What are the effects of air pollution
Origin：Hefan Hit： Time：2020-03-13
I: Global adverse effects
Freon, that is, increasing global emissions of chlorofluorocarbons (CFCs) and carbon dioxide (CO2), are mainly caused by the increase in ozone layer depletion and global warming.
1. Increased ozone depletion
Research work initiated by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) has confirmed that the main cause of ozone depletion is the combination of chlorine and bromine, such as CFCs widely used in refrigerators and air conditioners. Freon (CFCs) are widely used as refrigerants, sprays, foams, detergents, etc. The stratosphere discharged to the atmosphere and reaches the atmosphere is photolyzed to generate Cl atoms, which destroys the ozone layer. The lifetime of Freons (FCs) in the atmosphere is 50 to 100 years. Even if the production and use of Freon is completely stopped and other chemicals that have a destructive effect on the ozone layer are eliminated, it will take decades or even hundreds of years for the stratospheric ozone layer. restore.
According to scientists' predictions, if the stratospheric ozone is reduced by 1%, the amount of solar ultraviolet radiation will increase by about 2%, the incidence of skin cancer will increase by 3% to 5%, and the incidence of cataracts will increase by 0.2% to 1.6%. In addition, the increase in the amount of ultraviolet radiation also causes a large number of deaths of marine plankton and shrimp, crab larvae and shellfish, which makes some animals blind, and may even cause extinction of certain organisms, and may reduce yields of major crops such as wheat and rice. Some scientists believe that when the ozone layer is reduced to 1/5, it will be the critical point for the survival of the earth. Of course, this argument has not been confirmed by scientists, but it fully illustrates the serious harm of ozone depletion and the urgency of saving the ozone layer.
2. Global warming
According to statistics from meteorological departments around the world, the climate of the globe is indeed warming. Since the 1970s and 1980s, the temperature has increased by about 0.7 ° C. This is a phenomenon that humans have not seen for thousands of years and thousands of years. . Scientists agree that the continued release of greenhouse gases (CO, CFCs, etc.) will cause global warming.
On the earth, CO2 is the most important greenhouse gas that produces the effect of atmospheric insulation, which has attracted much attention. However, it accounts for only about 1/2 (50%) of the potential for warming caused by human activities. Based on the concentrations of major greenhouse gases in the atmosphere and their relative heat absorption potentials in the mid-1980s, their contribution rates are estimated as follows: carbon dioxide (CO2) 50%, chlorofluorocarbons (CFCs) 20%, and methane (CH4) 16 %, Tropospheric ozone (3) 8%, nitrous oxide (laughing gas, N2O) 6%. The contribution rate of the first three types of greenhouse gas is 86%, and the contribution rate of the first two types is 70%, mainly due to human factors. Therefore, controlling carbon dioxide and chlorofluorocarbon (Freon) emissions is an urgent and important task at present. Although the emission of chlorofluorocarbons is far less than that of carbon dioxide, the endothermic energy of the newly added molecules of CFC is 20,000 times that of the additional molecules of CO2.
CO2 can not only transmit light from the sun, but also absorb infrared rays reflected from the ground. This property of CO2 is called the greenhouse effect, that is, the effect of the atmosphere on the ground. CO2 is also an important factor affecting climate change. Global natural disaster losses due to global warming amount to US $ 30 billion annually. The earth's climate has increased by 0.8 ° C in the past 100 years. In the next 100 years, the average earth temperature will rise by 1.4 ~ 5.8 ° C. The global warming will cause 67% of the glaciers in the Himalayas and Tianshan Mountains to accelerate their melting, and the alpine vegetation in the Alps will shrink by 1 ~ 4m every 10 years. The European season is delayed by an average of 10.8 days, the African desert is accelerating, and the swamplands of Australia and New Zealand are drying up. From the 1950s to the early 1970s, snow and ice in the Arctic Circle melted by 10% to 15%, and the Antarctic Circle shrank to the south. Another negative consequence of global warming is rising sea levels. According to statistics, as the global climate has warmed by 0.6 to 0.7 ° C in the past century, the global sea level has risen by about 10 to 15 cm. If low-lying coastal areas are submerged due to rising sea levels, beaches and coasts are eroded, freshwater resources are damaged by backwatering of the sea, and floods may increase, as well as damage to port equipment and coastal buildings, affecting shipping, and affecting coastal aquaculture, these environments The disaster will cause huge economic losses to China, and strategic countermeasures should be studied in a timely manner.
