Continuous Source Apportionment of Ultrafine Particulate Matter (PM0.1) at an Urban Site at Wintertime
GEORGIA A. ARGYROPOULOU, Christina N. Vasilakopoulou, Andreas Aktypis, Maria Georgopoulou, Christos Kaltsonoudis, Angeliki Matrali, Katerina Seitanidi, Christina Christopoulou, Panagiotis Kalkavouras, Nikolaos Mihalopoulos, Spyros Ν. Pandis, Institute of Chemical Engineering Sciences, Greece
Abstract Number: 243
Working Group: Source Apportionment
Abstract
Ultrafine particles (diameter less than 100 nm) can penetrate sensitive human organs (e.g., brain) and are strongly associated with adverse health effects. Their low mass concentration and susceptibility to interference from larger particles hinder their accurate and continuous characterization. The few previous PM0.1 experimental source apportionment studies relied solely on cascade impactors, which offer low temporal resolution and are labor-intensive.
The Aerodynamic Aerosol Classifier (AAC, Cambustion) can function as a low pass separator with selectable cut-off. We used the AAC to separate PM0.1 from larger particles, followed by a High-Resolution Time of Flight Aerosol Mass Spectrometer (HToF-AMS, Aerodyne Research Inc.) for the continuous PM0.1 organic aerosol (OA) source apportionment. An SP2-XR (Droplet Measurement Technologies) for black carbon, and a Xact 625i (SailBri Cooper, Inc) for metals were also integrated for a comprehensive source analysis.
A month-long field campaign was conducted in the center of Athens, the capital of Greece, during the winter of 2025 to evaluate the numerous local anthropogenic sources of PM0.1. Organic aerosol was the dominant component of PM0.1 throughout the campaign, contributing approximately 70%, and peaked during the night. Approximately half of secondary PM0.1 OA was highly oxygenated OA (OOA). The primary PM0.1 was mainly hydrocarbon-like OA (HOA; 20-25%), followed by cooking OA (COA; 15-20%) and biomass burning OA (BBOA; 10-15%).
HOA and PM0.1 black carbon were highly correlated, peaking during morning rush hour and increasing at night probably due to boundary layer effects. The most prominent elements detected were K, Zn, and Ag. Potassium closely tracked BBOA, with both peaking at night, confirming biomass burning as a significant PM0.1 source. The temporal variations of the sources and their respective concentrations have been analyzed and will be discussed.