While the burning of coal has sustained production since the industrial revolution, it has also produced damaging side effects. For one thing, coal is not pure. It contains sulfur, which makes up only 1 percent of the total content but will turn into sulfur dioxide during combustion. Additionally, when coal is burning, the high temperature will lead to a combination of oxygen and nitrogen gas in the air. The two will react with each other and form nitric gases.

As a result, when we consume coal, harmful acidic gases are released into the air. They remain there until the moisture absorbs them and carries them down to the earth in the form of acid rain. When conditions permit, these gases can also fall down in the form of acid snow or fog.

In 1872, a British scientist discovered that the rain in London was acidic and the term “acid rain” was first used. At present, Europe, North America, and China are generally recognized as areas suffering most from acid rain.

Also called the “tears of paradise,” acid rain is believed to have a critical impact on our surroundings. It increases the acidity of soil, thus leading to the death of agricultural products in large quantity. It damages the ecosystem of forests, where trees grow more slowly and die more quickly. It kills microorganisms in polluted rivers and lakes, which consequently kills the fish and shrimp living on the microorganisms. Moreover, it seeps into the earth and makes ground water undrinkable.

According to the statistics available, acid rain has led to the death of 1 million hectares of forest in middle Europe and some 9,000 in northern Italy. In Sweden, more than 20,000 lakes are void of aquatic life and in Norway, fish and shrimp no longer exist in some 260 lakes. In 1980, 8,500 Canadian and at least 1,200 American lakes were measured as acidified and thus became “dead lakes” where no life prevailed.

Acid rain can also severely erode the surface of architecture, vessels, vehicles, power transmission lines, railway rails, and electromechanical equipment. Some specialists hold the opinion that the weathering of ancient Greek and Roman relics is getting worse with each passing day, largely because of acid rain. In eastern America, some 3,500 historic buildings and 10,000 monuments have been affected.

Acid rain and acid fog in particular put human health at risk. They can seep deep into our lungs and lead to pulmonary edema, pulmonary sclerosing hemangioma, and even lung cancer. According to an investigation in 1980, 1,500 people in the UK and Canada died of such diseases.

With regard to China, the country’s development relies heavily on the consumption of coal. Every year, sulfur dioxide is discharged in large quantities and many areas are troubled with acid rain. At present, acid rain is mainly observed in areas to the south of the Yangtze River, such as the Sichuan Basin, Guizhou, Hunan, Hubei, and Jiangxi, and costal areas, such as Fujian and Guangdong. All together, they account for 30 percent of China’s total territory. What is more, a large area in the country is now stricken by severe acid rain. All of these phenomena tell us that the pollution of acid rain in China is much heavier than that in Europe and North America.

As estimated by environmental protection specialists in 1995, damages caused by acid rain and sulfur dioxide in areas under special control totaled 110 billion yuan, accounting for 2 percent of total annual GDP. In 1998, southwestern China saw a sharp decline in forest output. A total of 6.3 million cubic meters of timber were lost, equivalent to a financial loss of 3 billion yuan. In Guangdong, the annual loss caused by acid rain amounts to 4 billion yuan.

Since the 1990s, China has made Herculean efforts to treat acid rain and curb emissions of sulfur dioxide. Thanks to this unremitting effort, the total area suffering from acid rain extend is no longer increasing. With the gradual reduction of sulfur dioxide emissions, officials are optimistic that acid rain could be completely eliminated in China.

(China.org.cn September 12, 2007)