The influence of environmental pollution on the weather

Greenhouse gases effectively absorb infrared radiation emitted by the same gases and clouds on the earth's surface and the atmosphere itself. Atmospheric radiation is emitted in all directions, including to the surface of the earth below. Greenhouse gases absorb heat in the ground-troposphere system. This is called "natural greenhouse effect". Atmospheric radiation is closely related to the temperature level of its gas emission. In the troposphere, the temperature generally decreases with the increase of altitude. Infrared radiation emitted into space from a certain height is generally generated at a height with an average temperature of-19℃, and the temperature of the earth's surface can be kept at an average temperature of 1 4℃ due to the income balance of solar radiation. The increase of greenhouse gas concentration leads to the enhancement of atmospheric opacity to infrared radiation, which leads to the emission of effective radiation into space from lower temperature and higher altitude. This creates radiation forcing, which can only be compensated by the temperature rise of the ground-troposphere system. This is the "enhanced greenhouse effect".

result

1) the increase of pests and diseases on the earth;

2) sea level rise;

3) Abnormal climate, increasing ocean storms;

4) The land is dry and the desertification area increases.

Scientists predict that if the earth's surface temperature continues to rise at the current rate, by 2050, the global temperature will rise by 2-4 degrees Celsius, the icebergs in the north and south poles will melt greatly, resulting in a sharp rise in sea level, and some island countries and coastal cities will be submerged in water, including several famous international universities.

The concept of air pollution

The atmosphere is a mixture of nitrogen, oxygen, carbon dioxide, water vapor and solid impurity particles in a certain proportion. As far as clean air is concerned, in terms of volume, in the standard state, nitrogen accounts for 78.08%, oxygen accounts for 20.94%, argon accounts for 0.93%, carbon dioxide accounts for 0.03%, and the volume of other gases can be ignored. Various natural changes often cause changes in atmospheric composition. For example, when a volcano erupts, a large amount of dust, carbon dioxide and other gases are injected into the atmosphere, which causes the volcanic eruption area to be full of smoke and toxic gases; Large-scale forest fires caused by natural causes such as lightning will also increase the content of carbon dioxide and smoke particles. Generally speaking, this natural change is local and short-lived. With the development of modern industry and transportation, more and more substances are continuously discharged into the atmosphere, and the types are becoming more and more complex, causing drastic changes in atmospheric composition. When substances other than normal components in the atmosphere are harmful to human health, animal and plant growth and meteorological climate, we say that the atmosphere is polluted.

2. Main pollution sources and pollutants in the atmosphere

Air pollution source is the source of air pollutants, mainly in the following three ways:

(1) Industry: Industry is an important source of air pollution. There are many kinds of pollutants discharged into the atmosphere by industry, including smoke, sulfur oxides, nitrogen oxides, organic compounds, halides, carbon compounds and so on. Some are smoke and some are gas.

(2) Living stoves and heating boilers: A large number of living stoves and heating boilers in cities need to consume a lot of coal, and coal will release a lot of harmful substances such as dust, sulfur dioxide and carbon monoxide to pollute the atmosphere during combustion. Especially when heating in winter, it often makes the polluted area filled with smoke and makes people cough, which is also a pollution source that cannot be ignored.

(3) Transportation: Cars, trains, planes and ships are the main means of transportation at present, and the waste gas produced by burning coal or oil is also an important pollutant. Especially, the number of cars in cities is large and concentrated, and the pollutants discharged can directly hit people's respiratory organs, causing serious air pollution in cities and becoming one of the main air pollution sources in big cities. The exhaust gas emitted by automobiles mainly includes carbon monoxide, sulfur dioxide, nitrogen oxides and hydrocarbons, and the first three substances are very harmful.

3. Hazards of air pollution

The hazards of air pollution mainly include the following aspects:

(1) Harm to human health: People need to breathe air to maintain their lives. An adult breathes about 20,000 times a day and inhales 1.5 ~ 20 cubic meters of air. Therefore, polluted air has a direct impact on human health.

The harm of air pollutants to human body is various, mainly manifested in respiratory diseases and physiological dysfunction, as well as the irritation of mucosal tissues such as eyes and nose.

For example,1February 5-8, 952, the soot incident in London, England, killed 4000 people. People call the smoke of this disaster "the smoke of killing". According to the analysis, this is because there was no wind and fog in London, and the smoke and dust generated by factory chimneys and residents' heating permeated the urban area of London for a long time. The highest concentration of smoke and dust reaches 4.46 mg/m3, and the daily average concentration of sulfur dioxide reaches 3.83 ml/m3. Sulfuric acid droplets produced by chemical reaction of sulfur dioxide attach to smoke or condense on fog droplets, and enter organs with breathing, which makes people sick or accelerates the death of patients with chronic diseases.

