Source Apportionment and Phase Partitioning of Atmospheric Semi-Volatile Organic Compounds during the Alaskan Wintertime

KAROLINA CYSNEIROS DE CARVALHO, Ellis Robinson, Andrew Holen, Judy Wu, Vanessa Selimovic, Damien Ketcherside, William Simpson, Peter F. DeCarlo, Kerri Pratt, Lu Hu, Robert J. Yokelson, Brent Williams, Washington University in St. Louis

     Abstract Number: 316
     Working Group: Aerosol Chemistry

Abstract
Air pollution sources and atmospheric chemical transformations in Arctic cities change dramatically from season-to-season. During the winter, extreme low temperatures combined with industrial processes and increases in heating, result in larger local particulate matter emissions. The cold temperatures in conjunction with reduced solar radiation are responsible for longer temperature inversions that trap pollutants in the lower atmosphere leading to poor outdoor air quality. According to previous studies, there is an accumulation of fine particle matter in the Arctic atmosphere during wintertime and early spring but the understanding of atmospheric chemical reactions of these pollutants is poor and so is the extent of human exposure. During the 2022 winter, the Alaskan Layered Pollution and Chemical Analysis (ALPACA) campaign was deployed in the city of Fairbanks with the goal of improving our understanding of how pollutants behave under these extreme wintertime conditions.

A Semi-Volatile Thermal Desorption Aerosol Gas chromatograph (SV-TAG), capable of identifying and quantifying speciated organic compounds in both gas and particle phases, was deployed along with complementary gas-phase (PTR-ToF-MS - Proton Transfer Reaction Time-of-Flight Mass Spectrometer) and particle-phase mass spectrometers (ATOFMS - Aerosol Time-of-Flight Mass Spectrometer and AMS - Aerosol Mass Spectrometer). Positive Matrix Factorization (PMF) was applied to the SV-TAG dataset to identify major emission sources. Preliminary results suggest that wood burning is the main source of residential heating when strong temperature inversions prevailed. Speciated phase partitioning of fresh and aged biomass burning markers will be analyzed to help recognize the complex chemical transformation processes that these compounds undergo in the atmosphere under sustained cold and dark conditions. The low temperatures demonstrated to strongly drive gas-to-particle phase partitioning and its impact will be evaluated against other parameters such as compound-specific vapor pressure and total organic aerosol mass.