Comparison of Organic Aerosol Composition and Source Distributions across Different Urban Microenvironments
SUNHYE KIM, Abhishek Anand, Pavithra Ethi Rajan, Albert A. Presto,
Carnegie Mellon University Abstract Number: 224
Working Group: Urban Aerosols
AbstractExposure to ambient fine particulate matter (PM
2.5) has hazardous health impacts worldwide. A major challenge in reducing PM
2.5 concentrations is that it comes from a variety of sources. This is especially true in urban areas, where there is a mixture of primary and secondary sources. In addition, there are large spatial variations in PM
2.5 concentration and composition in urban areas, and this variability is driven by differences in the spatial distribution of sources.
In summer 2021, field samples were collected at different urban sites at specified intervals (morning, midday, afternoon, and evening) using a mobile lab. NR-PM
1 was measured in real-time using an Aerosol Mass Spectrometer (AMS) along with Condensation Particle Counter (CPC), Aethalometer, and Gas monitors. Our results showed that organics generally increase with the traffic loads near sampling sites, especially during morning rush hour. The preliminary AMS-PMF (Positive Matrix Factorization) in our study demonstrated that the proportion of resolved factors can vary with land use. For instance, Cooking Organic Aerosols (COAs) were reliably identified (~20% of the total OA) in urban sampling locations near restaurants, while samples collected near asphalt paving had negligible COAs contributions. We also collected PM
2.5 samples on filters during the field campaign for the offline measurement using the iodide-based Chemical Ionization Mass Spectrometer (CIMS) with FIGAERO (Filter Inlet for Gases and AEROsols). This will provide additional molecular information (e.g. oxidation, chemical formula etc.) of OA in urban atmospheres.
This study aims to quantify the spatiotemporal variations of source-resolved organic emissions spanning a wide volatility range and analyze these trends in urban areas. To do so, we will examine the intra-city source contribution from multiple sectors including both traditional (e.g. traffic) and non-traditional (e.g. volatile chemical products [VCPs], paving, cooking) sources, and suggest possible marker ions of potential sites emitting VCPs.