Environ. Sci. Technol. 2009, 43, 4647–4652
Photooxidation of 2-Methyl-3-Buten-2-ol (MBO) as a Potential Source of Secondary Organic Aerosol ARTHUR W. H. CHAN,† MELISSA M. GALLOWAY,‡ ALAN J. KWAN,§ PUNEET S. CHHABRA,† FRANK N. KEUTSCH,‡ PAUL O. WENNBERG,§ R I C H A R D C . F L A G A N , †,§ A N D J O H N H . S E I N F E L D * ,†,§ Department of Chemical Engineering, California Institute of Technology, Pasadena, California 91125, Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, and Department of Environmental Science and Engineering, California Institute of Technology, Pasadena, California 91125
Received September 11, 2008. Revised manuscript received December 15, 2008. Accepted December 19, 2008.
2-Methyl-3-buten-2-ol (MBO) is an important biogenic hydrocarbon emitted in large quantities by pine forests. Atmospheric photooxidation of MBO is known to lead to oxygenated compounds, such as glycolaldehyde, which is the precursor to glyoxal. Recent studies have shown that the reactive uptake of glyoxal onto aqueous particles can lead to formation of secondary organic aerosol (SOA). In this work, MBO photooxidation under high- and low-NOx conditions was performed in dual laboratory chambers to quantify the yield of glyoxal and investigate the potential for SOA formation. The yields of glycolaldehyde and 2-hydroxy-2-methylpropanal (HMPR), fragmentation products of MBO photooxidation, were observed to be lower at lower NOx concentrations. Overall, the glyoxal yield from MBO photooxidation was 25% under highNOx and 4% under low-NOx conditions. In the presence of wet ammonium sulfate seed and under high-NOx conditions, glyoxal uptake and SOA formation were not observed conclusively, due to relatively low (
