A new sampling system of gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs) in ambient air is proposed. The system is composed of a commercially available multi-nozzle cascade impact sampler for collecting particles less than 10 μm and a newlydesigned glass cartridge (35 mm inner diameter) packed with 5.0 g of a styrene-divinylbenzene copolymer resin adsorbent (XAD-2) for collecting gas-phase PAHs at a flow rate of 20 L/min. A rapid sample preparation for the analysis of PAHs in XAD-2 resin by ultrasonic extraction was also studied. The recovery rates of selected PAHs, i.e. phenanthrene (PHEN), antrathene (ANT), fluorantene (FL), pyrene (PY), benzo[a]pyrene (BaP), benzo[k]fluoranthene (BkF), benzo[ghi]perylene (BghiP), and indeno[1,2,3-cd]pyrene (IP) after the pretreatment ranged from 80 to 100%. More than 95% of the PAHs were extracted from XAD-2 by ultrasonication twice for 20 min with dichloromethane. The newlydeveloped cartridge had more than 95% collection efficiencies of the gasphase PAHs (PHEN, ANT, FL and PY) in both the summer and winter seasons. Storage at -30°C for 4 weeks did not have an adverse effect on the gas-phase PAHs collected with the cartridge. The application of the new sampling system to a field observation at a tower with a height of 12 m in a small forest at Field Museum Tama Hills revealed that the concentrations of the gas-phase PAHs at the lower level of the tower were lower than those at the upper level of the tower. However, there were no changes in the concentrations of the particle-phase PAHs between at the upper and lower levels. These results suggested that the forest filter effects for the gas-phase PAHs might be higher than those for the particle-phase PAHs.
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