Wear and Resuspension Particles form Road Traffic - Source and Emissions Factors

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Wear and Resuspension Particles form Road Traffic - Source and Emissions Factors

  1. 1. Wear and Resuspension Particles from Road Traffic Sources and Emission Factors Robert Gehrig, Nicolas Bukowiecki EMPA Dübendorf (Switzerland) Urban Air Quality: The Challenge of Non-Exhaust Emissions from Traffic Sources, Health Risks and Mitigation; Barcelona, Spain July 11-12, 2013
  2. 2. Materials Science & Technolog y Outline  Emission factors from Swiss field campaigns  Road wear or resuspension?  Tyre wear  Conclusions R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  3. 3. Materials Science & Technolog y Non-exhaust sources  Brake wear  Road wear  Resuspension of road dust  Tyre wear R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  4. 4. Materials Science & Technolog y Motorway in Rural Area (Reiden LU) Measuring Site 1 Wind Direction Road Background + Traffic Emssions Background Only Measuring Site 2 50’000 vehicles per day Rural Motorway 120 km/h free-flowing HDV Fraction 15% R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013 cx, motorway traffic = cx, downwind – cx, upwind
  5. 5. Materials Science & Technolog y Motorway in Rural Area (Reiden LU) R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  6. 6. Materials Science & Technolog y Street Canyon (Zürich Weststrasse) 22’000 vehicles per day Measuring Site 1 Road Background Only Measuring Site 2 Urban Traffic Background Background + Traffic Emssions Urban Street Canyon Stop and Go Traffic HDV Fraction 10% R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013 cx, local traffic = cx, street canyon – cx, urban background
  7. 7. Materials Science & Technolog y Street Canyon (Zürich Weststrasse) R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  8. 8. Materials Science & Technolog y The Empa Rotating Drum Impactor (RDI) Bukowiecki et al. , Environmental Science and Technology (2005) 39, 5754-5762 Lundgren, D. , J. Air Pollut. Control Assoc. (1969) 17, 225-229. • Size fractionation by rectangular nozzles • Aluminum wheels • Substrate: 6 μm PP • Bouncing prevention: Apiezon M 1 bar = 1 hour 1 wheel = 4 days ~10 µg total aerosol mass per spot The Empa RDI is a modification of the original Lundgren impactor: 1.52 x 10 mm 0.68 x 10 mm 0.30 x 10 mm 1.52 x 10 mm 0.68 x 10 mm 0.30 x 10 mm backup filter for ultrafine fraction R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  9. 9. Materials Science & Technolog y Concentrations of PM10 and Antimony R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  10. 10. Materials Science & Technolog y Calculation of Emission Factors Concentration differences Traffic counts (LDV, HDV) Emission factors Dilution (from NOx) R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  11. 11. Materials Science & Technolog y Emission factors for selected elements Relative size distribution (Sum=1): (HDV) R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013 LDV HDV
  12. 12. Materials Science & Technolog y PM10 Emission factors Zürich-Weststrasse Zürich-Weststrasse: Urban Street Canyon Stop and Go Traffic HDV Fraction 10% R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  13. 13. Materials Science & Technolog y PM10 Emission factors Reiden Reiden: Rural Main Freeway 120 km/h free-flowing HDV Fraction 20% R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  14. 14. Materials Science & Technolog y Can this be modelled? R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  15. 15. Materials Science & Technolog y  Emission factors from Swiss field campaigns  Road wear or resuspension?  Tyre wear  Conclusions R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  16. 16. Materials Science & Technolog y How a Mobile Load Simulator works 2400mm 1200mm 940mm 300mm MMLSMMLS Model Mobile Load Simulator Ø 2400mm 1200mm 940mm 300mm MMLSMMLS Model Mobile Load Simulator Ø direction of moving wheel and induced air stream sampling point for dosing of particles and tracer gas tracer gas R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  17. 17. Materials Science & Technolog y MMLS in operation R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  18. 18. Materials Science & Technolog y View of MLS R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  19. 19. Materials Science & Technolog y View of MLS R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  20. 