Introduction to the formation of acid rain, please discuss how to control the formation of acid rain
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1. The discoverer and age of acid rain. “The term "acid rain" was first coined by the British chemist Smith in 1872 in his book "Air and Rainfall".: The proper term "acid rain" was proposed in "The Beginning of Chemical Climatology" 2. The definition of acid rain. Rain, snow or atmospheric precipitation formed by other means with a pH value less than 5.6 is called "acid rain", which is an air pollution phenomenon. 3. The concept of acid rain frequency. The frequency of acid rain in a certain area is the ratio of the number of acid rains in the area to the total number of rainfalls. 4. The concepts of dry deposition and wet deposition. When it doesn't rain, acidic substances in the atmosphere can be absorbed by vegetation or settle to the ground by gravity, which is called "dry deposition."” ； When it rains, high-altitude raindrops absorb acidic substances and then wash away the acidic substances and drop them to the ground when they fall, which is called "wet deposition". 5. The concept of acid rain zone. Whether a place is an acid rain area depends on the annual average. At present, the scientific standards for defining acid rain areas in my country are still under discussion, but it is generally believed that if the annual average precipitation pH value is higher than 5.65 and the acid rain rate is 0-20%, it is a non-acid rain area. 6. Acid rain is a global, cross-regional environmental pollution problem. Causes of Acid Rain Among the components of acid rain caused by human activities, sulfuric acid is the largest, generally accounting for about 60% to 65%, followed by nitric acid, about 30%, hydrochloric acid, about 5%, and organic acids, about 2%. Sulfuric acid is mainly caused by sulfur dioxide released by burning fossil fuels. The largest emission sources are power plants, steel plants, smelting plants, etc., as well as small coal stoves in every household. Currently, about 160 million tons of sulfur dioxide are released artificially around the world every year. Nitric acid is formed from nitrogen oxides. Nitrogen oxide gas is mainly produced during high-temperature combustion. Nitrogen oxides are emitted, for example, in car engine combustion chambers and when fossil fuels are burned at high temperatures. In addition to factories that use hydrogen chloride, artificial sources of hydrogen chloride also release the gas when burning garbage (plastics contain large amounts of chlorine) and burning fossil fuels. Although the amount of sulfur dioxide and nitrogen oxides caused by human activities is roughly the same as that of natural sources (that is, each accounts for about 50%), nature's self-cleaning ability is limited. This is like eating alone. No matter how big the belly is, if you let him eat twice as much food, the belly will be full. The process of sulfur oxides and nitrogen oxides forming acid rain in the atmosphere is a very complex atmospheric chemistry and atmospheric physics process. If there is no cloud or rain when acidic substances are formed, the acidic substances will gradually fall to the ground in the form of gravity sedimentation. This is called dry sedimentation to distinguish it from wet sedimentation such as acid rain and acid snow. Dry sediments compound into acids when they meet water on the ground. The acidity in acid clouds and acid fog is much stronger than acid rain because it is not diluted by raindrops with much larger diameters. Since there are often clouds and fog in high mountainous areas, forests in high mountainous areas in acid rain areas suffer the most damage and are often the first to die in large tracts. How to form acid rain? The sulfuric acid and nitric acid in acid rain are converted from sulfur dioxide and nitrogen oxides emitted by humans. One of the main substances that form acid rain is SO2. S02 and N0x can be emitted locally or migrated from a distance. Acid rain is the product of the comprehensive process of atmospheric pollutant release, migration, transformation, cloud formation, and rainfall under certain meteorological conditions. SO2 released into the atmosphere from coal and petroleum combustion and metal smelting generates sulfuric acid through a gas phase or liquid phase oxidation reaction. This chemical process can be simply expressed as follows: Gaseous phase reaction 2S02+02--2S03 S03+H20-H2S04 Liquid phase reaction S02+H20-H2S03 2H2S03+O2-2H2S04 It is generally believed that sulfur oxides entering the atmosphere must react with at least 200 water molecules to form acid rain. In recent years, experiments by scientists at the University of Manchester in the UK have proven that acid rain can be formed by reacting with only 12 water molecules. This shows that if sulfur pollution is not reduced, acid rain will also form in the dry atmosphere. High-temperature combustion generates