Any unwanted change in composition earth's atmosphere as a result of the entry into it of various gases, water vapor and solid particles (under the influence of natural processes or as a result of human activity).
Approximately 10% of pollutants enter the atmosphere due to natural processes, such as volcanic eruptions, which are accompanied by emissions of ash, pulverized acids, including sulfuric acid, and many poisonous gases into the atmosphere. In addition, the main sources of sulfur in the atmosphere are sea water splashes and decaying plant residues. It should also be noted forest fires, as a result of which dense clouds of smoke are formed, enveloping large areas, and dust storms. Trees and shrubs emit a lot of volatile organic compounds (VOCs), which form a blue haze that covers most of the Blue Ridge Mountains in the United States (translated as "blue ridge"). Microorganisms present in the air (pollen, fungi, bacteria, viruses) cause allergy attacks and infectious diseases in many people.
The remaining 90% of pollutants are of anthropogenic origin. Their main sources are: the combustion of fossil fuels in power plants (smoke emissions) and in car engines; industrial processes that do not involve fuel combustion but lead to atmospheric dusting, for example, due to soil erosion, open-pit coal mining, blasting and leakage of VOCs through valves, pipe joints in refineries and chemical plants and from reactors; solid waste storage; as well as a variety of mixed sources.
Pollutants entering the atmosphere are transported over long distances from the source, and then return to the earth's surface in the form of solid particles, droplets or chemical compounds dissolved in precipitation.
Chemical compounds, the source of which is at ground level, quickly mix with the air of the lower atmosphere (troposphere). They are called primary pollutants. Some of them enter chemical reactions with other pollutants or with the main components of the air (oxygen, nitrogen and water vapor), forming secondary pollutants. As a result, phenomena such as photochemical smog, acid rain and the formation of ozone in the surface layer of the atmosphere are observed. The source of energy for these reactions is solar radiation. Secondary pollutants - photochemical oxidants and acids contained in the atmosphere - represent a major threat to human health and global environmental change.
Air pollution has a harmful effect on living organisms in several ways: 1) delivering aerosol particles and toxic gases into respiratory system human and animal and in the leaves of plants; 2) increasing the acidity of precipitation, which, in turn, affects the change chemical composition soil and water; 3) by stimulating such chemical reactions in the atmosphere that lead to an increase in the duration of exposure of living organisms to harmful solar rays; 4) changing the composition and temperature of the atmosphere on a global scale and thus creating conditions unfavorable for the survival of organisms.
The atmosphere, or "ocean of air", is made up of the gases necessary to sustain life on Earth. According to its height, it can be divided into five layers, or shells, surrounding Earth: troposphere, stratosphere, mesosphere, thermosphere and exosphere. Their boundaries are determined by sharp changes in temperature due to differences in the absorption of solar radiation. Air density also changes with altitude. In the upper layers of the atmosphere, the air is cold and rarefied, and near the Earth's surface, due to gravity, it is denser. The two lower layers of the atmosphere are mainly polluted.
Two global environmental problems associated with air pollution pose a serious threat to the health and prosperity of mankind and other forms of life: abnormally high values of ultraviolet radiation from the Sun coming to the earth's surface, due to a decrease in the ozone content in the stratosphere, and climate change (global warming) caused by into the atmosphere of a large number of so-called. greenhouse gases.
Both problems are closely interrelated, since they depend on the entry into the atmosphere of almost the same gases of anthropogenic origin. For example, fluorochlorine-containing freons (chlorofluorocarbons) contribute to the destruction of the ozone layer and play an important role in the occurrence of the greenhouse effect.
Indoor air pollution is the leading cause of cancer. The main sources of this pollution are radon, products of incomplete combustion, and the evaporation of chemicals.
Datsenko I.I. Air environment and health. Lvov, 1981
Budyko M.I., Golitsyn G.S., Israel Yu.A. Global climate catastrophes. M., 1986
Pinigin M.A. Atmospheric air protection. M., 1989
Bezuglaya E.Yu. What breathes industrial city. L., 1991
Aleksandrov E.L., Israel Yu.A., Karol I.L., Khrgian L.Kh. Ozone shield of the Earth and its changes. St. Petersburg, 1992
Climate, weather, ecology of Moscow. St. Petersburg, 1995
For the preparation of this work, materials from the site were used.
