Abstract View
Chemical Characterization of Isoprene- and Monoterpene-Derived Secondary Organic Aerosol (SOA) Tracers in Marine Aerosols from the Galápagos Islands
TESSA SZALKOWSKI, Tianqu Cui, Karsten Baumann, Ryan Schmedding, Zhenfa Zhang, Jason Surratt, Jackson Seymore, William Vizuete, University of North Carolina at Chapel Hill
Abstract Number: 83
Working Group: Aerosol Chemistry
Abstract
Atmospheric fine particulate matter (PM2.5) plays a critical role in the global climate system, in which the oceans are an important primary and secondary source. The atmospheric processes that produce secondary remote marine PM2.5, however, remain unclear. This is partly due to a lack of characterization of particulate organic constituents and understanding of their links with biogenic volatile organic compounds (BVOCs) produced by phytoplankton that participate in secondary organic aerosol (SOA) formation. An approach to access the marine contribution to PM2.5 is to conduct concurrent atmospheric and marine measurements. The Galápagos Islands are an ideal location to make these measurements, as it is a pristine environment with few anthropogenic sources. Furthermore, the waters surrounding the islands harbor a diverse range of phytoplankton communities within small spatial scales.
This work presents the feasibility of using this site for real-time PM2.5 mass and off-line PM2.5 chemical characterization of marine aerosols. PM2.5 samples were collected onto high-volume quartz filters and chemically characterized at the molecular level using a recently developed hydrophilic interaction liquid chromatography (HILIC) method interfaced to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (ESI-HR-QTOFMS). PM2.5 organic constituents showed a correlation with chloride, indicating some contribution from marine sources. Strong correlations with methanesulfonic acid and oxalic acid indicated that marine bioactivity, such as algal production, may have contributed to the observed PM2.5 levels. We show, for the first time, evidence of isoprene-derived SOA contributing to PM2.5 collected on the Galápagos Islands. Our findings also suggest the presence of other sources of organic aerosol, such as primary OA from bubble-bursting processes and oxidative aging (heterogeneous oxidation) products from particulate 2-methyltetrol sulfate diastereomers. The composition and correlations from our measurements can provide an estimation of marine sources and their contribution to PM2.5, thus serving as model inputs for chemical and climate studies.