Fine Particle Emissions From Tropical Peat Fires Decrease Rapidly With Time Since Ignition

Southeast Asia experiences frequent fires in fuel‐rich tropical peatlands, leading to extreme episodes of regional haze with high concentrations of fine particulate matter (PM2.5) impacting human health. In a study published recently, the first field measurements of PM2.5 emission factors for tropic...

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Bibliographic Details
Published in:Journal of geophysical research. Atmospheres 2018-05, Vol.123 (10), p.5607-5617
Main Authors: Roulston, C., Paton‐Walsh, C., Smith, T. E. L., Guérette, É.‐A., Evers, S., Yule, C. M., Rein, G., Van der Werf, G. R.
Format: Article
Language:English
Subjects:
Aerosols
Aerosols and Particles
Air quality
Airborne particulates
Ash
Atmospheric Composition and Structure
Biogeosciences
Burning
Climate models
Composition and Chemistry
Emission analysis
Emission measurements
Emissions
fire
Fires
Fuels
Geophysics
Haze
Marine Pollution
Megacities and Urban Environment
Natural Hazards
Oceanography: Biological and Chemical
Oceanography: General
Other
Paleoceanography
Particulate emissions
Particulate matter
Particulate matter emissions
Particulates
Peat
Peatlands
PM2.5
Pollution: Urban and Regional
Pollution: Urban, Regional and Global
Suspended particulate matter
Tropical climate
Troposphere: Composition and Chemistry
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Summary:Southeast Asia experiences frequent fires in fuel‐rich tropical peatlands, leading to extreme episodes of regional haze with high concentrations of fine particulate matter (PM2.5) impacting human health. In a study published recently, the first field measurements of PM2.5 emission factors for tropical peat fires showed larger emissions than from other fuel types. Here we report even higher PM2.5 emission factors, measured at newly ignited peat fires in Malaysia, suggesting that current estimates of fine particulate emissions from peat fires may be underestimated by a factor of 3 or more. In addition, we use both field and laboratory measurements of burning peat to provide the first mechanistic explanation for the high variability in PM2.5 emission factors, demonstrating that buildup of a surface ash layer causes the emissions of PM2.5 to decrease as the peat fire progresses. This finding implies that peat fires are more hazardous (in terms of aerosol emissions) when first ignited than when still burning many days later. Varying emission factors for PM2.5 also have implications for our ability to correctly model the climate and air quality impacts downwind of the peat fires. For modelers able to implement a time‐varying emission factor, we recommend an emission factor for PM2.5 from newly ignited tropical peat fires of 58 g of PM2.5 per kilogram of dry fuel consumed (g/kg), reducing exponentially at a rate of 9%/day. If the age of the fire is unknown or only a single value may be used, we recommend an average value of 24 g/kg. Plain Language Summary This paper provides evidence that peat fire emissions of fine particulates are much larger than for other fires when the peat is newly ignited but decrease rapidly as the fire progresses. This is important because it means that newly ignited fires are particularly detrimental to ambient air quality in impacted regions. Key Points In this study we show that emissions of PM2.5 from Malaysian peat fires are likely 3 times larger than previously assumed We show that the emissions of fine particulate matter from peat fires in the field decrease rapidly with the age of the fire We show that the likely cause is the accumulation of an ash layer as the peat burns below the surface
ISSN:2169-897X
2169-8996
DOI:10.1029/2017JD027827