Abstract
Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere, and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.
| Original language | English |
|---|---|
| Pages (from-to) | 521-526 |
| Number of pages | 6 |
| Journal | Nature |
| Volume | 533 |
| Issue number | 7604 |
| DOIs | |
| Publication status | Published - 25 May 2016 |
| MoE publication type | A1 Journal article-refereed |
Funding
This research has received funding from the EC Seventh Framework Programme (Marie Curie Initial Training Network MC-ITN CLOUD-TRAIN no. 316662, EU Horizon 2020 Marie Curie grant no. 656994, ERC-Consolidator grant NANODYNAMITE no. 616075 and ERC-Advanced grant ATMNUCLE no. 227463), the German Federal Ministry of Education and Research (project no. 01LK1222A), the Swiss National Science Foundation (project nos 200020-135307, 200021-140663, 206021-144947/1 and 20FI20-149002/1), the Academy of Finland (Center of Excellence project no. 1118615), the Academy of Finland (135054, 133872, 251427, 139656, 139995, 137749, 141217, 141451), the Finnish Funding Agency for Technology and Innovation, the Vaïsälä Foundation, the Nessling Foundation, the Austrian Science Fund (FWF; project no. L593), the Portuguese Foundation for Science and Technology (project no. CERN/FP/116387/2010), the Swedish Research Council, Vetenskapsrådet (grant 2011-5120), the Presidium of the Russian Academy of Sciences and Russian Foundation for Basic Research (grant 12-02-91522-CERN), the UK Natural Environment Research Council (grant NE/K015966/1), the Royal Society (Wolfson Merit Award), the US National Science Foundation (grants AGS1136479, AGS1447056 and CHE1012293), Caltech ESE Grant (Davidow Foundation), Dreyfus Award EP-11-117, the French National Research Agency (ANR), the Nord-Pas de Calais, and the European Funds for Regional Economic Development (FEDER, Labex-Cappa, ANR-11-LABX-0005-01).