is investigating biochemical aspects of volatile organic compound (VOC)
formation in plants and bacteria. The "VOC tree" below illustrates
the large variety of VOCs formed in plants, and points out that many different
tissues,cellular compartments, and biochemical pathways are involved in
the biosynthesis of VOCs.
links provide more information about our current research regarding
leaf wound VOCs.
Why are we interested in biogenic VOCs?
Biogenic VOCs are a key part of one of
the major environmental problems of our time ? sustainability of the oxidative
power of the atmosphere in the face of human alterations to the World’s
forests and climate. What is the oxidative power of the atmosphere
and why is it important to the biosphere?
The oxidative power of the atmosphere, in simple terms, is defined as
the atmospheric capacity
to form hydroxyl radical (OH), otherwise
known as the "detergent of the atmosphere." The daily photochemical
production of OH controls the oxidation of major atmospheric gases, such
methane, carbon monoxide, and reduced nitrogen and sulfur gases.
oxidative power of the atmosphere affects the lifetimes of atmospheric
components of the major biogeochemical cycles.The strong oxidative power
of the Earth’s
atmosphere is a direct result of biological activity. Normal functioning
of the OH system is closely linked with a simple biological molecule,
isoprene (2-methyl-1,3-butadiene) and other reactive biogenic VOCs.In
the case of isoprene, emissions from the World’s forests are huge, estimated
at >500 million tons per year, comparable to global release of the greenhouse
gas, methane. In the presence of sunlight isoprene can trigger OHformation
or OH destruction, depending on the levels of nitrogen
oxides(NOx). Thus the oxidative
balance of the atmosphere is strongly linked to biospheric processes,
chemical reactions in plants may be responsible for the formation of ozone
OH holes in forested regions of the Earth. It is important to understand
biochemical and physiological controls on the formation and release of
these VOCs to the atmosphere, especially given man-made changes in global
levels and temperature, NOx emissions, and planting of large isoprene-emitting
R. Fall (1999) Biogenic emissions of VOCs from higher plants. In: Reactive
Hydrocarbons in the Atmosphere, C.N. Hewitt (ed.), pp. 43-96, Academic