EGU22-10738
https://doi.org/10.5194/egusphere-egu22-10738
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Chemical evolution of primary and secondary biomass burning aerosols during daytime and nighttime

Satoshi Takahama1, Amir Yazdani1, Jack Kodros2, Marco Paglione2,3, Mauro Masiol2, Stefania Squizzato2, Kalliopi Florou2, Christos Kaltsonoudis2, Spiro Jorga2, Spyros Pandis2,4, and Athanasios Nenes1,2
Satoshi Takahama et al.
  • 1Laboratory of atmospheric processes and their impacts (LAPI), ENAC/IIE, Ecole polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
  • 2Institute for Chemical Engineering Sciences, Foundation for Research and Technology Hellas (ICE-HT/FORTH), Patra, Greece
  • 3Italian National Research Council - Institute of Atmospheric Sciences and Climate (CNR-ISAC), Bologna, Italy
  • 4Department of Chemical Engineering, University of Patras, Patra, Greece

Fine particulate matter (PM) affects visibility, climate, and public health. Biomass burning (BB) in the forms of residential wood burning, wildfires, and prescribed burning is a major source of primary and secondary organic matter (OM, an important fraction fine PM), and brown and black carbon (BrC and BC). The contribution of BB to the atmospheric fine PM is only expected to increase in the foreseeable future. Recent studies have highlighted the enhancement in the biomass burning organic aerosol (bbOA) concentrations with aging and reported on the chemical composition of the secondary biomass burning organic aerosol (bbSOA) formed under different conditions. However, the chemical processing of the primary biomass burning organic aerosol (bbPOA) with aging is not well characterized. This chemical processing can potentially alter the chemical composition of bbOA drastically and render its identification and quantification in the atmosphere difficult.

 

             We used aerosol mass spectrometry (AMS) and Fourier transform infrared spectroscopy (FTIR) as two complementary methods to quantify the bbPOA aging in this study. AMS measures the bulk composition of OM with a relatively high temporal resolution but provides limited parent compound information due to the extensive fragmentation. FTIR, carried out on PTFE filter samples, provides detailed information about the functional group composition of the OM and certain bbOA makers at the expense of a relatively low temporal resolution. In a series of aging experiments at the Center for Studies of Air Qualities and Climate Change (C-STACC), primary emissions from wood and pellet stoves were injected into an environmental simulation chamber. Primary emissions were aged using hydroxyl and nitrate radicals simulating the atmospheric day-time and night-time oxidation.  A high-resolution time-of-flight (HR-TOF) AMS was used to identify the composition of non-refractory PM1. PM1 was also collected on PTFE filters before and after aging for the off-line FTIR analysis.

 

                AMS and FTIR agreed well in terms of the measured bbOA mass concentrations, elemental ratios, and the evolution of biomass burning tracers. We developed a procedure to quantify the bbPOA aging using AMS and FTIR. Using AMS, we found that up to 17 % of the bbPOA mass underwent some form of transformation with aging. This transformation was more intense under day-time conditions. FTIR detected a more extensive oxidation (up to two times that of AMS), suggesting a substantial processing of bbPOA, and revealing the limitations of AMS to capture bbPOA aging due to the extensive fragmentation. Different bbOA-related ion fragments were observed to decay at different rates under different conditions (e.g., oxidants and relative humidity). These different decay rates can potentially be used to identify the extent of bbPOA aging in the atmosphere. The bbSOA formed during the daytime oxidation was dominated by acid contributions, resembling certain atmospheric biomass burning samples. The unique, acid-dominated FTIR spectrum of bbSOA can potentially be used as another indicator of the aged bbOA in the atmosphere.

How to cite: Takahama, S., Yazdani, A., Kodros, J., Paglione, M., Masiol, M., Squizzato, S., Florou, K., Kaltsonoudis, C., Jorga, S., Pandis, S., and Nenes, A.: Chemical evolution of primary and secondary biomass burning aerosols during daytime and nighttime, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10738, https://doi.org/10.5194/egusphere-egu22-10738, 2022.