It's no secret to anyone that last years the most pressing issue for Russian citizens is an environmental issue. This is confirmed by a survey of the All-Russian Center for the Study public opinion(VTsIOM), carried out on behalf of the Ministry natural resources and ecology of the Russian Federation. During the survey, it was determined that the problems of municipal waste cause the greatest concern among residents - this is 44% of the total volume noted by citizens. environmental issues.
There are usually many problems associated with traditional landfills - they are breeding grounds for rodents and birds, pollute water bodies, ignite spontaneously, the wind can blow debris off them, etc. In the 1950s, the so-called "sanitary landfills" began to take root for the first time, where waste is poured over with soil every day.
Based on website articles: http://ztbo.ru/o-tbo/lit/ekologicheskie-problemi-otxodov/zaxoronenie-musora-tbo http://ztbo.ru/poligoni-tbo/rekultivaciya-poligonov-tbo http://news.ners. ru/dom-u-svalki-est-li-opasnost.html an article was written about the mortal danger for residents of the solid waste landfill
The landfill or landfill is a complex system, the detailed study of which has only recently begun.
With a lack of oxygen, organic waste in a landfill undergoes anaerobic fermentation, which leads to the formation of a mixture of methane and carbon monoxide (the so-called "landfill gas"). In the bowels of the landfill, a very toxic liquid (“leachate”) is also formed, the ingress of which into reservoirs or groundwater is highly undesirable.
Requirements for modern landfills include requirements for site selection, design, operation, monitoring, decommissioning and provision of financial guarantees (disaster insurance, etc.)
When choosing a site, it is necessary to avoid the proximity of airports, reservoirs, groundwater outlets, the proximity of wetlands, tectonic faults and seismically hazardous zones.
The safe operation of the landfill involves the following measures:
hazardous waste exclusion procedures and record keeping of all waste received and the exact location of their disposal;
providing daily coverage of dumped waste with soil or special foam to prevent waste from spreading;
control of disease vectors (rats, etc.), which is usually achieved by the use of pesticides;
pumping out explosive gases from the bowels of the landfill (methane can be used to generate electricity, for example, throughout the UK, such installations produce 80 MW);
controlled access of people and animals to the landfill - the perimeter must be fenced and guarded;
hydraulic structures should minimize the ingress of rainwater and surface water into the landfill;
surface runoff from the landfill should be sent for treatment; the liquid that is released from the waste should not enter the groundwater - for this, special drainage and waterproofing systems are created;
regular monitoring of air, ground and surface waters in the vicinity of the landfills should be carried out.
Particular attention should be paid to the decommissioning of the landfill with subsequent reclamation of the landfill. As a rule, the original design of the landfill should include an action plan for reclamation and long-term monitoring of the closed landfill, etc.
Reclamation of waste landfills (MSW)
Each landfill sooner or later closes when it accumulates the maximum allowable amount of waste. And it is quite logical that the land occupied by the landfill must be put back into economic use, or recultivated. Moreover, the costs of this event should be included in the cost even at the stage when the design of solid waste landfills is carried out.
Thus, the reclamation of solid waste landfills is a set of works aimed at restoring the national economic value and productivity of the restored territories. In addition, these works are also aimed at improving the environmental conditions of the environment.
The process of reclamation of solid waste landfills begins immediately after the end of the storage of garbage on it. This procedure is performed in two separate stages: technical and biological.
At the technical stage, the development of technological and construction measures, design solutions for the installation of protective screens for the base and surface of the landfill, the collection, purification and utilization of biogas, the collection and processing of leachate and surface Wastewater. Thus, the technical stage of landfill reclamation includes the following activities:
Stabilization of the landfill body (delivery of soil for backfilling dips and cracks, its layout and creation of slopes with the required angle of inclination, etc.).
Construction of a degassing system to collect landfill gas.
Creation of a system for the collection and removal of leachate and surface runoff.
Creation of a multifunctional reclamation protective screen.
The biological stage of reclamation provides for a complex of agrotechnical and phytomeliorative measures aimed at restoring disturbed lands. This stage is carried out after the engineering and technical stage of reclamation. This stage of landfill reclamation includes the following activities:
Soil preparation.
Selection of planting material.
Sowing plants.
In each case, the choice of design solutions for the reclamation of a closed landfill is carried out on the basis of preliminary engineering surveys.
