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Overview of CSN Data Relevant to OC/EC Artifact Adjustments presented by James Flanagan RTI International Davis, CA Janu PowerPoint Presentation
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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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Overview of CSN Data Relevant to OC/EC Artifact Adjustmentspresented byJames FlanaganRTI InternationalDavis, CAJanuary 22-23, 2008
slide2
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
csn timeline

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.

csn stn tot analysis method
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)
csn sampler types
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
csn sampler module types
CSN Sampler Module Types

URG MASS

Andersen RAAS

Cassette used for IMPROVE and 3000N Samplers

MetOne SASS

R&P 2300

csn field and trip blanks reported to aqs
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.
csn field trip blank averages original oc ec analyses
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.

csn laboratory qc data for original oc ec analyses not reported to aqs
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.
csn laboratory qc data received for oc ec 3000n not reported to aqs
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.
csn available blank types with 3000n sampler protocol blank data reported to aqs
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)
afterfilters frequency and availability of data for statistics
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?
tot afterfilter vs ambient levels with 3000n module
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
slide14

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

slide15

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

slide16

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

lab blank variability
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.

notable differences between original csn method and improve 3000n
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
slide19
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