Formation of Secondary Brown Carbon in Biomass Burning Aerosol Proxies through NO3 Radical Reactions

Chunlin Li, Quanfu He, Anusha Priyadarshani Silva Hettiyadura, Uwe Käfer, Guy Shmul, Daphne Meidan, Ralf Zimmermann, Steven S. Brown, Christian George, Alexander Laskin, Yinon Rudich

Research output: Contribution to journalArticlepeer-review


Atmospheric brown carbon (BrC) is an important contributor to the radiative forcing of climate by organic aerosols. Because of the molecular diversity of BrC compounds and their dynamic transformations, it is challenging to predictively understand BrC optical properties. OH radical and O3 reactions, together with photolysis, lead to diminished light absorption and lower warming effects of biomass burning BrC. The effects of night-time aging on the optical properties of BrC aerosols are less known. To address this knowledge gap, night-time NO3 radical chemistry with tar aerosols from wood pyrolysis was investigated in a flow reactor. This study shows that the optical properties of BrC change because of transformations driven by reactions with the NO3 radical that form new absorbing species and lead to significant absorption enhancement over the ultraviolet-visible (UV-vis) range. The overnight aging increases the mass absorption coefficients of the BrC by a factor of 1.3-3.2 between 380 nm and 650 nm. Nitrated organic compounds, particularly nitroaromatics, were identified as the main products that contribute to the enhanced light absorption in the secondary BrC. Night-time aging of BrC aerosols represents an important source of secondary BrC and can have a pronounced effect on atmospheric chemistry and air pollution.

Original languageEnglish
Pages (from-to)1395-1405
Number of pages11
JournalEnvironmental Science and Technology
Issue number3
Early online date19 Nov 2019
StatePublished - 4 Feb 2020

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Environmental Chemistry


Dive into the research topics of 'Formation of Secondary Brown Carbon in Biomass Burning Aerosol Proxies through NO3 Radical Reactions'. Together they form a unique fingerprint.

Cite this