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CSN Timeline

Overview of CSN Data Relevant to OC/EC Artifact Adjustments presented by James Flanagan RTI International Davis, CA January 22-23, 2008. Assignment: “Review of current artifact adjustment approach for CSN, including sampler-specific variations”.

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CSN Timeline

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  1. Overview of CSN Data Relevant to OC/EC Artifact Adjustmentspresented byJames FlanaganRTI InternationalDavis, CAJanuary 22-23, 2008

  2. Assignment: “Review of current artifact adjustment approach for CSN, including sampler-specific variations” • There is no artifact adjusted data currently being posted to AQS for any CSN species, therefore this presentation will focus on: • Blank data available that could be used for artifact adjustments: • Original CSN samplers and analysis • New 3000N samplers and analysis • CSN program timeline • CSN sampler types • Blank level differences between sampler types • Lab blanks and other QC data

  3. CSN Timeline 2/9/2000 – 7/7/2003 OC, EC analyses done by RTI International Laboratory using Sunset Labs Instruments No OC or EC fractions (“peaks”) reported “OCX” or “OCX2” were reported during this period 7/8/2003 – present OC, EC analyses for CSN samplers done by RTI International Laboratory. 4 OC fractions (plus Pyrolysis C) are reported; no OCX or OCX2. no EC fractions reported. -- Initial Set of 55 3000N Samplers Added to CSN in May, 2007 -- 5/2007 – present 3000N filters are being analyzed by Desert Research Inst. (DRI). 3000N samplers are collocated with the existing CSN samplers at each site, and are run collocated for 2 months 4 OC, Pyrolysis C, and 3 EC fractions, plus OC and EC by TOT and TOR are being uploaded to AQS without artifact correction.

  4. CSN: “STN” TOT Analysis Method • Filter: 47mm Whatman quartz w/ 5% borosilicate binder • Filters pre-fired at 900oC in air • Sunset Lab Carbon Aerosol Analyzers • Protocol: NIOSH 5040, optimized for PM2.5 • Time-driven analysis (12 min total) • Thermal-Optical Transmittance (TOT)

  5. CSN Sampler Types • URG MASS – Wins Impactor; Teflon module • Andersen RAAS - cyclone; Teflon coated module • MetOne SASS – mini-cyclone; alloy module • other types: • R&P 2300 – internal greased impactor; alloy module • R&P sequential FRM

  6. CSN Sampler Module Types URG MASS Andersen RAAS Cassette used for IMPROVE and 3000N Samplers MetOne SASS R&P 2300

  7. CSN: Field and Trip Blanks(reported to AQS) • Field Blanks are collected at 10% of routine frequency (monthly or bimonthly at each site) – filter modules mounted for a short period of time and removed. • Trip Blanks are collected at 3% of rout. freq. – filter modules not removed from shipping bag. • Field and Trip Blank results are very similar. • Field/Trip Blank levels differ significantly between sampler types.

  8. CSN: Field/Trip Blank Averages(Original OC/EC Analyses) Trip and Field Blank averages 2000 – 2006, ug/filter * * R&P module contains silicone impactor grease, which may appear as EC. • 47 mm Whatman filter with borosilicate binder. • CSN (STN) analysis protocol. • Each number is 100’s or 1000’s of measurements. Source: Max R. Peterson, James B. Flanagan, Larry C. Michael, and R.K.M. Jayanty. 2007. Analysis of PM2.5 Speciation Network Carbon Blank Data. AAAR 26th Annual Conference, Reno, NV, September 24-28.

  9. CSN: Laboratory QC Data for Original OC/EC Analyses(not reported to AQS) • Analyses are performed by RTI International’s OC/EC Laboratory in North Carolina using Sunset Labs Instruments. • Acceptance Blanks — full STN analysis of the larger of 2 or 2% of pre-fired filters. • Instrument Blanks — full STN analysis using a clean filter punch, usually from the preceding analysis. • Duplicate Analyses —10% of filter samples reanalyzed on the same analyzer to test uniformity of filter deposit. • Replicate Analyses — a group of filters analyzed on 3 or more analyzers to assess between-analyzer variability and to establish measurement uncertainties.

