Aerosol Diagnostics via Size/Time/Compositional Profiles

1. Aerosol Diagnostics via Size/Time/Compositional Profiles A proposal to LADCO by the UC Davis DELTA Group Tom Cahill, Professor and Head, DELTA June 13, 2002

2. Analysis of the problem • Aerosols can have major impacts via global climate change, visibility reduction, ecosystem impacts and health effects • Aerosols are complicated, with both size and composition vital for source identification and impact assessment. • Aerosols can be highly variable in time, with local, synoptic and diurnal patterns

3. Limitations of standard techniques • Filter based sampling integrates over both size (PM2.5 and PM10)and time (24 hrs) • Filter sampling integrates composition to deliver only mass in most cases • Filter sampling is usually limited to one-day-in-three or worse • Filter sampling makes serious personnel and infrastructure requirements

4. Alternatives to filter sampling • Sampling via impaction is both theoretically and experimentally well understood, unlike filter sampling, and has fewer sampling artifacts • Sampling by impaction allows- • Many size cuts, not just one • Continuous sampling with high time resolution • Modest infrastructure requirement • A newly developed DELTA Group suite of non-destructive compositional and morphological analyses

5. Problems with impaction sampling that limited use • Samplers are technically complex and thus can be more expensive than filter samplers • Collected masses (few mono-layer criterion) are low and sensitivities may suffer • Until recently, no viable method existed for measuring mass • Standard chemical methods can’t be used • Particle bounce can lead to poor size cuts unless special coatings are used

6. Impaction was still widely used • All major studies in California, 1969-1977 • Monitoring by rotating 3 drum impactor for the ARB, 1973-1977 – 14,100 days • Almost all NPS and EPA studies, 1980 to present, including WHITEX and SEAVS • Major international studies, most recently NSF ACE-Asia (2001, 21 sites, 78,000 samples), and NOAA ITCT (2002 - 2004)

7. DELTA Group personnel • Tom Cahill, Physics/Atmospheric Sciences • Pete Kelly, Chemistry (LDI TOF/MS) • Jim Shackelford, Materials Science (SEM, Eng) • Steve Cliff, Applied Science (S-XRF, ALS PRT) • Kevin Perry, Meteorology (Utah) • Graham Bench, Applied Science (CAMS, LLNL) • Michael Jimenez-Cruz, Applied Science (UCD lab) • Jeanette Martin, MSO, Lee Portnoff and Victor Rey, graduate students (3), foreign visitors (4), about 20 collaborators, many in Asia

8. DELTA Group efforts, 1990 - 2002 • Small, inexpensive, low labor continuously sampling rotating drum impactors in the field • Quick and cheap analyses for mass and optics, then archived for later analyses if desired • High technology beam based non – destructive mass, elemental and chemical analyses in ex-post-facto experiments at any later time • Mass closure to allow comparisons with filters • Quality assurance by “integral redundancy” or overlapping methods for key species

9. DELTA Group techniques • Mass by soft beta attenuation • Optical attenuation 320 – 820 nm • then archive the sample strips • Elements Na – U via synchrotron-XRF, DELTA Group beam line, ALS LBNL • Mass and hydrogen via STIM and PESA, CAMS, LLNL • Anions and speciated organic matter by LDI TOF/MS • Morphology via SEM

10. Summary of Proposed Program • Impaction vastly less expensive per sample • To collect • To analyze • To archive the large number of samples collected • Better representation of ambient aerosols • Non destructive analyses and easy archiving for later analyses • Highly diagnostic compositional and morphological data available

11. Proposal: • Purchase 4 3-stage rotating DRUM impactors, 2.5 μm IMPROVE inlet • Site at least one at existing IMPROVE site for QA, additional species, etc. • Initiate continuous sampling for mass and optics, plus archiving • Ex-post-facto analyze pollution episodes by S-XRF, STIM/PESA, LDITOF/MS, SEM

14. Precision of Soft Beta Mass Measurements – 3 repeated analyses of a 3 hr DRUM strip

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33. Summary of the Detroit study • The DRUM ran well with minimal oversight • 3 hr resolution and 1000 analyzable samples • Mass, optical, S-XRF elemental = 100,000 values • The site was characterized by short duration plumes of complex aerosols • The plumes possessed characteristic size and elemental species that with meteorology could identify urban and remote sources • The plumes (especially < 0.34 microns) should be traceable into rural and remote areas

34. Deliverables to LADCO Assume: 4 sites, 3 hr data, 3 6-week S-XRF intensives, STIM/PESA, partial LDITOF/MS • 35,000 mass values, 1.75 M optical scans • Available 1 week after samples received UC Davis • 12,100 elemental analyses, 360,000 data • 12,100 vacuum mass, hydrogen (organics) • Available 3 months after samples received UC Davis • 500 + anion, speciated organics • Annual Report in electronic and hard copy

35. Summary of Proposed Costs Assume: UC Davis research grant (Year 1) • 48.5% indirect, then 28.5% for future years • $50,000 operations, mass, optics scans • $40,000 S-XRF analyses elements Na - U • $40,000 STIM and PESA mass and total organics • $25,000 LDI TOF/MS speciated organics, ions • $ 3,000 SEM particle morphology • $ 5,000 Reports • TOTAL $123,000 Indirect $60,000 $183,000 Year 1 plus samplers, $30,000 $158,000 Year 2 +

36. Alternatives to the Proposal IMPROVE, 4 sites/1 year, one-day-in-three • PM2.5 Teflon, Nylon, quartz • Mass, organics by hydrogen, elements Na – Pb, anions (NO3, NO2, SO4), Organics by carbon elemental carbon • PM10 Teflon mass • 480 days/960 mass, 30 species, 14,400 data Est. $140,000. plus indirect $40,000 = $180,000/year+ samplers $66,000

37. Good reasons why not to use DELTA DRUMs • The DELTA Group has only operated one site for a full year under these protocols (Fresno EPA/CARB Super-site) , and thus lacks a serious “track record” • Data are non-standard, and comparisons to EPA and IMPROVE filters may be difficult • Only the DELTA Group can do this, making LADCO dependent on a “sole source” • Voluminous data will require additional personnel or contractors to interpret the results

38. Acknowledgements • All the Detroit personnel, but especially Ann Chevalier, who was extremely helpful in setting us up at their site • Members of the DELTA Group, • Lee Portnoff for the beta mass • Roger Miller for the optical scans • Steve Cliff for the S-XRF analyses • Kevin Perry for data reduction • Donna and Mike for LADCO who moved very rapidly to get the Detroit study going