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Chemical speciation of PM and mass closure

Chemical speciation of PM and mass closure. David Green, Gary Fuller & Anja Tremper King’s College London . Contents. London sampling campaigns Methodology Use of uncertainty Results Source apportionment – London and Paris. Sampling campaigns. Summer campaign Aug-Oct 2008

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Chemical speciation of PM and mass closure

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  1. Chemical speciation of PM and mass closure David Green, Gary Fuller & Anja Tremper King’s College London

  2. Contents • London sampling campaigns • Methodology • Use of uncertainty • Results • Source apportionment – London and Paris

  3. Sampling campaigns • Summer campaign • Aug-Oct 2008 • Brent & Tower Hamlets • Winter 2008 campaign • Nov-Dec 2008 • Camden, Brent & Tower Hamlets • Further Camden campaigns • May - June 2010 • PM10 and PM2.5 • Summer 2010 • Further PM10 • Construction and another roadside Brent - Ikea Tower Hamlets – Blackwall Tunnel Camden – Swiss Cottage

  4. Methodology • Pragmatic mass closure • 2 Partisols • 1 Teflon – Mass, IC, ICP-MS • 1 Quartz – EC/OC • ERG mass closure • Existing TfL monitoring sites • TEOM / FDMS • Aethalometer (EC) • Sampled onto alternate filters on different days • Mixed cellulose esters – ICP-MS • Quartz – EC/OC • Longer time period • Used one sampler Existing Defra monitoring at North Ken and Marylebone Road for concentrations of regional pollutants when not measured directly • IC and EC/OC • Nitrates, Sulphates, Chlorides, SOA • Aethalometer measurements for EC and POA using site specific empirical relationships • Results in time series composed of two datasets

  5. Methodology Mass FDMS – direct mass TEOM – used Volatile Correction Model (VCM)

  6. Methodology Elemental Carbon Dataset A Aethalometer using Xgenline empirical relationship Uncertainty included Dataset B Sunset

  7. Methodology Primary Organic Carbon EC tracer measurement used to split SOA and POA Evidence of organic gas adsorption onto filters Intercept and slope derived using min 5% of EC/OC ratios Factor for organic mass of 1.4 used (Japar, 1984) from direct measurements of diesel emissions

  8. Methodology Secondary Organic Carbon EC tracer measurement used to split SOA and POA SOA = OC - (EC/OC)prim x EC Evidence of organic gas adsorption onto filters Intercept and slope derived using min 5% of EC/OC ratios Factor for organic mass of 2.1 used (Turpin and Lim, 2001), recommended for non-urban aerosol Good agreement between sites Dataset A mean of available measurements in London direct Dataset B Sunset analysis Variation included in uncertainty calculation

  9. Methodology Nitrates, sulphates & chlorides Measurements from mean of Marylebone and North Kensington used Factors applied to account for cations Nitrate can be ammonium or sodium Masses similar (18 or 23) Harrison (2003) found 60% NH4NO3 Applied a factor of 1.32 (60% NH4NO3 and 40% NaNO3) Sulphate Applied factor of 1.19 Chloride Applied factor of 1.65

  10. Methodology Water Used Aerosol Inorganic Model (AIM) Used nitrate and sulphate measurements as inputs Used FDMS sampling conditions of 30% RH and 30ºC

  11. Methodology Iron Rich Dust Split into Minerals, Iron Oxide and Metals Measured wide range of metals (Fe, Ca, Al, Ba, Cu, Mo, Mn, Ni, Pb, Sb, Sr, V and Zn) Used Al as a tracer for feldspars (e.g. KAlSi3O8) Applied factor of 8.4 Included uncertainty in this factor Ca used as a tracer for calcite and gypsum Applied factor of 3.8 Included uncertainty in this factor These grouped together as minerals Fe used as a tracer for an iron oxide (FeO, Fe2O3 or Fe3O4) Applied factor of 1.37 Included uncertainty in this factor Other metals included as ‘raw’ mass On days when ICP-MS not undertaken (dataset B) difference between PM10 mass and available components used to assess this

  12. Alternate filters A B

  13. Site Variability

  14. Daily Variability

  15. Uncertainty analysis • Guide to uncertainty in measurement methodology (GUM) • Simple… • Measurement equation • TEOMVCM = TEOM – (ƒVCM x FDMS purge) – FDMS purge • Uncertainty equation • UVCM = 2 x √(uTEOM)2 + (uƒVCM x FDMS purge)2 + (ƒVCM x uFDMS purge)2 • Complex… • Total Mass • uTotalMassA = 2x √(uECa2 + uPOAMa2 + uSOAMregional2 + uNO3total2 + uSO4total2 + uCltotal2 + uWater2 + uMinerals2 + uIronOxide2 + uMetals2)

  16. Validation against PM10 Tower Hamlets 4 Brent 4 Camden 1 y = 0.91 (±0.05) x + 2.19 (±1.91) r2 =0.84 y = 0.87 (±0.11) x + 6.9 (±3.22) r2 =0.58 y = 1.11 (±0.07) x + -3.88 (±2.26) r2 =0.82

  17. Analysis outputs - Comparison to source apportionment

  18. Next steps and improvements… • Organic absorption onto quartz filters • Quartz back quartz study to assess adsorption in next 2 months • Efficiency of aqua regia digest for extracting Al • HF digest • ICP-MS for Ca and Al • Comparisons with ICP-AES • Al as a tracer for Si • XRF analysis • How representative is one location to another • More direct measurements

  19. Acknowledgements • London Borough of Camden • Transport for London

  20. Centre for Environment and Health Source apportionment of PM10 in London and Paris-intial results Gary Fuller and Anna Font Font King’s College London March 2010

  21. Relationship between annual mean PM10 and NOX in London Fuller et al., (2002), Fuller and Green (2006)

  22. Relationship between annual mean PM10 and NOX in Paris

  23. Primary PM10 : NOX ratio London and ParisProgressive Euro classes preferentially abate PM10 over NOX then grad should be decreasing!Effects of London specific PM measures?

  24. Non-primary PM10 London and ParisNon primary PM10 convergingParis did not experience 2006 elevation seen in London

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