Volatile organic compound emissions from Larrea tridentata (creosotebush) 1University of Arizona-Biosphere 2, 32540 S. Biosphere Road, Oracle, AZ 85623, USA
2University of Arizona, Departments of Chemistry & Biochemistry and Soil, Water & Environmental Science, P.O. Box 210038, Tucson, AZ 85721-0038, USA
3University of Arizona, School of Natural Resources and the Environment, Biological Sciences East Tucson, AZ 85721, USA
4University of Arizona, Department of Ecology and Evolutionary Biology, P.O. Box 210088, Tucson, AZ 85721, USA
5National Center for Atmospheric Research, Atmospheric Chemistry Division, 3450 Mitchell Lane, Boulder, CO 80301, USA
Received: 28 May 2010 – Published in Atmos. Chem. Phys. Discuss.: 12 Jul 2010 Abstract. We present results from the CREosote ATmosphere Interactions through
Volatile Emissions (CREATIVE 2009) field study in southern Arizona aimed at
quantifying emission rates of VOCs from creosotebush (Larrea tridentata) during the summer
2009 monsoon season. This species was chosen because of its vast
distribution in North and South American deserts and because its resins have
been reported to contain a rich set of volatile organic compounds (VOC).
While a variety of ecosystems have been investigated for VOC emissions,
deserts remain essentially unstudied, partially because of their low biomass
densities and water limitations. However, during the North American monsoon,
a pronounced increase in rainfall from an extremely dry June (<5 mm
precipitation) to a rainy July (>80 mm) occurs over large areas of the
Sonoran desert in the southwestern United States and northwestern Mexico. We
observed a strong diurnal pattern of branch emissions and ambient
concentrations of an extensive suite of VOCs with maxima in early afternoon.
These include VOCs typically observed in forest sites (oxygenated VOCs and
volatile isoprenoids) as well as a large number of other compounds, some of
which have not been previously described from any plant including
1-chloro-2-methoxy-benzene and isobutyronitrile. Although generally
considered to be derived from anthropogenic sources, we observed emissions
of aromatic compounds including benzene, and a broad range of phenolics.
Dimethyl sulfide emissions from creosotebush were higher than reported from
any previously studied plant suggesting that terrestrial ecosystems should
be reconsidered as an important source of this climatically important gas.
We also present direct, primary emission measurements of isoprene and its
apparent oxidation products methyl vinyl ketone, methacrolein, and 3-methyl
furan (the later three compounds are typically assumed to form from
secondary reactions within the atmosphere), as well as a group of compounds
considered to be fatty acid oxidation products. These results suggest that
one important function of some VOCs in creosotebush is as an antioxidant. We
also find that emissions of nitriles from creosotebush could represent a
significant but previously unaccounted nitrogen loss from this arid
ecosystem. Our results demonstrate the richness of creosotebush volatile
emissions and highlight the need for further research into their atmospheric
and ecological impacts.
Revised: 02 Dec 2010 – Accepted: 12 Dec 2010 – Published: 23 Dec 2010
Citation: Jardine, K., Abrell, L., Kurc, S. A., Huxman, T., Ortega, J., and Guenther, A.: Volatile organic compound emissions from Larrea tridentata (creosotebush), Atmos. Chem. Phys., 10, 12191-12206, doi:10.5194/acp-10-12191-2010, 2010.