Collection of landfill gas (syngas)
Landfill gas is formed as a result of fermentation of the organic components of the waste that are in the body of the landfill during the processes of biochemical decomposition. In addition, a sufficiently large amount of water vapor also occurs. The gases and vapors arising in the body of the landfill form a wet gas mixture, the main components of which are methane CH and carbon dioxide CO2.
Due to this chemical composition, as well as the presence of other hazardous components in landfill gas, its emission can have a negative impact on environment, which appears as:
fire and explosion hazards.
interference for the reclamation of the solid waste landfill.
the spread of the corresponding unpleasant odor.
release of components toxic and hazardous to human health.
negative impact on the climate.
Based on this, the landfill gases that form must be collected and subsequently disposed of (treated). To do this, at the stage when the construction of the solid waste landfill is carried out, special gas outlets are provided. Through them, landfill gas enters the storage site, where it undergoes a purification procedure.
The collection of landfill gas is a rather responsible business, since, if its collection is not properly managed, an excess amount of gas accumulates inside the landfill. This leads to an increase in pressure, the accumulated gas is looking for a way out, as a result of which the body of the landfill is destroyed. And that can lead to enough backfire, since raw landfill gas contains a huge amount of harmful and toxic substances that are extremely dangerous for human health.
There is another category of garbage dumps, which appeared as a result of the actions of the shadow business. Waste is accepted and stored on them in violation of all standards. As a result, groundwater, soil, air are polluted - from uncontrolled burning of garbage. “The biggest difficulty here is that often, having “shat” on a certain territory, “merchants” disappear or get off with minor fines for them, while dozens of hectares remain polluted forever,” says Sergei Vinogradov, chairman of the Green Front NGO.
Legal landfills - subject to all technological standards of operation and constant monitoring - theoretically should not harm the city and citizens. In practice, the so-called human factor is often included. “Any landfill is a source of potential danger. main factor negative impact These are landfill mass fires as a result of negligence and violation of the rules for the operation of landfills, ”says Gulnara Gudulova, assistant head of the Rosprirodnadzor Department for the Northwestern Federal District. 
Residents of areas located in relative proximity to solid waste landfills feel the results of such negligence on themselves, periodically inhaling smoke or “ambre” carried by the wind. “It can be argued with a high degree of probability that the unpleasant smell from landfills has a negative impact on human health,” says Sergey Vinogradov. In his opinion, when burning plastics, substances such as formaldehyde, acetic acid, acetaldehyde, carbon monoxide, dioxins can be released into the air. The latter have a powerful mutagenic, immunosuppressive, carcinogenic effect. When burning foam rubber, which is used to make furniture, toxic gases containing cyanide compounds enter the atmosphere. Burning rubber gives off dense black greasy smoke containing hydrogen sulfide and sulfur dioxide. Both gases are hazardous to health. As a result of the decay of garbage left in the ground, Vinogradov continues, dangerous radon gas is formed, which is difficult to detect, since it has no color and smell. But this gas is poisonous, and even radioactive.
4.1 Gases in soils.
Soils are known to be porous; the presence of pores determines the possibility of containing gases and water in soils. Depending on how filled the pores are with one of these components, the soils will be a two- or three-component system. Fully water-saturated soils are considered as a two-component system.
The volume of pores determines the limit values for the amount of water and gases in soils: the more pores are filled with water, the less gases they contain, and vice versa. The predominant component (water or gas) to a very large extent determines the properties of soils.
The intensity of gas exchange between the soil and the atmosphere depends on their composition and structure and is caused by diffuse mixing of gases, fluctuations in temperature and pressure, atmospheric air, precipitation and wind.
Between atmospheric air and the gas component of soils, the differences are greatest in the quantitative content of carbon dioxide, oxygen and nitrogen. If carbon dioxide in the atmospheric air is only hundredths of a percent (about 0.03%), then its content in soils and rocks increases to tenths and even whole percent, and in soil air can reach almost 10%. Oxygen and nitrogen in the thickness of soils are contained in different quantities.
Gases in the pores of soils can be in different states: free, adsorbed And pinched In addition, in the water that fills the pores, gases can be present in the form of small bubbles or be dissolved in it.
Adsorbed and trapped gases have a definite effect on soil properties. The amount of adsorbed gases on the surface of soil particles, held by molecular forces, depends on the mineralogical composition of soils, the presence of humus in them, and others. organic matter and compounds, on the degree of dispersion, heterogeneity, morphological parameters of soil particles and its porosity. IN most adsorbed gases are contained in absolutely dry soils, as they become moistened, their content decreases and at a moisture content of 5–10% becomes equal to zero.
