Brown Carbon in Primary and Aged Coal Combustion Emission

Haiyan Ni, Ru Jin Huang*, Simone M. Pieber, Joel C. Corbin, Giulia Stefenelli, Veronika Pospisilova, Felix Klein, Martin Gysel-Beer, Lu Yang, Urs Baltensperger, Imad El Haddad, Jay G. Slowik, Junji Cao, André S.H. Prévôt, Ulrike Dusek

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

40 Citations (Scopus)
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Abstract

Smog chamber experiments were conducted to characterize the light absorption of brown carbon (BrC) from primary and photochemically aged coal combustion emissions. Light absorption was measured by the UV-visible spectrophotometric analysis of water and methanol extracts of filter samples. The single-scattering albedo at 450 nm was 0.73 ± 0.10 for primary emissions and 0.75 ± 0.13 for aged emissions. The light absorption coefficient at 365 nm of methanol extracts was higher than that of water extracts by a factor of 10 for primary emissions and a factor of 7 for aged emissions. This suggests that the majority of BrC is water-insoluble even after aging. The mass absorption efficiency of this BrC (MAE365) for primary OA (POA) was dependent on combustion conditions, with an average of 0.84 ± 0.54 m2 g-1, which was significantly higher than that for aged OA (0.24 ± 0.18 m2 g-1). Secondary OA (SOA) dominated aged OA and the decreased MAE365 after aging indicates that SOA is less light absorbing than POA and/or that BrC is bleached (oxidized) with aging. The estimated MAE365 of SOA (0.14 ± 0.08 m2 g-1) was much lower than that of POA. A comparison of MAE365 of residential coal combustion with other anthropogenic sources suggests that residential coal combustion emissions are among the strongest absorbing BrC organics.

Original languageEnglish
Pages (from-to)5701-5710
Number of pages10
JournalEnvironmental Science and Technology
Volume55
Issue number9
DOIs
Publication statusPublished - 4-May-2021

Keywords

  • light absorption efficiency
  • optical property
  • secondary organic aerosol
  • smog chamber
  • UV-vis spectrophotometric analysis

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