A case study of gas-to-particle conversion in an eastern Canadian forest

摘要: Aerosol and trace gas measurements were made at Kejimkujik National Park, Nova Scotia, Canada, during the summer of 1996. A case study from July 7-8 provides evidence nucleation condensation products related to oxidation different biogenic emissions. Particles 5 nm 50 in diameter evolved afternoon early evening associated with variations isoprene. Late α- β-pinene mixing ratios aerosol particle volume increased. Soon after, there was a sharp increase RO 2 H/H O that persisted until about 0100 LT. The initial increases pinenes aerosols strong influenced by changes winds. After 2200 LT, into morning, winds relatively steady, α-and continually decreased. decay α-pinene is explained through reaction 3 . However, addition OH radicals terpenes necessary explain observed rate β-pinene. During same time, increased decrease distributed 40:60 between particles mode centered 80-90 > 150 nm. fine mass concentrations measured inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, calcium) organic (oxalate, formate, acetate, pyruvate, propionate) account for 25-30% total period (2.7 μm cm -3 ) indicating due unidentified species. Assuming result β-pinene, an yield 13% estimated. cloud nuclei active 0.2% supersaturation enhanced appearance pointing least some these forest-generated as being able serve droplets common atmospheric supersaturations.