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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,

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Presentation on theme: "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,"— Presentation transcript:

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 (PM 2.5 and PM 10 ) 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 cant 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

15 Run1 vs Run 2Run1 vs Run 3 Run2 vs Run 3






21 Aerosols












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/MSspeciated organics, ions $ 3,000 SEMparticle morphology $ 5,000 Reports »TOTAL $123,000Indirect $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 (NO 3, NO 2, 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

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