2: Regional adverse effects
Regional air pollution refers to a type of air pollution that causes adverse effects and damage to the environment of the province and beyond. Regional air pollution mainly includes: acid deposition (acid rain); ozone on the ground (Europe, North America). This is to analyze the problem from the perspective of the whole world. From the reality of China, the ground-level ozone is only regional or local pollution. Explained separately below.
Acid precipitation (acid rain)
Wet sedimentation (acid rain, snow, fog, and cloud vapor) and dry sedimentation (acid particulates and aerosols) are both formed when fossil fuel combustion and metal smelting release a large amount of SO2 and NO2. Acid rain is the most representative regional acid deposition that has received widespread attention from countries around the world.
Acid rain is usually defined as "rain with a pH of less than 5.6". Dr. Swiss soil scientist Dr. Ao Dan first identified the cause of the pollution and conducted a large-scale adjustment of the acid rain distribution area. Dr. Audan published an academic paper in 1967 that could be called a milestone in acid rain. The paper warned: "Acid rain will seriously endanger water quality, soil, forests and buildings in the future. This may be a chemical battlefield for humans." Many scientific workers in China have done a lot of research work, and research on the formation, distribution and harm of acid rain in China has achieved remarkable results.
The acid rain, which is called "the god of death in the air" abroad, has seriously endangered the domain environment. There are mainly the following aspects.
The earliest effects on water bodies and aquatic organisms are lakes and rivers. Acidic substances dissolved in rain and snow flow into the lake. When the acidic substances accumulate to a certain level, acidification begins to occur. When the pH value is lower than 5, the fish will decrease sharply. Plankton and aquatic organisms that are sensitive to pH are affected first and the food chain is cut off. When the pH value is below 4.5, it is difficult for fish eggs to hatch, and adult fish are also harmed. The fish that can survive are limited to a small number of species.
Harm to forests Acid rain may have direct and indirect damage to trees. The direct damage is that the acid rain invades the stomata of the leaves and prevents the plants from breathing; the indirect damage is the indirect damage to the trees due to changes in soil properties. Large-scale forest decline is the most surprising regional manifestation of the impact of air pollution on terrestrial ecosystems. The rapid decline of European forests since the 1970s is a striking example so far. Forest decline is also evident in North America, but it has not reached the level of forest decline in Europe. Recent research has pointed out that acid rain is the main cause of the severe top dryout of red spruce throughout the Appalachian Mountains. This modest forest decline has brought significant economic losses, including reduced timber production and losses related to the wood processing industry, and reduced social gains from recreation and other “non-timber industries”.
Damage to buildings and materials caused by acid rain is not the only problem people worry about. The erosion of stone and metal materials and monuments by acid rain has also become a serious problem. In particular, open-air artworks, ancient architectural complexes and other cultural relics and precious human cultural heritage are slowly decaying under the erosion of acid rain, which will cause incalculable losses.
Damage caused by acid rain to human health The impact of acidic aerosols that chemically convert SO2 and NO2 in the atmosphere on health has attracted increasing attention. Increasing evidence shows that acid aerosols are harmful to human health and cause respiratory diseases such as bronchitis and asthma. In the United States, some sciences have suggested that acidic aerosols should be the next pollutant restricted in the atmospheric environmental quality standards.
2. Ground Ozone
The regional effects of ground-level ozone are as deep and widespread as acid deposition. In summer in Europe and North America, high levels of ground-level ozone sometimes occur for several days in a row, and not only in urban areas. Evidence suggests that the levels of ozone in the environment are increasing in North America and Europe due to increasing levels of ozone precursor nitrogen oxides (NOx) and volatile organic compounds. Data show that ground-level ozone levels in the European continent have doubled since the beginning of the 0th century. Ground-level ozone precursors, NOx, and volatile organic compounds are widely distributed, including not only motor vehicle power stations, nitric acid and nitrogen fertilizer plants, oil refineries, and various small industries, but also residential emissions of house paint and other solvents, which are difficult to control .
Ground-level ozone can damage cells in the leaves of many trees and crops, interfere with photosynthesis, cause nutrient leaching, and eventually lead to slower plant growth and direct leaf damage. Plants damaged by oxygen are more susceptible to insect attack, and their roots are susceptible to decay. Exposure to ozone, coupled with acid rain and other unfavorable conditions are the main causes of large-scale forest decline in Europe and North America. The loss of agricultural production capacity caused by ozone is common in Europe and North America. It is estimated that current levels of ozone in the United States have caused crop yield losses of 5-10%.
The effects of ozone exposure on human and animal health are also severe, especially when large areas of high-level exposure for several days in a row caused by inverse summer weather are more harmful to health. Reducing urban and regional ozone levels so that they no longer have widespread ecological and health effects is an urgent and arduous task.