Atmospheric Aerosol Sources & Processes in Polluted Wintertime Fairbanks, Alaska

Poor wintertime air quality, particularly in high-latitude cities, is understudied. PM_2.5 (particulate matter less than 2.5 µm in diameter) levels accumulate in the near-surface atmosphere during frequent wintertime stagnation events in Fairbanks, Alaska, often resulting in exceedance of air quality standards. Previous measurements in Fairbanks have focused on bulk PM chemical composition measurements, limiting our ability to identify emission sources and understand secondary aerosol formation. The Alaskan Layered Pollution and Chemical Analysis (ALPACA) campaign was conducted during January – February 2022 in Fairbanks, Alaska. This presentation will focus on single-particle measurements from sampling at both downtown and residential field sites. Offline scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) provides the size, morphology, and elemental composition of individual particles, and online aerosol time-of-flight mass spectrometry (ATOFMS) provides the size and chemical composition of individual submicron particles in real-time. These single-particle observations are used to identify individual particle sources, including residential heating and vehicle combustion, and the distribution of chemical compounds, with a focus on sulfate, secondary organosulfur compounds, and air toxics, including metals and polycyclic aromatic hydrocarbons. Overall, these results provide insights into the sources and atmospheric processes leading to the elevated PM levels during wintertime in Fairbanks, Alaska.