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

Black carbon: Characterisation, measurement methods, and emission factors

Jana MoldanováIVL, Swedish Environmental Research Institute

Black carbon

Jana Moldanová, 2013-04-24

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)

Black carbon


Definitions

Black carbon


BC has a strong climate effect

Aamas et al., 2013

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BC sources - Europe

2. – non-industrial combustion4. – production processes9. – waste treatment and disposal10 – agriculture

van den Ggon, 2012

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BC sources - Global

Hendricks et al., 2013

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.

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Spatial distribution of BC in fine PM

TRANSPHORM, van den Ghon, 2012

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Uncertainties in source strength

Kindbom in Hansson et al, 2012

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BC mixing – uncertainties in light absorption

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Measurement methods

Optical (BC)– in situ (Aethalometer)– filter analyses (Reflectande, trasmitance, Aethalometer,

MAAP)

Thermal (EC/OC)– NIOSH, Improve, EUCAARI, VDI

Photo-acoustic (measures heat generated by absorbed radiation)

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Optical Methods Sampling on filter matrix Measurement of modification of filter optical properties

by the sampled PM Assumption of Beer-Lambert law for data analyses Response depends on filter loading and interaction

between radiation, particles, and filter - requires corrections

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Multi-angle absorption photometer – both reflection and transmission – 2-stream model applied to evaluate results, no corrections

Optical Methods

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Thermal methods

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

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Thermal-optical method

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Comparison of different optical and thermal methods (ship emissions)

PM1,

S1_

HFO

1%_

ME-

...

PM10

, S1_

HFO

1%_

ME.

..

TSP,

S1_

HFO

1%_

ME-

full

PM1,

S1_

HFO

1%_

ME.

..

PM10

, S1_

HFO

1%_

M...

TSP,

S1_

HFO

1%_

ME.

..

PM2.

5, S

2_H

FO1%

_ M

E...

PM10

, S2_

HFO

1%_

ME.

..

PM2.

5, S

2_H

FO0.

5%_

...

PM10

, S2_

HFO

0.5%

_ M

...

PM1,

S1_

MG

O_

AE

PM10

, S1_

MG

O_

AE

TSP,

S1_

MG

O_

AE

PM2.

5, S

2_M

GO

_ M

E-...

PM10

, S2_

MG

O_

ME-

...

0%

10%

20%

30%

40%

50%

60%

70% BC reflect.BC transmiss.EC

Different filter type for EC and BC

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Comparison EC/BC – typically in range 0.7-1.3

EPA, 2012

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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/vkmPC petrol EURO 5+ 0.1-0.3 mg/vkmPC diesel EURO 5+ 0.1-1 mg/vkm

– Residential wood burning 0.043 – 3.5 g BC/kg wood (Kuipiainen & Klimont, 2007)

Samaras, 2012

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Emission estimates

From PM inventory and BC/PM ratio of the individual sources

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Emission estimates

From PM inventory and BC/PM ratio of the individual sources

TRANSPHORM, van den Ghon, 2012

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Emission factors for BC – effect of 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).

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<-------------- Residual fuel ---------> Dist. Fuel

PM composition profiles – ship emissions

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PM composition profiles – ship emissions

Volatility measured with 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.).

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PM composition – structure and composition of particles

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.

a) b)c)

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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

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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


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

PM composition affects thermal stability

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Conclusions

Definition of BC is dependent of measurement technique used but also of impacts that are assumed (political definition)

Both optical and thermal methods give satisfactory results, impacts of PM composition on thermal methos need further consideration, further intercomparison of optical methods

Emission factors for BC and their variability with fuels, combustion conditions, technologies e.t.c. needs to be further developed

Consistency between PM and BC data important PM composition affect both measurement results and how the

particles behave in atmosphere (radiative properties, sink processes, health effects (?)

Relation between BC/EC emission at source and properties of these particles on mesoscale

Documents

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