Sulfur controls alone won’t curb soil acidification in China
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atmospheric chemist at Hong Since 2005, China has been agemissions, which result largely Kong Polytechnic University. gressively tackling sulfur emisfrom fossil fuel combustion in Whereas flue-gas desulfurization sions from power plants and power plants and vehicles, will technology can reduce sulfur other industrial sources to reduce increase by 30%, and NH3 emisemissions by about 90%, nitroits emissions of sulfur dioxide sions, generated largely from livegen-control technologies such as (SO2), one of the main precursors stock farming and fertilizer use, low-NOx burners typically only will rise by 57% from 2005 to of acid rain, by 10% by 2010. But 2020. Because of the combined the resulting improvements in soil achieve 10-60% efficiency, he acidification will be cansays. Technologies that can celed out by rising emisproduce up to 85-90% resions of nitrous oxides (NOx) ductions in NOx are availand ammonia (NH3), acable, but they are still expensive and not yet widely cording to a new study in used in China. “If the govES&T (2009, DOI 10.1021/ ernment can have a stricter es901430n) by Yu Zhao, Lei policy on NOx, as it does for Duan, and colleagues at Tsinghua University (China), SO2, NOx emissions can be Harvard University, and the significantly reduced in the Norwegian Institute for Wafuture,” says Wang, who is ter Research. the chief scientist for a large Sulfur deposition, stemnational project on acid rain ming largely from SO2 emisin China; this project proCoal-fired power plants are the leading source of SO2 vided some funding for the sions from power plant and NOx emissions in China. emissions study. smokestacks and industrial China, like the U.S., is boilers, leads to soil acidifigrappling with how to limit NH3 effects of sulfur and nitrogen cation. When soils become overly acidified, they lose key nutrients emissions, the area of China that emissions from fertilizers used in will exceed critical load for soil such as calcium and magnesium, agriculture. NH3 emissions are which are needed for the healthy acidification is likely to remain at very difficult to address because 28% in 2010. growth of forests. Heavily acidiagricultural regions are scattered To carry out their analysis, the fied soils can also leach toxic across large land areas, and little researchers developed a national metals such as aluminum into technology is available to directly emissions inventory for various underground water sources and capture these emissions, says pollutants in China, including cause toxic runoff into nearby Zhao. SO2, NOx, NH3, and particulate lakes. In 2005, China exceeded Another variable that could afthe critical load for soil acidificafect China’s ability to manage its matter. They then took into action in 28% of its territory, priemissions and soil acidification is count emissions projections for marily in the eastern and souththe country’s future energy de2010 and 2020 and applied atmocentral regions of the country. To mand, says David Streets, an enspheric simulation models to decombat this problem, as well as ergy and environmental policy termine the sulfur and nitrogen the worsening air pollution from scientist at Argonne National deposition across the country. fossil-fuel combustion, China iniLaboratory. The worldwide ecoThe long-term outlook for soil tiated an aggressive management nomic recession has contributed acidification largely depends on plan to rein in its SO2 emissions to recent SO2 emissions reducemission-control policies in China over the next decade, says Zhao. by phasing out older, low-effitions, says Streets, because it has “This result indicates that controlciency units and by installing slowed the growth of manufacturling NOx and NH3 emissions has flue-gas desulfurization technoling and exports. “When industry ogy in newly built power plants. is not operating at full capacity, it become a very urgent problem for Although China is likely to meet tends to lower emissions,” says China.” its 10% reduction goal for SO2 by Streets. “The extent to which Although the Chinese governemissions will increase probably ment has already begun enacting 2010, these measures will not be depends on the strength of the policies to address the growing enough to stem the growing probChinese economy.” nitrogen problem, nitrogen emislem of soil acidification, the resions are more difficult to curtail searchers conclude. If current —AMANDA LEIGH MASCARELLI than sulfur, says Tao Wang, an trends continue, they found, NOx 10.1021/es9028809
2009 American Chemical Society
Published on Web 09/30/2009
November 1, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 8005
