Seasonal patterns of non-terpenoid C-6-C10VOC emission from seven Mediterranean woody species

The seasonal pattern of non-terpenoid C-6-C-10 VOC emission by seven Medite rranean woody species (Bupleurum fruticosum, Cistus albidus, Pinus halepens is, Arbutus unedo, Erica arborea, Quercus coccifera, and Q. ilex) was studi ed under field conditions. Branch chamber samples were sorbed on carbotrap and analyzed by thermal desorption in combination with GC-MS. These non-ter penoid C-6-C-10 VOC emissions were large, almost of similar magnitude to th ose of terpenes. Overall, maximum values were recorded in spring and summer (up to 12 mug g(-1) DM h(-1) in Q. ilex) and minimum values in autumn and winter (up to 5 mug g(-1) DM h(-1) in Q. ilex). These C-6-C-10 VOC emission s represented 2.82% of the photosynthetic C fixation in summer and 0.22% in winter. Some compounds such as 2-ethoxyethyl acetate were emitted by most species, others such as 3-hexen-1-ol, phenol or decanal were significantly emitted only by few species. The greatest diversity of emitted non-terpenoi d C-6-C-10 VOCs was observed in spring and in Q. ilex. Temperature seemed a strong driver of these seasonal changes but other species-specific and sea sonal factors seem involved. These results indicate that C-6-C-10 non-terpe noid VOCs contribute a rather significant fraction of the total biogenic VO C flux from these Mediterranean species, especially in spring and summer, a nd therefore should be considered in VOC emission inventories and in model predictions of tropospheric chemistry. (C) 2001 Elsevier Science Ltd. All r ights reserved.