RESEARCH IN ACTION

 

Biogenic volatile organic compounds: The state of knowledge in Southern Africa and the challenges for air quality management

 

 

M. Zunckel^I; K. Chiloane^II; M. Sowden^I; L. Otter^III

^ICSIR Natural Resources and the Environment, P.O. Box 17001, Congella 4013, South Africa
^IICSIR Natural Resources and the Environment, P.O. Box 395, Pretoria 0001, South Africa
^IIIClimatology Research Group, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa

 

 

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ABSTRACT

Emissions of biogenic volatile organic compounds (BVOCs) on an urban and regional scale compare with those from anthropogenic sources, both in magnitude and in their role in atmospheric photochemistry and in the formation of ozone. Despite this, research on BVOC emissions in southern Africa has been limited to relatively few plant species in savannas, woodlands and shrublands. Extrapolation of these values provides an estimated annual emission of 80 Tg C for the subcontinent. Isoprene and monoterpene emissions vary widely according to plant species, temperature, foliar density and photosynthetically active radiation, and also diurnally and with season. Savanna trees such as Acacia nigrescens and Burkea africana are high isoprene emitters, and monoterpene emissions from Colophospermum mopane and Acacia tortilis are significant. By comparison, some tree species, such as Combretum molle and Sclerocarya birrea, emit neither compound. The legal prerequisite for holistic air quality management in South Africa, together with the dearth of information on BVOC emissions and an understanding of their role in the formation of ozone, poses significant challenges for policy-makers, air quality managers and scientists in southern Africa.

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Funding for the BVOC project is provided by the CSIR’s Strategic Research Panel through the Thematic Fund.
* Author for correspondence. E-mail:mzunckel@csir.co.za