1。 Atmospheric definition

In a clean atmosphere, the composition of trace gases can be ignored. However, in a certain range of the atmosphere, trace substances have appeared, and their quantity and duration may have adverse effects and harm on people, animals, plants, articles and materials. When the concentration of pollutants in the atmosphere reaches a harmful level, even destroying the ecological system and the conditions for the normal survival and development of human beings, the phenomenon that harms people or things is called air pollution. The causes of air pollution are both natural factors and human factors, especially human factors, such as industrial waste gas, combustion, automobile exhaust and nuclear explosion. With the rapid development of human economic activities and production, while consuming a lot of energy, a lot of waste gas and smoke are discharged into the atmosphere, which seriously affects the quality of the atmospheric environment, especially in densely populated cities and industrial areas. The so-called dry and clean air refers to the air (composed of mixed gas, water vapor and impurities) in a natural state without water vapor and impurities, and its main component is nitrogen, accounting for 78.09%; Oxygen, accounting for 20.94%; Argon, accounting for 0.93%; Other trace gases (such as neon, helium, carbon dioxide and krypton) with the content less than 0. 1%.

Second, the source and harm of air pollution

There are many sources of air pollution, such as: the increasing number of cars is the main source of urban air pollution; In winter in Beijing, air pollution is caused by burning coal for heating; Chemical plants often emit a strong pungent smell, which is seriously harmful to human body; Gray dust mainly comes from cement plants and lime production plants; Black smoke contains a lot of tar and carbon black, mainly from coal-burning and oil-burning industries; Mining blasting is a man-made source of dust in the atmosphere. Urban pollution in China, Beijing and Chicago is very serious.

Air pollution has a great influence on the climate. The pollutants discharged by air pollution will have a certain impact on the local and global climate, especially on the global climate. In the long run, this effect will be very serious.

First, the greenhouse effect.

Fuel contains all kinds of complex components, which will produce all kinds of harmful substances after combustion. Even if the fuel without impurities is completely burned, water and carbon dioxide will be produced. It is precisely because of fuel combustion that the concentration of carbon dioxide in the atmosphere is increasing, which destroys the balance of carbon dioxide in nature and may even trigger a "greenhouse effect" and raise the temperature of the earth.

The increase of carbon dioxide concentration in the atmosphere prevents the loss of heat on the earth and makes the earth feel the rise of temperature. This is the famous "greenhouse effect". The gas that raises the temperature of the earth is called "greenhouse gas", which can destroy the normal relationship between the atmosphere and the ground and absorb the infrared radiation released by the earth, just like a "greenhouse". Carbon dioxide is the largest greenhouse gas, accounting for about 0.03% of the total capacity of the atmosphere. Many other trace gases also produce greenhouse effect, some of which are stronger than carbon dioxide.

Second, acid rain.

Some people think that acid rain is a silent crisis, the most serious environmental threat that has ever attacked us, and an invisible enemy.

This is not an alarmist. With the increase of industrialization and energy consumption, acid emissions are also increasing. They enter the air and form acid rain after a series of actions.

The pH value of acid rain is less than 5.6. Acid rain in China is mainly sulfuric acid rain. The fuel containing sulfur minerals is first oxidized to SO2, which is further oxidized to SO3 by some pollutants in the air, and SO3 reacts with water to generate sulfuric acid.

Three. ozone hole

Due to human emissions of substances that destroy the ozone layer, the area of the ozone layer has expanded tenfold from 1985 to 1998. 1998 or so, the damaged area of ozone layer exceeded 2,700 square kilometers for the first time, which was larger than the combined area of North America, Canada and the United States. Ozone layer destruction is not only a polar problem, but also begins to develop in Central America. According to the report of 1998 United Nations Expert Committee on the Impact of Ozone Layer Destruction on the Environment, the ultraviolet radiation on the ground is intensified due to ozone layer destruction, with the increase of 7% in winter and summer in the mid-latitude area of the northern hemisphere, 4% in summer and autumn in the mid-latitude area of the southern hemisphere, 6% in the mid-latitude area of the southern hemisphere, and a significant increase in spring in the Antarctic and Arctic regions.

Three. Atmospheric protection

Many environmental problems are transnational or even global, such as the greenhouse effect, ozone layer destruction and other air pollution problems, which need the concerted efforts of all countries in the world and Qi Xin to be solved step by step. People began to realize that HCFCs may be harmful to the environment in the early 1970s, and began to look for alternatives. By the middle of1980s, the evidence of ozone layer destruction became more and more obvious, and the call for concerted action became louder and louder. 1987, representatives from many countries gathered in Montreal, Canada's second largest city, and signed the Montreal Protocol on Substances that Deplete the Ozone Layer. The agreement is a pioneering international agreement to deal with environmental pollution in the world, aiming at controlling the consumption of HCFCs and other substances that destroy the ozone layer, protecting the "coat" of the earth and protecting human beings themselves.

Suggestions on prevention and control of air pollution;

1. Strengthen air quality monitoring; 2. Improve fuel or deal with automobile exhaust; Use clean fuel

For example, Brazil uses sugarcane juice to make ethanol instead of gasoline as the fuel of automobiles, which reduces automobile exhaust pollution. Newly manufactured cars must be equipped with catalytic converters to reduce pollution.

Strengthen air quality monitoring, set an example, do a good job of publicity, use clean fuel, and refuse air pollution! ! !