Seasonal variability of 1-chloropyrene on atmospheric particles and photostability in toluene

The occurrence of a mutagenic compound, 1-chloropyrene (Cl-Py), in extracts of ambient particulate matter at an urban site in Japan has been investigated. Samples were collected with a high-volume air sampler for 24 h periods over the course of 1 week in winter (February), spring (May), summer (August), and autumn (November) 2002. The Cl-Py levels showed seasonal variation, ranging from 2.4 pg/m3 (summer) to 18.9 pg/m3 (winter). This variation would indicate that the lower temperatures in winter results in an increased distribution of Cl-Py from vapor phase to the particle phase. In addition, there is also the possibility that ambient Cl-Py is emitted from seasonal sources or is susceptible to photodegradation by sunlight, or both. The photodegradation of Cl-Py in a laboratory experiment was conducted to simulate the compound’s fate on airborne particle surfaces. The degradation of Cl-Py proceeded by a first-order reaction with a rate constant of 0.72 h−1. In the presence of a radical sensitizer, 9,10-anthraquinone (AQ), the photodegradation rate of Cl-Py was elevated in comparison with the rate in the absence of AQ. In addition, the dechlorination of Cl-Py (i.e., the formation of Py) occurred in the presence of AQ.