Apportionment of Primary and Secondary Carbonaceous Aerosols Using an Advanced Total Carbon – Black Carbon (TC-BC(λ)) Method in Southern California
MATIC IVANČIČ, Asta Gregorič, Gašper Lavrič, Bálint Alföldy, Irena Ježek Brecelj, Payam Pakbin, Faraz Ahangar, Mohammad Sowlat, Steven Boddeker, Sina Hasheminassab, Martin Rigler,
Aerosol d.o.o. Abstract Number: 304
Working Group: Carbonaceous Aerosol
AbstractCarbonaceous aerosols (CA) have a negative impact on public health and Earth's radiative balance. They are characterized by extreme diversity and comprise a large fraction of ambient fine particulate matter (PM2.5). The apportionment of CA to more components is crucial to prepare efficient measures to improve local air quality and create effective mitigation strategies to limit further warming on a global level. In this study, we used the Carbonaceous Aerosol Speciation System (CASS, Aerosol Magee Scientific, Slovenia, EU), comprised of two instruments, a Total Carbon Analyzer TCA08 in tandem with an Aethalometer AE33, which allows us to perform high-time-resolution measurements of total carbon (TC) and black carbon (BC). Integrating different numerical algorithms to high-time-resolution measurements with CASS, we recently published an advanced method to apportion CA into six components based on their optical absorption properties and their primary or secondary origin: CA=BC
ff + BC
bb + POA
BrC + POA
non-abs + SOA
BrC + SOA
non-abs,
where BC
ff and BC
bb represent fossil fuel and biomass burning related BC components, POA
BrC and SOA
BrC are the primary emitted and secondarily formed light-absorbing organic aerosols (brown carbon, BrC), and POA
non-abs and SOA
non-abs non-light-absorbing aerosols.
The multi-year and high-time-resolution CA measurements were performed at different measurement sites in Southern California operated by South Coast AQMD. Similar temporal patterns were observed at all locations: the morning rush hour traffic, especially in winter, resulted in the contribution of primary emitted carbonaceous aerosols (BC
ff + BC
bb + POA
non-abs + POA
BrC) up to 90% of the total CA. On the other hand, secondary formed SOA (SOA
non-abs + SOA
BrC) is a dominant component of CA in summer afternoons when their contribution can reach 80% of the total CA. Considering the methodology limitations and recommendations, we believe the presented measurement system and methodology have a high potential to be implemented for real-time analyses.