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Published July 1, 2009 | public
Journal Article

Photooxidation of 2-methyl-3-buten-2-ol (MBO) as a potential source of secondary organic aerosol


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 high-NOₓ 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 (<30 ppb) glyoxal concentrations. Slight aerosol formation was observed under low-NOₓ and dry conditions, with aerosol mass yields on the order of 0.1%. The small amount of SOA was not related to glyoxal uptake, but is likely a result of reactions similar to those that generate isoprene SOA under low-NOₓ conditions. The difference in aerosol yields between MBO and isoprene photooxidation under low-NOₓ conditions is consistent with the difference in vapor pressures between triols (from MBO) and tetrols (from isoprene). Despite its structural similarity to isoprene, photooxidation of MBO is not expected to make a significant contribution to SOA formation.

Additional Information

© 2009 American Chemical Society. Received September 11, 2008. Revised manuscript received December 15, 2008. Accepted December 19, 2008. Publication Date (Web): January 29, 2009. This research was funded by U.S. Department of Energy Biological and Environmental Research Program DE-FG02-05ER63983, U.S. Environmental Protection Agency STAR grant RD-83374901, and U.S. National Science Foundation grant ATM-0432377. This work was also supported by the Camille and Henry Dreyfus Foundation and development of the Madison-LIP instrument was supported by the National Science Foundation, Division of Atmospheric Sciences, Atmospheric Chemistry Program(grant 0724912),and the NDSEG-ARO.This publication has not been formally reviewed by the EPA. The views expressed in this document are solely those of the authors and EPA does not endorse any products mentioned in this publication. We thank Henrik Kjaergaard for density functional theory calculations of the dipole moments and polarizabilities of various gas-phase species. This article is part of the Particulate Matter and Human Health special issue.

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