A QUALITATIVE ASSESSMENT OF THE EMISSION OF NONMETHANE HYDROCARBON COMPOUNDS FROM THE BIOSPHERE TO THE ATMOSPHERE IN THE UK - PRESENT KNOWLEDGE AND UNCERTAINTIES

The potential emission of the reactive non-methane hydrocarbons (NMHC), isoprene and the monoterpenes, have been qualitatively assessed for the most abundant tree, crop and plant species in the U.K. Most coniferous trees, some deciduous trees, and a few herbaceous, grass and crop species emit one or more of these compounds. Factors likely to influence NMHC emissions from vegetation are reviewed as are current literature estimates of their emission rates for the U.K. These estimates are considered to be very uncertain at the present time, but may lie in the range 50-100 kt yr-1, with emissions of monoterpenes dominating those of isoprene. Assessment is made of the likely causes of uncertainty.