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IMPROVE Ion Study Plan

IMPROVE Ion Study Plan. Presented by Marc Pitchford to the RPO Technical Groups Dallas, TX 12/3/02. IMPROVE nitrate. IMPROVE nitrate %. Routine IMPROVE sampling/analysis. 4 modules Module B for PM 2.5 ions Carbonate-coated denuder removes acidic gases Nylon filter

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IMPROVE Ion Study Plan

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  1. IMPROVE Ion Study Plan Presented by Marc Pitchford to the RPO Technical Groups Dallas, TX 12/3/02

  2. IMPROVE nitrate

  3. IMPROVE nitrate %

  4. Routine IMPROVE sampling/analysis • 4 modules • Module B for PM2.5 ions • Carbonate-coated denuder removes acidic gases • Nylon filter • Extracted with carbonate/bicarbonate solution (anion IC eluent) for anion analysis – used for a number of years • Extracted with water for anion + cation analysis – used in recent year to remove a sodium interference from IC eluent • Analyzed by IC

  5. Apparent Change in Nitrate Trend Glycerin Added to the Denuder in 1996?

  6. NH4NO3 NH3(g) Sampling and extraction issues • What happens to NH4NO3 volatilized from nylon filters? • HNO3 trapped? Decrease in water extraction efficiency? • NH3 lost? Bias in measured PM2.5 ammonium? • Does water efficiently extract nitrate from nylon filters? • Nitric acid collected on nylon filters is not efficiently recovered with water extraction • Other nitrates efficiently extracted NH3(g) + HNO3 (g)  NH4NO3(p)

  7. IMPROVE ion special study goals • Determine characteristics of ionic aerosol present at selected IMPROVE sites • Ionic composition and size distribution by region & season • Gas-particle distribution of Nitric acid/nitrate & ammonia/ammonium • Evaluate IMPROVE ion sampling and analysis approach • Denuder efficiency • Nitrate volatilization on Teflon filters with/without denuders • Ammonium bias on nylon filters • Filter extraction efficiency

  8. IMPROVE Ion Study Approach • Field Studies • Six 30-day studies • Various denuder/nylon filter/ denuder arrangements • MOUDI sampling for ion size distributions • Laboratory Studies • Denuder efficiency testing for newly coated and used denuders as a function of relative humidity • Filter extraction efficiency testing for samples collected in Ft. Collins, CO & Davis, CA using deionized water & sodium carbonate/sodium bicarbonate solution

  9. IMPROVE ion study field plans • Six 1-month studies • Bondville – February 2004 • San Gorgonio – March/April 2003 & July 2003 • Brigantine – November 2003 • Sequoia – February 2004 • Grand Canyon – May 2004

  10. IMPROVE Network & Ion Study Sites Bondville Brigantine Sequoia Grand Canyon San Gorgonio

  11. IMPROVE ion study field plans • Equipment • 12-hour & 24-hour sampling with various URG denuder/filter pack arrangements using nylon & Teflon filters • 48-hour MOUDI sampling for ion size distributions • Analyses • Major particulate anions (NO3-, Cl-, & SO4=) and cat ions (Na+, K+, NH4+, Ca++, & Mg++) by IC & comparing water versus basic IC extract solution from the filter pack and MOUDI samples • Gaseous ammonia and nitric acid from denuders

  12. Modules 1 and 2 • Daily, 24 hr samples • Compare nylon filter extraction (H2O vs. carbonate/bicarbonate) • Examine loss of HNO3 and NH3 from nylon filter • Provide gas-particle phase distribution for N(-III) and N(V) • Module 3 • Day/night sampling • Replicates for precision • Aerosol acidity/NH4NO3 volatilization on Teflon filters

  13. Recent Preliminary Findings • Nylon filter extraction by water? • EPA study of fall filters collected at numerous STN and IMPROVE sites gave average 90% extraction efficiency • CSU Fort Collins samples (Spring 2002) yielded no evidence of lower water extraction efficiency • Fate of volatilized NH4NO3? • EPA study indicated significant ammonia loss

  14. Possible Additional Monitoring for IMPROVE Ion Study • Particle Into Liquid System (PILS) • High time resolution ion concentrations • During the Yosemite study PILS data showed that the dominate nitrate compound can change quickly between ammonium nitrate and sodium nitrate (produced by nitric acid reacting with sea salt)

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