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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 18, 8137-8154, 2018
https://doi.org/10.5194/acp-18-8137-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
08 Jun 2018
Different roles of water in secondary organic aerosol formation from toluene and isoprene
Long Jia1,2 and YongFu Xu1,2 1State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
2Department of Atmospheric Chemistry and Environmental Sciences, College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Abstract. Roles of water in the formation of secondary organic aerosol (SOA) from the irradiations of toluene-NO2 and isoprene-NO2 were investigated in a smog chamber. Experimental results show that the yield of SOA from toluene almost doubled as relative humidity increased from 5 to 85 %, whereas the yield of SOA from isoprene under humid conditions decreased by 2.6 times as compared to that under dry conditions. The distinct difference of RH effects on SOA formation from toluene and isoprene is well explained with our experiments and model simulations. The increased SOA from humid toluene-NO2 irradiations is mainly contributed by O–H-containing products such as polyalcohols formed from aqueous reactions. The major chemical components of SOA in isoprene-NO2 irradiations are oligomers formed from the gas phase. SOA formation from isoprene-NO2 irradiations is controlled by stable Criegee intermediates (SCIs) that are greatly influenced by water. As a result, high RH can obstruct the oligomerization reaction of SCIs to form SOA.
Citation: Jia, L. and Xu, Y.: Different roles of water in secondary organic aerosol formation from toluene and isoprene, Atmos. Chem. Phys., 18, 8137-8154, https://doi.org/10.5194/acp-18-8137-2018, 2018.
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Short summary
In this work, the opposite effects of relative humidity (RH) on secondary organic aerosol (SOA) formation from toluene and isoprene were observed and have been well explained in terms of various experimental data and model simulations. The increase in SOA from toluene under humid conditions is mainly contributed by aqueous reactions of water-soluble products, whereas SOA formation from isoprene-NO2 irradiations is controlled by stable Criegee intermediates that are greatly influenced by water.
In this work, the opposite effects of relative humidity (RH) on secondary organic aerosol (SOA)...
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