India Is Overtaking China as the World’s Largest Emitter of Anthropogenic Sulfur Dioxide

Abstract

Severe haze is a major public health concern in China and India. Both countries rely heavily on coal for energy, and sulfur dioxide (SO2) emitted from coal-fired power plants and industry is a major pollutant contributing to their air quality problems. Timely, accurate information on SO2 sources is a required input to air quality models for pollution prediction and mitigation. However, such information has been difficult to obtain for these two countries, as fast-paced changes in economy and environmental regulations have often led to unforeseen emission changes. Here we use satellite observations to show that China and India are on opposite trajectories for sulfurous pollution. Since 2007, emissions in China have declined by 75% while those in India have increased by 50%. With these changes, India is now surpassing China as the world’s largest emitter of anthropogenic SO2. This finding, not predicted by emission scenarios, suggests effective SO2 control in China and lack thereof in India. Despite this, haze remains severe in China, indicating the importance of reducing emissions of other pollutants. In India, ~33 million people now live in areas with substantial SO2 pollution. Continued growth in emissions will adversely affect more people and further exacerbate morbidity and mortality.

Washability and Distribution Behaviors of Trace Elements of a High-Sulfur Coal, SW Guizhou, China

“…ZnCl 2 aqueous solution serves as the dense liquid, the density of which varies from 1.30 g/cm 3 to 1.80 g/cm 3 with a step size of 0.1 g/cm 3 . A certain amount of dense liquid was loaded individually in different barrels, which had a height of 500-600 mm and a volume of more than 50 L. A smaller barrel with a mesh bottom with apertures of 0.5 mm was used to separate the coal sludge and to transport the coal from one barrel to another.…”

“…The waste water was stored in a container and the settling was recovered as the coal sludge (the secondary coal sludge). Then, the mesh-bottomed barrel with washed ROM coal was put into the barrel with dense liquid of 1.3 g/cm 3 . After slight stirring and resting for about 2 min (the time was extended to 5 min for size fraction 0.5-1.0 mm), the float coal was collected and the mesh-bottomed barrel was taken out and put into the barrel with dense liquid of 1.4 g/cm 3 .…”

“…The rest were done in the same manner. Thus, each size fraction of the ROM coal was furtherly separated into 7 fractions: <1.30 g/cm 3 , 1.30~1.40 g/cm 3 , 1.40~1.50 g/cm 3 , 1.50~1.60 g/cm 3 , 1.60~1.70 g/cm 3 , 1.70~1.80 g/cm 3 , >1.80 g/cm 3 and a coal sludge product which is less than 0.5 mm. Finally, samples of the same density range from different size fractions were blended to make a single density fraction, thus 7 density fraction samples were obtained.…”

“…The concentrations of 46 trace elements were determined by using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS, ELAN DRC-e, Perkin Elmer, Waltham, MA, USA) in ALS Chemex Co Ltd (Guangzhou, China). Before analysis, 50 mg of the sample was calcined at 750 • C for 2 h and put into a polytetrafluoroethylene crucible, together with 1 mL HF and 1 mL HNO 3 ; sealed in a steel bushing and kept in an oven at 190 • C for 36 h; then cooled and evaporated to dryness; 1 mL HNO 3 was added and it was then dried again. After that, 500 ng Rh (interior label), 2 mL HNO 3 , and 3 mL deionized water was added into the crucible; placed into the steel bushing again; heated at 140 • C for 5 h; then cooled and diluted, ready for the test.…”

“…Generally, coal washing is conducted to remove minerals from the Run-of-Mine (ROM) coal, with the purpose of improving the coal quality and reducing the emissions of contaminants (such as SO 2 and PM 2.5) from coal burning and conversion. Actually, recent research [3] shows that China's SO 2 emission in 2016 was 8.4 Mt, which was only 26% of that in 2005 (31.8 Mt). This might have benefited greatly from the enhancement of the country's coal washing rate of ROM coal (from 32% in 2005 to 66% in 2015) [4,5].…”