A Passive Sampler with Improved Performance for Collecting Gaseous and Particulate Phase Polycyclic Aromatic Hydrocarbons in Air

Abstract

A passive sampler which can be used to collect both gaseous and particulate phase polycyclic aromatic hydrocarbons (PAHs) in air was previously developed and calibrated. The sampler was successfully used in a field study in North China Plain. However, the relatively low uptake rate for particulate phase PAHs prevented it from being applied in nonseverely contaminated environment. The sampler was redesigned to increase the uptake rate for particulate phase PAHs and calibrated in the field for individual PAH compounds of various molecular sizes. The effect of a fine-screen-mesh wrapping on the performance of the sampler was tested. It was found that the sampling efficiencies of the sampler for various PAH compounds were different depending on their molecular weights. For particulate phase PAHs, the uptake rates for high molecular weight compounds, which are favorably associated with fine particles, were generally lower than those for low molecular weight ones. Two calibration equations with molecular weight as an independent variable were developed to predictthe ambient air concentrations of gaseous and particulate phase PAHs based on the results of the passive sampling. The uptake rates of the sampler were different for various PAH compounds. On average, the uptake rates of the sampler for gaseous and particulate phase PAHs were 0.38 +/- 0.51 m3/d and 0.61 +/- 1.41 m3/d, respectively. The latter was 2 orders of magnitude higher than the old model. The sampler was less efficient than active sampler for collecting fine particles in the air and such bias in sampled size distribution can be moderated by a fine-screen-mesh wrapping. However, the wrapping could also reduce the sampling efficiency.