ATMOSPHERIC MERCURY EMISSIONS FROM COAL-FIRED POWER PLANTS IN NORTHERN CHINA

Hg emissions from coal-fired power plants (CFPPs) in Northern China are the major source of anthropogenic atmospheric mercury (Hg) emissions. The impact of denitrification devices on Hg emission, together with difference in Hg emission from different boilers and specific data of air pollution control devices (APCDs) are critical factors for the estimate of Hg emissions. Combined with unprecedented meta-analysis, this paper applies emission factor method to examine Hg emissions in 1995, 2003, 2011 and projection to 2015. Hg emissions from CFPPs were estimated to rise from 13.28 ton to 23.61-36.67 ton with an increase rate of 77.8% to 176.3%, while coal consumption increased by 325.5%. The emissions of Hg-0, Hg2+ and Hg-P are estimated to reach 11.80-18.34 ton, 9.45-14.66 ton and 2.36-3.67 ton, respectively. Low increase of Hg emissions benefits from the wide application of APCDs, especially the sound operation of denitrification devices. However, there are uncertainties in the estimation of Hg emission due to variation of parameters in the method, and Hg content was proved to be the predominant parameter that results in the uncertainties. The paper addresses the effect of denitrification devices and their operation rate on Hg removal, and reduces the uncertainties of Hg emissions through comprehensive emission factors.