AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Measurement of Atmospheric Organic Aerosol Hygroscopicity and Oxidation Level as a Function of Volatility
KERRIGAN CAIN, Spyros Pandis, Carnegie Mellon University
Abstract Number: 512 Working Group: Aerosols, Clouds, and Climate
Abstract Hygroscopicity, oxidation level, and volatility of organic pollutants are three crucial properties that determine their fate in the atmosphere. This study assesses the feasibility of a novel measurement and analysis technique to determine these properties at the same time and to establish their relationship. The proposed experimental setup utilizes a cloud condensation nuclei counter to quantify hygroscopic activity, an aerosol mass spectrometer to measure the oxidation level, and a thermodenuder to evaluate the volatility. The setup was first tested with secondary organic aerosol (SOA) formed from the ozonolysis of α-pinene in a 10 m3 smog chamber at Carnegie Mellon University. The results of the first experiments indicated that, for this system, the less volatile SOA contained components that had lower O:C ratios and hygroscopicity parameters, κ. The proposed analysis technique is used to express hygroscopicity and oxidation level as a function of volatility. The results from this analysis confirmed that the SOA had some low volatility material with a low O:C ratio and κ. These results also showed that both low and high volatility material can have a comparable oxidation level and hygroscopicity.
The technique was tested further with several other SOA systems generated from the oxidation of other monoterpenes and sesquiterpenes as well as ambient aerosol from Pittsburgh, PA. These results can provide valuable insights about the relationships among organic aerosol hygroscopicity, oxidation level, and volatility.