Publication: Influence of Seed Aerosol Surface Area and Oxidation Rate on Vapor-Wall Deposition and SOA Mass Yields: A case study with α-pinene Ozonolysis

Publication - Influence of Seed Aerosol Surface Area and Oxidation Rate on Vapor-Wall Deposition and SOA Mass Yields: A case study with α-pinene Ozonolysis

Title: Influence of Seed Aerosol Surface Area and Oxidation Rate on Vapor-Wall Deposition and SOA Mass Yields: A case study with α-pinene Ozonolysis
DOI: 10.5194/acp-16-9361-2016
Publication Year: 2016
Author list: Nah, T., McVay, R. C., Zhang, X., Boyd, C. M., Seinfeld, J. H., and Ng, N. L
Journal Short Name: ACP
Publisher: Copernicus

Abstract
Laboratory chambers, invaluable in atmospheric chemistry and aerosol formation studies, are subject to particle and vapor wall deposition, processes that need to be accounted for in order to accurately determine secondary organic aerosol (SOA) mass yields. Although particle wall deposition is reasonably well understood and usually accounted for, vapor wall deposition is less so. The effects of vapor wall deposition on SOA mass yields in chamber experiments can be constrained experimentally by increasing the seed aerosol surface area to promote the preferential condensation of SOA-forming vapors onto seed aerosol. Here, we study the influence of seed aerosol surface area and oxidation rate on SOA formation in α-pinene ozonolysis. The observations are analyzed using a coupled vapor–particle dynamics model to interpret the roles of gas–particle partitioning (quasi-equilibrium vs. kinetically limited SOA growth) and α-pinene oxidation rate in influencing vapor wall deposition. We find that the SOA growth rate and mass yields are independent of seed surface area within the range of seed surface area concentrations used in this study. This behavior arises when the condensation of SOA-forming vapors is dominated by quasi-equilibrium growth. Faster α-pinene oxidation rates and higher SOA mass yields are observed at increasing O3 concentrations for the same initial α-pinene concentration. When the α-pinene oxidation rate increases relative to vapor wall deposition, rapidly produced SOA-forming oxidation products condense more readily onto seed aerosol particles, resulting in higher SOA mass yields. Our results indicate that the extent to which vapor wall deposition affects SOA mass yields depends on the particular volatility organic compound system and can be mitigated through the use of excess oxidant concentrations.

Additional Notes



Experiments (6)

ID Name Start date Experiment Category Reaction Type Reactant(s) Oxidant Name Temperature Humidity Type of Seed RO2 Main Fate Data Sets (count) Actions
699 Ng Research Group_20150112_a-Pinene_Ozone_Ammonium sulfate 2015-01-12 Aerosol formation, Instrument/Chamber characterization Dark oxidation a-Pinene Ozone 25 5 Ammonium sulfate Not Sure 4 Download
723 Ng Research Group_20150123_a-Pinene_Ozone_No Seed 2015-01-23 Aerosol formation, Instrument/Chamber characterization Dark oxidation a-Pinene Ozone 25 5 Not Sure 5 Download
724 Ng Research Group_20150224_a-Pinene_Ozone_Ammonium sulfate 2015-02-24 Aerosol formation, Instrument/Chamber characterization Dark oxidation a-Pinene Ozone 25 5 Ammonium sulfate Not Sure 5 Download
725 Ng Research Group_20150126_a-Pinene_Ozone_Ammonium sulfate 2015-01-26 Aerosol formation, Instrument/Chamber characterization Dark oxidation a-Pinene Ozone 25 5 Ammonium sulfate Not Sure 5 Download
726 Ng Research Group_20150128_a-Pinene_Ozone_Ammonium sulfate 2015-01-28 Aerosol formation, Instrument/Chamber characterization Dark oxidation a-Pinene Ozone 25 5 Ammonium sulfate Not Sure 5 Download
727 Ng Research Group_20150301_a-Pinene_Ozone_Ammonium sulfate 2015-03-01 Aerosol formation, Instrument/Chamber characterization Dark oxidation a-Pinene Ozone 25 5 Ammonium sulfate Not Sure 5 Download