Tropical peat fire emissions: 2019 field measurements in Sumatra and Borneo and synthesis with previous studies (original) (raw)
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Atmospheric Chemistry and Physics Discussions, 2016
Peat fires in Southeast Asia have become a major annual source of trace gases and particles to the regional-global atmosphere. The assessment of their influence on atmospheric chemistry, climate, air quality, and health has been uncertain partly due to a lack of field measurements of the smoke characteristics. During the strong 2015 El Niño event we deployed a mobile smoke sampling team in the Indonesian province of Central Kalimantan on the island of Borneo and made the first, or rare, field measurements of trace gases, aerosol optical properties, and aerosol mass emissions for authentic peat fires burning at various depths in different peat types. This paper reports the trace gas and aerosol measurements obtained by Fourier transform infrared spectroscopy, whole air sampling, photoacoustic extinctiometers (405 and 870 nm), and a small subset of the data from analyses of particulate filters. The trace gas measurements provide emission factors (EFs, g compound per kg biomass ...
Peat-fire-related air pollution in Central Kalimantan, Indonesia
Environmental Pollution, 2014
The past decade marked record high air pollution episodes in Indonesia. In this study, we specifically focus on vegetation fires in Palangkaraya located near a Mega Rice Project area in Indonesia. We analyzed various gaseous air pollution data such as particulate matter (PM10), SO 2 , CO, O 3 , and NO 2 study region. We also conducted elemental analysis at two different sites. Results from 2001-2010 suggested the longest hazardous air pollution episode during 2002 lasting about 80 days from mid-August to late-October. Maximum peak concentrations of PM10, SO 2 , CO, and O 3 were also observed during 2002 and their values reached 1905, 85.8, 38.3, and 1003 10-6 gm-3 respectively. Elemental analysis showed significant increase in concentrations during 2011 and 2010. Satellite retrieved fires and weather data could explain most of the temporal variations. Our results highlight peat fires as a major contributor of photochemical smog and air pollution in the region.
Remote Sensing
Deforestation and draining of the peatlands in equatorial SE Asia has greatly increased their flammability, and in September-October 2015 a strong El Niño-related drought led to further drying and to widespread burning across parts of Indonesia, primarily on Kalimantan and Sumatra. These fires resulted in some of the worst sustained outdoor air pollution ever recorded, with atmospheric particulate matter (PM) concentrations exceeding those considered "extremely hazardous to health" by up to an order of magnitude. Here we report unique in situ air quality data and tropical peatland fire emissions factors (EFs) for key carbonaceous trace gases (CO 2 , CH 4 and CO) and PM 2.5 and black carbon (BC) particulates, based on measurements conducted on Kalimantan at the height of the 2015 fires, both at locations of "pure" sub-surface peat burning and spreading vegetation fires atop burning peat. PM 2.5 are the most significant smoke constituent in terms of human health impacts, and we find in situ PM 2.5 emissions factors for pure peat burning to be 17.8 to 22.3 g•kg −1 , and for spreading vegetation fires atop burning peat 44 to 61 g•kg −1 , both far higher than past laboratory burning of tropical peat has suggested. The latter are some of the highest PM 2.5 emissions factors measured worldwide. Using our peatland CO 2 , CH 4 and CO emissions factors (1779 ± 55 g•kg −1 , 238 ± 36 g•kg −1 , and 7.8 ± 2.3 g•kg −1 respectively) alongside in situ measured peat carbon content (610 ± 47 g-C•kg −1) we provide a new 358 Tg (± 30%) fuel consumption estimate for the 2015 Indonesian fires, which is less than that provided by the GFEDv4.1s and GFASv1.2 global fire emissions inventories by 23% and 34% respectively, and which due to our lower EF CH4 produces far less (~3×) methane. However, our mean in situ derived EF PM2.5 for these extreme tropical peatland fires (28 ± 6 g•kg −1) is far higher than current emissions inventories assume, resulting in our total
Revised estimate of particulate emissions from Indonesian peat fires in 2015
Atmospheric Chemistry and Physics Discussions
Indonesia contains large areas of peatland which are being drained and cleared of natural vegetation, making them susceptible to burning. Peat fires emit considerable amounts of carbon dioxide, particulate matter (PM) and other trace gases, contributing to climate change and causing regional air pollution. However emissions from peat fires are uncertain due to uncertainties in emission factors and burn depth of peat. We used the Weather Research and Forecasting model with chemistry, and measurements of PM concentrations to constrain PM emissions from Indonesian fires during 2015, one of the largest fire seasons in recent decades. We estimate PM2.5 (particles with diameters less than 2.5 μm) emissions from fires across Sumatra and Borneo during September to October 2015 were 7.33 Tg, a factor 3.5 greater than those in Fire Inventory from NCAR (FINNv1.5), which does not include peat burning. We estimate similar dry fuel consumption and CO2 emissions to those in
Fires in tropical peatlands account for >25% of estimated total greenhouse gas emissions from deforestation and degradation. Despite significant global and regional impacts, our understanding of specific gaseous fire emission factors (EFs) from tropical peat burning is limited to a handful of studies. Furthermore, there is substantial variability in EFs between sampled fires and/or studies. For example, methane EFs vary by 91% between studies. Here we present new fire EFs for the tropical peatland ecosystem; the first EFs measured for Malaysian peatlands, and only the second comprehensive study of EFs in this crucial environment. During August 2015 (under El Niño conditions) and July 2016, we embarked on field campaigns to measure gaseous emissions at multiple peatland fires burning on deforested land in Southeast Pahang (2015) and oil palm plantations in North Selangor (2016), Peninsula Malaysia. Gaseous emissions were measured using open-path Fourier transform infrared spectroscopy. The IR spectra were used to retrieve mole fractions of 12 different gases present within the smoke (including carbon dioxide and methane), and these measurements used to calculate EFs. Peat samples were taken at each burn site for physicochemical analysis and to explore possible relationships between specific physicochemical properties and fire EFs. Here we present the first evidence to indicate that substrate bulk density affects methane fire EFs reported here. This novel explanation of interplume, within-biome variability, should be considered by those undertaking greenhouse gas accounting and haze forecasting in this region and is of importance to peatland management, particularly with respect to artificial compaction.
Fine Particle Emissions From Tropical Peat Fires Decrease Rapidly With Time Since Ignition
Journal of Geophysical Research: Atmospheres, 2018
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 th...
Proceedings of the National Academy of Sciences, 2018
Significance We report radiocarbon ( 14 C) measurements of carbonaceous aerosol originating from fires on the islands of Sumatra and Borneo. These data provide information about what types of ecosystems burned and are critical for linking the human health effects of fires to the anthropogenic build-up of atmospheric CO 2 . Our measurements confirm that peat emissions were the dominant source of aerosols in Singapore during the 2015 El Niño and provide a means for monitoring the success of policies designed to protect peatland areas during future drought events.