Polluted acidic gases present in the atmosphere with a pH less than 5.65 precipitation is called acid rain. What is acid? Pure water is neutral and tasteless, lemonade, orange juice, sweet and sour, the sour taste of vinegar, they are weak acids, alkaline taste slightly astringent alkaline soda and water, astringent compared to caustic soda, caustic soda alkaline, but belongs to the baking soda salt is alkaline. Scientists have found that the magnitude of the sour taste is related to the concentration of hydrogen ions in aqueous solution; involving the flavor and the concentration of hydroxide ions in the alkaline aqueous solution, which then creates an indicator: the concentration of hydrogen ions, the pH value is mentioned as a negative number. Thus, the pH of pure water (distilled water) is 7; the lower the pH the more acidic; the more alkaline the higher the pH. Harmless sleet (pH usually between 0-14) is close to neutral pH to 7, with carbon dioxide in the atmosphere, slightly acidic (water and carbon dioxide are saturated as carbonate when it is saturated), pH 5.65. Rain with a pH of less than 5.65 is called acid rain, snow with a pH of less than 5.65 is called acid snow, and clouds of mist fill the air in high-altitude mountainous areas, such as Mount Emei, with a pH of less than 5.65, which is called acid fog.
Testing the pH value of water can generally use a variety of tools: litmus test solution \ phenolphthalein test solution \ PH test paper (high precision, you can test the pH value) \ PH meter (more accurate measurement of pH).
What is acid rain rate?
This year will fall there are a few showers and a lot of acid rain, there are not acid rain, it is often called an area? What is the acid rain rate in that area? Total acid rain divided by rainfall. Its minimum value is 0% to 100% of the maximum value. If dependent on rainfall snowfall.
Sometimes, a rainfall may last for several days, so the acid rain rate should be the total number of people throughout the precipitation process divided by the amount of precipitation throughout the year during the course of the annual acid rain acid rain precipitation process.
Average annual precipitation pH, acid rain rate to discern the area of acid rain area is another important indicator.
What is the acid rain area?
Collected acid rain samples can not be considered acid rain area, because dozens of annual rainfall, rainfall acid rain, rain may not be acid rain, according to the annual average. Acid rain refers to the current scientific standards are still under discussion, but is it generally accepted that the annual average precipitation pH? Above 5.65, the rate of acid rain is 0-20%, the proportion of the value of the non-acid rain area, pH in the 5.30 - 5.60 10-40%, light acid rain area? Acid rain, pH value of 5.00 - 5.30, the acid rain rate is 30% to 60%, moderate acid rain, pH value of 4.70 - 5.00, the rainfall for heavy acid rain area is 50% - 80%, pH value less than 4.70 acidic, heavy acid rain, the acid rain rate is 70% - 100%. This is the so-called five criteria. In fact, Beijing, Xining, Lanzhou, Urumqi, acid rain collection, but the average annual pH value and acid rain rate in the acid rain area standards, it is a non-acid rain area.
Three major acid rain zones, including: sulfuric acid rain
1. Southwest acid rain zone: regional precipitation,, central China acid? rain is heavily polluted.
2. Central China acid rain area: it has become the largest range of acid rain pollution, acid rain pollution intensity of the highest regional center.
3. The pollution intensity of the acid rain area in the east coast of China is lower than that of the acid rain area in central and southwest China.
[edit]Acid rain,
The modern industrial revolution, burning coal to produce steam from steam engines, boilers, propulsion machines, starling, coal-fired power plants, coal-fired, and more soared. Unfortunately, coal contains sulfur impurities, about 1% of the sulfur dioxide emissions in the combustion gases produced by the combustion of acid at high temperatures, which can contribute to chemical changes in the combustion of air, part of the oxygen and nitrogen compounds, and emissions of acid gases, nitrogen oxides. Rain and snow at high altitudes, soil erosion, acid rain, rain, these acid gases rain impurities sulfate, nitrate and ammonium ions dissolved. In 1872, the British scientist Smith analyzed the composition of rainwater in the city of Renton acidic ammonium bicarbonate rural rainwater is not acidic, suburban rainwater containing ammonium sulfate, slightly acidic urban rainwater containing sulfuric acid or acidic sulfates, acidic. Thus, Smith was the first in his term, "acid rain" air and precipitation chemical climatology.
