Epoxide-driven secondary organic aerosol formation is modulated by aerosol-cloud cycling

Epoxide-driven secondary organic aerosol formation is modulated by aerosol-cloud cycling | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Epoxide-driven secondary organic aerosol formation is modulated by aerosol-cloud cycling Laura Fierce, Payton Beeler, Alla Zelenyuk, Manish Shrivastava, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9053420/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Isoprene-derived epoxydiols secondary organic aerosol (IEPOX SOA) and sulfate particles are major contributors to atmospheric particulate matter and play central roles in transforming gaseous emissions into secondary organic and inorganic aerosol. Although both species form through aqueous-phase reactions, the timing and lifecycle controls governing aqueous secondary organic aerosol (SOA) formation remain poorly constrained, in contrast to the relatively well-understood in-cloud formation of sulfate. Here, we combine single-particle measurements and a particle-resolved model of aerosol-cloud cycling to quantify processes governing aqueous sulfate and IEPOX SOA chemistry in aerosol particles and cloud droplets observed during the HI-SCALE field campaign, representing the first comparison of single-particle observations with particle-resolved simulations of cloud-processed aerosol. . We identify fundamental differences in the processes controlling their formation: sulfate production is governed by aqueous oxidation kinetics within cloud droplets, whereas IEPOX SOA forms rapidly during droplet evaporation and is strongly controlled by cloud-water acidity and the transient concentration of nucleophiles. These results demonstrate that sulfate and IEPOX SOA form at distinct stages of the aerosol–cloud life cycle and suggest that models neglecting droplet-scale concentration effects may substantially underestimate IEPOX SOA formation. More broadly, our findings indicate that evaporation-driven concentration dynamics during cloud cycling likely regulate other aqueous SOA pathways that depend on nucleophile availability. Earth and environmental sciences/Climate sciences/Atmospheric science/Atmospheric chemistry Earth and environmental sciences/Climate sciences/Atmospheric science Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SIBeeler2026IEPOXthroughcloudcycling.pdf Supplementary Information: Epoxide-driven secondary organic aerosol formation is modulated by aerosol–cloud cycling Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9053420","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":603071413,"identity":"903e0f79-9b88-479f-b319-2c86b7933d70","order_by":0,"name":"Laura 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