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 eight plant species and three different types of grass land typical for natural deciduous and agricultural vegetation in Austria. In addition to the emissions of isoprene and monoterpenes, 33 biogenic oxygenated volatile 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 the groups of emitted VOCs (isoprene, terpenes, BOVOCs) the grain plants wheat and rye, grape, oilseed rape and the decidous trees hornbeam and birch could be classified as ''BOVOC''-emitters. For the grass plots examined, BOVOCs and terpenes appear to be of equal importance. The emission rates of the total assigned organic plant emissions ranged from 0.01 mu gg(-1) h(-1) for wheat to 0.8 mu gg(-1) h(-1) for oak (based on dry leaf weight). Intercomparison with available data from other studies show that our emission rates are rather at the lower end of reported ranges. The influence of the stage of growth was examined for rye, 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 and nonblossoming rye to a factor of six for the grape with fruits vs grape without fruits (emission rate based on dry leaf weight). The major decidous tree in Austria (beech) is a terpene emitter, with the contribution of BOVOCs below 5% of the total assigned emissions of 0.2 mu gg(-1) h-(1) for the investigations of 20 degrees C.