[edit]Causes of acid rain
Acid rain is caused by a complex phenomenon of atmospheric chemistry and atmospheric physics. The vast majority of acid rain contains a variety of organic and inorganic acids, sulfuric acid and nitric acid. From burning coal, oil combustion within the cloud condensation nucleation sulfuric acid nitrogen oxides, sulfur dioxide emissions and automobile exhaust emissions condensation in the rainfall process, industrial production and civil life occurs nitric acid liquid phase oxidation reaction, the formation of sulfuric acid raindrops and nitric acid raindrops; acid-containing raindrops in the descent process continues to merge the adsorption, erosion, and acid rain acidic gases, the formation of larger raindrops and the process of cloud erosion and finally land on the ground, the formation of acid rain, acid rain is a complex atmospheric chemical and atmospheric phenomenon. Formation of acid rain, acid rain is sulfuric acid rain.
Acid rain burning fossil fuels and:
(1) S → H2SO4 (bright) S + O2 → SO2
SO2 + H2O → H2SO3 (sulfuric acid)
The chemical reaction equation of 2H2SO3 + an O2 → 2H2SO4 is: (sulfuric acid)
S + O2 (ignition) = SO2 2SO2 +2 H2O + O2 = 2H2SO4 <BR /(2) Oxides of nitrogen dissolve in water to form an acid:
a. NO → HNO3 (Nitric acid)
2NO + O2 = 2NO2 3NO2 + H2O = 2HNO3 + NO
The chemical equation of the reaction is as follows:
4NO + 2 H2O + 3 O2 = 4HNO3 < /p>
B. NO2 → HNO3
The overall chemical reaction equation:
4NO2 +2 H2O + O2 → 4HNO3 <BR / (*Note: the number after the subscript of the element, preceded by the stoichiometric number of the chemical formula) .
[edit]Factors affecting the formation of acid rain
Acidic pollutant emissions and transfer conditions
Generally, sulfur dioxide pollution is severe, sediment siltation of higher concentrations of sulfate ions, resulting in pH is low.
Acid rain in the atmosphere of ammonia, ammonia (NH3) formed in the atmosphere, is very important. Ammonia is a common atmospheric gaseous alkali metal atmospheric ammonia volatile? The decomposition of organic matter that is evolved and farmland. Reduces acidity due to its role as a water-soluble acid in acidic aerosols or rainwater, the main source of nitrogen fertilizer. Ammonia volatilization from the soil increases the soil pH, increasing the soil?pH by 7?8 days in Beijing, Tianjin, Chongqing, and Guiyang, usually 5-6, and is an important reason for the low buffering capacity of soil acidity from north to south in the buffering capacity of atmospheric ammonia levels in dust. These two factors could explain, at least in China, the buffering capacity of the acid rain distribution in the south.
3
Atmospheric particulate pollutants are sources of acidity, acid gases SO2 and NO2, and an important member of the very complex - particulate matter particles, dust and sand. It is estimated that about one-third of the south and one-half of the north and the latter. The role of particulate matter in the formation of acid rain, SO2 oxidation catalyzes the oxidation of metals, acids, and particulate matter is acidic, it can not play a role, but also become a source of acid is usually high concentrations of particulate matter in the atmosphere of foreign countries a few times to ten times the study of natural acid rain can not be ignored.
Weather conditions
If the weather and terrain conditions are favorable for the diffusion of pollutants and reduce the concentration of atmospheric pollutants, the acid rain attenuation is heavier (such as the phenomenon of inversion), and vice versa.
[edit]Hazards of acid rain
Sulfur and nitrogen are nutrients, soluble minerals that are absorbed by terrestrial plants if the acidity is too high and the pH drops below 5.6 in acidic precipitation, which can lead to serious harm. Large tracts of forests, crops wither and die directly, but also inhibit the decomposition of organic matter in the soil, nitrogen fixation, leaching and soil calcium, magnesium, potassium and other nutrients, soil infertility, but also in the acidification of lakes and rivers and the dissolution of heavy metals in the soil and water sediment into the water, the combination of poisonous fish, accelerated corrosion of buildings and monuments and weathering process; may endanger human health.
Perhaps the most obvious effects of acid rain are heavily publicized in Europe and the northeastern United States, but threatened areas, including Canada, Sierra Leone, the Rocky Mountains of California, and China are some places where rainwater is occasionally observed to be as acidic as vinegar. Acid rain, and the extent of its effects, is a subject of much debate. Hazards to aquatic life in lakes and rivers were initially the key issue, but now it is the costly consequences to human health of acid rain air pollution on buildings, bridges and equipment recognized as hazardous in the field that are the most difficult to quantify.
