Abundance and Mixing State of Bioaerosols at the BNF Site: Insights from Microscopy and WIBS Analyses

NURUN NAHAR LATA, Ashfiqur Rahman, Zezhen Cheng, Darielle Dexheimer, Swarup China, Pacific Northwest National Laboratory

     Abstract Number: 552
     Working Group: Bioaerosols

Abstract
Primary biological aerosol particles (PBAPs), including pollen, fungal spores, and their fragments, are an important yet understudied component of the atmospheric aerosol population in forested environments. In the southeastern U.S., dense forests contribute a wide array of aerosols both through direct biological emissions and secondary processes involving biogenic volatile organic compounds (BVOCs). While ground-based studies have provided valuable insight into PBAP emissions, there is limited understanding of how these particles are distributed, their abundance and how they interact with other aerosol types during atmospheric transport. Aerosol population emitted from forest environment is essential to assess the transformation, mixing state, and potential roles of PBAPs in atmospheric processes such as cloud interactions and deposition.

To address this gap, we will investigate the distribution and chemical-morphological characteristics of surface aerosols at Bankhead National Forest (BNF) using samples collected with the Size and Time resolved Aerosol Collector (STAC) at DOE-ARM’s research facility AMF3. STAC enables size-resolved sampling of ambient particles, facilitating detailed analysis of PBAPs and their association with other aerosol components. We will apply computer-controlled scanning electron microscopy with energy dispersive x-ray spectroscopy (CCSEM/EDX) to examine the morphology and elemental composition of particles, allowing for classification of potential bioaerosols and their mixtures with mineral dust and carbonaceous material. These offline analyses are complemented by in situ measurements from the Wideband Integrated Bioaerosol Sensor (WIBS), which detects PBAPs based on intrinsic fluorescence properties.

This approach allows us to identify and classify PBAPs, evaluate their size-resolved distributions, and investigate potential mixing with other aerosol types such as mineral dust or carbonaceous particles. The study aims to establish a foundational dataset for understanding bioaerosol variability in forested environments and guide future efforts to characterize the composition and behavior of atmospheric bioaerosols.