COMPARISON OF ORGANIC-COMPOUND COMPOSITIONS IN THE EMISSIONS INVENTORY AND AMBIENT DATA FOR THE LOWER FRASER VALLEY

Non-methane organic compound (NMOC) composition in an episode-specific emissions inventory is systematically compared with the average summe r ambient NMOC composition in the Lower Fraser Valley (LFV) of British Columbia, Canada. The comparison is made on the basis of NMOC classes , carbon numbers of species and classes, and individual chemical speci es. The composition of species present in the inventory but not measur ed in the atmosphere is also presented. It is found that the ambient a nd emissions inventory compositions are in reasonable agreement, with a few exceptions. Because of the similarity in the compositions, the e missions profile in the LFV can be used to approximate the ambient NMO C profile in photochemical modeling of the region. A similar validatio n procedure would be required in other regions. Discrepancies exist be tween the emissions inventory and the ambient data for the biogenic co mpounds isoprene, alpha-pinene, and beta-pinene and for some species r elated to light-duty vehicle emissions. The results indicate that more emphasis is needed to analyze ambient air in the areas where biogenic emissions are concentrated. Also, speciation profiles for emissions o f light-duty gasoline vehicles need to be updated as future emissions inventories are developed.