Comparative Assessment of Bioaerosol Fluorescence, Microbial Communities, and Ice Nucleating Particle Abundance During Strong Relative Humidity Shifts in Colorado Grasslands

MARINA NIETO-CABALLERO, Noelle Bryan, Claudia Mignani, Thomas C. J. Hill, Kevin R. Barry, Brian Heffernan, Teresa Feldman, Chamari Mampage, Ben Ascher, Jacob Escobedo, Nick Falk, Sean Freeman, Gabrielle Leung, Allie Mazurek, Christine Neumaier, Daniel Veloso-Aguila, Jessie Creamean, Susan van den Heever, Elizabeth Stone, Leah Grant, Russell Perkins, Paul DeMott, Sonia Kreidenweis, Colorado State University

     Abstract Number: 544
     Working Group: Aerosol-Ecosystem Interactions

Abstract
Aerosol particles of biological origin have been described as key agents in atmospheric processes; however, microbial communities, size distributions, abundance of atmospheric bioaerosols, and their relationship with atmospheric processes are still largely unknown. In this study, part of the NSF BROADN project (Bii Regional OneHealth Aerobiome Discovery Network), we evaluate the relationship between significant relative humidity (RH) shifts during diurnal cycles and their effects on different bioaerosol components, such as microbial composition (i.e., 16S rRNA and ITS gene markers), ice nucleating potential, fluorescence properties, and size distributions during high and low relative humidity (RH) periods (i.e., ΔRH = 53.23% ± 6.18). This study was performed in May-June of 2022 at the Semi-arid Grasslands Research Center (SGRC, Colorado), representative of the North American Great Plains, by studying bioaerosol composition during diurnal RH shifts with an average high RH of 80.37% ± 9.65 and an average low RH of 27.14% ± 11.17.

Preliminary WIBS-NEO (Wideband Integrated Bioaerosol Sensor NEO) results show an increase in fluorescent particles during high RH periods, pointing towards increased concentrations of biological particles and shifts in particle size distributions. Unexpectedly, given the changes in fluorescence profile, 16S rRNA results show that bacterial community composition of bioaerosols, collected with a SASS 3100 (Research International) at 300 Lpm, are not significantly different during high and low RH levels (UniFrac PERMANOVA p-value > 0.05). Although these differences are not evident for bacterial bioaerosols, we hypothesize that airborne fungal community composition, as well as ice nucleating particle (INP) abundance, will show differences during high and low RH levels of diurnal cycles (work in progress). More specifically, we expect fungal taxa community shifts and an increase in biological INP concentrations during night periods (i.e., high RH).