References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-9-2061-2009

Methyl chavicol: characterization of its biogenic emission rate, abundance, and oxidation products in the atmosphere

Bouvier-Brown

N. C.

¹ Goldstein

A. H.

¹ Worton

D. R.

¹ Matross

D. M.

¹ Gilman

J. B.

² Kuster

W. C.

² Welsh-Bon

² Warneke

² de Gouw

J. A.

² Cahill

T. M.

³ Holzinger

⁴

Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA

NOAA Earth System Research Laboratory & Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, CO, USA

Division of Mathematical and Natural Sciences, Arizona State University, West Campus, Phoenix, AZ, USA

Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, The Netherlands

23 03 2009

9 6 2061 2074

This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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We report measurements of ambient atmospheric mixing ratios for methyl chavicol and determine its biogenic emission rate. Methyl chavicol, a biogenic oxygenated aromatic compound, is abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol was detected simultaneously by three in-situ instruments – a gas chromatograph with mass spectrometer detector (GC-MS), a proton transfer reaction mass spectrometer (PTR-MS), and a thermal desorption aerosol GC-MS (TAG) – and found to be abundant within and above Blodgett Forest. Methyl chavicol atmospheric mixing ratios are strongly correlated with 2-methyl-3-buten-2-ol (MBO), a light- and temperature-dependent biogenic emission from the ponderosa pine trees at Blodgett Forest. Scaling from this correlation, methyl chavicol emissions account for 4–68% of the carbon mass emitted as MBO in the daytime, depending on the season. From this relationship, we estimate a daytime basal emission rate of 0.72–10.2 μgCg−1 h−1, depending on needle age and seasonality. We also present the first observations of its oxidation products (4-methoxybenzaldehyde and 4-methyoxy benzene acetaldehyde) in the ambient atmosphere. Methyl chavicol is a major essential oil component of many plant species. This work suggests that methyl chavicol plays a significant role in the atmospheric chemistry of Blodgett Forest, and potentially other sites, and should be included explicitly in both biogenic volatile organic carbon emission and atmospheric chemistry models.

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