Quantification and Characterization of Microbial Emissions over the Northeastern Atlantic Using Mesocosm Experiments

Primary biological aerosol particles (PBAPs) can significantly influence the Earth’s climate as ice-nucleating particles. To enhance our comprehension of PBAP aerosolization, particularly bacteria, through sea spray aerosol, we conducted mesocosm experiments in the Azores archipelago using a sea spray simulation chamber. Using fluorescence microscopy, 16S rRNA sequencing for microbial community analysis, and data from an online bioaerosol spectrometer, we quantified and characterized biological particles present in the seawater and aerosol. Microbial enrichment factors, normalized to sodium concentration, ranged from 9 to 158, and a comparison of the airborne cell estimates with bioaerosol spectrometer data revealed notable differences between the measurement approaches. Additionally, 16S rRNA sequencing unveiled selective aerosolization of specific taxa, resulting in a less diverse aerosol community compared to seawater. Selective growth in the seawater led to a reduction in alpha diversity and closer clustering of the community composition with nascent sea spray aerosol samples throughout each mesocosm experiment.