Secondary organic aerosol production from terpene ozonolysis. 2. Effect of NOx concentration.
We report secondary organic aerosol (SOA) yields from the ozonolysis of alpha-pinene in the presence of NO and NO2. Experimental conditions are characterized by the [VOC]0/ [NOx]0 ratio (ppbC/ppb), which varies from approximately 1 to approximately 300. SOA yield is constant for [VOC]0/[NOx]0 > approximately 15 and decreases dramatically (by more than a factor of 4) as [VOC]0/[NOx]0 decreases. Aerosol production is completely suppressed in the presence of NO for [VOC]0/[NOx]0 < or = 4.5. Fouriertransform IR analysis of filter samples reveals that nitrate-containing species contribute significantly to the total aerosol mass at low [VOC]0/[NOx]0. Yield reduction is a result of the formation of a more volatile product distribution as [VOC]0/[NOx]0 decreases; we propose that the change in the product distribution is driven by changes in the gas-phase chemistry as NOx concentration increases. We also present two-product model parameters to describe aerosol production from the alpha-pinene/0/NOx system under both high- and low-NOx conditions.
Presto
Albert A
AA
Department of Chemistry and Department of Chemical Engineering, Doherty Hall, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Hartz
Kara E Huff
KE
Donahue
Neil M
NM
D000336:Aerosols / Q000032:analysis; D000393:Air Pollutants / Q000032:analysis; D001272:Atmosphere; D000081008:Bicyclic Monoterpenes; D005740:Gases; D006838:Hydrocarbons; D008956:Models, Chemical; D015233:Models, Statistical; D039821:Monoterpenes / Q000032:analysis; D009569:Nitric Oxide / Q000032:analysis*; D009585:Nitrogen Dioxide / Q000032:analysis*; D009589:Nitrogen Oxides / Q000032:analysis*; D009930:Organic Chemicals / Q000032:analysis*; D010083:Oxidants, Photochemical / Q000032:analysis; D010126:Ozone / Q000032:analysis*; D010316:Particle Size; D017550:Spectroscopy, Fourier Transform Infrared; D013729:Terpenes / Q000737:chemistry*
D000336:Aerosols; D000393:Air Pollutants; D000081008:Bicyclic Monoterpenes; D005740:Gases; D006838:Hydrocarbons; D039821:Monoterpenes; D009589:Nitrogen Oxides; D009930:Organic Chemicals; D010083:Oxidants, Photochemical; D013729:Terpenes; D009569:Nitric Oxide; D010126:Ozone; C005451:alpha-pinene; D009585:Nitrogen Dioxide