Continuous observations of PM 2.5 speciation at a rural Illinois site

Allen L. Williams, Michael Caughey, David A. Gay, Clyde Sweet

Research output: Contribution to journalConference articlepeer-review


Continuous measurements of ammonium, sulfate, and nitrate in PM 2.5 aerosol are reported for a 4-month summer period at an established background aerosol monitoring site in central Illinois. Diurnal averages of the aerosol speciation indicate that during the nighttime the inorganic constituents of the aerosol are predominantly a mixture of ammonium sulfate and ammonium nitrate. During the daylight hours the ammonium nitrate decreases, leaving ammonium sulfate as the primary inorganic constituent. The ammonium/sulfate/nitrate ionic charge balance in the aerosol is also analyzed from the standpoint of wind direction. The diurnal average inorganic aerosol mass loading is approximately twice as large when the winds at this central Illinois site are from a general southerly direction compared with a general northerly direction. The aerosol has higher proportions of sulfate for southerly winds, and higher proportions of nitrate for northerly winds.

Original languageEnglish (US)
Pages (from-to)1991-2000
Number of pages10
JournalProceedings of the Air and Waste Management Association's Annual Meeting and Exhibition
StatePublished - 2004
Externally publishedYes
EventProceedings of the A and WMA's 97th Annual Conference and Exhibition; Sustainable Development: Gearing Up for the Challenge - Indianapolis, IN, United States
Duration: Jun 22 2004Jun 25 2004

ASJC Scopus subject areas

  • General Engineering


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