AGS-PRF: Synthesizing Laboratory and Field Measurements of Biogenic Volatile Organic Compounds

Nguyen Tran B, Pasadena CA

Investigators

Abstract

This objective of this research is to investigate the major chemical and physical loss pathways for isoprene (C5H8) and its oxidation products in the atmosphere and assess their role in the formation of secondary organic aerosol (SOA). An AGS Postdoctoral Research Fellow will conduct laboratory studies in Caltech's newly built smog chambers to explore potential mechanisms for SOA formation under various conditions. The three primary mechanisms that will be investigated are: (1) the gas-phase OH-oxidation of isoprene-derived epoxydiols (IEPOX), that are formed in pristine environments, in the presence of varying amounts of NOx, (2) the reactive uptake and aqueous photochemistry of isoprene-derived organic compounds (hydroperoxide (ISOPOOH), IEPOX, glycolaldehyde, etc.) in aerosol liquid water, and (3) the formation of hydroperoxides from the water vapor reaction with stabilized Criegee intermediates from the ozonolysis of isoprene. Multifunctional organic compounds that are important precursors to SOA were measured during an NSF sponsored field campaign in the summer of 2013, the Southern Oxidant and Aerosol Study (SOAS), using a state-of-the-art chemical ionization mass spectrometer (CIMS). Results from the laboratory studies will be used to assess possible mechanisms for SOA formation that might explain the observational data collected during the SOAS field campaign. Isoprene is emitted by forests and plants and is among the most highly emitted organic compounds in the atmosphere. The products of isoprene oxidation form ozone and secondary organic aerosols, which are harmful to human health and perturb the Earth's climate. This research will produce information that is critical to modeling the influence of isoprene oxidation products on climate change. This research is supported under the AGS Postdoctoral Research Fellowship program.