As the environment is one of the components of the ecosystem, its change will affect the stability of the ecosystem. There are many examples of destroying the environment and breaking the balance of the ecological environment, such as: the formation of eutrophication in lakes and marshes; Mercury poisoning in Japan; Fluoride destroys the ozone layer; The ecological environment of Aswan Dam has deteriorated; The bad consequences after the application of "bhc" and "DDT"; The "wet room effect" of the earth, etc.

2. Destroying vegetation, the vegetation with forest as the main body is the lever of land ecological balance, and the ecological disasters caused by destroying vegetation on the earth are the most, such as the black storm in the western United States in 1934, which destroyed more than 45 million mu of cultivated land; In 1963, a big storm occurred in the former Soviet Union's agricultural reclamation area, destroying more than 3 million mu of land; Also because of the destruction of forests, the ancient Babylonian civilization perished; The Tal Plain between India and Pakistan has become a desert due to forest destruction, with a desert area of 65, square kilometers; The deterioration of ecological conditions in the Yellow River Basin in China stems from the destruction of forest vegetation in the upper reaches, and the Yangtze River will become the second Yellow River today. The deterioration of ecological conditions in northeast forest areas is mainly due to unreasonable logging and excessive logging of forests in southwest forest areas and northeast forest areas.

3. Destroying the food chain: Examples of destroying the food chain and breaking the ecological balance are: excessive killing of natural enemies of pests causes forest diseases and insect pests; India once killed a large number of otters, which increased the number of sick fish and decreased the fish production. In Australia, where animal husbandry is developed, the case of dung beetle rescue caused by cow dung covering grassland is more fresh. Of course, in the biological circle, there are often several incentives. Nine phenomena of pollution and destruction of the earth's environment

1. Air pollution

Definition of air pollution

In a dry and clean atmosphere, the composition of trace gases is negligible. 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 clean air refers to the air in the natural state (composed of mixed gas, water vapor and impurities) from which water vapor and impurities are removed, and its main component is nitrogen, accounting for 78.9%; Oxygen, accounting for 2.94%; Argon, accounting for .93%; Other trace gases (such as neon, helium, carbon dioxide, krypton) with content less than .1%.

classification of air pollutants

air pollutants can be mainly divided into two categories, namely, natural pollutants and man-made pollutants, and the man-made pollutants that cause public hazards often come from fuel combustion and large-scale industrial and mining enterprises.

particulate matter: refers to liquid and solid substances in the atmosphere, also known as dust.

sulfur oxides: the general term for sulfur oxides, including sulfur dioxide, sulfur trioxide, sulfur trioxide, sulfur monoxide, etc.

oxides of carbon: mainly include carbon dioxide and carbon monoxide.

nitrogen oxides: the general term for nitrogen oxides, including nitrous oxide, nitric oxide, nitrogen dioxide, nitrogen trioxide, etc.

hydrocarbons: compounds formed by carbon and hydrogen, such as methane, ethane and other hydrocarbon gases.

other harmful substances: such as heavy metals, fluorine-containing gases, chlorine-containing gases and so on.

harm of air pollution

air pollution has a great influence on the climate, and pollutants discharged by air pollution will have a certain impact on the local and global climate, especially on the global climate. From a long-term point of view, this impact will be very serious.

First, the content of carbon dioxide in the atmosphere is increasing. Fuel contains various complex components, which will produce various 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 constantly increasing, which destroys the balance of carbon dioxide in nature, and may even trigger a "greenhouse effect", resulting in an increase in the earth's temperature. Second, the ozone layer is destroyed.

after the air is polluted, due to the different sources, properties and duration of pollutants, the differences of meteorological conditions, geographical environment and other factors in the polluted areas, and the differences of people's age and health status, the harm to human body is not the same. Harmful substances in the atmosphere invade the human body mainly through the following three ways:

(1) They enter the human body through direct breathing;

(2) adhering to food or dissolving in water, so that it can invade the human body with diet;

(3) entering the human body by contacting or stimulating the skin. Among them, invading the human body through breathing is the main way and the most harmful.

The harm of air pollution to people can be roughly divided into three types: acute poisoning, chronic poisoning and carcinogenesis.

atmospheric protection

many environmental problems are transnational or even global, such as air pollution such as greenhouse effect and ozone layer destruction, which need the concerted efforts of all countries in the world to be solved step by step. People began to realize that HCFCs may be harmful to the environment in the early 197s, and began to look for substitutes. By the mid-198s, the evidence of ozone layer destruction had become increasingly clear, and the call for concerted action was also growing. In 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. This agreement is a pioneering international agreement to deal with environmental pollution in the world, with the aim of controlling the consumption of HCFCs and other substances that destroy the ozone layer, protecting the "coat" of the earth and protecting human beings themselves.

