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Published May 16, 2014 | public
Journal Article

Oxidation Products of Biogenic Emissions Contribute to Nucleation of Atmospheric Particles


Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations.

Additional Information

© 2014 American Association for the Advancement of Science. Received for publication 22 July 2013. Accepted for publication 21 April 2014. We thank CERN for supporting CLOUD with important technical and financial resources and providing a particle beam from the CERN PS; J.-L. Agostini, P. Carrie, L.-P. De Menezes, F. Josa, I. Krasin, R. Kristic, O. S. Maksumov, S.V. Mizin, R. Sitals, A. Wasem, and M. Wilhelmsson for their important contributions to the experiment; and C. Kuang and V.-M. Kerminen for providing the observational data sets used in Fig. 1A and the authors that contributed to them. This research was funded by the European Commission Seventh Framework Programme (Marie Curie Initial Training Network "CLOUD-ITN," grant no. 215072), the European Research Council Advanced Grant "ATMNUCLE" (no. 227463), the Academy of Finland via the Centre of Excellence program (project no. 1118615) and grant no. 1133872, the German Federal Ministry of Education and Research (project no. 01LK0902A), the Swiss National Science Foundation (project no. 206621_125025 and 206620_130527), the Austrian Science Fund (project no. P19546 and L593), the Portuguese Foundation for Science and Technology (project no. CERN/FP/116387/2010), the Russian Foundation for Basic Research (grant N08-02-91006-CERN), the Davidow Foundation, the Royal Society Wolfson Award, and the NSF (grants AGS1136479 and CHE1012293). The data reported in this paper are available online as .txt files in the supplementary materials).

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