Emission of volatile organic compounds from Portuguese eucalyptus forests

Abstract

Emission to the atmosphere of volatile organic compounds (VOCs) by Eucalyptus globulus was studied in the laboratory with young specimen, and in the field with adult trees. Eucalyptus emits both monoterpenes and isoprene. The leaves of young trees emit at higher rates than the leaves of adult trees. The emission of isoprene is highly predominant during the day. The emission of isoprene is dependent on temperature and solar radiation. The emission rate follows the Guenther algorithm if a based emission factor of $\text{32}\text{μg}\text{g}{}_{\mathrm{<mtext>dw</mtext>}}{}^{\mathrm{-1}}\text{h}{}^{\mathrm{-1}}$ is used, increasing with temperature, to a maximum at 40°C. At higher temperatures there is a decrease in the emission rate. The main C₁₀ emitted compound is 1,8-cineol. Cineol emissions increase exponentially with temperature, and are also seasonally dependent. Application of the emission algorithm to the Portuguese eucalyptus forests shows that during summer isoprene and monoterpene emissions by eucalyptus are of the same order of anthropogenic VOC production. Furthermore, in certain regions, in the center-north of Portugal, where eucalyptus forests are predominant, isoprene emissions can reach an order of magnitude higher than anthropogenic production of VOCs during daytime periods in July and August.