AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Study the Effects of Atmospheric Environmental Conditions on Fluorescence Spectra of Bioaerosols Using a Laboratory Reaction Chamber
YONG-LE PAN, Joshua Santarpia, Shanna Ratnesar-Shumate, Elizabeth Corson, Steven Hill, Mark Coleman, Chatt Williamson, Christopher Bare, Sean Kinahan, Jonathan Eshbaugh, US Army Research Laboratory
Abstract Number: 59 Working Group: Bioaerosols: Characterization and Environmental Impact
Abstract Real-time single bioaerosol particle detection and characterization technologies based on fluorescence spectra, elastic scattering patterns, and Raman spectra will be briefly reviewed. Mainly, the effects of atmospheric environment conditions (humidity, ozone etc) on the properties (size, concentration, viability, fluorescence intensity and spectral profile) of bioaerosols will be presented. Micron sized bioaerosol particles (mode size ~2 um) of Bacillus thuringiensis (Al Hakam) spores, MS2, and an octapeptide that contains one tryptophan and one tyrosine, are generated from their slurry solution and injected into a rotating drum reaction chamber. The chamber rotated at 1 rpm to keep particles aloft for several hours. Bioaerosols are sampled from the chamber hourly for the measurements of particle size distribution, concentration, total fluorescence via 355-nm excitation, and single particle fluorescence spectra via 266-nm and 351-nm excitation under different controlled relative humidity (20%, 50%, or 80%) and ozone concentration (0 or 150 ppb). Bioaerosols are also collected by all-glass impingers (AGI) for the analysis of viability (by culturing) and total (live+dead) organisms of the species generated using q-PCR. The results show the following. 1) Particle size, concentration, and 263-nm-excited fluorescence intensity decrease at different rates under different conditions. 2) 263-nm-excited fluorescence at 280-400 nm decreases faster than that at 400-600 nm. 3) The UV fluorescence peak near 340 nm has blue-shift with time in the chamber. 4) 351-nm-excited fluorescence does not change when ozone is absent, but increase when ozone is present, especially at high humidity. 5) Increases in 351-nm-excited fluorescence that occur with higher ozone concentration and humidity, along with decreases in 263-nm-excited tryptophan emission (more apparent in octapeptide) are consistent with the oxidation of tryptophan by ozone, and (in the presence of high humidities) conversion to kynurenine. Further analysis is in progress and will be presented.
Acknowledgements
This research was supported by the Basic and Supporting Science--program of the Defense Threat Reduction Agency (DTRA) and US Army Research Laboratory (ARL) mission fund.