As can be seen from the above example, when the concentration of pollutants in the air is high, it will cause acute pollution poisoning, or aggravate the symptoms, and even kill thousands of people within a few days. In fact, even if the concentration of pollutants in the atmosphere is not high, breathing this polluted air all the year round will cause chronic bronchitis, bronchial asthma, emphysema, lung cancer and other diseases.

(2) Harm to plants: Air pollutants, especially sulfur dioxide and fluoride, are very harmful to plants. When the concentration of pollutants is high, it will cause acute damage to plants, damage to the surface of plant leaves, or directly cause leaves to wither and fall off; When the concentration of pollutants is not high, it will cause chronic damage to plants, make the leaves of plants fade, or have no harmful symptoms on the surface, but the physiological functions of plants are affected, leading to the decline of plant yield and deterioration of quality.

(3) Impact on weather and climate: The impact of air pollutants on weather and climate is very significant, which can be explained from the following aspects:

(1) Reduce the amount of solar radiation reaching the ground: A large number of smoke particles discharged into the atmosphere by factories, power stations, automobiles, household heating equipment, etc. make the air very turbid, which blocks the sunlight and reduces the amount of solar radiation reaching the ground. According to observation and statistics, in the days when smoke and dust are not scattered in large industrial cities, the direct sunlight on the ground is reduced by nearly 40% compared with the days without smoke and dust. In cities with serious air pollution, people, animals and plants will be stunted due to lack of sunshine every day.

(2) Increase atmospheric precipitation: Many particles emitted by large industrial cities have the function of water vapor condensation nuclei. Therefore, when there are other precipitation conditions in the atmosphere, there will be precipitation weather. In the downwind areas of large industrial cities, there is more precipitation.

③ Acid rain: Sometimes, the rain falling from the sky contains sulfuric acid. This kind of acid rain is the oxidation of sulfur dioxide, a pollutant in the atmosphere, to form sulfuric acid, which falls with the precipitation in nature. Sulfuric acid rain can destroy large areas of forests and crops, corrode and destroy paper products, textiles and leather products, degrade metal antirust coatings and reduce their protective effects, and also corrode and pollute buildings.

(4) Raise the atmospheric temperature: Over large industrial cities, the air temperature near the ground is higher than that in the surrounding suburbs due to a large amount of waste heat discharged into the air. This phenomenon is called "heat island effect" in meteorology.

⑤ Impact on global climate: In recent years, people have gradually noticed the impact of air pollution on global climate change. After research, people think that carbon dioxide plays an important role in various air pollutants that may cause climate change. About 50% of the carbon dioxide released into the atmosphere by countless chimneys and other exhaust pipes on the earth remains in the atmosphere. Carbon dioxide can absorb long-wave radiation on the ground and raise the air temperature near the ground, which is the so-called "greenhouse effect". It is roughly estimated that the near-surface temperature will increase by 0.5 ~ 2℃ for every 25% increase of carbon dioxide content in the atmosphere. If 100% is increased, the near-surface temperature can be increased by 1.5 ~ 6℃. Some experts believe that the carbon dioxide content in the atmosphere will increase at the current rate, which will melt the ice in the North and South poles in a few years, leading to global climate anomalies.

4. Air pollution prevention and control

There are many measures to prevent and control air pollution, but the most fundamental thing is to reduce pollution sources. The following measures are usually taken:

(1) Reasonable industrial layout: This is an important measure to solve air pollution. Factories should not be too concentrated to reduce pollutant emissions in an area. In addition, chemical plants with raw material supply relations should be put together to reduce waste gas emissions through comprehensive utilization of waste gas.

(2) District heating and central heating: stoves scattered in thousands of households and short chimneys as dense as trees in cities are the main pollution sources of soot dust pollution. It is an important measure to eliminate soot by central heating and district heating, that is, to replace the stoves of thousands of households in several large thermal power plants with efficient dust removal equipment set in the suburbs.

(3) Reduce the pollution of traffic exhaust: The key to reduce the pollution of automobile exhaust is to improve the combustion design of the engine, improve the combustion quality of gasoline, and make the engine oil burn fully, thus reducing harmful exhaust.

(4) Changing fuel composition: changing coal into gas, and stepping up research and development of other new energy sources, such as solar energy, hydrogen fuel and geothermal energy. In this way, the pollution of smoke can be greatly reduced.