When moistening is associated with the capillary rise of water in soils, gases from open pores are displaced into the atmosphere. With simultaneous excessive moistening of the soil from below and from above, in some of its sections, the gases are closed in the pores inside the soil. These are the so-called "pinched gases" or "pinched air", which is often characteristic of the rocks of the surface zones. earth's crust. Pinched gases occupy significant areas in the soil or are in small quantities in the finest micropores of the soil, which is common for silty and clayey soils.
Maximum amount trapped gases, in contrast to adsorbed gases, is formed in soils at some moisture content that is optimal for a given soil. For example, in clayey soils, trapped gases can occupy up to 20–25% of the pore volume of soils.
Adsorbed and trapped gases are removed from soils with great difficulty by external pressure.
The presence of adsorbed and trapped gases in soils causes long-term settlement of embankments from clay soils, deformations and ruptures of earthen embankments, and a decrease in soil water permeability.
The air we breathe is a mixture of gases: oxygen, nitrogen, carbon dioxide and others. Special gases are used in the household and in various industries. Synthetic materials are made from gases. Some types of vehicles run on gas.
Some facts
- The gas that people use at home and at work is natural gas. Natural gas is a mineral. It is formed in the bowels of the Earth and is a mixture of various gases.
Gas, like fire, helps a person, but in some cases it becomes dangerous:
- if there was an uncontrolled leakage;
- if a lot of gas has accumulated in a closed room.
In nature, there are different gases with different properties: some gases rise up, while others collect below, near the surface of the earth. Some gases are harmless, others are life-threatening. Situations may arise when, in order to save your life, as well as to help the victim, you must know what kind of gas you are dealing with.
In high school chemistry lessons, you will learn all the properties of various gases, but for now let's get acquainted with them from the point of view of life safety.
Let's talk more about dangerous gases, the most common in everyday life.
Carbon monoxide ruins a lot human lives in case of fires, as well as in baths, country and rural houses with improper use of stove heating. It is extremely poisonous, and since it is odorless and colorless, it does not irritate the eyes and is difficult to detect. In a dwelling, in a bathhouse, the source of carbon monoxide is incomplete combustion of fuel in stoves, premature closing of the stove valve. Carbon monoxide poisoning - over common cause deaths in fires than fire and heat. The same gas is the cause of death in the cold season of people basking in a car with the engine running. Carbon monoxide is also formed during the incomplete combustion of household gas. Therefore, poor ventilation in the kitchen and bathroom (with a geyser) can also lead to death. Carbon monoxide gas rises, and, therefore, in the room where this gas has accumulated, one must crawl.
In addition to carbon monoxide, car exhaust contains and accumulates along highways and another toxic gas - nitrogen oxide. Therefore, it is best to avoid walking on busy streets and close windows facing the road, especially during rush hours. And also never pick mushrooms and berries near roads where cars often drive!
Toxic gases are also emitted during the combustion of synthetic finishing materials, carpets. In order not to get poisoned, it is better to move low crouching. More air is stored at the bottom.
You should be aware of the poisonous gas that forms in the ground - the uppermost layer of the earth's surface, and which can accumulate in depressions in the terrain. For example, in old landfills, in swamps, in sewer wells, basements, mines. This gas also has no taste and smell, it is heavier than air. In such cases, it is necessary to approach the victim in protective equipment.
city gas. It can be of two types: main gas, more often used in major cities, and liquefied gas in cylinders, consisting of a mixture of two gases - propane and butane. Propane is lighter than air and therefore rises; butane is heavier and therefore, when leaking, it fills first of all basements and underground utilities.
Household gas has neither color nor smell. Therefore, a strongly smelling substance is added to it, giving it a special “gasy” smell. Thanks to him, we can detect a "leak" of gas.
Causes of household gas leakage:
- malfunction of gas pipes, stoves, columns, cylinders;
- improper installation of gas equipment;
- weak fastening of the rubber hose between the cylinder (pipe) and the stove;
- incomplete closing of the gas stove tap;
- flooding the fire of a gas burner with boiling water;
- blowing out a weak fire with a draft.
Explosion, fire and poisoning of people can result from gas leakage.
