RELATIVE CONTRIBUTION OF OXYGENATED HYDROCARBONS TO THE TOTAL BIOGENIC VOC EMISSIONS OF SELECTED MID-EUROPEAN AGRICULTURAL AND NATURAL PLANT-SPECIES

Emission rates of more than 50 individual VOCs were determined for eig ht plant species and three different types of grass land typical for n atural deciduous and agricultural vegetation in Austria. In addition t o the emissions of isoprene and monoterpenes, 33 biogenic oxygenated v olatile organic compounds (BOVOCs) were detected. Of these, 2-methyl-1 -propanol, 1-butanol, 2-butanol, 1-pentanol, 3-pentanol, 1-hexanol, 6- methyl-5-hepten-2-one, butanal and ethylhexylacetate were observed for the first time as plant emissions. In terms of prevalence of one of t he groups of emitted VOCs (isoprene, terpenes, BOVOCs) the grain plant s wheat and rye, grape, oilseed rape and the decidous trees hornbeam a nd birch could be classified as ''BOVOC''-emitters. For the grass plot s examined, BOVOCs and terpenes appear to be of equal importance. The emission rates of the total assigned organic plant emissions ranged fr om 0.01 mu gg(-1) h(-1) for wheat to 0.8 mu gg(-1) h(-1) for oak (base d on dry leaf weight). Intercomparison with available data from other studies show that our emission rates are rather at the lower end of re ported ranges. The influence of the stage of growth was examined for r ye, rape (comparing emissions of blossoming and nonblossoming plants) and for grape (with and without fruit). Emission rate differences for different stages of growth varied from nondetectable for blossoming an d nonblossoming rye to a factor of six for the grape with fruits vs gr ape without fruits (emission rate based on dry leaf weight). The major decidous tree in Austria (beech) is a terpene emitter, with the contr ibution of BOVOCs below 5% of the total assigned emissions of 0.2 mu g g(-1) h-(1) for the investigations of 20 degrees C.