Substantial Contribution of Transported Emissions to Organic Aerosol in Beijing
Daellenbach et al.
Nature Geoscience
DOI: 10.1038/s41561-024-01493-3
This recent publication in Nature Geoscience, led by researchers from Beijing University of Chemical Technology, INAR, and PSI as well as our colleagues at Aerodyne Research, utilizes the TOFWERK Vocus 2R and the Aerodyne TOF Aerosol Mass Spectrometer (TOF-ACSM) to better understand the contribution of organic aerosols to transported emissions. The latter combines Aerodyne’s aerosol sampling and sizing technology with TOFWERK TOF mass analyzer technology.
Air pollution, particularly in megacities, causes millions of premature deaths globally. In China, despite stringent pollution controls, poor air quality persists, primarily due to fine particulate matter (PM2.5). The health risks associated with PM2.5 are closely linked to secondary organic aerosol (SOA), which, unlike its major inorganic constituents (ammonium, nitrate, sulfate), has been less understood. Recent reductions in these inorganic components have not led to expected health improvements, underscoring the need to better understand SOA sources and formation. SOA results from complex atmospheric reactions involving various organic compounds, complicating source identification with traditional mass spectrometers. However, new field-deployable soft-ionization mass spectrometers enable detailed, real-time molecular analysis, improving SOA source identification and informing more effective mitigation strategies.
In Beijing, haze is closely related to SOA. The study found that winter SOA primarily arises from fresh solid-fuel emissions and secondary aerosols formed through combustion and aqueous processes involving aromatic compounds. Severe haze is linked to SOA from solid-fuel combustion, resulting in transported emissions from the Beijing–Tianjing–Hebei Plain and rural areas west of Beijing. In summer, aromatic emissions from the Xi’an–Shanghai–Beijing region dominate, while biogenic emissions play a minor role. These findings highlight the importance of addressing regional organic precursor emissions for effective pollution mitigation.
Effective haze management in megacities requires detailed molecular data to identify SOA sources. The study demonstrates that SOA in Beijing is influenced by various chemical and geographic sources beyond the city, suggesting that haze is a regional issue with particles traveling long distances before removal. This necessitates coordinated, large-scale air quality policies across regions like Xi’an–Shanghai–Beijing. Observations during the COVID-19 lockdown, where local emission reductions did not fully mitigate pollution, further emphasize the need for comprehensive, region-wide strategies. Learn more about field-deployable soft-ionization mass spectrometers from TOFWERK and Aerodyne.
