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Intercomparison of Near Real-Time Monitors of PM2.5 Nitrate and Sulfate at the U.S. Environmental Protection Agency Atlanta Supersite

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Abstract: Five new instruments for semi-continuous measurements of fine particle (PM2.5) nitrate and sulfate were deployed at the Atlanta Supersite Experiment during an intensive study in August 1999. The instruments measured bulk aerosol chemical composition at rates ranging from every 5 minutes to once per hour. The techniques included a filter sampling system with automated water extraction and on-line ion chromatographic analysis (IC), two systems that directly collected particles into water for IC analysis, and 2 techniques that converted aerosol nitrate or sulfate either catalytically or by flash vaporization to gaseous products that were measured with gas analyzers. During the one-month study 15-minute integrated nitrate concentrations were low ranging from about 0.1 to 3.5 ug m-3 with a mean value of 0.5 ug m-3. Ten-minute integrated sulfate concentrations varied between 0.3 and 40 ug m-3 with a mean of 14 ug m-3. By the end of the one-month study most instruments were in close agreement with r-squared values between instrument pairs typically ranging from 0.7 to 0.94. Based on comparison between individual semi-continuous devices and 24-h integrated filter measurements, most instruments were within 20 to 30% for nitrate (~0.1-0.2 ug m-3) and 10 to 15% for sulfate (1-2 ug m-3). Within 95% confidence intervals, linear regression fits suggest no biases existed between the semi-continuous techniques and the 24-h integrated filter measurements of nitrate and sulfate, however, for nitrate, the semi-continuous intercomparisons showed significantly less variability than intercomparisons amongst the 24-h integrated filters.

The United States Environmental Protection Agency through its Office of Research and Development (funded and managed or partially funded and collaborated in) the research described here under (CR824849) to the Georgia Institute of Technology. It has been subjected to Agency review and approved for publication.
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Citation:Weber, R., D. Orsini, Y. Duan, K. Baumann, C. S. Kiang, W. L. Chameides, Y. N. Lee, F. Brechtel, P. Klotz, P. Jongejan, H. Ten Brink, J. Slanina, C. B. Boring, Z. Genfa, P. Dasgupta, S. Hering, M. Stolzenburg, D. D. Dutcher, E. Edgerton, B. Hartsell, P. A. Solomon, and R. Tanner. Intercomparison of Near Real-Time Monitors of PM2.5 Nitrate and Sulfate at the U.S. Environmental Protection Agency Atlanta Supersite. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108(D7):9-1 to 9-13, (2003).
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Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
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Division: Human Exposure & Atmospheric Sciences Division
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Branch: Human Expsoure Research Branch
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Product Type: Journal
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Published: 01/29/2003
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Downloads:
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Bullet Item Intercomparison of Near Real-Time Monitors of PM2.5 Nitrate and Sulfate at the U.S. Environmental Protection Agency Atlanta Supersite
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Related Entries:
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Bullet Item Heasd PM Research Methods: Particle Methods Evaluation and Development
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