20. Materials Science & Technolog y Preparation of the test surface porous asphalt asphalt concrete R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  21. 21. Materials Science & Technolog y Typical mass size distribution 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.1 1 10 100 aerodynamic particle diameter (µm) dM/dlogDp Ambient air Simulator in operation Difference (= abraded fraction) R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  22. 22. Materials Science & Technolog y Abrasion from asphalt concrete pavement 0.00 0.05 0.10 0.15 0.20 0.25 0.30 -24 -12 0 12 24 36 48 60 72 84 96 108 120 132 144 156 168 180 min PM10(µg/m3 ) Red: ambient air concentration Black: MMLS in operation R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  23. 23. Materials Science & Technolog y PM10 emission factors for fresh particle abrasion Type of mobile load simulator MMLS (LDV) MMLS (LDV) MLS (HDV) MLS (HDV) Type of pavement asphalt concrete porous asphalt asphalt concrete asphalt concrete Condition of pavement new new good poor PM10 emission factor (mg/km/wheel) 0.25 0 – 0.2 0.7 8 PM10 emission factor (mg/km/LDV) 3 0 - 2 PM10 emission factor (mg/km/HDV) 7 80 R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  24. 24. Materials Science & Technolog y PM10 emission factors for resuspension Type of mobile load simulator MMLS (LDV) MMLS (LDV) MLS (HDV) MLS (HDV) Type of pavement asphalt concrete porous asphalt asphalt concrete asphalt concrete Condition of pavement new new good poor PM10 emission factor (mg/km/wheel) 6.3 0.41 11 66 PM10 emission factor (mg/km/LDV) 76 5 PM10 emission factor (mg/km/HDV) 110 660 R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  25. 25. Materials Science & Technolog y Resuspension of dust R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013 0 100 200 300 400 500 600 700 0 20 40 60 80 mg/km min porous asphalt asphalt concrete
  26. 26. Materials Science & Technolog y Resuspension of dust (detail view) R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013 0 5 10 15 20 25 30 35 40 45 50 0 10 20 30 40 50 60 70 mg/km min porous asphalt asphalt concrete
  27. 27. Materials Science & Technolog y  Emission factors from Swiss field campaigns  Road wear or resuspension?  Tyre wear  Conclusions R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  28. 28. Materials Science & Technolog y PM10- emission factors for Fe and Zn MLS-Messungen (HDV) Fe Zn Tyre (1% Zn) Simulator in operation (µg·m-3) 1.68 0.129 12.9 Ambient air (µg·m-3) 0.32 0.008 0.8 Difference (metal abrasion, (µg·m-3) 1.36 0.121 12.1 Emission factor per HDV (mg·km-1) 1.91 0.17 17 MMLS-Messungen (LDV) Fe Zn Tyre (1% Zn) Total concentration (µg·m-3) 1 0.02 2.0 Emission factor per LDV (mg·km-1) 0.40 0.008 0.80 R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  29. 29. Materials Science & Technolog y Tyre wear particles in PM10 Julie M. Panko et al.; Atmospheric Environment 72 (2013) 192-199 R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  30. 30. Materials Science & Technolog y % Tyre wear in PM (Günter Stein et al. VDI 2009) R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  31. 31. Materials Science & Technolog y Tyre abrasion Photo: V. Dietze, Deutscher Wetterdienst, Referat Lufthygiene Freiburg i.Br.(D) R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  32. 32. Materials Science & Technolog y Conclusions  Abrasion related particles and resuspended road dust were mainly found in the 1-10 µm particle size range.  In the street canyon and along the motorway, abrasion sources and vehicle induced dust resuspension made up about 50% of the traffic related PM10 emissions.  Brake wear and resuspension were found to be more mass relevant in the street canyon than road wear and tire wear.  Road wear was found to be of minor importance for intact pavements, but damaged pavements can lead to substantial road wear emissions.  Vehicle induced resuspension is not strictly correlated with traffic numbers but is strongly influenced by available road dust. Difficult to describe with conventional emission factor models.  Tyre wear seems to be of minor importance. R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013
  33. 33. Materials Science & Technolog y Acknowledgements We thank for the financial support by:  Swiss Federal Roads Office (ASTRA)  Swiss Federal Office for the Environment (FOEN) R. Gehrig; International Workshop Urban Air Quality, Barcelona, July 2013

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