nitric oxide, which is mostly converted into nitrogen dioxide after being discharged into the atmosphere. When it meets water, it generates nitric acid and nitrous acid. This chemical process can be roughly expressed as follows: 2NO+02—2N02 2N02+H20—HN03+HN02 Human activities and natural processes also cause many gaseous or solid substances to enter the atmosphere, which also affects the formation of acid rain. Atmospheric particulate matter Fe, Mn, Cu, Mg, V, etc. become catalysts for acid reactions. Ozone and hydrogen peroxide generated by atmospheric photochemical reactions are oxidants that oxidize SO2. Is all the sulfur in acid rain caused by man-made emissions of sulfur dioxide? This is not the case. Since 1987, scientists from the Institute of Geochemistry, Chinese Academy of Sciences have participated in * * “The Seventh Five-Year Plan's key project is "Research on the Sources, Impacts and Control Countermeasures of Acid Rain in Southwest and South China." They are the first in the world to use stable isotope theory and technology to study the source of sulfur in rainwater. This method uses the different isotope composition markers of sulfur in rainwater to determine its different sources. After three years of hard work, they systematically collected 160 large-volume rain samples, several atmospheric and atmospheric particulate matter samples, and coal samples from major coal mines in 15 provinces and regions in the central region of Guizhou Province, where acid rain is the most severe in China. They analyzed and measured the ratio of the isotopes sulfur 34 to sulfur 32 and other chemical components in these samples. Their research results confirmed that there are at least 5 important sources of sulfur in rainwater in central Guizhou: Gaseous sulfur dioxide released by coal burning, atmospheric particulate matter, natural volatile sulfides released by biological activities, sulfur-containing aerosols transmitted from neighboring provinces north of Guizhou, and ocean splashes brought by warm and humid air currents in the Bay of Bengal. More importantly, in different seasons, the contribution rate of these five sulfur sources to sulfur in rainwater changes significantly. In the winter and spring from November to April, the proportion of anthropogenic sulfur dioxide emissions * * Rising, it has become the main source after local particulate matter, accounting for 30% of rainwater sulfur. Sulfur transported long distances from northern my country in the form of water aerosols can also reach 20%, while natural sulfur sources are negligible. In contrast, in the summer and autumn months from May to October, natural sulfur sources rise to 30%, exceeding sulfur dioxide emissions from anthropogenic coal-burning activities, while the share of sulfur transported over long distances is small. Research confirms that this natural source of sulfur is primarily released by natural biological activities. Central Guizhou is dotted with many natural lakes, reservoirs, rivers and rice fields, which constitute a natural reducing environment for biogenic sulfides. Rice fields, in particular, have been identified as source areas for several biogenic volatile sulfur compounds. Therefore, scientists from the Institute of Geochemistry divide winter and spring rainfall and summer and autumn rainfall into two types. The former is defined as the type polluted by man-made coal burning, and the latter is defined as the type polluted by the natural environment. Does acid rain only contain acidic substances? This is not the case. In addition to acidic substances, acid rain also contains alkaline substances from the atmosphere, mainly soil particles, industrial dust and natural sources of ammonia. Acid-base substances undergo neutralization reactions, and the pH value of rainwater is actually the result of acid-base neutralization balance. The concentration of gaseous ammonia is very different between the south and the north, which is one reason why there is little acid rain in the north. Moderator: Following this post, Comrade zxs from Sichuan University raised the issue of acid rain: "There are more and more chemical plants now, and the emissions of acidic gases are also gradually increasing. What methods should be used to better control them?" ”(See the 10th floor for details) In order to facilitate everyone's discussion on the acid rain issue, zxs's topic thread has been merged here. I hope zxs and this poster will understand and support! Thank you. This post was last edited by Fightinghard on 2009-4-24 20:25 ]
Acid rain is mainly caused by SO2 CO2 H2S NO2, etc. emitted into the air.
LZ's theory is very clear. In fact, the simplest form of acid rain is when sulfur dioxide or sulfur trioxide formed after the combustion of sulfur in coal combines with water in the air to form sulfurous acid or sulfuric acid, making the pH of the rain acidic. This is acid rain. The main hazards of acid rain should be discussed.
