A Summary of Recent Biomass Burning Emissions MeasurementsS. Akagi (sheryl.akagi@umontana.edu), R. Yokelson (bob.yokelson@umontana.edu), I. Burling, T. Christian;

University of Montana, T. Karl; National Center for Atmospheric Research, J. Reid; Naval Research Laboratory

2. ApproachWe:• Emphasize recent/comprehensive studies that sampled a large number of

fires and measured a wide range of species in fresh smoke. • Compile EF estimates for convenient use in atmospheric models. • Maintain the link between the fire emissions and the fire type at a high

level of detail, while preserving the option for less detailed schemes.• Propose a method for dealing with unmeasured non-methane organic

compounds (NMOC) and their uncertainty.• Summarize post emission processes.• Compile estimates of biomass consumption by the main fire types on a per

unit area and global basis.

1. Introduction

Biomass burning (BB) is a significant source of trace gases and particles in the troposphere. Recently numerous BB emission factors (EF) have been measured from ground-based and airborne platforms.

We summarize the recent BB EF measurements in an effort to improve the accuracy of atmospheric models using a bottom-up approach.

TAGB (pre-fire)

Biomass burn

Airborne

Ground-basedEmission factor (g X/kg biomass

burned)

TAGB (post-fire)

Biomass consumption(Mg/ha)

Total combusted biomass (Tg)

Global emissions estimate

Plume/chemical transport models

5. Role of EF in Chemical Models

6. Example Table: Pasture Maintenance Burning EF

Total EF was calculated as a 60% airborne/40% groundbased weighted average [1].

Only airborne data collected for these species. EF computed from 2.00 times the air average [2].

When only airborne data the uncertainty was reported as 45% EF [2].

Taken as fractional uncertainty in ground data, which dominates the total variability [2].

EF measurements from studies were averaged according to platform (airborne/groundbased).

Only 20 out of 73 measured species are shown here

Platform Airborne Airborne Airborne Avg Ground Avg Total Avg

Compound

from Yokelson et

al. [2007]

1 firea

from Ferek et

al. [1998]

