AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Organic Peroxide Formation from Photooxidation of Methylglyoxal in the Aqueous Phase
YONG LIM, Barbara Turpin, Rutgers University
Abstract Number: 42 Working Group: Aerosol Chemistry
Abstract Aqueous chemistry in atmospheric waters (e.g., cloud droplets or wet aerosols) is well accepted as an atmospheric pathway to produce secondary organic aerosol (SOAaq). Water-soluble organic compounds with small carbon numbers (C2-C3) are precursors for SOAaq and products include organic acids, organic sulfates, and high molecular weight compounds/oligomers. Fenton reactions and the uptake of gas-phase OH radicals are considered to be the major oxidant sources for aqueous organic chemistry. If these are the only sources, aqueous oxidation chemistry will be oxidant-limited. However, sources and availability of oxidants in atmospheric waters and their reactions with dissolved organic compounds in the aqueous phase are still not well understood.
In this work, laboratory experiments and ultra high resolution Fourier Transform Ion Cyclotron Resonance electrospray ionization mass spectrometry (FTICR-MS) are used to demonstrate that organic peroxides form during aqueous photooxidation of methylglyoxal. It is already well known that organic peroxides form and recycle OH in the gas-phase. And that these organic peroxides partition into particles forming secondary organic aerosol (SOAgas) We argue that photolysis of organic peroxides in clouds and wet aerosols provides a source of OH radicals (OH recycling) for aqueous chemistry and SOAaq formation. Organic peroxides formed through aqueous chemistry could be a yet unrecognized source of light absorbing "brown" carbon in aerosols.