Lakes with poor buffering capacity are the most harmful. Natural alkaline buffers, acid rain? Acidic compounds (mainly sulfuric acid, nitric acid and small amounts of organic acids), however, formed in granite lakes are susceptible to direct damage because of dissolved aluminum and manganese metal ions (acids) by acid rain, which can lead to a reduction in the amount of plant and algal growth and, in some lakes, but also cause fish to decline or disappear. The harmful effects of this form of pollution cause harmful effects on plants, including the leaves fine roots until destroyed.
Reduction of PollutantsChemical scrubber towers are considered a possible remedy to prevent the emission of pollutants from burning coal power plants with high sulfur content in the northeastern United States. Chemical scrubber towers are used for the treatment of exhaust gases, or to dissolve or precipitate or eliminate pollutants from stationary and mobile sources to improve air quality is another example of the chemical action of the method of reducing emissions of nitrogen oxides, the amount of catalyst of the device
Acid Rain Profit or
Analyzed and the formula
D = DH + DA + DF + DB + DC + DT
D - total losses caused by air pollution
DH - air pollution
DA - losses caused by air pollution losses caused by losses to human health losses caused by agricultural losses
DF - forest losses
DB - building materials air pollution caused by air pollution
DC - increase in the cost of cleanup of air pollution
DT - acid rain impacts, losses visibility
DT - acid rain impacts, losses visibility
DT - acid rain impacts, losses visibility
Estimated losses air pollution on the human body BR /> DH, DHM +, DMT + DHD
where
DHM - respiratory illnesses, medical costs of production
Losses
DMT - respiratory illnesses of the DHD - early deaths of patients with lung cancer losses of the Causes air pollution damage to forests estimated
DA = DAV + DAG
DAV - damage caused by atmospheric pollution by cutting vegetables
DAG - damage caused by atmospheric pollution damage to forests ecological food production losses
Estimated air pollution forests
DF = DFW + DFE
This <
DFW - economic loss of forest cut wood <BR / DFE - economic loss of welfare (non-forest products)
Estimation of losses from air pollution of building materials
DB = DBS + DBP
DBS - economic loss of damage to galvanized steel
DBP - damage to paints
Economic loss estimation of Increased Air Pollution from Cleanup Costs
DC = DCH + DCR
DCH - Household Cleaning Costs
DCR - Exterior Cleanup Costs for Townhomes
Visibility, Reduced Transportation Loss Estimates
DT = DTH + DTW
DTH - Acid Mist Overland Transportation
DTW - Economic loss caused by economic loss caused by acid mist waterborne transportation
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Measures to control acid rain The fundamental measure to control acid rain is to reduce emissions of sulfur dioxide and nitrogen oxides.
Governance measures, the world's most serious acid rain in many countries in Europe and North America suffered many years of acid rain hazards, and finally realized that there are no national boundaries, the atmosphere, after repeated consultations, the United States of America United Nations Conference of Ministers of the Environment to prevent acid rain is an international environmental problem and can not be relied upon to solve it by a country alone, it is necessary to * * * together with the measures taken to reduce the emissions of sulphur oxides and NOx emissions. The Geneva Convention for the Control of Long-range Transboundary Air Pollution of the Economic Commission for Europe was adopted in November 1979 and entered into force in 1983. By the end of 1993, the contracting parties must reduce sulfur dioxide emissions by 70% of the cause of acidic emissions in 1980 in Europe and North America (including the United States and Canada) 32 countries signed the "Convention", most countries have taken active measures to fulfill the commitment to develop regulations to reduce the emission of substances. For example, the Acid Rain Act provides that in the east of the Mississippi River, sulfur dioxide emissions in 1983 were 200,000 tons / year, 10 years later reduced to 100,000 tons / year, sulfur Canada in 1983 and 4.7 million tons / year, reducing carbon dioxide emissions in 1994 to 2.3 million tons / year, and so on. Currently, the main measures to reduce sulfur dioxide emissions in the world:
1, raw coal desulfurization technology, you can remove about 40% to 60% of the inorganic sulfur from coal.
Use fuels with low sulfur content, such as low-sulfur high-quality coal and natural gas.
