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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

IMPROVE Ion Study Plan

Presented by Marc Pitchford to the

RPO Technical Groups

Dallas, TX 12/3/02

routine improve sampling analysis
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
sampling and extraction issues



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)

improve ion special study goals
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
improve ion study approach
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
improve ion study field plans
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
improve network ion study sites
IMPROVE Network & Ion Study Sites




Grand Canyon

San Gorgonio

improve ion study field plans1
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

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
recent preliminary findings
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
possible additional monitoring for improve ion study
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)