MEASUREMENT OF BIOGENIC HYDROCARBON EMISSIONS FROM VEGETATION IN THE LOWER FRASER VALLEY, BRITISH-COLUMBIA

Biogenic volatile organic compounds (VOCs) participate in many chemica l reactions in the atmosphere and in some cases, adversely affect air quality through increased production of photochemical ozone near urban sources of nitrogen oxides. Tn order to implement an effective contro l strategy, the relative role of these biogenic hydrocarbon emissions in producing ground-level ozone must be known. During the summers of 1 995 and 1996, a field study was undertaken to determine fluxes of biog enic VOCs from both natural and agricultural surfaces in the Lower Fra ser Valley located in southwestern British Columbia. Emissions from ag ricultural surfaces were measured using a flux gradient approach while emissions from the dominant tree species in the region were measured with a branch enclosure system. Results show very little biogenic VOC production from many agricultural crops such as pasture, Potatoes or B lueberries. Cranberries showed very high emissions during the summer o f 1994 but failed to show similar results during the summer of 1995. E missions of isoprene and monoterpenes from native tree species such as Western Red Cedar, Douglas Fir and Coastal Hemlock were quite low. Co ttonwood trees on the other hand had fairly low emissions of monoterpe nes but extremely high emissions of isoprene. Measurements provided he re will be useful for improving our database of hydrocarbon emissions rates from vegetation for future emission inventories and model testin g. (C) 1998 Elsevier Science Ltd. All rights reserved.