Semi-continuous PM 2.5 nitrate and sulfate measurements at the Pittsburgh Air Quality Study Supersite

Ann E. Witttig, Satoshi Takahama, Andrei Y. Khlystov, Spyros N. Pandis, Susanne Hering, Cliff Davidson

Research output: Contribution to journalConference Articlepeer-review


A method for semi-continuous (10 minute time resolution) PM 2.5 nitrate and sulfate measurements, based on the humidified impaction with flash volatilization design of Stolzenburg and Hering, was evaluated during the Pittsburgh Air Quality Study from July 2001 to August 2002.l The semi-continuous measurements were corrected for several operating parameters. The overall corrections were less than 10% on average, but could be quite large for individual 10 minute measurements. These corrections resulted in an improvement in the agreement of the measurements with the filter-based measurements, with a major axis regression relationship of y=0.83x+0.20 μg m -3 and R 2 of 0.84 for nitrate and y=0.71x+0.42 μg m -3 and R2 of 0.83 for sulfate. The corrected semi-continuous measurements were calibrated over the entire year using collocated denuder/filter-pack based measurements. These calibrated semi-continuous measurements are used in conjunction with temporally resolved gas phase measurements of total (gas and aerosol phase) nitrate and meteorological measurements to investigate short-term phenomena at the Pittsburgh Supersite. The gas-to-particle partitioning of nitrate varied daily and seasonally, with a majority of the nitrate in the particle phase at night and during the winter months.

Original languageEnglish (US)
Pages (from-to)279-296
Number of pages18
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


  • Atmospheric Aerosols
  • Continuous Monitors
  • PM Nitrate
  • PM Sulfate

ASJC Scopus subject areas

  • General Engineering


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