Single particle size and fluorescence spectra from emissions of burning materials in a tube furnace to simulate burn pit
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Single particle size and fluorescence spectra from emissions of burning materials in a tube furnace to simulate burn pits Yong-Le Pan • Joshua D. T. Houck • Pamela A. Clark • Ronald G. Pinnick
Received: 19 November 2012 / Accepted: 5 March 2013 / Published online: 25 March 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com
Abstract A single-particle fluorescence spectrometer (SPFS) and an aerodynamic particle sizer were used to measure the fluorescence spectra and particle size distribution from the particulate emissions of 12 different burning materials in a tube furnace to simulate open-air burning of garbage. Although the particulate emissions are likely dominated by particles \1 lm diameter, only the spectra of supermicron particles were measured here. The overall fluorescence spectral profiles exhibit either one or two broad bands peaked around 300–450 nm within the 280–650 nm spectral range, when the particles are illuminated with a 263-nm laser. Different burning materials have different profiles, some of them (cigarette, hair, uniform, paper, and plastics) show small changes during the burning process, and while others (beef, bread, carrot, Styrofoam, and wood) show big variations, which initially exhibit a single UV peak (around 310–340 nm) and a long shoulder in visible, and then gradually evolve into a bimodal spectrum with another visible peak (around 430–450 nm) having increasing intensity during the burning process. These spectral profiles could mainly derive from polycyclic aromatic hydrocarbons with the combinations of tyrosine-like, tryptophan-like, and other humiclike substances. About 68 % of these single-particle fluorescence spectra can be grouped into 10 clustered spectral templates that are derived from the spectra of millions of atmospheric aerosol particles observed in three locations; while the others, particularly these bimodal spectra, do not fall into any of the 10 templates. Therefore, the spectra from particulate emissions of burning materials can be easily discriminated from that of common atmospheric Y.-L. Pan (&) J. D. T. Houck P. A. Clark R. G. Pinnick U.S. Army Research Laboratory, Adelphi, MD 20783, USA e-mail: [email protected]
aerosol particles. The SFFS technology could be a good tool for monitoring burning pit emissions and possibly for distinguishing them from atmospheric aerosol particles.
1 Introduction Open-air burn pits are widely used for disposal of garbage, military waste, and human waste on US military bases in Iraq and Afghanistan. This practice has attracted much attention since hundreds war veterans claimed that they are suffering respiratory problems and believe that burn pit exposure is the major cause for their illnesses [1–3]. Efforts have been taken to mitigate this practice. Congress has passed legislation requiring the military to justify any further use of burn pits, and the Pentagon is conducting a review of burn pits and their current status in Iraq and Afghanistan and has shut down many in Iraq. The
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