AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Characterization of Black Carbon and Trace Metals Using Soot-Particle Aerosol Mass Spectrometer: Insight into Organic Aerosol Sources in a Complex Urban Environment
LAURA-HELENA RIVELLINI, Max Adam, Nethmi Kasthuriarachchi, Alex Lee, National University of Singapore
Abstract Number: 224 Working Group: Source Apportionment
Abstract Atmospheric carbonaceous aerosol have significant impacts on human health and climate. Understanding how emissions and atmospheric processes can influence their physico-chemical properties is essential to evaluate such impacts. Co-emission of black carbon (BC) and primary organic aerosol (POA) from combustion and secondary OA (SOA) formation on BC through oxidation of gas-phase precursors and POA are well-known. However, the relative importance of individual BC source and how BC interact with OA during chemical aging remains largely unexplored.
A soot-particle aerosol mass spectrometer (SP-AMS) was deployed to characterize OA, refractory BC (rBC) and trace metals in Singapore, a highly urbanised city in the Southeast Asia. In addition to OA fragments, rBC and trace metals ions were integrated to our positive matrix factorization for source apportionment analysis. This work provides evidence that fuel combustion-related OA (hydrocarbon-like OA) and less-oxidised oxygenated OA (LO-OOA, i.e., fresh SOA produced via photochemistry under the influences of industrial emissions) are largely associated with rBC (63 and 29% respectively). In contrast, cooking-related OA (COA) and more-oxidised OOA (MO-OOA, i.e., more aged OA) factors were composed of low rBC content (<10% of total rBC). Potassium and rubidium were mainly associated with MO-OOA, indicating the significance of biomass burning emissions from the nearby countries to this aged OA component.
Furthermore, C1+/C3+ and V/Ni ratios are used to identify different types of combustion. In particular, the aerosol pollutants transported from industrial area and shipping ports gave higher C1+/C3+ (~1.0) and V/Ni ratios than those associated with traffic (C1+/C3+ < 0.8). Single particle measurements will be discussed to evaluate the aerosol mixing state emitted from the identified sources. Overall, this work demonstrates that the rBC fragments and trace metal characterized by SP-AMS can provide important insight into the sources and characteristics of OA in a complex urban environment.