Isoprene and monoterpene emission from the coniferous species Abies Borisii-regis -: implications for regional air chemistry in Greece

The emission of isoprene has been studied from a forest of Abies Borisii-regis, a Mediterranean fir species previously thought to emit only monoterpenes. Emission studies from two independent enclosure experiments indicated a standardised isoprene emission rate of (18.4 +/- 3.8) mug g(dry-weight)(-1), h(-1), similar in magnitude to species such as eucalyptus and oak which are considered to be strong isoprene emitters. Isoprene emission depended strongly on both leaf temperature (2 degreesC-34 degreesC) and photosynthetically active radiation (PAR) below 250 mu mol m(-2)s(-1), becoming saturated with respect to PAR above this value. The annual isoprene emission rate was estimated to be (132 +/- 29) kT yr(-1) for those trees growing within Greece, comparable to current estimates of the total isoprene budget of Greece as a whole, and contributing significantly to regional ozone and carbon monoxide budgets. Monoterpene emission exhibited exponential temperature dependence, with 1,8-cineole, a-pinene, fl-pinene and limonene forming the primary emissions. A standardised total monoterpene emission rate of (2.7 +/- 1.1) mug g(dry-weight)(-1), h(-1) was calculated, corresponding to an annual monoterpene emmission rate of (24 12) kTyr-'. Research was conducted as part of the AEROBIC'97 (AEROsol formation from BIogenic organic Carbon) series of field campaigns. (C) 2001 Elsevier Science Ltd. All rights reserved.