The Acid Rain Issue
---- In China and some other places of the world
The acid precipitation is also called acid rain, which means the pH value of the precipitation is lower than 5.6 levels. The forms of acid precipitation include rain, snow and fog, and the acid rain is the most common one, people often use “the acid rain” to denote the acid precipitation. The acidity of the acid rain can be 100 times higher than the normal rain. We cannot recognize the acid rain by our eyes. It is smelled-less; even cannot be tasted out. The acid rain has lots of kinds of inorganic acid and organic acid. Most of these acids are sulfuric acid and nitric acid turn from sulfur dioxide and nitrogen oxides, which are expellant gas exhausted by human beings.
The first presenter of the acid rain was Smith, a British chemist. He advanced the conception of acid rain in the year 1872 while people began to pay more attention on acid rain and its affects till 1940s. And the research of acid rain in Scandinavia in 1950s was the beginning of the modern research of the acid rain.
China started to monitor and research on the issue of the acid precipitation later than Europe. It was started at the west suburb of Beijing in the year 1974. In the year 1979, some other cities in China such as Shanghai, Chongqing, Nanjing and Guiyang etc. started to focus on this issue. In the national investigate in the year 1982-1984, it was founded out that some cities in Southwest China and South China had the acid rain pollution. After that, 189 monitoring stations and 523 precipitation sampling points were set in a national area in the year 1985-1986. That was the beginning of systematic monitoring in China. And the character of distribution of the acid rain in China is obviously areal differentiation.
1. The formation mechanism of the acid precipitation
1.1 The main pollutants
The main pollutants which may cause acid rain include: sulfur oxides, such as sulfur dioxide and sulfur trioxide, NOx (shorts for nitrogen oxides), heavy metal particulates, some organic compounds which are steady in the environment, some active organic materials which can turn into photochemical oxidant and some inorganic materials such as chlorine, fluorine and some other elements. Human beings exhaust most of these pollutants.
1.2 The formation process of the acid rain
The sulfur dioxide (SO2) in the air can have chemical reaction with oxygen in the air under the sunshine. Then sulfur dioxide may turn into sulfur trioxide (SO3). The chemical equation of this reaction is: 2SO2 + O2 ----> 2SO3. And then sulfur trioxide may change into sulfuric acid with water in the air. The equation is: SO3 + H2O -- H2SO4. The nitrogen oxides (NOx) can become nitric acid (HNO3) in a similar way: NOⅹ+ O2 -- N2O5, N2O5 + H2O -- 2HNO3. And some other organic materials can be changed into organic acids. These acids can release hydrogen ion: H2SO4 -- 2H+ + SO42-, HNO3 -- H+ + NO3-. When the ion density reaches the balance point, the pH volume is just lower than 5.6, then there comes the acid rain.
So we can see that the sulfur oxides and nitrogen oxides exhausted from the burn of fossil fuel such as from electric stations, auto-mobiles and industries etc. are the main reasons of acid rain. Acid rain is actually a common nomenclature to express the pollution cause by sulfur oxides, nitrogen oxides and their reaction products.
2. Distribution of the acid rain
We woke up to realize that the acid rain had become a global environmental issue from the meeting of the United Nations in the year 1972. Swedish government informed the whole world that the damages may bring by the acid rain in a report. But in the next 10 years after this meeting, the average of acid rain in Europe had become wider and wider. It was not just in North Europe such as Norway and Sweden but also covered Middle Europe and East Europe until it covered the whole area of Europe.
In east part of the United States and south part of Canada, the acid rain has become a very big problem of pollution. There are 15 states in the United States have the problem of the acid rain. And there is an area about 1.2 to 1.5 million square kilometers in Canada has the same issue. In Japan, it has been reported since the year 1971.
The data in China show that the distribution of the acid rain is obviously regionally. The acid rain pollution usually happened in southwest China such as Chongqing, Guiyang and Liuzhou etc. in 1980s, and that was covered about 1.7 million square kilometers; the acid rain belt had developed to an area from south of Changjiang River to the east of Qinghai-Tibet Altiplano and Sichuan Basin till mid-1990s, that was more than 1 million square kilometers bigger than before. In the year 1999, middle part of China, south part, southwest part and east part of China were the most serious places. Nowadays, 30 per cent of China has the acid rain pollution problem. The mid-China the acid rain belt including Changsha, Ganzhou and Nanchang is the most severe polluted area in China. (Tang Xiaoyan, Xie Shaodong. 2001.5 Acid Rain) In this area, the pH value of annual precipitation is under 4.0. China is the third zone, which has the acid rain problem in the world right after Europe and North America.
In Australia, the problem of the acid rain is not as serious as Europe, North America and China because Australia is geographically isolated from other continents. But Australia do has the issue of the acid rain. On average Sydney rain has a pH value of 4.3 through a report. (Australia State of the Environment Report 2001)
Even in Antarctica, Chinese scientists reported in early 2001, that they found the pH value of precipitation was 5.46. That was the eighth time from 1998. Antarctica is not the pure land any more.
3. The damage of acid rain
The acid rain may cause great damage to natural resource, ecosystem, animals, plants, building, cultural relics, historic sites, public health, economy and even relationships among countries.
3.1 Affects on ecosystem
The acid rain may cause the acidification of soil. The nutriment will be dissolve and the soil will be arid. And the active of microorganism in the soil will fall. These affects will cause other issues. There are 85 thousand lakes in Sweden; 20 thousand of them were impacted by the acid rain; 1500 of them were acidificated.