If you are heating or cooking food yourself, stay close to the gas stove and keep an eye on the gas burner.
It is very important to ensure good ventilation in the room where the gas stove is installed. If there is no exhaust installation, then during long-term operation of the gas stove, you must always keep the window or window ajar. If there is a ventilation hole in the kitchen, it is necessary to monitor the cleanliness of the filter installed in it, as it gradually becomes clogged with dust and soot.
Know that the flame of burning gas should be even, blue. If it is red or yellow, and carbon deposits appear on the dishes, the gas does not burn completely. We need to call the master.
Remember! If there is a smell of domestic gas in the house or entrance, you can not use electricity: turn on the light, ring the electric bell, call the elevator, as well as matches and lighters. Any spark can cause a gas explosion throughout the house. If you smell the gas, quickly open the doors and windows to let the draft blow out the accumulation of poisonous gas. Shut off the gas pipe. All this must be done while holding your breath and covering your mouth and nose with any tissue. If the cause of the gas contamination is unclear and it is not possible to eliminate it on your own, then you should quickly leave dangerous place and call the emergency gas service by calling "04".
When poisoned with any gas, a person first begins to get very sick and dizzy, there is tinnitus. Then it darkens in the eyes, nausea begins. If this happens to you, you need to quickly leave this room and inform adults about your condition and the danger that has arisen.
With more severe poisoning, consciousness is disturbed, muscle weakness and drowsiness appear. Loss of consciousness, convulsions and death are possible.
First aid for a victim of carbon monoxide or household gas: immediately take (take out) him to the street. If breathing is weak or stops, artificial respiration should be applied. Rubbing the body, applying a heating pad to the legs, short-term inhalation of ammonia vapors help in such cases. If a person has signs of severe poisoning, then an ambulance should be called urgently.
Questions
- What dangerous gases do you know?
- Where does carbon monoxide accumulate in an enclosed space? Why?
- What should a person do if he feels signs of gas poisoning?
- Which rescue service should I contact in case of a household gas leak?
- What can not be done in the event of a household gas leak in an apartment or other enclosed space?
- situational task.
- Misha came home and smelled gas. He immediately went to the kitchen and turned on the light... Did Misha do the right thing?
- How to help a person if he was poisoned by household or carbon monoxide gas?
- Where and under what conditions Everyday life can you meet with carbon monoxide?
The problem of the detrimental effect on forest and green plantations (especially coniferous ones) of industrial emissions of gases and fumes has now become one of the most important in the protection of forests.
Of the toxic substances found in the soil and affecting plants, it should be noted natural (luminous) gas, sulfuric acid and others. Natural gas, acting on the root systems of plants, causes them to develop abnormal roots, slowing down the growth of the plant. This gas kills tree seeds in the soil. The odorous elements of the gas are easily absorbed by soil particles and are retained by them for a long time. The most sensitive to gas are hardwoods (poplar, elm, ash, maple), conifers are less sensitive.
Sulfuric acid causes burns on the roots of seedlings: the first time after dressing, the soil (in nurseries) dries up from the surface and, as a result, the concentration of acid in the soil increases.
Harmful gases, ash, soot, and solid mineral particles in the atmosphere have a different effect on the vital activity of plants. From dust containing harmful substances, the needles of plants begin to turn brown, turn yellow, and fade. Coal dust particles are almost harmless, as well as street and cement dust. Soot, while not causing the leaves and needles to dry out during the summer heat, is, however, one of the elements that hinder the growth of coniferous plants in the parks of large cities.
Currently, a large amount of dust comes from industrial enterprises. The forest plays a big role in its absorption,
Damage caused by the smoke of the Pitsunda pine in Georgia leads to serious consequences and drying out.
In the pine-spruce plantations of Scandinavia, located in the coastal regions of the seas, yellowing of pine needles is quite often observed. The latter is associated with increased air humidity and high concentrations of salt evaporation in the atmosphere.
Similarly, pines and spruces located along highways are affected by the evaporation of chloride salts, which are used in winter to clear roads from snow and ice.
As a result of industrial emissions into the atmosphere, a large amount of nitrogen and sulfur compounds falls to the ground along with precipitation in the form of snow and rain. "Acid rain" acts as a solvent for aluminum in the soil. As a result, compounds of this metal fall into lakes, rivers and infect groundwater, and an increased content of aluminum compounds in water and food harms plants, animals and people.
