Absorptivity of brown carbon in fresh and photo-chemically aged biomass-burning emissions

作者：Saleh R; Hennigan C J; McMeeking G R; Chuang W K; Robinson E S; Coe H; Donahue N M; Robinson A L^*

来源：Atmospheric Chemistry and Physics, 2013, 13(15): 7683-7693.

DOI：10.5194/acp-13-7683-2013

Experiments were conducted to investigate light absorption of organic aerosol (OA) in fresh and photochemically aged biomass-burning emissions. The experiments considered residential hardwood fuel (oak) and fuels commonly consumed in wild-land and prescribed fires in the United States (pocosin pine and gallberry). Photochemical aging was performed in an environmental chamber. We constrained the effective light-absorption properties of the OA using conservative limiting assumptions, and found that both primary organic aerosol (POA) in the fresh emissions and secondary organic aerosol (SOA) produced by photo-chemical aging contain brown carbon, and absorb light to a significant extent. This work presents the first direct evidence that SOA produced in aged biomass-burning emissions is absorptive. For the investigated fuels, SOA is less absorptive than POA in the long visible, but exhibits stronger wavelength-dependence and is more absorptive in the short visible and near-UV. Light absorption by SOA in biomass-burning emissions might be an important contributor to the global radiative forcing budget.

• 出版日期2013