  10. CSN: Laboratory QC Data Received for OC/EC 3000N(not reported to AQS) • Analyses are being done by Desert Research Institute (DRI) in Reno, NV. • System Blanks — Full IMPROVE_A analysis without a filter punch. • Replicate Analyses — Analysis of a second punch from 10% of filter samples on a randomly-chosen (different or same) analyzer used to evaluate between-analyzer variability. • DRI performs additional QC not reported to RTI.

  11. CSN: Available Blank Types with 3000N Sampler Protocol(blank data reported to AQS) • Afterfilters – identical to IMPROVE NEW to CSN • IMPROVE-type “field blanks” (passive blank in 4th position of cassette) NEW to CSN • Field Blanks (like existing CSN Trip and Field Blanks)

  12. Afterfilters – Frequency and Availability of Data for Statistics • Since May, 2007, CSN runs afterfilters at all sites equipped with 3000N at a rate of 10% • Sufficient afterfilter data are available to calculate reliable statistics on a monthly basis • Median • Standard Deviation • other?

  13. TOT Afterfilter vs. Ambient Levelswith 3000N Module Original CSN field and trip blanks are generally poorly correlated to season or site location; however, afterfilters from 3000N show some correlation with ambient levels. • Data from 3000N: • X-axis = front filter • Y-axis = afterfilter • N = 820, R2=0.2378 • 55 sites nationwide • 5/2007 – 12/2007

  14. CSN: Temporal Variability in Trip and Field Blank Levels Average Total Carbon Blank by Year, ug/m3 (subset of sites with long-term data) • Between 2002 and 2005, STN field and trip blank annual averages for Met One (SASS) and Anderson (RAAS) samplers decreased 33% and averages for URG (MASS) samplers increased 25%. From “Carbon Measurements and Adjustments “, presented by Neil Frank at Air Quality Data in Health Effects Research conference, Nov 30 – Dec 1, 2006

  15. From “Carbon Measurements and Adjustments “, presented by Neil Frank at Air Quality Data in Health Effects Research conference, Nov 30 – Dec 1, 2006

  16. CSN: Temporal Variability in Trip and Field Blank Levels MetOne Sampler Total Carbon Field and Trip Blanks, μg/m3 From “Carbon Measurements and Adjustments “, presented by Neil Frank at Air Quality Data in Health Effects Research conference, Nov 30 – Dec 1, 2006

  17. Lab Blank Variability “Second” “Third” • Instrument blanks are typically less than 10% of trip and field blanks when expressed in the same units • Between-instrument variability and the effect of a software upgrade are visible • One of the lab analyzers appears to be more sensitive to the software change than the other. Source: Max R. Peterson, James B. Flanagan, Larry C. Michael, and R.K.M. Jayanty. 2007. Analysis of PM2.5 Speciation Network Carbon Blank Data. AAAR 26th Annual Conference, Reno, NV, September 24-28.

  18. Notable Differences Between Original CSN Method and IMPROVE/3000N • Face velocity and deposit density are potentially up to 10x greater for IMPROVE/3000N relative to MetOne due to flow rate and filter size. • Different filter materials. • Different flow control technology (IMPROVE) • Different analysis protocols: • temperature steps • timebase • TOT vs. TOR

  19. Summary Slide: Pros and Consfor the use of existing field and trip blank data for artifact correction of original CSN data • Pro: Lots of existing data 2000 - present • Pro: Probably closer to truth than lab blanks • Con: May not represent “true” artifact • Con: Questionable relevance to IMPROVE data • Con: Unlike afterfilters, the existing CSN trip and field blanks are not sensitive to seasonal or geographic variations

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