One more thing to add. Acid rain is caused by atmospheric pollution. Acid rain refers to atmospheric precipitation such as rain, freezing rain, snow, hail, and dew with a pH value less than 5.6. Our country covers parts of Sichuan, Guizhou, Guangdong, Guangxi, Hunan, Hubei, Jiangxi, Zhejiang, Jiangsu and Qingdao. The acid rain area covers an area of more than 2 million square kilometers and is one of the three largest acid rain areas in the world. Acid rain has brought serious impact and damage to the earth's ecological environment and human social economy. Research shows that acid rain brings serious harm to soil, water bodies, forests, buildings, scenic spots and other cultural landscapes, not only causing major economic losses, but also endangering human survival and development. Acid rain acidifies the soil and reduces its fertility. Toxic substances further poison the crop root system, killing root hairs and leading to stunted development or death. Acid rain also kills plankton in the water, reduces food sources for fish, and damages aquatic ecosystems ； Acid rain pollutes rivers, lakes and groundwater, directly or indirectly harming human health. ； The harm of acid rain to forests cannot be ignored. Acid rain washes the surface of plants and damages them directly or indirectly through the soil. Promote forest decline. Acid rain has a strong corrosive effect on metal, stone, cement, wood and other building materials, thus causing serious damage to wires, rails, bridges, houses, etc. In acid rain areas, the damage caused by acid rain is everywhere, which is shocking. For example, among the more than 90,000 lakes in Sweden, more than 20,000 have been harmed by acid rain, and more than 4,000 have become fishless lakes. Many lakes in the United States and Canada have become stagnant, devoid of fish, plankton, and even aquatic plants and algae. Large tracts of forest have been found dead from acid rain in North American acid rain areas. More than 7 million hectares of forests are dying in countries such as Germany, France, Sweden, and Denmark, and more than 100,000 hectares of forests are dying in my country's Sichuan, Guangxi and other provinces. Many ancient buildings and stone sculptures around the world have been severely damaged by acid rain corrosion, such as my country's Leshan Giant Buddha and Canada's Parliament Building. Recently, it was discovered that the stone lions at Beijing's Lugou Bridge, nearby stone monuments, and the Vajra Pagoda at the Five Pagoda Temple were all seriously damaged by acid rain.
study* , have some understanding of its nature
Acid rain has no advantages, is it all disadvantages?
The harm of acid rain is indeed shocking. Year-round acid rain has destroyed countless monuments and facilities.
The above data are scary, but there are still many companies that create acid rain. Human civilization is based on the prosperity of people all over the world.
Acid rain is mainly caused by sulfur dioxide produced by the burning of sulfur-containing coal, and carbon dioxide is also one of the causes. The generation of acid rain is related to local climate conditions, such as Guizhou Province
Nowadays, there are more and more chemical plants, and the acidic gas emissions are also gradually increasing. What methods should be used to better control them?
China's acid rain areas are mainly distributed south of the Yangtze River, but acid rain often occurs in large industrial cities in the north such as Qingdao, Harbin, Beijing, and Tianjin during heavy rains and torrential rains in summer. To the south of the Yangtze River, from Mount Emei in Sichuan, Jinfoshan in Chongqing, Zunyi in Guizhou, Liuzhou in Guangxi, Hongjiang and Changsha in Hunan, and to Xiamen in Fujian in the east, a prominent acid rain belt is formed, with the frequency of acid rain above. The three most serious acid rain areas in my country are the southwest acid rain area centered on Chongqing and Guiyang, the South China acid rain area centered on Changsha and so on. Southeast acid rain area centered on Fuzhou. In recent years, the degree of acid rain pollution in our country has increased year by year, and the contaminated area has expanded year by year. In 1999, the area of acid rain in our country has reached 10% of the country's total land area. ? ? . The boundaries of the acid rain area have basically coincided with the 400mm equal precipitation line, that is, the vast humid and semi-humid areas in the southeast half have been harmed by acid rain. This post was last edited by Fightinghard on 2009-4-24 15:01 ]
Everyone knows the cause. This is the consequence of industrialization. If we want to reduce it, we must start with reducing the S content of energy. Only by reducing the S content in the current main industrial fuels------coal and oil can we effectively change it.