The amended Montreal Protocol is a binding international agreement. According to the regulations, the emissions of HCFCs and other restricted substances in industrial countries must be reduced immediately, and the use of such substances should be phased out completely before 2. Developing countries can continue to increase the consumption of these substances in a limited way before 1996, and then they should gradually reduce it, and they must completely stop using these harmful substances by 21. In addition to time concessions, this agreement also contains two clauses beneficial to developing countries: one is to establish a temporary multilateral fund to help developing countries adopt technologies to replace HCFCs; The other is the technology transfer clause, which requires signatory countries to transfer the best technology according to "fair and most favorable conditions".

China has joined the revised Montreal Protocol and formulated a national action plan to fulfill its international obligations, including establishing the management organization for ozone layer protection, formulating management norms for relevant industries, actively conducting research on substitutes and alternative technologies, and arranging matching funds for enterprises' alternative technological transformation.

second, acid rain

some people think that acid rain is a silent crisis, and it is the most serious environmental threat that has ever hit us, and it is an invisible enemy. This is not 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.

people have controlled the acid emissions, but there is still acid rain. Atmospheric dust may be another cause of acid rain.

acidic emissions

the condensation of water vapor is caused by the existence of condensation nuclei in the range of .1 ~ 1μ m in the free atmosphere, and then it grows further through the processes of collision and coalescence to form clouds and raindrops. In the cloud, cloud droplets collide with each other or with aerosol particles, and at the same time absorb gas pollutants in the atmosphere, and a chemical reaction occurs inside the cloud droplets. This process is called the removal of pollutants in the cloud or rain removal. In the process of raindrops falling, raindrops wash away gases and aerosols in the air they pass through, and chemical reactions also occur inside raindrops. This process is called the removal or washing of pollutants under the cloud. These processes are also the removal processes of particulate matter from gaseous substances in the atmosphere by precipitation, and acidification is formed in these processes.

atmospheric dust

The recent discovery shows that acid rain is a much more complicated phenomenon than originally thought. The results show that the alkali compounds in the atmosphere play a key role unexpectedly. Alkali counteracts the effect of acid rain by neutralizing acidic pollutants. Scientists have found that people focus all their attention on acidic substances in the atmosphere, which masks the fact that alkali emissions have also decreased. It seems that many factors are reducing the content of these alkalis in the atmosphere, thus aggravating the ecological impact of acid rain. Ironically, several of these factors are exactly the measures taken by governments to improve air quality.

most of the alkali in the atmosphere can be found in airborne particles called atmospheric dust. These dust particles are rich in minerals such as calcium carbonate and magnesium carbonate, which act as alkali when dissolved in water. Atmospheric dust particles are formed by many sources. The combustion of fuel, as well as industrial activities such as cement production, mining and metal smelting, will produce alkaline particles. Vehicle driving on construction sites, farms and unpaved roads can also cause dust particles.

Third, ozone layer destruction

The ozone layer is the best umbrella for the earth, which absorbs most of the ultraviolet rays from the sun. However, scientific research and atmospheric observation in recent twenty years have found that the ozone layer in the Antarctic atmosphere has been thinning every spring, and in fact there is an ozone "hole" in the polar atmosphere.

This ozone depletion phenomenon is an abnormal phenomenon. Does this indicate that this ultraviolet absorption layer is in a global disaster? Through continuous scientific research, people have found that substances released by human social activities have seriously damaged the ozone layer. Of course, this phenomenon is also affected by the unique meteorological conditions in this area (polar vortex, cold stratospheric temperature, polar stratospheric clouds).

discovery process

atmospheric scientists from the British Antarctic Survey conducted a research project in Antarctica, which was conducted on the ground and in the air respectively. Ball-borne instruments generally detect the composition and chemical properties of the atmosphere in which the instrument travels. Land-based detectors and space-borne detectors perform telemetry tasks. These research activities take the form of international cooperation. For example, in 1987, about 15 scientists and auxiliary personnel representing 19 organizations and four countries gathered in punta arenas, Chile, and conducted an unprecedented research, namely the airborne Antarctic ozone experiment. This experiment shows that the size of ozone hole reached the largest in history in 1987. This discovery shocked the scientific community.

