Abstract
It is important to get informations on size distribution of air borne particulate matters to investigate their emission sources, transportation process, and behavior in the atmosphere. The Andersen impactor has been generally used as a size selective sampler for this purpose, but the operation of this sampler is not very simple, and is not easy if analysis of all 8 stage samples and a back up filter was required to know a size distribution. This paper presents a simple and economical technique of collection of aerosol particles by the use of two filters in series in an idea to separate sample particles into two groups, fine and coarse particles. Another advantage of this technique is that the particles collected on filters can be directly analyzed without any physical or chemical procedure by X-ray fluorescence method.
Two Nuclepore filters of 47 mm in diameter set up to a commercially available sequential filter holder are placed in series at the pass of air flow for sampling. The coarse fraction (>2 μm) is collected on the first filter (pore size, 8 μm), and the fine fraction (<2 μm) on the second filter (pore size, 0.4 μm) at the air flow rate of 20 l/min. For the evaluation of proper fraction, the Two stage filter sampler was operated simultaneously with a conventional Andersen impactor. No significant difference was observed between results by two samplers. The results demonstrated that the Two stage filter sampler can be usefully applied for the fractionated collection of fine and coarse particles in the atmosphere.
The X-ray fluorescence method was effectively applied for analysis of the samples collected by the present method. Eight elements, Al, Si, S, K, Mn, Fe, Ni, and Zn were determined in each fraction of particles collected by 4 hours sequential sampling using the Two stage filter sampler, at Hiyoshi, Yokohama. Informations on the variation of elemental concentrations of aerosols at short time period could be obtained by the use of the present method.
