Sea Spray Aerosol Structure and Composition Using Cryogenic Transmission Electron Microscopy

Area of Science:

• Atmospheric chemistry
• Environmental science
• Microscopy

Background:

• Aerosol particle composition and surface properties influence climate by affecting water uptake, heterogeneous reactions, and ice nucleation.
• Conventional electron microscopy alters native aerosol structures due to vacuum conditions, leading to inaccurate surface and internal property analysis.

Purpose of the Study:

• To develop and present a novel cryogenic transmission electron microscopy (cryo-TEM) technique for analyzing atmospheric aerosol particles.
• To preserve the native state of aerosol particles, including their surface and internal structures, for accurate characterization.

Main Methods:

• Laboratory-generated sea spray aerosol particles were flash-frozen to capture their native state.
• Iterative and controlled thermal and/or pressure exposures were applied before cryo-TEM analysis.
• Cryogenic transmission electron microscopy was used to probe the frozen aerosol particles.

Main Results:

• The cryo-TEM method successfully preserved the native state of sea spray aerosol particles.
• The technique allowed for the detection of mixed salts, soft materials, hydrated bacteria, diatoms, viruses, marine vesicles, and gel networks within hydrated salt droplets.
• These findings highlight the presence of complex biological and organic components within aerosol particles.

Conclusions:

• Cryogenic transmission electron microscopy offers a unique approach to analyze aerosol particles without structural alteration.
• This method enables the study of diverse components, including biological and organic species, within aerosol particles.
• The technique is expected to advance the analysis of ocean-derived and other aerosol types, particularly concerning biosphere-atmosphere interactions.