The Organic Acids Composition of Aerosols Originating from the Canadian Wildfires in College Park, MD

ESTHER OLONIMOYO, Martin Ahn, Dewansh Rastogi, Yue Li, Akua Asa-Awuku, University of Maryland

     Abstract Number: 354
     Working Group: Combustion

Abstract
Wildfires in Canada began in March 2023, intensified in June, and spread over thirteen million hectares by August 1 st , 2023. Smoke emerging from these wildfires traveled across the North American continent, as air quality alerts were issued in 20 states within the US. Its effects were visible in the College Park, Maryland, area as the air quality index (AQI) increased to very unhealthy levels. Air particles were sampled actively from the rooftop lab of the Atmospheric and Oceanic Sciences building located on the University of Maryland campus at a flow rate of 29 mL/min onto a 0.22 µm Polyvinylidene fluoride (PVDF) membrane. Daytime (9 am to 6 pm) and nighttime (6 pm to 9 am) samples were collected from the 7 th to the 9 th of June 2023. Air particles were also collected onto a PVDF membrane for a 60-hour period from the 9 th to the 12 th of June 2023. Collected membranes were kept in a petri dish below -4 ᵒC until extraction. Membranes were extracted with 20 mL of ultra-purified water by sonication and heating to 40ᵒC for 1 hour, after which the solution was filtered (90 mm Whatman filter paper) and kept below -4 ᵒC until chemical analysis. In this work, we present measurements of the organic acids determined from chemical analysis using a Bruker Maxis-II Q-TOF mass spectrometer coupled with a Waters Acquity I-Class PLUS LC system. We also explored changes in chemical composition as a result of atmospheric aging by performing Hysplit NOAA Back Trajectory analyses. Thus, this work significantly contributes information about the prevalence of organic acids in urban centers from intensifying North American wildfire events.