3.2 Affects on animals
The acid rain may cause acidification of surface water such as rivers and lakes and soil and then cause death to aquatic animals. 1750 out of 5000 lakes in south Norway had no fish or shrimps and other 900 lakes were polluted badly during a period, which the acid rain was most fearful. Fish in 450 lakes in Sweden died because of the acid rain.
3.3 Affects on plants
The acid rain has badly affects on forests. Alpine forests and Black forest in Germany are typical examples. In the early 1980s, there were reports about the death of forests in Europe. The acid rain also causes death of forests in North America. In China, there were some similar reports, especially in the south. There were 280 thousand hectare of forest harmed by acid rain in Sichuan Basin, and there were about 140 thousand hectare of forest had the same problem in Guizhou Province. The acid rain can also cause reduction of farm produce especially wheat. It will reduce 13.7% if the pH value is 3.5; 21.6% if the pH value is 3.0; and 34% if it is 2.5. The production and content of protein of soybeans and other vegetables will drop because of the acid rain.
3.4 Affects on buildings
The acid rain can erode the structure of buildings, cultural relics and historic sites. These can obviously cause the losing of property, culture and even human death.
3.5 Affects on human beings
The acid rain may cause death of 7,500 – 12,000 people per year by estimate. And the acid rain can cause cancer, nephropathy and congenital defect. It can also cause the decline of children’s immune function, increase of incidence of chronic pharyngitis and bronchial disease; it can cause eyes’ disease in aged group.
3.6 Loss of economy
The data show that the United States loses 5 billion dollars because of the acid rain per year. Germany loses about 19 billion marks per year. In China, the acid rain pollution caused a loss of 11 billion RMB in the year 1995, which was 2 per cent of the whole GNP; and it causes a direct loss of 14 billion RMB per year.
3.7 Damage of the relationships among countries
We can see it clear that those sulfur oxides and nitrogen oxides can be transported for a long distance in the atmosphere. So the acid rain may affect the areas, which are far away from the place of pollutant exhaustion. That is why the acid rain has become a global issue.
In North America, the United States and Canada had a dissension because of the acid rain. According to the department of environment of Canada in the year 1980, there were about 3.2 million tons of sulfur oxides from the United States. So Canadian government outcries against the United States and screamed for reparation. And the US government had to admit the truth and make amends to Canada for it. At the same time, the US asked for reparation from Mexico, because there were pollutants came from Mexico.
In Mid-Europe and Scandinavia, forests and life forms are dying because of the acid rain. People blamed the United Kingdom and Germany because the acid rain is from these two countries.
4. What we should do with the acid rain?
The acid rain has become a global issue. People try to control it. The basic way to control the acid rain is reducing the exhaustion of sulfur dioxide and nitrogen oxides by human beings. Lots of the countries are trying to reduce the using of coal and petroleum, use the low sulfur fuel, update the combustion trains, try to desulphurization and denitrificate and control the exhaustion of tail gases of motor-driven vehicle.
4.1 In Europe and North America
The acid rain and acidic materials can move across the boundary, so making laws of nations is a very important way to control the acid rain. In Europe, the main countries signed a series of laws to control the exhaustion of sulfur dioxide and nitrogen oxides such as in the year of 1980, 1985 and 1994. And those European countries have their own laws basic on the pacts.
In the United States, they have an expert part to control the acid rain since the year 1990. Meanwhile, they have a very flexible program. That is a permit system of pollutant discharge. The license can be sale, bought or kept to use in the future. And of course, the government has plenty of plans to teach people, and let them know the harms of the acid rain.
4.2 In China and some other places of the world.
From the year 1992, Chinese government began to collect fees for discharging pollutants. After that, the bounds of charge were widened in the year 1996, 1998, 2000 and 2001 considering the differences among different areas. In 1995, controlling of the acid rain and sulfur dioxides was brought into the air pollution prevention and control law of China. There are 112 cities and areas in the acid rain control areas, 14.8 per cent of all the cities, 8.4 per cent of the area of China; 63 cities and areas are in the control areas of sulfur dioxide, that is 8 per cent of all the cities, 3 per cent of the Chinese area. In 1992, Chinese government began to collect fees of sulfur dioxide exhaustion in 8 provinces including Guangdong, Guangxi, Shandong, and Zhejiang etc. The fee was not higher than 0.2 RMB per kg of sulfur dioxide, and depended on the different conditions in these 8 provinces. In 1998, the fee was higher and reached 0.2 RMB per kg of sulfur dioxide. In Beijing, the fee was even higher. There are some similar policies in some other countries.
The damage of the acid rain is far-reaching, and probably it is an irreversible injury to the natural system. We should avoid the damage by control the exhaustion of acidic materials such as nitrogen removal and removal of sulfur. We are getting to know more and more about the acid rain though we still have no idea or very limited knowledge in some parts of this issue. But we still can do something to control the acid rain.
Manins Peter 2001. Australia State of the Environment Report 2001
Tang Xiaoyan, Xie Shaodong. May 2001. Acid Rain
Qu Geping 2001《环境保护知识读本》
Wang Qi, Guo Likun, Dong Lu, Wang Yeyao, November. 2001., Environmental Issues in Cities
July 2001, a Report on the Resources, Environment and Development in China, 1950-2050: Evolution and Countermeasures.
Eldon D. Enger, Bradley F. Smith June 2000, Environmental Science – A study of Interrelationships (seventh edition)