(5) Afforestation: Dense forests can reduce wind speed and a lot of dust carried in the air. The surface of leaves is rough, some have fluff, and some can secrete mucus and oil, so they can absorb a lot of floating dust. Dusty leaves can continue to absorb dust after being washed by rain. Such reciprocating blocking and adsorption of dust can purify the air.

I. Overview of air pollution

Even if the sky is clear, the atmosphere around us is not as clear as it looks. The air is full of invisible solids, liquids and gases, such as pollen, bacteria, smoke and dust, moisture and so on. The so-called air pollution means that the air contains one or more pollutants, whose quantity, nature and time will do harm to the life of human beings, plants and animals, damage property, or interfere with the comfortable living environment, such as the existence of odor. In other words, as long as a substance exists in sufficient quantity, nature and time and has an impact on human beings or other creatures and property, we can call it an air pollutant; And the phenomenon caused by its existence is air pollution. We need to know the composition of clean air before we know what will cause pollution when it enters the air. The composition of clean air is shown in table 1: what we usually call "air pollutants", such as nitrogen dioxide and ozone. The content of sulfur dioxide, carbon monoxide and other substances in clean air is very small; But in the case of pollution, some kinds of these specific substances will increase greatly. In other words, the abnormal increase of some substances in the air will produce air pollution.

Second, the types of air pollutants

There are many kinds of air pollutants, and their types may be solid particles, drops or gases, or a mixture of these types. What are the definitions of air pollutants in Chinese laws and regulations at present? According to the definition and relevant regulations of the Air Pollution Prevention Law, air pollutants can be divided into four categories, namely gaseous pollutants (including sulfur oxides, carbon monoxide, nitrogen oxides, hydrocarbons, chlorine, gasified hydrogen, fluoride, chlorinated hydrocarbons, etc. ), particulate pollutants (including suspended particulate matter, gold bureau smoke, black smoke, acid fog, dust, etc. ), as well as secondary pollutants (pollution caused by photochemical reactions of pollutants in the air). Common air pollutants include suspended particles, carbon monoxide, sulfur oxides, nitrogen oxides, hydrocarbons, etc., which are mostly caused by human factors. In China's laws and regulations, most air pollutants (such as chimney emissions, automobile emissions, etc.) are produced by human factors. ) have "emission standards" to regulate their own emissions.

Three. Air pollution index

The pollutant standard index (PSI) refers to the index determined by the US Environmental Protection Agency and other institutions, and the value from 0 to 500 represents the degree of air pollution. The relationship between the index value and health impact is divided into the following five levels:

Index value 0 ~ 50

5 1~ 100

10 1~ 199

200~299

300~350

Health effects: good

(good)

medium

(moderate):

serious

(unhealthy):

Extremely bad

(very unhealthy):

harmful

(danger):

http://ies.dyu.edu.tw/es_25.htm

Air pollutants include smoke, steam, carbonized paper, dust, soot, coal dust, carbon dust, gas, mist, dust, particulate matter and radioactive substances.

Air pollution prevention and control

The prevention and control of air pollution is a huge systematic project, which requires the joint efforts of individuals, collectives, countries and even countries all over the world. The following measures can be considered:

1, reducing pollutant emissions. Reforming the energy structure, using pollution-free energy (such as solar energy, wind energy and hydropower) and low-pollution energy (such as natural gas), pretreating fuel (such as desulfurization before burning coal) and improving combustion technology can reduce pollution emissions. In addition, before pollutants enter the atmosphere, some pollutants in waste gas can be eliminated by dust removal and smoke elimination technology, condensation technology, liquid absorption technology and recycling technology, so as to reduce the amount of pollutants entering the atmosphere.

2, control emissions, make full use of the self-purification ability of the atmosphere. Different meteorological conditions have different atmospheric capacity of pollutants, and the same pollutant discharge will cause different pollutant concentrations. For areas and time periods with strong wind, good ventilation, strong turbulence and strong convection, the atmosphere has strong diffusion and dilution ability and can accept more activities of factories and mines. In the area and time period of inversion, the diffusion and dilution ability of the atmosphere is weak, and it cannot accept more pollutants, otherwise it will cause serious air pollution. Therefore, effective emission control should be carried out in different regions and different time periods.

3. Site selection, chimney design, urban and industrial zone planning, etc. It should be reasonable, and should not allow large emitters to be over-concentrated, and should not cause repeated pollution and serious local pollution incidents.

Afforestation will make more plants absorb pollutants and reduce the degree of air pollution.