Semi-Continuous Measurement of Particulate Matter Sulfate and Nitrate

1. 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

2. 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

3. PM-2.5 Sulfate in St. Louis 1 2 3 air mass back trajectories (NOAA/HYSPLIT) 1 2 3 Weather Systems Fine Particulate Matter Sulfate & Air Mass Back Trajectories

4. 8/28/02, 1200 CST 9/1/02, 0000 CST Movable Platform Deployment in Reserve, KS: Sulfate Events Comparison to NRL model…

5. Baltimore, 2002; Ondov and coworkers

6. Baltimore, 2002; Ondov and coworkers Background Bkgnd, 6 µg/m3

7. Baltimore, 2002; Ondov and coworkers A Stagnation Aged Local, ~ 18 µg/m3 Bkgnd, 6 µg/m3

8. Baltimore, 2002; Ondov and coworkers Regional Transport Inter-regional transport, ~ 25 µg/m3 Bkgnd, 6 µg/m3

9. Baltimore, 2002; Ondov and coworkers Local Power Plants, ~ 13 µg/m3 Inter-regional transport, ~ 25 µg/m3 Bkgnd, 6 µg/m3 • plume arrives 1.5 hrs after local winds shift to 170o 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/m3

10. Baltimore, 2002; Ondov and coworkers Event Done Bkgnd, 6 µg/m3

11. Baltimore, 2002; Ondov and coworkers

12. 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

13. Simultaneous Measurement of Gas- and Particle-Phase NitratePittsburgh, 2001; Wittig, et al. (2004) Atmos. Environ. Concentration (mg m-3)

14. 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)

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

16. Aerosol Nitrate - Collocated R&P 8400N Nitrate Units R&P 8400N Nitrate versus HEADS (filter) NitrateMarch - May 2002 Semicontinuous Aerosol Nitrate (NO3-) 24-Hour-Average R&P Nitrate, mg/m3 24-Hour-Integrated HEADS Nitrate, mg/m3

17. 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]

18. 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

19. 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