Increase of High Molecular Weight Organosulfate with Intensifying Urban Air Pollution in the Megacity Beijing
Authors/Creators
- 1. State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
- 2. Department of Chemistry, University of California, Irvine, California 92697-2025, United States
- 3. Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China
- 4. State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, Beijing 100085, China
- 5. State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
- 6. School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
- 7. Max Planck Institute for Chemistry, Multiphase Chemistry Department, Hahn-Meitner-Weg 1, 55128 Mainz, Germany
- 8. Chubu Institute for Advanced Studies, Chubu University, Kasugai 487-8501, Japan
Description
Organosulfates (OSs), a key component of secondary organic aerosols (SOA), account for up to one third of organic matter in the atmosphere. However, high-molecular-weight (HMW, 500–800 Da) OSs in ambient aerosolsare poorly characterized at a molecular level, due to experimental difficulties. With Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICRMS),we are able to identify more than eight thousand OSsin wintertime aerosols in Beijing. We found that both the number and signal magnitudesof HMW OSs with low H/C and O/C ratios and degrees of unsaturation were greatly enhanced during hazy days, indicating that most HMW OSs were freshly formed during stagnant air-pollution episodes. They are most likely to be the oxidation products of semi- to low-volatility precursors (e.g., polycyclic aromatic hydrocarbons and fatty acids) and have showed a strong influence of anthropogenic emissions.The molecular corridor analysissuggests that the high abundance of HMWaromatic-like and aliphatic OSsconsiderably decreases the volatility of organic aerosols in the urban atmosphere.