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 PM 2.5 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. Sampling and extraction issues What happens to NH 4 NO 3 volatilized from nylon filters? –HNO 3 trapped? Decrease in water extraction efficiency? –NH 3 lost? Bias in measured PM 2.5 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 NH 4 NO 3 NH 3 (g) NH 3 (g) + HNO 3 (g)  NH 4 NO 3 (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 BondvilleBrigantine Grand Canyon Sequoia 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 (NO 3 -, Cl -, & SO 4 = ) and cat ions (Na +, K +, NH 4 +, 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 HNO 3 and NH 3 from nylon filter Provide gas-particle phase distribution for N(-III) and N(V) Module 3 Day/night sampling Replicates for precision Aerosol acidity/NH 4 NO 3 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 NH 4 NO 3 ? –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)