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High-time Resolution Apportionment of Primary and Secondary Carbonaceous Aerosols Using Advanced TC-BC Method
MARTIN RIGLER, Matic Ivančič, Jerzy Debosz, Uwayemi Sofowote, Jonathan Wang, Robert Healy, Aerosol d.o.o.
Abstract Number: 298
Working Group: Carbonaceous Aerosol
Abstract
High-time resolution apportionment of carbonaceous aerosol is essential to identify the main pollution sources and separate species that have the highest impact on public health and planetary radiation balance. Carbonaceous aerosols were measured by the CASS system (Carbonaceous Aerosol Speciation System, Rigler et al., 2020), which combines the Total Carbon Analyzer TCA08 and the Aethalometer AE33, providing high time-resolved data on carbonaceous aerosol composition and optical properties in real-time.
Apportionment of the carbonaceous matter is based on the simplified TCA08 method, where the organic carbon (OC) content is calculated as the difference between total carbon (TC) and black carbon (BC). The BC tracer method is used to separate organic carbon into the primary and secondary OC (Wu and Yu, 2016). Furthermore, multiple-wavelength analysis of the AE33 absorption data provides optical apportionment to BC and brown carbon (BrC).
The intensive measurement campaign was conducted between 30 April and 14 May 2019 at a roadside monitoring station located adjacent to Highway 401 in Toronto, Canada. This is the busiest section of highway in North America, with average traffic volumes of over 400,000 vehicles per day. Measurement results were evaluated with complementary measurements of OC/EC, PM2.5, organics measured by an aerosol chemical speciation monitor (ACSM), and various trace gases. During workdays, the diurnal variations of BC, BrC, primary and secondary OC were strongly influenced by the temporal patterns of emissions from traffic. On the weekend evenings, a small contribution from biomass burning was also observed. Primary carbonaceous emissions (BC+POC) contributed 60% to TC during workdays, while secondary OC prevailed during weekends with a share of almost 70%.
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