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[AAS11-P09] Observation of bio-aerosol concentration by filter sampling and fluorescence spectra measurement
Keywords:Bioaerosol, Measurement technology, fluorescence
Bioaerosols (BAs), which are primary organic aerosol particles released from the biosphere into the atmosphere, have been recognized as significant ice nuclei at relatively high temperatures. Fungal spores are also important as a carrier for re-suspension of radioactive cesium. In order to understand these effects, it is necessary to establish an observation method for quantifying BA of each category (bacteria, fungal spores, pollen, etc.).
A fluorescent aerosol counter such as WIBS are used to measure BA concentration, but it is uncertain whether it can separately measure various category BA particles or not. Because it is so expensive, multipoint observation and/or long-term observation are difficult with the fluorescent aerosol counter. In this research, we have developed a BA filter sampler that enables multipoint measurement easily and a system that quantifies each category BA by measuring the detailed fluorescence spectrum of BA collected by the filter.
Developed BA filter sampler is a kind of low volume air sampler, which consists of a Teflon membrane filter, a MFC, pressure sensor, and the microcomputer (Raspberry Pi) which is used for control and flow rate recording. At the specified timing. aerosols can be sampled simultaneously on multiple filters. The filter that collects the aerosol is brought back to the laboratory, and the fluorescence spectrum is measured with a spectrometer. The excitation light of four different wavelengths is alternately irradiated using UV-LED.
For establishing this observation method, fluorescence spectra of multiple kinds of particles of pollen, basidiomycete spores, ascomycete spores, bacteria, and soil particles on a filter were measured to confirm that there was a significant difference between them. In addition, the particle density on the filter samples was measured by observation with a fluorescence microscope to determine the proportionality coefficient with the fluorescence spectrum intensity. These studies performed that it possible to quantify the BA concentration in each category from the fluorescence spectral intensity of the filter sample obtained by sampling the atmospheric aerosols.
A fluorescent aerosol counter such as WIBS are used to measure BA concentration, but it is uncertain whether it can separately measure various category BA particles or not. Because it is so expensive, multipoint observation and/or long-term observation are difficult with the fluorescent aerosol counter. In this research, we have developed a BA filter sampler that enables multipoint measurement easily and a system that quantifies each category BA by measuring the detailed fluorescence spectrum of BA collected by the filter.
Developed BA filter sampler is a kind of low volume air sampler, which consists of a Teflon membrane filter, a MFC, pressure sensor, and the microcomputer (Raspberry Pi) which is used for control and flow rate recording. At the specified timing. aerosols can be sampled simultaneously on multiple filters. The filter that collects the aerosol is brought back to the laboratory, and the fluorescence spectrum is measured with a spectrometer. The excitation light of four different wavelengths is alternately irradiated using UV-LED.
For establishing this observation method, fluorescence spectra of multiple kinds of particles of pollen, basidiomycete spores, ascomycete spores, bacteria, and soil particles on a filter were measured to confirm that there was a significant difference between them. In addition, the particle density on the filter samples was measured by observation with a fluorescence microscope to determine the proportionality coefficient with the fluorescence spectrum intensity. These studies performed that it possible to quantify the BA concentration in each category from the fluorescence spectral intensity of the filter sample obtained by sampling the atmospheric aerosols.