3, improved coal technology to reduce sulfur emissions in the coal combustion process of sulfur dioxide and nitrogen oxides, for example, coal liquefaction technology is one of the new technologies that are welcome in all countries, it is mainly the addition of limestone and dolomite, from sulfur dioxide, calcium sulfate ash reaction.
Flue gas desulfurization before the formation of the flue gas is discharged into the atmosphere, as shown in Figure 4. Evening after combustion of coal with quicklime, 85% of 90% of the sulfur dioxide gas in the flue gas can be removed. However, the effect is still good, but very expensive desulfurization. For example, the installation of flue gas desulfurization devices in thermal power plants, 25% of the total investment cost of the power plant. This is one of the main difficulties in combating acid rain.
> 5. The development of new energy sources, such as solar, wind, nuclear, combustible ice, but the technology is not mature enough, if the use of pollution and consumption costs are very high.
Acid rain, the working manifestation of air pollution, the earliest concern of acidic rainfall, known as acid rain is formed by dissolving carbonic acid in which
Pure rain and snow fall, carbon dioxide in the air, so it has a slightly acidic. The concentration of carbon dioxide in the air usually occurs when the precipitation pH is about 316ppm to 5.6, which is a normal phenomenon and is not what we usually call acid rain.
We are talking about acid rain, acidic precipitation due to the effects of human activities that lower the pH below 5.6. With the development of modern industrialization, the precipitation has started to appear and is on the rise year by year. It has begun to affect human survival, and the human living environment.
Ancient rain and snow acidity is undocumented, about 180 years ago, Greenland's ice accumulation test showed that when the snowfall pH 6?7.6.
In the 1950s, the pH of precipitation was generally greater than 5 in the world, and some industrial areas had falling acid rain. From the 1960s, in the midst of industrial development and consumption of fossil fuels, precipitation pH in some industrialized areas of the world (e.g., in declining southern northern Europe and eastern North America)? increased by five, extending to ecosystem damage.
In 1872 the chemist Smith, the first to use the term "acid rain" in Air and Rainfall: The Year of Chemical Climatology began, a book that pointed out the chemical properties of precipitation coal and the decomposition of organic matter, but also pointed out that the effects of acid rain are harmful to plants and materials.
In the mid-1950s, the U.S. aquatic ecologist Golem had a series of research work, revealing the relationship between acidic precipitation acidity in lake waters and soils, precipitation acidity is caused by the burning of fossil fuels, metal smelting sulfur dioxide emissions. However, their work has not gone unnoticed.
In the 1960s, Swedish soil scientist Greg Oden first documented the correlation between limnology, agronomy, chemistry, and atmospheric chemistry to comprehensively study the discovery that acid precipitation is a widespread phenomenon in Europe, and that precipitation on the ground increases the migration of sulfur and nitrogen pollutants from the acidic water over thousands of kilometers in Europe
In 1972, the Swedish government, the United Nations Conference on the Human Environment, presented a report: Crossing Borders. Report submitted to the United Nations Conference on the Human Environment: Transboundary Air Pollution in the Atmosphere and Precipitation on the Environment" knock on the door Since then, more and more countries are concerned about the problem of acid rain, but also to expand the scale of the study.
The first international discussion of acid precipitation and forest ecosystems was held in May 1975 at Ohio State University, USA. The International Conference on Environmental Acidification was held in Stockholm, Sweden, in June 1982, and acid rain has become one of the major problems of current global environmental pollution.
The formation of acid rain is a complex phenomenon of atmospheric chemistry and atmospheric physics. Acid rain contains a variety of inorganic and organic acids, most of which must be sulfuric acid, nitric acid, sulfuric acid, sulfuric acid and nitric acid converted to anthropogenic local emissions of sulfur dioxide and nitrogen oxides emissions, but also migrated from a distance /> industrial activities, such as the combustion of coal and petroleum, as well as smelting of metals sulfur dioxide, is released into the air through the gas-phase or liquid-phase oxidation reaction to generate sulfuric acid, which will be produced by the high temperature of the burning With air, nitrogen and oxygen, nitric oxide, and continue with atmospheric oxygen, and most converted to nitrogen dioxide, nitric acid and nitrite will generate water or steam.
