Partitioning model of PAHs between gaseous and particulate phases with consideration of reactivity of PAHs in an urban atmosphere

Abstract

The reactivity of PAH substances in urban atmosphere and its influence on the partitioning models between gaseous and particulate phases for semi‐volatile PAHs were investigated in this study. A new sampling experiment for gaseous and particulate PAHs during day, night and whole day (24 hours) time periods was conducted at a monitoring station in downtown Taipei in 1991. The reactivity of PAH substances was determined by the characteristic ratio, reactive PAH / non‐reactive PAH and the order of reactivity are as follows, Benzo(a)anthracene > Phenathrene + Anthracene > Acenaphthene > Chrysene > Pyrene > Naphthalene > Fluoranthene > Fluorene. On the other hand, the partitioning models for day, night, and whole day for semi‐volatile PAHs, Fluoranthene, Pyrene, Chrysene, and Benzo(a)anthracene, were evaluated. It is indicated that higher coefficients of determination (r²) of the regression analysis between the partitioning term and inverse of temperature were obtained for day or night models compared to whole day model for Pyrene and Benzo(a)anthracene particularly for Benzo(a)anthracene, which is the most reactive substance investigated in this study. In contrast, no significant difference between model for day or night and whole day was found for Fluoranthene. Thus, the performance of partitioning models for semi‐volatile PAHs in atmosphere is influenced by the reactivity of PAHs. The influence is more profound for reactive PAHs. It is shown that general model developed from continuous 24 hours sampling may be reasonable for less reactive PAHs, but separate models for day and night models will be needed for reactive PAHs.

Key words:

• PAHs
• reactivity
• partitioning model
• TSP