Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 5607-5617 |
| Number of pages | 11 |
| Journal | Journal of Geophysical Research: Atmospheres |
| Volume | 123 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - 27 May 2018 |
Funding
Enormous thanks are due to Professor Cathy Yule’s family for providing space for the “pop-up haze laboratory” in their backyard and coping with the copious amounts of smoke that resulted. Thanks are also due to Jessa H. Thurman for helping out with the last of the bulk density weighing when Chris got sick and to Olivia Pang for help in collecting peat samples. Grateful thanks are also due to colleagues at the New South Wales Office of Environment and Heritage (particularly John Kirkwood and Matt Riley) for lending us equipment and for helping with calibrations of the CO analyzer. Thanks also to Melita Keywood of CSIRO for equipment loans. This research was supported by a University of Wollongong small grant and an Australian Government Research Training Program (RTP) scholarship. Stephanie Evers’ travel allowance was supported by the LJMU Faculty of Science ECR Development and Collaboration Fund. Finally, we thank Bob Yokelson and all the anonymous reviewers of this manuscript and Kathryn Emmerson and Christine Cowie for their helpful comments to improve this paper. The data collected in this study are available in the supporting information provided. This paper is based on Christopher Roulston’s MSc project. He contributed to the project logistics, experimental design, all field-work, all experimental burns, troubleshooting, data analysis, QA/QC and calibrations, scientific interpretation, and editing. Clare Paton-Walsh (Murphy) wrote the paper and contributed to the experimental design, some fieldwork, most of the experimental burns, troubleshooting, data analysis, QA/QC and calibrations, and scientific interpretation. Thomas Smith conceived of and led the project, took care of most of the logistics, and contributed to the experimental design, all fieldwork, all experimental burns, troubleshooting, scientific interpretation, and editing. Élise-Andrée Guérette contributed to the data analysis, QA/QC and calibrations, and editing. Stephanie Evers led the carbon and nitrogen analysis and contributed to data analysis and editing. Cathy Yule provided expert knowledge of peat fires and their impacts and contributed to logistics and editing. Guillermo Rein contributed to the design of the experimental burns/ignition strategy, scientific interpretation, and editing. Guillermo Rein was funded by the European Research Council (ERC) Consolidator Grant HAZE (682587). Guido van der Werf contributed to the assessment of the impact of the study results on global carbon budgets, regional emissions, and likely impact on human health.
| Funders | Funder number |
|---|---|
| Australian Government Research Training Program | |
| RTP | |
| Horizon 2020 Framework Programme | 682587 |
| European Research Council | |
| University of Wollongong |
Keywords
- 5
- PM2
- emissions
- fire
- peat