As a result of human activity and natural processes, gases or solids into the atmosphere, but also the formation of acid rain in the atmosphere photochemical reactions affecting atmospheric particles of iron, copper, magnesium acid catalysts. Ozone and hydrogen peroxide act as oxidizing agents to oxidize sulfur dioxide; fly ash, calcium oxide, calcium carbonate in the soil, natural and man-made sources, ammonia and other alkaline substances react with and leave the acid.
Precipitation acidity is actually primarily a dry anion and cation precipitation balance. Atmosphere, sulfur dioxide and nitric oxide concentrations of precipitation acidity; a high concentration of several major alkaline substances represented by Young Hurricane will be a high precipitation acidity, and may even present alkaline, alkaline soils in the region, or high concentrations of particulate matter in the atmosphere, which is often the case on the contrary, even if the concentration of sulfur dioxide, and nitric oxide in the atmosphere is not high, the alkaline substances are relatively small, and there is still high acidity of precipitation! The acidity of precipitation in industrial areas tall chimney-like sulfur carbon dioxide spreads over great distances, which also drops a lot of acid rain in high mountains and wilderness areas.
Sulfur and nitrogen are indispensable nutrients for plant growth, and animals and plants absorb the dissolved minerals deposited in the weakly acidic crust. For example, if the acidity is too high and the pH drops below 5, the ecosystem is destroyed
Soils with low salt saturation, thin soil layers, and rocky areas, the acid rain will not fall on the ground and will make the soil, lakes,
Lakes or rivers with a pH of less than 5:00, soils and water basins will be acidified by the deposition of metals (e.g., aluminum) that will be dissolved in rivers and dissolved into the water, poisoning fish and their reproduction and development severely! Changes in the structure of aquatic organisms in acidified water bodies affecting the assemblage can also lead to an increase and decrease in acid-tolerant algae, fungi, bacteria in the roots of plants and invertebrates, reducing the rate of decomposition of organic matter. As a result, the reduction of acidification of lakes, rivers, and fish, many lakes in the southern regions of Sweden and Norway, as well as the northeastern United States have become dead fish from the lake.
The U.S. National Adirondack Lakes and Mountains, 700 meters above sea level, is more than half of the eastern half of the lake's water pH ? 5,90 percent were below and no longer fishable between 1929 and 1937, and only 4 percent of the lakes had a pH of 5 or lower, or no fish. In Sweden more than 18,000 large and medium-sized lakes were acidified, and about 4,000 were severely acidified and aquatic life was seriously injured.
Acid rain can also inhibit the fixation of nitrogen in the soil, leaching and soil particles, calcium, magnesium, potassium and other nutrients, soil infertility, decomposition of organic matter in the plant
Acid rain can harm newborn bamboo shoots, thus affecting the growth and development of the combination; Acid rain corrodes building materials, metal structures, paints, old buildings, statues will be destroyed, acidification of lakes and groundwater due to the dissolution of metals will be affect the health of consumers harmful.
Fundamental measures to control acid rain to reduce anthropogenic emissions in Sweden and other countries to acidify the soil and water with alkaline lime in another test, and achieved good results
How to reduce acid rain in the short term?
Acid rain, sulfur dioxide and nitrous oxide. Important air quality, one of the problems we face today. Acids and compounds formed in the combustion of fossil fuels for power generation and transportation of these substances are mainly acids from sulfur oxides and nitrogen oxides in the acid, some natural sources of these compounds, such as lightning, volcanoes, biomaterials, combustion, and microbial activity, but except for rare volcanic eruptions, these natural gas emissions from automobiles, power plants, and smelters, this? s a relatively small amount.
Different strategic responses to reduce acid rain, you may need billions of dollars of investment each year due to such a huge and very important a good understanding of the atmospheric processes involved in the migration of chemical pollutants, transforming the fate of the cost.
Acid deposition consists of two parts, i.e., the "wet" form of precipitation (rain, snow) and dry fallout (aerosols or gaseous compounds that fall onto surfaces in the form of acidic compounds such as soil particles, plant leaves). As often as settlement substances? In a very different chemical form of atmosphere, for example, the sulfur in coal is oxidized to sulfur dioxide, which is the gaseous form, which is discharged from the chimney as they slowly oxidize the atmosphere moving to react with water to form sulfates - which may be hundreds of kilometers downwind in the form of settlements
Nitrogen oxides are formed and undergo routing in the atmosphere in the reaction, and the final removal is Very complex, when power units are heated at high temperatures in nitrogen and oxygen, in folk stoves and automobile engines, to produce nitric oxide (NO), nitrogen dioxide (NO2) is generated, and balanced with an oxidizing agent, nitric acid (HNO3), the global oxides of nitrogen - quantitative estimates of where they are and where they lead are still quite uncertain.
