Laboratory Measurements of Secondary Organic Aerosol Formation from Semi-Volatile Organic Compounds
EMSL Project ID
32291
Abstract
We are proposing to collaborate with EMSL staff member M. Lizabeth Alexander in using the EMSL proton transfer reaction mass spectrometer (PTR-MS) and High Resolution Aerosol Time-of-Flight Mass Spectrometer (HR-ToF AMS) to measure the effect of the presence of low-volatility organic hydrocarbon compounds and highly-oxidized organic aerosols on the formation and yield of secondary organic aerosols (SOA). Recent results by several of atmospheric researchers point to the importance of low volatility VOCâ??s in explaining the large discrepancy between calculated and observed secondary organic aerosol loadings in the atmosphere. Resolution of this disagreement is critical to the improvement and validation of global climate models. The proposed work will take place in the environmental chamber maintained by the Atmospheric and Global Climate Change Division at PNNL. Previous collaboration between M. Lizabeth Alexander and these researchers demonstrated that the presence of primary organic aerosol does not increase the yield of SOA formation. This significant result was in sharp contrast to the assumptions currently used in atmospheric modeling of SOA. We propose to extend that work to measure the effect of existing, highly-oxidized, aged aerosols on the yield for new aerosol formation. The work will use individual compounds as surrogates for aged aerosols as well as oxidized lube oil vapor to give a multi-component mixture. As part of the lube oil study the carbon mass balance between the gas and aerosol phase will be determined and compared with current models. This is an important result in determining the role of lube oil vapor as a source of semi-volatile compounds as an atmospheric source of SOA. Time resolved measurement of gas-phase carbon mass will involve the use of the PTR-MS with a special, rapid cycling pre-concentrator developed in EMSL and will be supplemented by standard GC-MS measurements at a slower sample rate. The real-time ratio of carbon, oxygen and hydrogen present in the aerosols will be determined by the HR-ToF AMS and standard TOC measurements will be made on selected filter samples to establish absolute elemental aerosol values. These results will be compared with models and results from diesel exhaust to determine the significance of lube oil vapor in those systems.Project Details
Project type
Exploratory Research
Start Date
2009-01-19
End Date
2010-01-24
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members