Journal Article

Secondary organic aerosol reduced by mixture of atmospheric vapours

Pullinen, Iida, Faxon, Cameron, Ehn, Mikael, Schmitt, Sebastian, Le Breton, Michael, Kang, Sungah, Hallquist, Mattias, Bannan, Thomas J., McFiggans, Gordon, Alfarra, M. Rami, Topping, David, Kleist, Einhard, Thornton, Joel A., Springer, Monika, Wildt, Jürgen, Zhao, Defeng, Hallquist, Åsa M., Bergström, Robert, Priestley, Michael, Mentel, Thomas F., Jenkin, Michael E., Tillmann, Ralf, Kiendler-Scharr, Astrid, Simpson, David, Percival, Carl J., Wu, Cheng

2019

Overview

Secondary organic aerosol contributes to the atmospheric particle burden with implications for air quality and climate. Biogenic volatile organic compounds such as terpenoids emitted from plants are important secondary organic aerosol precursors with isoprene dominating the emissions of biogenic volatile organic compounds globally. However, the particle mass from isoprene oxidation is generally modest compared to that of other terpenoids. Here we show that isoprene, carbon monoxide and methane can each suppress the instantaneous mass and the overall mass yield derived from monoterpenes in mixtures of atmospheric vapours. We find that isoprene ‘scavenges’ hydroxyl radicals, preventing their reaction with monoterpenes, and the resulting isoprene peroxy radicals scavenge highly oxygenated monoterpene products. These effects reduce the yield of low-volatility products that would otherwise form secondary organic aerosol. Global model calculations indicate that oxidant and product scavenging can operate effectively in the real atmosphere. Thus highly reactive compounds (such as isoprene) that produce a modest amount of aerosol are not necessarily net producers of secondary organic particle mass and their oxidation in mixtures of atmospheric vapours can suppress both particle number and mass of secondary organic aerosol. We suggest that formation mechanisms of secondary organic aerosol in the atmosphere need to be considered more realistically, accounting for mechanistic interactions between the products of oxidizing precursor molecules (as is recognized to be necessary when modelling ozone production). Adding reactive gases such as isoprene to mixtures lowers the production of secondary organic aerosol in the atmosphere, thus reducing the atmospheric particulate burden, with implications for human health and climate.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 704/106/35/824 / 704/172/169/824 / Aerosols / Air pollution / Air pollution control / Air quality / Analysis / Analytical Chemistry / Analytisk kemi / Annan kemi / Atmosphere / Atmospheric chemistry / Atmospheric models / Carbon monoxide / Chemical Sciences / Climate Science / Earth and Related Environmental Sciences / Emissions / Environmental aspects / Environmental Sciences / Equilibrium / Flowers & plants / Free radicals / Fysikalisk kemi / Geovetenskap och relaterad miljövetenskap / Global aerosols / Humanities and Social Sciences / Hydroxides / Hydroxyl radicals / Isoprene / Kemi / Klimatvetenskap / Meteorologi och atmosfärsvetenskap / Meteorology and Atmospheric Sciences / Methane / Miljövetenskap / Monoterpenes / multidisciplinary / Natural gas / Organic compounds / Other Chemistry Topics / Oxidation / Oxidation-reduction reactions / Oxidizing agents / Ozone / Ozone production / Particle mass / Peroxy radicals / Physical Chemistry / Precursors / Scavenging / Science / Science & Technology - Other Topics / Science (multidisciplinary) / Secondary aerosols / Terpenes / VOCs / Volatile organic compounds / Volatility