Formation mechanism

At present, the cause of the Antarctic "ozone hole" is still inconclusive, and the most convincing one is the theory of pollutants. In addition, CALLIS of Hampton Zhili Center of NASA and others suggested that the destruction of Antarctic ozone layer was related to strong solar activity; TUNG of Massachusetts Institute of Technology and others believe that the unique atmospheric environment in Antarctica causes ozone depletion in late winter and early spring. According to the theory of atmospheric dynamics, it is pointed out that a large number of chlorofluorocarbons are used and there is not enough sunlight in early spring in Antarctica to produce a large number of oxygen atoms, and therefore a circulation mechanism without oxygen atoms is proposed.

Through the analysis, it seems that we can draw the following main points: (1) The Antarctic "ozone hole" is a special phenomenon caused by the participation of polar stratospheric clouds and heterogeneous chemical reactions under the special temperature and circulation conditions in Antarctic spring. (2) The influence of polar vortex and other factors on the transport of gas components is not the decisive factor for the formation of Antarctic "ozone hole", but only affects the intensity of ozone hole. (3) The influence of solar cycle change on the strength of Antarctic ozone hole through photochemical reaction can be ignored.

iv. water pollution

human activities will cause a large number of industrial, agricultural and domestic wastes to be discharged into the water, which will pollute the water. Definition of "water pollution": The phenomenon that the chemical, physical, biological or radioactive characteristics of a water body are changed due to the intervention of a certain substance, thus affecting the effective use of water, endangering human health or destroying the ecological environment, and causing the deterioration of water quality is called water pollution.

there are two kinds of water pollution: one is natural pollution; The other is man-made pollution. At present, man-made pollution is the most harmful to water bodies. Water pollution can be divided into three categories: chemical pollution, physical pollution and biological pollution.

1. Seawater pollution

Sewage, waste residue, waste oil and chemicals continuously flow into the sea. In many sea areas, it is illegal to dump sewage mixed with oil, but it still happens from time to time, and the real oil disaster occurs when a giant oil tanker leaks or sinks. Now scientists try to use chemicals to precipitate oil in water in order to remove oil.

The practice of dumping chemical and radioactive wastes into the sea has been going on for many years. The container will corrode one day and harmful substances will enter the sea water. Scientists don't know much about the circulation of deep water and surface water, and the process may be faster than they thought before. Therefore, harmful substances will spread into the water layer of biological activities.

2. Surface water pollution

More than 5 years ago, people thought it was dangerous to drink river water flowing through big cities, but industrialization, population growth and new toxic chemicals made the situation worse and worse.

The laying of drainage system and the use of cleaning agents are increasing, which makes the phosphate content in our waterways and lakes increase day by day. This over-nutrition leads to the rapid proliferation of algae. Consume oxygen in water, kill fish and worsen ecosystem. Due to improper treatment of mercury compounds and other heavy metals in industry, serious water pollution has also been caused. Mercury gradually concentrates through the food chain, and finally causes serious nerve damage to fish-eating birds or humans.

3. Groundwater pollution

Like surface water, groundwater is also threatened by pollution, mainly from the infiltration of surface or soil water. Agricultural nitrogen fertilizer and oil and phenol in garbage pollute groundwater. Once the nitrate in nitrogen fertilizer enters the ground, it will be transformed into nitrite, which can be transformed into carcinogens in human body. The destruction of ground vegetation and the drainage of wetlands reduce the infiltration of surface water, thus reducing the water table. Due to the excessive demand of cities and industries, fresh water is continuously pumped out as domestic and industrial water, and then discharged again as surface sewage, which will further reduce the groundwater table. On the other hand, a large number of frequent irrigation can enhance infiltration and make the water table rise to the surface. However, in arid areas, the land infiltrated by water will precipitate salts in groundwater due to abnormal evaporation, and sooner or later it will become an uncultivated saline-alkali land.

water resources protection

There seems to be an inexhaustible supply of water on the earth. In fact, according to the current situation of human use, only fresh water is the main water resource, and only a small part of it can be used by people. Fresh water is a renewable resource, and its renewability depends on the water cycle of the earth. With the development of industry and the increase of population, a large number of water bodies are polluted; In order to extract river water, many countries have built dams in the upper reaches of rivers, which have changed the flow situation and seriously affected the circulation and self-purification of water.

v. solid waste

all solid or semi-solid substances produced in the course of all human activities that are no longer of use value to the owner and are discarded are generally called solid waste. Solid waste produced in various production activities is commonly known as waste residue; Solid produced in life activities