6 firesb

Uncertaintyc Airborne

Averaged Uncertaintye from Christian

et al. [2007]fUncertaintyg Weighted Total

Averageh Uncertaintyi

Carbon dioxide (CO2)1591 1700 36 1684 36 1343 123 1548 142

Carbon monoxide (CO) 112.08 65.3 18.4 72 20.3 229 64.6 135 38

Methane (CH4)6.916 2.48 1.47 3.11 1.85 17.1 10 8.71 4.97

Nitrogen oxides (NOx as NO) 0.606 1.11 0.40 1.04 0.37 0.33 0.26 0.75 0.59

Nitric oxide (NO) 0.34 0.26 0.34 0.26 0.30 0.18 0.32 0.19

Nitrogen dioxide (NO2)0.93 0.93 0.15 0.2 0.62 0.82

Ethylene (C2H4)1.238 1.175 0.260 1.184 0.262 1.42 0.79 1.28 0.71

Acetic acid (CH3COOH) 4.172 4.172 19.7 12.9 10.38 6.80

Propane (C3H8)0.110 0.025 0.110 0.025 0.220 0.10

Formaldehyde (HCHO) 1.912 1.912 1.88 1.10 1.90 1.11

Methanol (CH3OH) 2.874 2.874 10.3 6.03 5.84 3.42

Nitrous Acid (HONO) 0.167 0.167 0.15 0.06

Hydrogen cyanide (HCN) 0.537 0.537 0.35 0.34 0.46 0.45

Ammonia (NH3)1.364 1.364 1.64 1.44 1.47 1.29

Acetaldehyde (CH3CHO) 1.202 1.202 2.40 1.08

Formic acid (HCOOH) 0.519 0.519 0.26 0.40 0.42 0.64

Acetylene (C2H2)0.295 0.085 0.295 0.085 0.07 0.10 0.21 0.29

Phenol (C6H5OH) 2.42 4.49 1.92 3.34

Acetol (C3H6O2) 8.89 7.53 7.07 5.60

Propylene (C3H6)0.728 0.410 0.120 0.455 0.133 1.43 1.12 0.845 0.66

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References[1] Kauffman, J. B., D. L. Cummings, and D. E. Ward: Fire in the Brazilian Amazon 2. Biomass, nutrient pools and losses in cattle pastures, Oecologia, 113, 415–427, 1998.[2] Yokelson, R. J., Christian, T. J., Karl, T. G., and Guenther, A.: The tropical forest and fire emissionsexperiment: laboratory fire measurements and synthesis of campaign data, Atmos. Chem. Phys., 8, 3509–3527, 2008.[3] MODIS burned area image courtesy of NASA and UMD (http://modis-fire.umd.edu/MCD45A1.asp)[4] Yevich, R. and Logan, J. A.: An assessment of biofuel use and burning of agricultural waste in thedeveloping world, Global Biogeochem. Cy., 17(4), 1095, doi:10.1029/2002GB001952, 2003.[5] Yokelson, R., Crounse, J. D., DeCarlo, P. F., et al.: Emissions from biomass burning in the Yucatan, Atmos.Chem. Phys. Discuss., 9, 767–835, 2009.[6] Crutzen, P. J., Lawrence, M. G., and Poschi, U.: On the background photochemistry of troposphericozone, Tellus B, 51, 123-146, 1999.[7] Trentmann, J., Yokelson, R. J., Hobbs, P. V. et al.: An analysis of the chemical processes in the smokeplume from a savanna fire, J. Geophys. Res., 110, D12301, doi: 10.1029/2004JD005628, 2005.[8] Alvarado, M. J., and Prinn, R. G.: Formation of ozone and growth of aerosols in young smoke plumesfrom biomass burning: 1. Lagrangian parcel studies, J. Geophys. Res., 114, D09306, doi:10.1029/2008JD011144, 2009.[9] Keene, W. C., Lobert, J. M., Crutzen, P. J. et al.: Emissions of major gaseous and particulate speciesduring experimental burns of southern African biomass, J. Geophys. Res., 111, D04301, doi:10.1029/2005JD006319, 2006.[10] Yokelson, R. J., Karl, T. G., Artaxo, et al.: The tropical forest and fire emissions experiment: Overviewand airborne fire emission factor measurements, Atmos. Chem. Phys., 7, 5175–5196, 2007b.[11] Li, Q., Jacob, D. J., Bey, I. et al.: Atmospheric hydrogen cyanide (HCN): biomass burning source, oceansink?, Geophys. Res. Lett., 27, 357-360, doi: 10.1029/1999GL010935, 2000.[12] de Gouw, J. A., Warneke, C., Parrish, D. D., et al.: Emission sources and ocean uptake of acetonitrile(CH3CN) in the atmosphere, J. Geophys. Res., 108(D11), 4329, doi:10.1029/2002JD002897, 2003.[13] Crounse, J. D., DeCarlo, P. F., Blake, D. R., et al.: Biomass burning and urban air pollution over theCentral Mexican Plateau, Atmos. Chem. Phys., 9, 4929–4944, 2009.[14] Bond, T. C., Streets, D.G., Yarber, J.F., et al.: A technology-based global inventory of black andorganic carbon emissions from combustion, J. Geophys. Res., 109, D14203, doi:10.1029/2003JD003697, 2004.

HCN and CH3CNAndreae and Merlet (2001) stressed the need for more measurements given the potential for HCN and CH3CN as biomass burning tracers [11,12]. Within the past decade HCN has been both frequently measured and applied [10,13]. The ΔCH3CN/ΔHCN ER has been shown quite consistent (~0.41) in both laboratory and field measurements [5].

HONO NO + OH

Uncertainty in FiresFire have high natural variability:

• relative fuel consumption by flaming/smoldering varies

• Many different plume dilution/transport scenarios

• Different parts of plume can age at different rates.

We try to characterize this natural variability in reported standard deviations.

9. Uncertainty / Gaps in Present Knowledge

Key Remaining Questions• How can we quantify unidentified

NMOC, and what is their role in post-emission processing?

• How does so much secondary organic aerosol (SOA) form?

• Are HCN or CH3CN useful biofueltracers?

• How should we account for fast processes in fresh plumes in global models?

8. Some Key Species

HONOOriginally thought to be formed by secondary heterogeneous reactions, HONO is now thought to be directly emitted [9,10,5]. Photolysis of HONO occurs within ~10 min and provides ample OH to spur “fast” plume chemistry.

0

500

1000

1500

2000

2500

3000

0 0.05 0.1 0.15 0.2 0.25

Alt

itu

de (

m A

GL

)

DHONO/DNOx (molar emission ratio)

Forest Fire, Brazil [10]

Lab data [9]

Lab data [Burling et al., prelim]

Forest Fire, Mexico [5]

Crop Residue, Fire 1 [5]

Crop Residue, Fire 2 [5]

Aged Haze Layer [5]

t

x

C

C

gCmassmolar

gXmassmolar

biomasskg

Carbong

)(

)(EF =

where is the number of moles emitted of

species X divided by the total number of moles of carbon emitted.

Emission Ratio (ER) =

where ∆X and ∆Y are the amount of species above background level (excess mixing ratios, or EMR). ER is a dimensionless molar ratio between two emitted compounds (measured at the source).

Ozone formation• Yokelson et al. (2009) observed a rapid

increase in ΔO3/ΔCO within 1 h in the downwind plume of a tropical fire [5], suggesting ozone formation via photochemical oxidation of NMOC [6].

• Atmospheric models often underestimate the amount of ozone formation when using measured levels of NMOC as baseline input.

• An increase in NMOC input more accurately predicts measured ozone levels [7,8].

Secondary Organic Aerosol (SOA)• SOA formation in young plumes may be

due to condensation of low volatility organic compounds, many of which currently go undetected.

• An ΔOA/ΔCO growth factor of 2.3 was observed in 1.4 h [5]. Applying that to the global BB emission estimate of 32 Tg /y of primary OC [14] suggests a BB source of ~100 Tg/y of OA, compared to ~3 Tg/y from fossil fuels.

7. Impacts

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Estimated relative smoke age (hours)

O3

O3+NO2+PANs

∆O

3/∆

CO

or

∆O

x/∆

CO

Uncertainty in measurements Instrumental error is small (5-10%) compared with the natural variability between fires. However, many trace gases go unidentified in initial and processed emissions.

Undersampled Fuel TypesFew EF have been measured for domestic biofueluse, and temperate/boreal forests. Christian et al. (2009) made several of the first measurements of garbage burning, showing a potentially significant contribution to urban pollution.

3. EF and ER Definitions

t

x

C

C

4. Biomass ClassificationVegetation

Boreal Tropical

Peatlands Savanna

Agriculture/wasteGarbage Crop Residue

Pasture maintenance

BiofuelPatsari Open Charcoal

Stove Cooking Making

Charcoal DungBurning Burning

Burned area (ha)

Y

X

D

D