The Trend of Sulfur Dioxide Emissions in China after 2000

With the rapid development of the economy, the sulfur dioxide (SO2) emission from China since 2000 is of increasing concern. In this work, we first presented the change of SO2 emission in China since 2000 using a technology-based methodology. Then, we compared the SO2 emission data with a variety of official statistics, ground-based measurements and satellite observations of sulfur related quantities over East Asia. The results indicate that from 2000 to 2006, total SO2 emission in China increased by 53%, from 21.7 Tg to 33.2 Tg. The emission growth rate slowed around 2005, and emissions began to decrease after 2006 mainly due to the wide application of flue-gas desulfurization (FGD) devices in power plants. The trend of estimated SO2 emission in China is consistent with the trends of SO2 concentration and acid rain pH and frequency in China, as well as with the increasing trends of background SO2 and sulfate concentration in East Asia. A longitudinal gradient in the percentage change of urban SO2 concentration in Japan is found during 2000-2007, indicating that the transport of increasing SO2 from the Asian continent partially counteracts the local reduction of SO2 emission downwind. Both surface solar radiation (SSR) measurements and satellite aerosol optical depth (AOD) products show that China and East Asia excluding Japan underwent a continuous dimming after 2000. The arrested growth in SO2 emissions since 2006 is also reflected in the decreasing trends of SO2 and SO4 concentrations, acid rain pH values and frequencies, and AOD over East Asia.