Journal Article

Ion-induced nucleation of pure biogenic particles

Ehrhart, Sebastian, Schobesberger, Siegfried, Curtius, Joachim, Kim, Jaeseok, Breitenlechner, Martin, Praplan, Arnaud P., Wagner, Andrea C., Onnela, Antti, Seinfeld, John H., Wimmer, Daniela, Baltensperger, Urs, Dias, Antonio, Steiner, Gerhard, Carslaw, Kenneth S., Lehtipalo, Katrianne, Sarnela, Nina, Peräkylä, Otso, Stratmann, Frank, Kangasluoma, Juha, Chen, Xuemeng, Virtanen, Annele, Adamov, Alexey, Piel, Felix, Almeida, João, Amorim, Antonio, Heinritzi, Martin, Pringle, Kirsty, Junninen, Heikki, Rap, Alexandru, Yan, Chao, Mathot, Serge, Bernhammer, Anne-Kathrin, Rissanen, Matti P., Hoyle, Christopher R., Rondo, Linda, Ortega, Ismael K., Donahue, Neil M., Jokinen, Tuija, Vogel, Alexander L., Kulmala, Markku, Wagner, Robert, Stozhkov, Yuri, Petäjä, Tuukka, Zhang, Xuan, Weingartner, Ernest, Riipinen, Ilona, Dommen, Josef, Sengupta, Kamalika, Kirkby, Jasper, Ye, Penglin, Worsnop, Douglas R., Fuchs, Claudia, Scott, Catherine E., Guida, Roberto, Brilke, Sophia, Sipilä, Mikko, Wagner, Paul E., Tröstl, Jasmin, Flagan, Richard C., Richards, Nigel A. D., Hakala, Jani, Tomé, Antonio, Kürten, Andreas, Hansel, Armin, Sim

2016

Overview

Aerosol particles can form in the atmosphere by nucleation of highly oxidized biogenic vapours in the absence of sulfuric acid, with ions from Galactic cosmic rays increasing the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Aerosol particles can form in the atmosphere by nucleation of highly oxidized biogenic vapours in the absence of sulfuric acid, with ions from Galactic cosmic rays increasing the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Aerosol particle formation in clean air The effect of atmospheric aerosols on clouds and the radiative forcing of the climate system remains poorly understood. It is thought that nucleation of aerosol particles from atmospheric vapours rarely proceeds in the absence of sulfuric acid. Now two papers in this week’s Nature point to a previously unappreciated role for highly oxygenated molecules (HOMs) in promoting new particle formation and growth, essentially a mechanism that produces aerosols in the absence of pollution. Jasper Kirkby et al . show that aerosol particles can form as a result of ion-induced nucleation of HOMs in the absence of sulfuric acid under conditions relevant to the atmosphere in the CLOUD chamber at CERN. Jasmin Tröstl et al . examined the role of organic vapours in the initial growth of nucleated organic particles in the absence of sulfuric acid in the CERN CLOUD chamber under atmospheric conditions. They find that the organic vapours driving initial growth have extremely low volatilities. With increasing particle size, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility. Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood 1 . Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours 2 . It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere 3 , 4 , and that ions have a relatively minor role 5 . Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded 6 , 7 . 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.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 704/106/35/824 / 704/106/694/2739 / Aerosols / Aerosols - chemistry / Air Pollution - analysis / Anthropogenic factors / Atmosphere / Atmosphere - chemistry / Atoms & subatomic particles / Bicyclic Monoterpenes / Charged particles / Chemical properties / Climate Change / Clouds / Cosmic Radiation / Cosmic rays / Environment / Environmental aspects / Experiments / Gases / Human Activities / Humanities and Social Sciences / Ions / Ions - chemistry / letter / Monoterpenes - chemistry / multidisciplinary / Nitrates / Nucleation / Oxidation / Oxidation-Reduction / Oxygen - chemistry / Ozone - chemistry / Particle Size / Particulate Matter - chemistry / Quantum Theory / Science / Sulfuric acid / Sulfuric Acids - analysis / Terrestrial environments / Vapors / Volatility / Volatilization