Chlorinated polycyclic aromatic hydrocarbons in the atmosphere: seasonal levels, gas-particle partitioning, and origin.

Ambient concentrations of 26 chlorinated polycyclic aromatic hydrocarbons (CIPAHs) with 2- to 5-rings were investigated in a Japanese urban city from December 2004 to December 2005. All the targeted CIPAHs were detected in either the gaseous or particulate phase. During the study, the ambient (gaseous + particulate) concentration of total CIPAH ranged from 18 to 330 pg m(-3). The concentrations of gaseous CIPAHs tended to be 2 approximately 100 times higher than those of particulate CIPAHs. A seasonal variability of both gaseous and particulate CIPAH concentrations was observed, with higher concentrations in winter than in summer. A compositional analysis also showed a characteristic trend: relatively low molecular weight CIPAHs dominated in warmer seasons, and high molecular weight CIPAHs dominated in colder seasons. For some CIPAHs, temperature dependence of gas-phase concentrations was statistically significant (p < 0.05), and temperature accounted for 27-63% of the variability in their concentrations. The natural logarithm of total concentrations of particulate CIPAHs were significantly correlated (p < 0.05) with the reciprocal mean temperatures, but not for gaseous CIPAHs, suggesting that there are differences of the sources and ambient fates between gaseous and particulate CIPAHs. Back trajectory analyses suggested that air masses, originating from China, were associated with the highest CIPAH concentrations.

Simultaneous determination of gaseous and particulate chlorinated polycyclic aromatic hydrocarbons in emissions from the scorching of polyvinylidene chloride film.

An analytical method for the determination of gaseous and particulate chlorinated polycyclic aromatic hydrocarbons (ClPAHs) was investigated. By means of this method, concentrations and isomer profiles of the 27 target ClPAHs could be analyzed. To evaluate the usefulness of the method for analyzing ClPAH emissions, laboratory-scale scorching tests were performed on polyvinylidene chloride (PVDC) plastic wrap over a flame of the gas burner. Only seven of the target ClPAHs were detected, and all compounds detected had 2, 3, or 4 rings. The detected ClPAHs were present in both the particulate phase and the gaseous phase, but they were present at higher concentrations in the gaseous phase than in the particulate phase. Relationships between the number of chlorine substituents on the naphthalene/phenanthrene rings and the overall concentration and the percentage in the particulate phase were also investigated.

Fabrication and properties of fullerodendron thin films.

Thin films of fullerodendron (C(60)(Gn-COOMe) (n = 0.5, 1.5, 2.5)), which was synthesized from fullerene and anthracenyl poly(amido amine) dendron with methyl ester terminals and different generations (G), were fabricated by the Langmuir-Blodgett (LB) and adsorption techniques. It was characterized by X-ray reflectometry that the LB films possessed well-ordered structure, although the adsorption method led to random orientation of molecules. As to C(60)(G0.5-COOMe) and C(60)(G1.5-COOMe), the LB films took a four-layer structure consisting of a double layer of molecules, and fullerene moieties exist in the interior of the LB films. On the other hand, C(60)(G2.5-COOMe) led to a two-layer structure in which the fullerene moieties were at the air side and the dendron moieties were at the substrate side. With increasing generation of dendron, the monolayer formation ability at the air/water interface as amphiphilic molecule strengthens and the amphiphilic property becomes superior to the fullerene-fullerene attractive interaction that prevents the monolayer formation. Furthermore, in the case of C(60)(G0.5-COOMe) and C(60)(G1.5-COOMe), the reduction peak in cyclic voltammetry of the LB film remained even after UV light irradiation. On the contrary, the peak of the C(60)(G2.5-COOMe) LB film disappeared, indicating that molecular arrangement in the films affects electrochemical properties.