Semi-Continuous Measurement of Particulate Matter Sulfate and Nitrate Jay R. Turner Environmental Engineering Program Department of Chemical Engineering Department of Civil Engineering Washington University in St. Louis EMEP Particulate Matter Measurement and Modeling Workshop New Orleans, LA / USA April 20-23, 2004

Today’s Presentation Examples of sulfate and nitrate dynamics on the subdaily time scale… added value from semicontinuous measurements Instrumentation... ready for routine deployments? Reflect upon several of the leading questions… not exhaustive in light of yesterday’s discussions

1 23 Weather Systems air mass back trajectories (NOAA/HYSPLIT) Fine Particulate Matter Sulfate & Air Mass Back Trajectories PM-2.5 Sulfate in St. Louis

Movable Platform Deployment in Reserve, KS: Sulfate Events 8/28/02, 1200 CST9/1/02, 0000 CST Comparison to NRL model…

Baltimore, 2002; Ondov and coworkers

Bkgnd, 6 µg/m 3 Background

Baltimore, 2002; Ondov and coworkers Bkgnd, 6 µg/m 3 Aged Local, ~ 18 µg/m 3 A Stagnation

Baltimore, 2002; Ondov and coworkers Bkgnd, 6 µg/m 3 Inter-regional transport, ~ 25 µg/m 3 Regional Transport

Baltimore, 2002; Ondov and coworkers Bkgnd, 6 µg/m 3 Inter-regional transport, ~ 25 µg/m 3 Local Power Plants, ~ 13 µg/m 3 plume arrives 1.5 hrs after local winds shift to 170 o at 3m/s = 16.2 km… coincident with local power plant at same angle and distance local power plant 15 km plumes raise sulfate concentration  13 µg/m 3

Baltimore, 2002; Ondov and coworkers Bkgnd, 6 µg/m 3 Event Done

Baltimore, 2002; Ondov and coworkers

Selected Opportunities  Daily coverage (e.g., daily averages from hourly data)  Probe diurnal patterns (define mean diurnal patterns and deviations from such mean behavior) Rapid assessments of relative role of atmospheric ventilation  Robust data sets for model development and testing (often need additional parameters)… Diagnose problems in model/measurements comparisons Daily-average comparisons may be reasonable but the subdaily behavior might be inadequately captured  Can often explain dynamics in the fine mass concentration, visibility by considering sulfate and/or nitrate  Daily metrics beyond the daily-average (e.g., 1-hour maximum, maximum 8-hour rolling average)  In some cases, certain types of artifacts may be suppressed

Concentration (  g m -3 ) Simultaneous Measurement of Gas- and Particle-Phase Nitrate Pittsburgh, 2001; Wittig, et al. (2004) Atmos. Environ.

Measurement Methods Several research and commercial grade instruments, including but not limited to… R&P 8400N and 8400S Steam- and related-systems (ten Brink, Weber, Dasgupta) Harvard School of Public Health (sulfate, nitrate) Thermo Electron is commercializing the sulfate unit Aerosol Mass Spectrometer (Aerodyne) Edgerton/ARA “fertilizer” (nitrate and related species) [single particle mass spectrometers] Variants can get size-dependent concentrations (e.g., Aerosol Dynamics cascaded flash volatilization nitrate) Poster session… Olga Hogrefe will present sulfate and nitrate climatology and instrument performance metrics (emphasis on R&P 8400N, 8400S)

Collocated R&P 8400N, St. Louis hourly-average data, 1/12/04 - 2/26/04

Semicontinuous Aerosol Nitrate (NO 3 - ) Aerosol Nitrate - Collocated R&P 8400N Nitrate Units R&P 8400N Nitrate versus HEADS (filter) Nitrate March - May Hour-Integrated HEADS Nitrate,  g/m 3 24-Hour-Average R&P Nitrate,  g/m 3

Brief Summary of the STL Experience Particle-into-Liquid Sampler (PILS) showed very good agreement with filter sulfate (daily-average, 6-hour average) Harvard School of Public Health sulfate Evolution of design improvements, can get nearly 100% recovery compared to filter sulfate and excellent agreement with PILS at hourly resolution Currently beta-testing the Thermo Electron version… very good agreement with PILS and filters based on one month of operation, appears to be field robust… need longer field operations experience, still steps from beta version to engineered product Recently deployed an R&P 8400S… [See Olga’s poster for New York Supersite experience with R&P 8400S]

Brief Summary of the STL Experience (con’t) Particle-into-Liquid Sampler (PILS) showed very good agreement with filter nitrate (daily-average, 6-hour average) Thermal (flash) volatilization methods R&P 8400N, Aerosol Dynamics prototype to the 8400N, Harvard School of Public Health thermal method All are low (~10-60%) compared to filter nitrate Instrument-dependent differences? Aerosol / environment-dependent differences? We are currently working to sort out these issues Not (quite) ready for routine deployments… Field robustness questionable (can even be taxing for research teams conducting sustained measurements) Instrument/site – dependent differences

Summary Semicontinuous measurement of particulate matter sulfate and nitrate provides valuable insights into aerosol climatology and can be used for model validation Often need additional contemporaneous measurements to elucidate the governing dynamics A suite of research grade instruments are available and with proper care robust measurements can be made Cautiously optimistic that commercial instruments will soon be available for routine deployments