AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
A Study of the Aqueous Phase Processing of Organic Aerosols through Compound Specific Stable Isotope Analysis
DENISE NAPOLITANO, Pierre Herckes, Arizona State University
Abstract Number: 593 Working Group: Aerosol Chemistry
Abstract Secondary organic aerosols (SOAs) are formed in the atmosphere through oxidative and photochemical reactions of primary organic aerosols (POAs) or volatile organic compounds (VOCs). While gas-phase SOA formation from VOCs has been well-studied and documented, aqueous-phase SOA formation remains a poorly understood process, likely causing substantial errors in the estimation of organic aerosol concentrations in atmospheric models. Field studies of SOA formation involving all three phases of aerosol particulate matter (PM), gas phase VOCs, and aqueous phase organic substances have not been conducted, but it would be greatly beneficial to isolate and track compounds in the atmosphere through all phases as these reactions proceed. Both an understanding of how SOAs form in the aqueous phase, as well as whether the SOA precursors originated from POAs or VOCs, can be addressed through studying the stable carbon isotopic composition of organic atmospheric species. Analyses of aerosol particulate matter (PM) and fog collected from various regions of North America for total carbon isotopic composition by isotope ratio mass spectrometry (IRMS) clearly reveal processes that involve isotope effects when fog is present. Performing compound-specific isotope analysis (CSIA) using a gas chromatography-combustion-IRMS (GC-C-IRMS) system on various types of atmospheric species as fog forms and evaporates will aid in identifying the processes that lead to isotope fractionation and show how these processes affect the carbon isotopic composition of SOAs formed in the aqueous phase (aqSOA). This information will allow us to determine the precursors of specific aqSOA and if the precursors originated as PM or VOCs. These analyses will provide novel analytical results to add to the community’s knowledge of aqueous SOA processing and demonstrate the effects that these reactions have on model estimates of the organic aerosol budget.