Sponsor
This work was supported by EPA Office of Exploratory Research Grant R8l-9305 and by NSF Grant ATM 8615163.
Published In
Journal of the Atmospheric Sciences
Document Type
Article
Publication Date
4-1-1995
Subjects
Air -- Pollution, Hydroxyl group -- Measurement
Abstract
FAGE (fluorescence assay with gas expansion) was developed as a sensitive technique for the detection of low-concentration free radicals in the atmosphere. The application of FAGE to tropospheric hydroxyl (H0) and hydroperoxyl (H0₂) radicals has yielded calibrated measurements of both species in both clean air and highly polluted urban air. For HO calibration, a continuously stirred tank reactor provides a uniform external HO concentration, which can be measured by gas chromatography of an HO-reactive hydrocarbon. The aerodynamics of the air-sampling process has been modeled computationally, with results that agree with empirical observations of the effects of nozzle diameter on HO loss during sampling. The authors have also modeled airborne fluid dynamics of a FAGE probe. They have recently obtained FAGE sensitivity as high as ± 1 × 10⁶ cm-³ for a 6-minute averaging period, during field studies in highly polluted Los Angeles air, yielding a 7:1 signal-to-noise ratio near midday. Multipass excitation can further improve this sensitivity. The authors summarize their recent field studies of HO and HO², current work on improved calibration methods, other improvements, and future plans.
DOI
10.1175/1520-0469(1995)052<3354:FDOTHA>2.0.CO;2
Persistent Identifier
http://archives.pdx.edu/ds/psu/7353
Citation Details
Hard, T. M., L. A. George, R. J. O'Brien (1995). FAGE Determination of Tropospheric HO and H02. J. Atmos. Sci., 52, 3354-3372.
Included in
Environmental Health and Protection Commons, Environmental Indicators and Impact Assessment Commons, Environmental Monitoring Commons
Description
Originally published in Journal of the Atmospheric Sciences (http://journals.ametsoc.org/loi/atsc). Copyright 1995 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS's permission. Republication, systematic reproduction, posting in electronic form, such as on a web site or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/) or from the AMS at 617-227-2425 or copyright@ametsoc.org.