Before an in-depth understanding of the biogeochemical cycles of nitrogen, sulfur, and carbon in their various chemical forms originates and culminates in these chemicals, it is easy to see how the world is difficult, and you can feel confident in choosing an air pollution control strategy to achieve cleaner atmospheric chemistry, the chemistry of the environment, and the core of a healthy environment. Reliable measurements are available for trace chemicals in the air, the most important atmospheric chemical reaction kinetics, and to reduce pollutant emissions, a new, more efficient chemical process, these are national goals that must be undertaken in the next 10 years.
[edit]Acid Rain Biological Control
The Worldwatch study, recently published in the 1994 Global? Trends Report 1994 life characteristics: overall, not a very good situation for the planet, all the indicators to measure the health of the planet, we have only succeeded in reversing the deterioration of the indicators - the empty Freon ozone layer to reduce carbon dioxide emissions, rather than reducing air pollution is getting worse and worse, according to statistics, to the atmosphere annually emits SO21.15 tons, NO2, about 50.12 million tons. In the world's urban population, about half of the people live too much SO2 in the atmosphere, there are 1 billion people live too large particulate matter air pollution in the environment has become a hidden killer. Hugh certificates SO2 culprits. Twenty-six countries in Europe and Canada recently signed a new proposal to reduce sulfur dioxide emissions by 87 percent if the United Nations Economic Commission for Europe agreement, the U.S. committed to 80 percent reduction in sulfur dioxide emissions by 2010. European countries and Canada, hailed the new agreement as a milestone in the prevention and control of air pollution. SO2 not only pollutes the air, endangering human health, and the formation of acid rain is the main raw material in the atmosphere, SO2 and NO2 dissolved in the rain, in the air oxidizer meteor shower, sleet, snow, hail, etc. Such as pH value is less than 5.6, i.e., measured, according to the U.S. authorities, acid rain, sulfuric acid acid acid rain accounted for 60%, 33% nitric acid, hydrochloric acid (6%), the rest of the carbonic acid and a small amount of organic acids.
Severe acid rain causes adverse effects on the earth's ecological environment, socio-economic and man-made damage, acid rain, soil acidification, reducing soil fertility, root toxicity root many toxic substances are absorbed by the object to kill the root hairs, so that plants can not absorb water, soil and nutrients, inhibiting plant growth and development, acid rain, rivers, lakes, water acidification, inhibiting the growth and reproduction of aquatic organisms, and even lead to the death of fish fry suffocation. Even lead to the death of fish fry suffocation; Acid rain also kills plankton in the water, reducing fish food sources, aquatic ecosystem diseases, acid rain, pollution of rivers, lakes and groundwater, directly or indirectly endangering human health, acid rain through the surface of the plants (leaves, stems) direct damage or indirect damage through the soil, promoting deforestation, acid rain also leads to outbreaks of pests and diseases leading to large-scale death of the forests of Europe Sulfur emissions of 22 million tons per year in China, Sichuan, destroying large tracts of forests, Guangxi Province has more than 100,000 hectares of forest dead. Strongly corrosive acid rain, metal, stone, wood, cement and other construction materials have many ancient buildings and stone works of art, and the world's acid rain corrosion damage, the world has formed in Canada's Parliament Building Leshan acid rain also directly damaged power lines, railroad tracks, bridges and houses.
Three major acid rain zones, centered in Germany, France, Britain and other countries, cover more than half of Europe's northern European acid rain zone. In the late 1950s, acid rain zones were formed in North America, including the United States and Canada. The 2 acid rain areas have reached a total area of more than 100,000 square kilometers? Less precipitation pH less than 5.0, some even less than 4.0, some of our areas in Sichuan, Guizhou, Guangdong, Guangxi, Hunan, Hubei, Jiangxi, Zhejiang, Jiangsu, Qingdao and other cities, areas? Million square kilometers of acid rain area began to take shape in the mid-1970s, is the world's third largest acid rain area of China's acid rain area is small, but the rapid growth and expansion of precipitation acidification rate in the world, it is rare due to air pollution is no national boundaries. "