Seasonal and particle size-dependent variations in gas/particle partitioning of PCDD/Fs

Abstract

This study monitored particle size-dependent variations in atmospheric polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Two gas/particle partitioning models, the subcooled liquid vapor pressure (P-L(0)) and the octanol-air partition coefficient (KOA) model, were applied to each particle sizes. The regression coefficients of each fraction against the gas/particle partition coefficient (K-P) were similar for separated particles within the same sample set but differed for particles collected during different periods. Gas/particle partitioning calculated from the integral of fractions was similar to that of size-segregated particles and previously measured bulk values. Despite the different behaviors and production mechanisms of atmospheric particles of different sizes, PCDD/F partitioning of each size range was controlled by meteorological conditions such as atmospheric temperature, O-3 and UV, which reflects no Source related with certain particle size ranges but mixed urban Sources within this city. Out-observations emphasize that when assessing environmental and health effects, the movement of PCDD/Fs in air should be considered in conjunction with particle size in addition to the bulk aerosol. (c) 2007 Elsevier Ltd. All rights reserved.