The most common gases that pollute the atmosphere and accompany certain production processes are carbon monoxide, nitrogen oxides, carbon dioxide and sulfur dioxide, hydrogen chloride, sulfur dioxide; less common are fluorine and hydrogen fluoride. Substances harmful to plants also include sulfuric acid, fluorine compounds in the form of dust and gaseous substances.
Nitrogen oxides in a concentration of more than 2 mg/m 3 cause severe damage to the needles (reddening of the tips of the needles).
Acid precipitation (or acid rain) is 60% due to sulfur dioxide and 40% to nitrogen oxides. They adversely affect the surface of the needles, impede respiration and gas exchange, poison plants as a result of the penetration of acidic compounds into the needles and branches, reduce the intensity of photosynthesis and seed germination. The most vulnerable to acid rain is white pine, and among the deciduous - downy birch and aspen-shaped poplar.
Interesting studies on the effect of acid rain (SO 2 ) on young growth of the Aleppo pine have been carried out in Greece. During one growing season, annual seedlings of Allepo pine were irrigated with acid precipitation with a pH of 3.1-3.5 (pH 5.1 in the control). By the end of vte. the first growing season, the seedlings were treated with the same solution (pH 3.3). Pines had a height of 22.6 cm, 8.2% less than in the control. The total sulfur content in the needles of pine trees treated with "sour rain" was 0.13%, in the control 0.12%. Ultimately, "acid rain" had a negative effect on the formation of thermal nights, dissolved and leached significant amounts of calcium carbonate from the soil.
Under the action of sulfur in an amount of 20-30 mg / m 3 for 10 hours, no changes in the vegetative organs of plants occur, at 50 mg / m 3 they are already noticeable, and at 100 mg / m 3 the vegetative organs die off. The content of sulfur dioxide in the needles of spruce trees not damaged by the gas reaches 0.23% of the absolutely dry weight, and 0.74% in damaged trees. If the amount of sulfur dioxide in the air reaches 260 mg / m 3, conifers die within a few hours.
With an increase in humidity, there is an increase in the concentration of harmful fumes and gases, which can often reach toxic values that can cause not only chronic damage invisible to the eye, but also acute poisoning, directly leading to the death of the plant.
In dry years, sulfur dioxide does less harm to plants than in wet years. Sulfur dioxide is more dangerous in the presence of water vapor and surfactant dust, especially soot, when it oxidizes to sulfur dioxide and forms sulfuric acid. This is consistent with the lower susceptibility of plants in dry weather. The toxicity of sulfur dioxide gases to some extent also increases if they contain carbon monoxide, impurities of aldehydes and especially ozonides. The presence of nitrogen oxides in them greatly increases the toxicity of sulfur dioxide.
The gas resistance of tree species is different. Pine and spruce are very sensitive to smoke. Of hardwoods, alder, oak, goof, elm, birch bark, and ash-leaved maple are insensitive. The most gas-resistant poplars are Canadian poplar and balsamic. Mostly drought-resistant rocks are also gas-resistant.
Acid gases cause burns on plants. This is due to the penetration of gases into the tissues of the leaves, which occurs mainly through the stomata.
N. P. Krasinsky distinguishes 3 types of gas resistance: biological, morphological-anatomical and physiological. The first is related to the plant's ability to quickly restore plant organs (leaves, shoots) damaged by gases. The second is based on the features of the morphological and anatomical structure of plants, limiting gas exchange, and therefore hindering the flow of gas into leaf tissues.
Physiological gas resistance is associated with the ability of plants to withstand the harmful effects of gases due to their internal properties and characteristics. physiological processes, as well as the chemical and physico-chemical state of the cellular environment.
Yu. Z. Kulagin proposed to replace the term “smoke resistance” with the term “gas resistance” and singled out its various forms at the cellular-tissue, organismal, and population-coenotic levels.
The acceleration of the drying process of forests under the influence of smoke in the zone of industrial enterprises is affected by: 1) incorrect felling planning (the width and direction of cutting areas are assigned without taking into account the influence of flue gases); 2) unsystematic sanitary cabins (over large areas).
The drying process is more intensive in spring and summer (it is absent in winter), drying begins from the tops. Mixed plantations are more resistant to gas than pure ones, natural forests are more stable than artificial ones, high-density forests are more stable than low-density ones.
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