons in human economic activity(as sprayers, in the refrigeration industry). At the surface of the earth, these gases are practically harmless, since they do not enter into any chemical reactions. But, once in the stratosphere, freons, under the influence of solar radiation, enter into photochemical reactions, releasing atomic chlorine. And one chlorine atom, as mentioned above, during its long life is capable of destroying up to one hundred thousand ozone molecules. Here's one warrior in the field. And the amount of freons in the atmosphere is growing year by year, increasing by about 8-9% annually.
We looked at the reasons for the destruction of the Earth's ozone layer. To sum it up sadly: human activity is destroying the planet. It's time to move on to the next point of this article. What threatens us with the depletion of the Earth's ozone layer?
Consequences of destruction and depletion of the Earth's ozone layer.
Depletion of the ozone layer increases the flow of solar radiation to Earth.
According to doctors, every percentage of ozone lost on a planetary scale causes:
- up to 150 thousand additional cases of blindness due to cataracts,
- the number of skin cancers increases by 2.6 percent,
- The number of diseases caused by a weakened human immune system is significantly increasing.
But it's not just people who suffer. Ultraviolet radiation is also extremely harmful to plankton, fry, shrimp, crabs, algae living on the surface of the ocean, and other organisms of the biosphere.
You can read more about the importance of the Earth's ozone layer and the impact of ultraviolet radiation on the human body and other living organisms on our planet