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Published July 25, 2017 | Supplemental Material + Published
Journal Article Open

Evaporation of sulfate aerosols at low relative humidity


Evaporation of sulfuric acid from particles can be important in the atmospheres of Earth and Venus. However, the equilibrium constant for the dissociation of H_2SO_4 to bisulfate ions, which is the one of the fundamental parameters controlling the evaporation of sulfur particles, is not well constrained. In this study we explore the volatility of sulfate particles at very low relative humidity. We measured the evaporation of sulfur particles versus temperature and relative humidity in the CLOUD chamber at CERN. We modelled the observed sulfur particle shrinkage with the ADCHAM model. Based on our model results, we conclude that the sulfur particle shrinkage is mainly governed by H_2SO_4 and potentially to some extent by SO_3 evaporation. We found that the equilibrium constants for the dissociation of H_2SO_4 to H_SO_4^−(K_(H_2SO)_4) and the dehydration of H_2SO_4 to SO_3 (^xK_(SO_3)) are K_(H_2SO)_4) = 2–4 × 10^9 mol kg^(−1) and ^xK_(SO)_3 ≥  1.4  ×  10^(10) at 288.8 ± 5 K.

Additional Information

© Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 23 Nov 2016 – Discussion started: 16 Dec 2016. Revised: 10 May 2017 – Accepted: 12 May 2017 – Published: 25 Jul 2017. Author contributions. GT and JD designed and performed the experiments. GT, JD and PR analysed the data. PR developed the model code. PR and GT performed the simulations. GT, JD, LR, JT, JGS, and AK collected the data and contributed to the analysis. GT, PR, JD, and NMD assisted in drafting the manuscript. GT, PR, JD, MB, JC, RCF, MK, NMD and FS contributed to scientific interpretation and editing of the manuscript. All authors contributed to the development of the CLOUD facility and analysis instruments and commented on the manuscript. The authors declare that they have no conflict of interest. We would like to thank CERN for supporting CLOUD with important technical and financial resources, and for providing a particle beam from the CERN Proton Synchrotron. We also thank Patrick Carrie, Louis-Philippe De Menezes, Jonathan Dumollard, Roberto Guida, Katja Ivanova, Francisco Josa, llia Krasin, Robert Kristic, Abdelmajid Laassiri, Osman Maksumov, Serge Mathot, Benjamin Marichy, Herve Martinati, Antti Onnela, Robert Sitals, Hansueli Walther, Albin Wasem and Mats Wilhelmsson for their important contributions to the experiment. This research has received funding from the EC Seventh Framework Programme (Marie Curie Initial Training Network "CLOUD-ITN" no. 215072 and "CLOUD-TRAIN" no. 316662, ERC-Starting "MOCAPAF" grant no. 57360 and ERC-Advanced "ATMNUCLE" grant no. 227463), the German Federal Ministry of Education and Research (project nos. 01LK0902A and 01LK1222A), the Swiss National Science Foundation (project nos. 200020 135307 and 206620 141278), the Academy of Finland (Centre of Excellence project no. 1118615 and other projects: 135054, 133872, 251427, 139656, 139995, 137749, 141217, 141451), the Finnish Funding Agency for Technology and Innovation, the Vaisala Foundation, the Nessling Foundation, the Austrian Science Fund (FWF; project no. J3198-N21), the Portuguese Foundation for Science and Technology (project no. CERN/FP/116387/2010), the Swedish Research Council, Vetenskapsradet (grant 2011-5120), the Presidium of the Russian Academy of Sciences and Russian Foundation for Basic Research (grants 08-02-91006-CERN and 12-02-91522-CERN), the US National Science Foundation (grants AGS1136479, AGS1447056, AGC1439551 and CHE1012293), the PEGASOS project funded by the European Commission under the Seventh Framework Programme (FP7-ENV-2010-265148), and the Davidow Foundation. We thank the tofTools team for providing tools for mass spectrometry analysis. Pontus Roldin would like to thank the Cryosphere-Atmosphere Interactions in a Changing Arctic Climate (CRAICC) Nordic Top-Level Research Initiative and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning FORMAS (project no. 214-2014-1445) for financial support. Edited by: Yafang Cheng. Reviewed by: two anonymous referees.

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Supplemental Material - acp-17-8923-2017-supplement.pdf


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