1. In acid rain control areas in my country, precipitation with a pH value less than 5.60 is generally called acid rain, and areas with an average annual precipitation pH value less than 5.60 are called acid rain areas. At present, the area with average annual precipitation pH value below 5.60 in my country has reached about 40% of the country. Acid rain is a regional problem ； Acid rain in most areas is only caused by the long-distance transmission of acidic substances emitted by a small number of cities through the atmosphere. As long as the pollution sources in a few cities are eliminated, the phenomenon of large-scale acid rain will naturally disappear. Therefore, the acid rain control area should be different from the acid rain area and much smaller than the acid rain area. When the pH value of precipitation is lower than 4.60, it will cause damage to forests, crops and materials. Western developed countries * * The precipitation pH value below 4.60 is often used as the standard for controlled objects. The area with precipitation pH below 4.60 is much smaller than the area with precipitation pH below 5.60. In addition to this standard, the ability of the ecosystem to withstand acid rain must also be considered. Ecosystems such as soil and vegetation in different areas have different tolerances for sulfur deposition. The sulfur deposition load reflects the magnitude of this tolerance. When the actual sulfur deposition exceeds the sulfur deposition load, areas should be controlled. In addition, the acid rain control area should include the areas with the most serious acid rain pollution and their surrounding areas with the largest sulfur dioxide emissions. According to this standard, the area of acid rain control areas in my country is approximately 800,000 square kilometers, accounting for 8.40% of the country's land area. It mainly includes Shanghai City, Chongqing City and some urban areas in Zhejiang, Anhui, Fujian, Jiangxi, Hubei, Hunan, Guangdong, Guangxi, Sichuan, Guizhou, Yunnan and other provinces. 2. my country’s “Dual Control Zone” my country is a legal system * * , pollution control cannot rely solely on public opinion, there must be laws to follow. August 1995, nationwide * * * * The Council passed the newly revised "Atmospheric Pollution Prevention and Control Law of the People's Republic of China", which clearly stipulates that acid rain control areas and sulfur dioxide pollution control areas must be demarcated nationwide in order to strengthen the control of acid rain and sulfur dioxide pollution in the dual control areas. On the one hand, this means * * Attention should be paid to acid rain control and should be put into action ； On the other hand, this also expresses the strategy for controlling acid rain: we cannot just grasp the beard and eyebrows, we must grasp the key points, grasp the key, increase investment, and solve the problem. 3. Acid rain in the sulfur dioxide control areas in the south of my country is also related to the large amount of sulfur dioxide emissions in the north. Only controlling the emissions of acidic substances in acid rain areas and ignoring sulfur dioxide emissions in the north still cannot effectively control acid rain. The secondary standard for the annual average concentration of sulfur dioxide is 0.06 mg/cubic meter. Under this concentration, people will not be harmed by long-term exposure to the environment. ； The third-level standard for the daily average concentration of sulfur dioxide is 0.25 mg/cubic meter. Under this concentration, short-term exposure of people to the environment will not cause acute health damage. The main hazard of sulfur dioxide in ambient air is to cause respiratory diseases and increase mortality. Sulfur dioxide pollution mainly comes from coal burning and is concentrated in cities. Cities, especially large cities, should be the control unit. Currently, 62.3% of cities across the country have an average annual sulfur dioxide concentration exceeding * * Second level standard, which does not meet the basic requirements of protecting residents and the ecological environment from harm. ； The average daily concentration exceeds * * The third-level standard does not meet the minimum requirements to protect residents and the ecological environment from acute hazards. According to this standard, my country’s sulfur dioxide pollution control area covers an area of 290,000 square kilometers, accounting for 3% of the country’s land area. It mainly includes Beijing, Tianjin and some cities in Hebei, Shanxi, Inner Mongolia, Liaoning, Jilin, Jiangsu, Henan, Shaanxi, Gansu, Ningxia, Xinjiang and other provinces. As for the prevention and control of acid rain, based on its causes, it mainly focuses on controlling the emissions of sulfur oxides and nitrogen oxides. Furthermore, it is to control the emissions of two types of gases after fuel combustion. Of course, this can be achieved by using clean energy, desulfurizing and denitrifying the burned gas, etc. In addition, car exhaust cannot be ignored, so car exhaust purifiers have appeared. Furthermore, like global warming, the control of acid rain also requires the cooperation of all countries around the world!
Current measures to control acid rain include: Restricting the mining and use of high-sulfur coal； Focus on controlling sulfur dioxide pollution from thermal power plants ； Prevent and control sulfur dioxide pollution in the production processes of chemical industry, metallurgy, non-ferrous metal smelting and building materials industries. The fundamental way to control acid rain is to reduce the emission of acidic substances into the atmosphere. The current effective means are to use clean energy, develop hydropower and nuclear power plants, use sulfur-fixing coal briquettes, use new technologies for boiler sulfur fixation, desulfurization, and dust removal, develop alternative fuels for internal combustion engines, install catalytic converters for motor vehicle exhaust gases, and cultivate acid rain-resistant crops and tree species. Can acid rain be controlled by simply controlling and reducing the discharge of acidic substances in acid rain areas? Acid rain is formed in high-altitude rain clouds and can be transmitted over long distances. Therefore, the emission of acidic substances cannot only be controlled in acid rain areas, but should also be controlled in surrounding areas. Scientists have estimated that in most provinces in my country, half of the SO2 emitted by them is deposited in the province in the form of dry and wet deposition. ； 20-30% subsides to surrounding provinces ； Others settled into more distant provinces. Big cities are even more prominent. Only about 20% of the SO2 they emit is deposited within the city, while 80% is transmitted to other places. It can be seen that it is necessary to control and reduce the emission of acidic substances not only in acid rain areas, but also in surrounding areas, especially in large cities, in order to completely solve the acid rain problem in our country.