Abstract View
Characterization of Sub-Pollen Particles in Atmospheric Aerosol During Summer Rain Events
CHAMARI MAMPAGE, Dagen Hughes, Lillian Jones, Nervana Metwali, Peter Thorne, Elizabeth Stone, University of Iowa
Abstract Number: 559
Working Group: Bioaerosols
Abstract
Osmotic rupturing of pollen grains (10-100 µm) can release sub-pollen particles (SPP; <2.5 µm). Due to their smaller size, SPP have longer atmospheric lifetimes, and are capable of long-range transport, affecting the Earth’s climate, and penetrating deeper into the lung. The current study examines SPP in size-resolved atmospheric particulate matter (PM) in August – September 2019, during ragweed season in the Midwestern United States. On rainy days, PM2.5 concentrations of fructose and sucrose, which are chemical tracers of pollen, increased suggesting possible pollen rupturing events that released SPP to the atmosphere. Co-located single-particle measurements showed an influx of submicron fluorescent particles during rain, especially convective thunderstorms. The concentrations of submicron SPP remained elevated after rain events, continuing to the next day, consistent with elevated chemical tracer concentrations. The size-resolved PM collected using a 5-stage impactor indicated that SPP ranged <0.25-2.5 µm in diameter. Field observations of SPP were complemented by laboratory studies of giant ragweed pollen rupturing, which released an estimated 1400 SPP per pollen grain ranging 0.02 - 6.5 µm in diameter, and suggested ragweed can be a contributing factor to submicron SPP during summertime. Mannitol, a fungal spore tracer and bacterial endotoxins were also analyzed, and their size-resolved concentrations showed minimal contribution to submicron particles during summer rain events. Collectively, the results show that the highest increase of pollen tracers in submicron particles compared to fungal spores and bacteria, indicating that SPP were likely responsible for the submicron fluorescent particles observed during summer rain events.