Hygroscopicity and CCN potential of DMS-derived aerosol particles

Bernadette Rosati*, Sini Isokaanta, Sigurd Christiansen, Mads Mork Jensen, Shamjad P. Moosakutty, Robin Wollesen de Jonge, Andreas Massling, Marianne Glasius, Jonas Elm, Annele Virtanen, Merete Bilde*

*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review

Abstract

Dimethyl sulfide (DMS) is emitted by phytoplankton species in the oceans and constitutes the largest source of naturally emitted sulfur to the atmosphere. The climate impact of secondary particles, formed through the oxidation of DMS by hydroxyl radicals, is still elusive. This study investigates the hygroscopicity and cloud condensation nuclei activity of such particles and discusses the results in relation to their chemical composition. We show that mean hygroscopicity parameters, κ, during an experiment for particles of 80 nm in diameter range from 0.46 to 0.52 or higher, as measured at both sub- and supersaturated water vapour conditions. Ageing of the particles leads to an increase in κ from, for example, 0.50 to 0.58 over the course of 3 h (Exp. 7). Aerosol mass spectrometer measurements from this study indicate that this change most probably stems from a change in chemical composition leading to slightly higher fractions of ammonium sulfate compared to methanesulfonic acid (MSA) within the particles with ageing time. Lowering the temperature to 258 K increases κ slightly, particularly for small particles. These κ values are well comparable to previously reported model values for MSA or mixtures between MSA and ammonium sulfate. Particle nucleation and growth rates suggest a clear temperature dependence, with slower rates at cold temperatures. Quantum chemical calculations show that gas-phase MSA clusters are predominantly not hydrated, even at high humidity conditions, indicating that their gas-phase chemistry should be independent of relative humidity.

OriginalsprogEngelsk
TidsskriftAtmospheric Chemistry and Physics
Vol/bind22
Nummer20
Sider (fra-til)13449-13466
Antal sider18
ISSN1680-7316
DOI
StatusUdgivet - okt. 2022

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