Regional and intercontinental modelling - Air Pollution Modeling and Its Application - page 233

2.30 Experimental Determination of the Partition
Coefficient for Bifunctional Carbonyls in the
Atmosphere and in Smog Chamber
Ricardo Ortiz, Kenji Enya, and Kazuhiko Sakamoto *
Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura,
Saitama 338-8570, Japan
Abstract Bifunctional carbonyls can undergo heterogeneous reactions producing
species with lower vapor pressure and increase their abundance in the particulate
phase. Hence, the predicted aerosol production by these compounds is sometimes
underestimated. Atmospheric concentrations of bifunctional carbonyls in gaseous
and particulate phases during summer from 2003 to 2006 in the Kanto region,
Japan, were measured and their partition coefficients calculated. Additionally smog
chamber experiments of toluene oxidation were carried out and the partition
coefficient of bifunctional carbonyls experimentally determined. Our results showed
that the distribution of these species to the particulate phase is higher in the
atmosphere than in chamber experiments, and these values are higher than those
predicted thermodynamically. In average, the Log K p values measured in the
atmosphere were 3.73 times higher for glyoxal and 12.37 times higher for methyl-
glyoxal than those measured in the smog chamber.
Keywords Bifunctional carbonyls, Field measurements, PFBHA derivatization,
Partition coefficient
1. Introduction
The transformation and dynamics of aerosol particles complicate the description
of the life and fate of particles. Temporal and geographical distribution of acti-
vities and sources in combination with climate and topography influence the
aerosols composition. Organic carbon is a ubiquitous component in the aerosol,
however, its aerosol-phase chemistry is not well understood yet and hence, it is
not included in many atmospheric models (Molina et al., 2004). Partitioning of
semi-volatile organics affect the evolution of organic aerosol, photochemical
reactions generate compounds with lower vapor pressure that will be partially
* Corresponding author: Tel/Fax: [phone]; E-mail: [e-mail]