Size-Dependent Nascent Sea Spray Aerosol Bounce Fractions and Estimated Viscosity: The Role of Divalent Cation Enrichment, Surface Tension, and the Kelvin Effect
Viscosity, or the "thickness," of aerosols plays a key role in atmospheric processes like ice formation, water absorption, and heterogeneous kinetics. However, the viscosity of sea spray aerosols (SSA) has not been widely studied. This research explored the relationship between particle size and viscosity of authentic SSA particles through particle bounce, atomic force microscopy analysis, and predictive viscosity modeling from molecular composition. The study found that 40 nm SSA particles had estimated viscosities around 10<sup>4</sup> Pa·s and bounce fractions three times higher than 100 and 200 nm particles with less than 10<sup>2</sup> Pa·s at a relative humidity (RH) of 60%. Additional studies revealed the Kelvin effect and particle density, influenced by particle size, have a greater impact on size-dependent bounce fractions than changes in RH across impactor stages. While changes in the level of surfactants can impact particle bounce, the increased viscosity in smaller SSA is attributed to the formation of gel-like phase states caused by cation-organic cross-links between divalent calcium ions and organic anions enriched in the smaller particles. This work shows the smallest gel-like SSA particles observed in the field are highly viscous, which has implications for cloud formation, secondary aerosol growth, and pollutant transport in coastal environments.
Authors
- Raymond J. Leibensperger (ORCID: https://orcid.org/0009-0003-0099-6864)
- Elizabeth A. Stone (ORCID: https://orcid.org/0000-0003-0078-141X)
- Jonathan H. Slade (ORCID: https://orcid.org/0000-0002-5026-4229)
- Alexei V. Tivanski (ORCID: https://orcid.org/0000-0002-1528-2421)
- Paul R. Tumminello (ORCID: https://orcid.org/0000-0002-3632-3640)
- Ke’La A. Kimble (ORCID: https://orcid.org/0000-0003-1176-0868)
- Dilini Kirindigoda Gamage (ORCID: https://orcid.org/0000-0002-5452-7380)
- Grant B. Deane (ORCID: https://orcid.org/0000-0002-4848-8637)
- M. Dale Stokes (ORCID: https://orcid.org/0000-0002-2243-5078)
- Francesca Malfatti (ORCID: https://orcid.org/0000-0002-0957-9288)
- Brandon E. Boor (ORCID: https://orcid.org/0000-0003-1011-4100)
- Chathuri P. Kaluarachchi (ORCID: https://orcid.org/0000-0003-2538-3952)
- Chamika K. Madawala
- Chunxu Huang (ORCID: https://orcid.org/0009-0009-1608-496X)
- Julie Dinasquet (ORCID: https://orcid.org/0000-0002-3401-764X)
- Christopher T. Lee (ORCID: https://orcid.org/0000-0002-0670-2308)
- Kimberly A. Prather (ORCID: https://orcid.org/0000-0003-3048-9890)
- Renee Niles
- Vanessa Valdez
Institutions
- University of Iowa (US)
- University of Trieste (IT)
- California State University, Fullerton (US)
- Scripps Institution of Oceanography (US)
- Purdue University West Lafayette (US)
- University of California San Diego (US)
Publication Details
- Journal
- Environmental Science & Technology
- Published
- 2024-10-23
- DOI
- https://doi.org/10.1021/acs.est.4c04312
- Citations
- 12
- Primary Topic
- Atmospheric chemistry and aerosols
- Type
- article
- Field-Weighted Citation Impact
- 4.52
Funders
- National Science Foundation
- Purdue University
- University of California, San Diego
- Division of Chemistry
- Center for Aerosol Impacts on Chemistry of the Environment, University of California, San Diego