Size Characterization of Urban Airborne Particles Using Sedimentation/Steric Field-Flow Fractionation (Sd/StFFF)

摘要

This study aims to investigate the applicability of Sd/StFFF and to develop a method for size characterization of urban airborne particles, focusing primarily on particles larger than about 1 mm. It was found that the airborne concentration vary with time, although no particular seasonal trend was observed. When averaged over time, the airborne concentration was the lowest in the park areas with 99 mg/m3. The apartment, industrial, and central city area showed similar levels of the airborne concentrations with 166, 170, and 171 mg/m3, respectively. The housing area showed the highest airborne concentration with 201 mg/m3 among all tested areas. A power-programmed Sd/StFFF was used for size analysis of airborne particles with the initial field strength of 300 rpm, ta = 4, ti = -16, p = 8, and the flow rate of 7 mL/min. It was found that urban airborne samples were mostly populated by particles having diameters between about 5 to 20 mm, although all have broad size distributions ranging up to about 50 mm. Under the Sd/StFFF condition used in this study, no significant differences were found in size distributions among the airborne particles collected at different urban sites, and also among those collected at different times.