May 12, 2024
Journal Article

Formation of secondary organic aerosol from wildfire emissions enhanced by long-time ageing


Wildfire smoke, consisting primarily of organic aerosols, has profound impacts on air quality, climate and human health. Wildfire organic aerosol evolves over long-time photochemical oxidation due to the formation and ageing of secondary organic aerosol, which substantially changes its magnitude and properties. However, there are large uncertainties in the long-time ageing of wildfire organic aerosol because of the distinct ageing behaviours of the complex organic emissions. Here we developed an oxidation model that simulates the ageing of wildfire organic emissions in the full volatility range on a precursor level and integrated insights from single-species ageing and wildfire emissions ageing experiments and field plume observations to constrain the long-time ageing of wildfire organic aerosol. The model captured the enhancement of organic aerosol mass (2–8 times) and oxygen-to-carbon ratio (1–4 times) in the wildfire ageing experiments. It also reconciled a long-standing discrepancy between field and laboratory observations of the magnitude of secondary organic aerosol formation. The model indicated large emissions-driven variations in precursor contributions to secondary organic aerosol, which further evolve with long-time ageing. The estimated global wildfire secondary organic aerosol production (139?±?34?Tg?per year) was much higher than previous studies omitting or under-constraining long-time ageing.

Published: May 12, 2024


He Y., B. Zhao, S. Wang, R. Valorso, X. Chang, D. Yin, and B. Feng, et al. 2024. Formation of secondary organic aerosol from wildfire emissions enhanced by long-time ageing. Nature Geoscience 17, no. 2:124–129. PNNL-SA-194012. doi:10.1038/s41561-023-01355-4

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