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Black carbon : Characterisation , measurement methods , and emission factors

Jana Moldanová IVL, Swedish Environmental Research Institute. Black carbon : Characterisation , measurement methods , and emission factors. Definitions. Optical properties: Black carbon

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Black carbon : Characterisation , measurement methods , and emission factors

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  1. Jana Moldanová IVL, Swedish Environmental Research Institute Black carbon: Characterisation, measurementmethods, and emission factors

  2. Definitions • Optical properties: Black carbon • Is formed by incomplete combustion of hydrocarbon fuels, and is the most effective component of PM, by mass, at absorbing solar energy • Mass of combustion-generated, sp2-bonded carbon that absorbs the same amount of light as the emitted particles. Absorption efficiency of the reference particles as 7 m2/g for 550-nm incident radiation (Bond 2004) • Thermal stability: Elemental carbon • Structure: Soot • Composition: Carbonaceous aerosol (includes OC)

  3. Definitions

  4. BC has a strong climateeffect Aamas et al., 2013

  5. BC sources - Europe 2. – non-industrial combustion 4. – production processes 9. – wastetreatment and disposal 10 – agriculture van den Ggon, 2012

  6. BC sources - Global BB for biomass burning, AWB for agricultural waste burning, AIRC for aviation, ANTH for other anthropogenic sources, VOLC for volcanoes and BIOG for biogenic sources. Hendrickset al., 2013

  7. Spatial distribution of BC in fine PM TRANSPHORM, van den Ghon, 2012

  8. Uncertainties in source strength Kindbom in Hansson et al, 2012

  9. BC mixing – uncertainties in light absorption

  10. Measurementmethods • Optical (BC) • in situ (Aethalometer) • filter analyses (Reflectande, trasmitance, Aethalometer, MAAP) • Thermal (EC/OC) • NIOSH, Improve, EUCAARI, VDI • Photo-acoustic (measures heat generated by absorbedradiation)

  11. OpticalMethods • Sampling on filter matrix • Measurementofmodificationof filter opticalproperties by the sampled PM • Assumptionof Beer-Lambert law for data analyses • Responsedepends on filter loading and interaction betweenradiation, particles, and filter - requirescorrections

  12. OpticalMethods • Multi-angle absorption photometer – bothreflection and transmission – 2-stream modelappliedtoevaluateresults, no corrections

  13. Thermalmethods • Simple optical methods (oxidizing atmosphere, rizing T) • Two-step methods (thermal pre-treatment to remove OC) • Thermal-optical (optical correction for charring OC) • Thermal stability and the optical correction can be affected by presence of sulphate and metals in the PM

  14. Thermal-optical method

  15. Comparison of different optical and thermal methods (ship emissions) Different filter type for EC and BC

  16. Comparison EC/BC – typically in range 0.7-1.3 EPA, 2012

  17. Emission estimates • From emission factors for EC/BC for individual sources • Traffic: HDV wo DPF 45-150 mg/vkm, HDV w DPF 9-16 mg/vkm, PC w catalyst 1-2 mg/vkm PC petrol EURO 5+ 0.1-0.3 mg/vkm PC diesel EURO 5+ 0.1-1 mg/vkm • Residential wood burning 0.043 – 3.5 g BC/kg wood (Kuipiainen & Klimont, 2007) Samaras, 2012

  18. Emission estimates • From PM inventory and BC/PM ratio of the individual sources

  19. Emission estimates • From PM inventory and BC/PM ratio of the individual sources TRANSPHORM, van den Ghon, 2012

  20. Emission factors for BC – effectof sampling Figure 5 Composition of PM (as mg/m3 exhaust gas) collected on filters in the diluted and hot exhaust gas (Moldanová et al., 2009).

  21. PM compositionprofiles – ship emissions <--------------Residualfuel ---------> Dist.Fuel

  22. PM compositionprofiles – ship emissions Volatilitymeasuredwith online instruments (EEPS, GRIMM spectrometer, Thermodenuder) Part of PM mass and PM number volatilized at 90ºC (Vol. 90), 150ºC (Vol. 150) and 300ºC (Vol. 300) in the thermodenuder and the non-volatile part (Nonvol.).

  23. PM composition– structure and compositionofparticles c) a) b) STEM image of an agglomerate of soot-type particles from HFO combustion. Composition: C 77.1 wt%, N 15.7 wt% and O 6.9 wt% and traces of V, Ca and S (about 0.1 wt% of each element). b – Elemental composition map of V, Ca and S for the soot-type particles in a. c – Elemental composition of different particles with respect to N, V, and S.

  24. PM composition– structure and compositionofparticles STEM image of an agglomerate of soot-type particles from MGO combustion. b – Elemental composition map of S and Ca for the soot-type particles in a

  25. PM composition– structure and compositionofparticles a - TEM picture of a small soot-type aggregate and its corresponding selected area electron diffraction (SAED) pattern, b - zoom on soot-type particles with dark dots and its associated SAED pattern

  26. PM compositionaffectsthermalstability Oxidation behaviour of PM (TSP in black and PM2.5 in red) sampled in a – HFO exhaust, b – MGO exhaust.

  27. Conclusions • Definition of BC is dependentofmeasurementtechniqueusedbutalsoofimpactsthatareassumed (political definition) • Bothoptical and thermalmethodsgivesatisfactoryresults, impactsof PM composition on thermalmethosneedfurtherconsideration, further intercomparison ofopticalmethods • Emission factors for BC and theirvariabilitywithfuels, combustionconditions, technologiese.t.c. needsto be furtherdeveloped • Consistencybetween PM and BC data important • PM compositionaffectbothmeasurementresults and how the particlesbehave in atmosphere (radiative properties, sink processes, healtheffects (?) • Relation between BC/EC emission at source and propertiesoftheseparticles on mesoscale

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