Society

A hard rain is falling as acid erodes beauty

By Li Jing in Beijing and Peng Yining in Xiamen (China Daily)
Updated: 2011-01-12 07:16

Daunting challenges

Environmental authorities announced that in the upcoming 12th Five-Year Plan (2011-2015), China will include two more pollutants - nitrogen oxides and ammonia nitrogen, which leads to excessive nutrients and causes algae outbreaks in water - under its mandatory pollution-control program.

The new target proposed by the Ministry of Environmental Protection is to slash both pollutants by 10 percent in the next five years.

For sulfur dioxide and chemical oxygen demand, which is a measurement of water pollution, the new reduction goals will be set at about 8 percent, slightly lower than the 10-percent target between 2006 and 2010, according to a source with the Ministry of Environmental Protection who did not want to be identified discussing policy that has not yet been approved.

The proposal is still awaiting clearance from the State Council, with a final decision expected in March during the annual two sessions of the National People's Congress and the Chinese People's Political Consultative Conference.

The ministry official admitted China will face even more pressure to achieve its air pollution control targets, considering its expanding appetite for coal consumption.

Tao Wang, an atmospheric chemist at Hong Kong Polytechnic University, said nitrogen emissions are more difficult to curtail than sulfur. Whereas sulfur-scrubbing technology can reduce emissions at power plants by about 90 percent, nitrogen-control technologies such as low-NOx burners typically only achieve 10 to 60 percent efficiency, he explained.

Technologies that can produce 85- to 90-percent reductions in NOx are available, but they are still too expensive and not yet widely used in China.

Bosses at several power plants visited by China Daily reporters complained the original designs of their facilities do not allow physical space to install new equipment. To meet the new pollution control targets will require them to completely revamp their plants.

It will be even more difficult to deal with the nitrogen emissions from vehicles, which remain a worldwide challenge.

There is already little room left for China to further slash sulfur emissions, said the ministry source. By the end of 2009, about 71 percent of coal-fired power plants had been equipped with sulfur scrubbers, compared to 12 percent back in 2005. "The next step is to take a closer look at whether these facilities are actually put into use," he said.

The ministry official admitted the biggest challenge remains China's enormous coal consumption, which is set to grow at a relatively high rate during the coming years to fuel the country's economic growth. "Studies by some experts have suggested that burning 3 billion tons of coal every year would be the upper limit if we want to keep the sulfur and nitrogen emissions to a reasonable level," he added.

Despite the central government's pledge to rely more on renewable energy sources, Wang Xianzheng, president of the China National Coal Association, recently projected annual coal consumption will reach 3.8 billion tons by 2015, an increase of 800 million tons compared to 2009.

Rain's reign of terror BEIJING - Acid rain not only causes buildings, statues and bridges to deteriorate faster than usual, but it also does serious damage to the ecology. Downpours dissolve the beneficial minerals and nutrients in soil, and in extreme cases can lead to croplands becoming infertile. Acidified soil also affects the roots of crops planted by farmers and can reduce yields. This poses a serious threat to food security, especially at a time when China's farmlands are already shrinking due to rapid urbanization. Rivers, lakes and streams polluted by acid rain become more acidic, which can cause them to lose the ability to sustain fish and other aquatic life. Over long periods, entire lakes and steams can become lifeless, except for algae. This, in turn, will then have a significant effect on the food chain. For example, terrestrial animals depending on aquatic organisms for nourishment and nutrients will die out as food sources decline. Acid rain cannot hurt a human's health directly, say scientists. For example, swimming in an acidic lake or walking in an acidic puddle is no more harmful than swimming or walking in clean water. However, sulfur dioxide and nitrogen oxides - the pollutants that cause acid rain - can cause respiratory disease in humans, as well as make existing conditions worse. Li Jing

Zhang Xiaomin in Dalian contributed to this story.

 

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