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Cloud Activation Potentials for Atmospheric α-Pinene and β-Caryophyllene Ozonolysis Products

[Image: see text] The formation of atmospheric cloud droplets due to secondary organic aerosol (SOA) particles is important for quantifying the Earth’s radiative balance under future, possibly warmer, climates, yet is only poorly understood. While cloud activation may be parametrized using the surfa...

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Autores principales: Gray Bé, Ariana, Upshur, Mary Alice, Liu, Pengfei, Martin, Scot T., Geiger, Franz M., Thomson, Regan J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2017
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532715/
https://www.ncbi.nlm.nih.gov/pubmed/28776013
http://dx.doi.org/10.1021/acscentsci.7b00112
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author Gray Bé, Ariana
Upshur, Mary Alice
Liu, Pengfei
Martin, Scot T.
Geiger, Franz M.
Thomson, Regan J.
author_facet Gray Bé, Ariana
Upshur, Mary Alice
Liu, Pengfei
Martin, Scot T.
Geiger, Franz M.
Thomson, Regan J.
author_sort Gray Bé, Ariana
collection PubMed
description [Image: see text] The formation of atmospheric cloud droplets due to secondary organic aerosol (SOA) particles is important for quantifying the Earth’s radiative balance under future, possibly warmer, climates, yet is only poorly understood. While cloud activation may be parametrized using the surface tension depression that coincides with surfactant partitioning to the gas–droplet interface, the extent to which cloud activation is influenced by both the chemical structure and reactivity of the individual molecules comprising this surfactant pool is largely unknown. We report herein considerable differences in the surface tension depression of aqueous pendant droplets that contain synthetically prepared ozonolysis products derived from α-pinene and β-caryophyllene, the most abundant of the monoterpenes and sesquiterpenes, respectively, that are emitted over the planet’s vast forest ecosystems. Oxidation products derived from β-caryophyllene were found to exhibit significantly higher surface activity than those prepared from α-pinene, with the critical supersaturation required for cloud droplet activation reduced by 50% for β-caryophyllene aldehyde at 1 mM. These considerable reductions in the critical supersaturation were found to coincide with free energies of adsorption that exceed ∼25 kJ/mol, or just one hydrogen bond equivalent, depending on the ammonium sulfate and oxidation product concentration in the solution. Additional experiments showed that aldehyde-containing oxidation products exist in equilibrium with hydrated forms in aqueous solution, which may modulate their bulk solubility and surface activity. Equilibration time scales on the order of 10(–5) to 10(–4) s calculated for micrometer-sized aerosol particles indicate instantaneous surface tension depression in the activation processes leading to cloud formation in the atmosphere. Our findings highlight the underlying importance of molecular structure and reactivity when considering cloud condensation activity in the presence of SOA particles.
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spelling pubmed-55327152017-08-03 Cloud Activation Potentials for Atmospheric α-Pinene and β-Caryophyllene Ozonolysis Products Gray Bé, Ariana Upshur, Mary Alice Liu, Pengfei Martin, Scot T. Geiger, Franz M. Thomson, Regan J. ACS Cent Sci [Image: see text] The formation of atmospheric cloud droplets due to secondary organic aerosol (SOA) particles is important for quantifying the Earth’s radiative balance under future, possibly warmer, climates, yet is only poorly understood. While cloud activation may be parametrized using the surface tension depression that coincides with surfactant partitioning to the gas–droplet interface, the extent to which cloud activation is influenced by both the chemical structure and reactivity of the individual molecules comprising this surfactant pool is largely unknown. We report herein considerable differences in the surface tension depression of aqueous pendant droplets that contain synthetically prepared ozonolysis products derived from α-pinene and β-caryophyllene, the most abundant of the monoterpenes and sesquiterpenes, respectively, that are emitted over the planet’s vast forest ecosystems. Oxidation products derived from β-caryophyllene were found to exhibit significantly higher surface activity than those prepared from α-pinene, with the critical supersaturation required for cloud droplet activation reduced by 50% for β-caryophyllene aldehyde at 1 mM. These considerable reductions in the critical supersaturation were found to coincide with free energies of adsorption that exceed ∼25 kJ/mol, or just one hydrogen bond equivalent, depending on the ammonium sulfate and oxidation product concentration in the solution. Additional experiments showed that aldehyde-containing oxidation products exist in equilibrium with hydrated forms in aqueous solution, which may modulate their bulk solubility and surface activity. Equilibration time scales on the order of 10(–5) to 10(–4) s calculated for micrometer-sized aerosol particles indicate instantaneous surface tension depression in the activation processes leading to cloud formation in the atmosphere. Our findings highlight the underlying importance of molecular structure and reactivity when considering cloud condensation activity in the presence of SOA particles. American Chemical Society 2017-07-05 2017-07-26 /pmc/articles/PMC5532715/ /pubmed/28776013 http://dx.doi.org/10.1021/acscentsci.7b00112 Text en Copyright © 2017 American Chemical Society This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
spellingShingle Gray Bé, Ariana
Upshur, Mary Alice
Liu, Pengfei
Martin, Scot T.
Geiger, Franz M.
Thomson, Regan J.
Cloud Activation Potentials for Atmospheric α-Pinene and β-Caryophyllene Ozonolysis Products
title Cloud Activation Potentials for Atmospheric α-Pinene and β-Caryophyllene Ozonolysis Products
title_full Cloud Activation Potentials for Atmospheric α-Pinene and β-Caryophyllene Ozonolysis Products
title_fullStr Cloud Activation Potentials for Atmospheric α-Pinene and β-Caryophyllene Ozonolysis Products
title_full_unstemmed Cloud Activation Potentials for Atmospheric α-Pinene and β-Caryophyllene Ozonolysis Products
title_short Cloud Activation Potentials for Atmospheric α-Pinene and β-Caryophyllene Ozonolysis Products
title_sort cloud activation potentials for atmospheric α-pinene and β-caryophyllene ozonolysis products
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532715/
https://www.ncbi.nlm.nih.gov/pubmed/28776013
http://dx.doi.org/10.1021/acscentsci.7b00112
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