IMPROVE Sampling & Analysis: Evaluation & Development

Transcription

1 IMPROVE Sampling & Analysis: Evaluation & Development Chuck McDade Crocker Nuclear Laboratory University of California, Davis Okefenokee, Georgia October 2008

2 AEROSOL GENERATION CHAMBER

3 Selected Species Samples, Known Concentration XRF benchmark independent of Micromatter standards (builds upon our recent purchase of multiple Micromatter standards) Choose single or multiple species to avoid interferences or to simulate known interferences Samples are prepared on IMPROVE filters using an IMPROVE sampler

4 Aerosol Generation System SAMPLER Dilution Air IMPROVE PM2.5 Module Atomizer Particle Dryer Mixing Chamber RH Monitor Analyte Solution Dilution Air Dryer

5 Atomizer & Sampler SAMPLER ATOMIZER

6 Sulfur by IC and Gravimetric Mass

7 Upcoming Work Characterize the atomizer (compare to TSI) Prepare samples using compounds other than ammonium sulfate (KCl is next) Assess possible handling artifacts that may affect weighing, such as gain or loss of water Verify expected molar ratios (from IC analysis) Assess sample homogeneity using SEM

8 CRUSTAL ELEMENT SAMPLING

9 FM has been erratic in collocated measurements at Phoenix

10 The differences appear episodically and can remain for several months Z = 2 2 ( CONC CONC ) UNC collo + UNC routine collo routine

11 Deviations observed in the Phoenix A module, principally with crustal elements

12 Further evidence of crustal element intrusion

13 Tests underway to limit the influence of coarse particles PM-10 inlet preceding the PM-2.5 cyclone in the A module At Phoenix (both samplers) At the UC Davis rooftop test site In a new dust resuspension chamber

14 CARBON SAMPLING AND ANALYSIS

15 A Sunset Labs carbon analyzer in Davis allows timely sample analysis

16 The Sunset Labs analyzer was calibrated to mimic IMPROVE

17 A thermocouple measured the temperature at the filter

18 How might heat affect carbon samples prior to analysis? 12 parallel samples were collected for each sampling event A B Filter #1 Filter #3 Filter #2 Heated 24h Heated 48h Heated 96h Immediately Analyzed Samples were maintained at 40º C

19 Greatest loss of material occurs during first 24 hours of heating ~40 to 60% of OC1 lost in 24 hours

20 In fact, much OC1 is lost during the first 6 to 12 hours ~30 to 40% lost in 12 hours

21 Most of the losses occur in OC1 and OC2

22 Effects of 96 hour heating on TOC ~10 to 20% lost in 96 hours

23 Effects of 96 hour heating on TC ~5 to 15% lost in 96 hours

24 CARBON ARTIFACT TESTING

25 Four PM 2.5 IMPROVE Modules Cyclone Quartz Quartz Teflon A C B XAD denuder Cyclone Quartz One cassette in each module will have Q and Q (XAD) field blanks XAD denuder Quartz (XAD) Cyclone Quartz Quartz (XAD) Teflon Cyclone Quartz Quartz (XAD) D

26 Configuration A Current IMPROVE Method Cyclone A Qtz Primary Qtz - Secondary IMPROVE sampling method Use daily Secondary to correct daily Primary (not monthly medians) Particulate OC = Primary - Secondary

27 Configuration B Denuded OC (no gases) Denuder removes gas phase Quartz = particulate OC + denuder breakthrough Quartz (XAD) = volatilized OC (negative artifact) + denuder breakthrough B XAD denuder Cyclone Quartz Quartz (XAD)

28 Configuration C Denuder Breakthrough C Teflon XAD denuder Cyclone Quartz Quartz (XAD) Teflon removes particles Quartz = gas phase denuder breakthrough Quartz (XAD) = highly sorptive filter for additional gas phase breakthrough denuder breakthrough= Quartz + Quartz (XAD)

29 Configuration D Undenuded to Determine Denuder Efficiency (compare to config C) Teflon D Cyclone Quartz Quartz (XAD) Teflon removes particles Quartz + Quartz (XAD) = Total Gases ESTIMATE of Denuder Efficiency = 1 denuder breakthrough/total gases 1 config C/config D

30 Best Estimate of Particulate OC If denuder 100% efficient POC = collected particles + negative artifact POC determined from Config B (denuded) If denuder < 100% efficient (real world) POC = collected particles + negative artifact denuder breakthrough POC determined from Config B Config C

31 Upcoming Work Sampling conducted this summer, to continue in Analyses will be conducted on the Sunset Labs analyzer at UC Davis Work to be completed by Fall 2009 Results will illuminate biases in our current sampling approach

32 CALIFORNIA FIRES SUMMER 2008

33 A View of Northern California on June 25, 2008 We sampled for 40 days at Davis in June and July 2008

34 8 hour samples minimized clogging & tracked wind shifts

35 Same site on a clearer day

36 Some samples were very dark

37 PM-2.5 mass was very high during some fire episodes

38 Upcoming work on fire samples Review 15-minute flowrate data to better understand sampler behavior in thick smoke Analyze filters for elements (XRF), ions (IC), and carbon (TOR) Assess sources of the haze

39 A BRIGHT FUTURE

40 Warren & the IMPROVE Elves