U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights

Monoterpenes Play Important Antioxidant Roles, Serve as Sources of Secondary Organic Aerosol Precursors
Published: March 06, 2015
Posted: November 03, 2015

Despite orders of magnitude difference in atmospheric reactivity and great diversity in biological functioning, little is known about monoterpene speciation in tropical forests. In a recent study, researchers report vertically resolved ambient air mixing ratios for 12 monoterpenes in a central Amazon rainforest, including observations of the highly reactive cis-β-ocimene [160 parts per trillion (ppt)], trans-β-ocimene (79 ppt), and terpinolene (32 ppt), which accounted for an estimated 21% of total monoterpene composition, yet 55% of the upper canopy monoterpene ozonolysis rate. All 12 monoterpenes showed a mixing ratio peak in the upper canopy, with three demonstrating subcanopy peaks in seven of 11 profiles. Leaf-level emissions of highly reactive monoterpenes accounted for up to 1.9% of photosynthesis, confirming light-dependent emissions across several Amazon tree genera. These results suggest that highly reactive monoterpenes play important antioxidant roles during photosynthesis in plants and serve as near-canopy sources of secondary organic aerosol precursors through atmospheric photooxidation via ozonolysis.

Reference: Jardine, A. B., K. J. Jardine, J. D. Fuentes, S. T. Martin, G. Martins, F. Durgante, V. Carneiro, N. Higuchi, A. O. Manzi, and J. Q. Chambers. 2015. “Highly Reactive Light-Dependent Monoterpenes in the Amazon,” Geophysical Research Letters 42(5), 1576–83. DOI: 10.1002/2014GL062573. (Reference link)

Contact: Jared DeForest, SC-23, (301) 903-3251, Daniel Stover, SC-23.1, (301) 903-0289
Topic Areas:

  • Research Area: Atmospheric System Research
  • Research Area: Terrestrial Ecosystem Science

Division: SC-23.1 Climate and Environmental Sciences Division, BER


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