Tropical peat fire emissions: 2019 field measurements in Sumatra and Borneo and synthesis with previous studies
Year: 2022
Type: article
Abstract: . Peat fires in Southeast Asia are a major source of trace gases and particles to the regional-global atmosphere that influence atmospheric chemistry, climate, and air quality. During the 2015 November record-high Ocean Niño Index (ONI, 2.6) our mobile smoke sampling team made the first, or rare, field measurements of numerous trace gases, aerosol optical properties, and aerosol chemistry and mass emissions for fires burning only peat in the Indonesian province of Central Kalimantan (on the island of Borneo). The measurements used Fourier transform infrared spectroscopy (FTIR), whole air sampling (WAS), photoacoustic extinctiometers (PAX, 401 and 870 nm), and detailed off-line analyses of particulate matter (PM) collected on filters. In September–November 2019 we measured peat fire trace gas emissions again, using WAS only, under ENSO-neutral conditions (ONI, 0.3) in more remote areas of Central Kalimantan and also the Indonesian provinces of Riau, Jambi, and South Sumatra, all on the island of Sumatra. The 2019 measurements significantly expanded the geographic range and climate conditions sampled. This paper presents the 2019 results and synthesizes them with the previous field work to converge on more robust regional average emission factors (EFs, g compound per kg biomass burned) for authentic peat fires. In addition, samples of peat imported from Indonesia were burned in U.S. laboratories and the EFs and optical properties were characterized in more detail than in the field by a larger suite of instrumentation. We use the improved knowledge of regional emissions based on the expanded field measurements to select the most representative lab data and compute a synthesized, more “chemically-complete” set of EFs and aerosol optical properties for tropical peat fires. The modified combustion efficiency (MCE) values for the peat smoke sampled in 2019 were within the range of MCEs sampled in 2015, but with a lower average in 2019 (0.718 ± 0.021, range 0.687–0.736) than 2015 (0.772 ± 0.035, range 0.693–0.835). Averaging the new and older data together suggests an updated MCE for tropical peat fires of ~0.76. Despite the difference in MCE, the study-average methane emission factors (EF CH4) were remarkably similar across the two years probing different regions: 9.42 ± 2.51 g kg-1 in 2019 and 9.51 ± 4.74 g kg-1 in 2015. When parsing the 2019 samples by province, the EFs for non-methane organic gases (NMOG) were about 3 times higher in South Sumatra and Central Kalimantan than in Jambi and Riau, but the overall 2019 study average was only ~15 % higher than the 2015 study average. South Sumatra peat fires emitted higher amounts of carbonyl and dimethyl sulfide, suggesting a volcanic or marine influence or effects of agricultural chemicals. The lab and field work taken together provide EFs for 230 trace gases including CO2 (1538 g kg-1), CO (305 g kg-1), and CH4 (10.3 g kg-1). These are significant adjustments to IPCC-recommended EFs, -10 %, +45 %, and -49 %, respectively. We also report EFs for numerous NMOG, 46 N-containing compounds, and 14 sulfur or halogen-containing species. The use of high-resolution mass spectrometry in the lab allowed measurement of 82 % more NMOG mass than in the field. Gravimetrically measured EF PM2.5 in the field in 2015 (17.3 ± 5.8 g kg-1) was ~20 % lower than the average from lab studies (22.4 ± 10.4 g kg-1) perhaps due to higher field temperatures. Taken together the lab and field data show that the single scattering albedo (SSA) was largely independent of wavelength and MCE in the visible (~0.998), but lower at low MCE at 401 and 405 nm with a value of 0.958 at the study-average MCE. The absorption Ångstrӧm exponent (AAE) at the average MCE was 5.7. By far the largest PM component was weakly-absorbing insoluble organic carbon.
Authors: Robert J. Yokelson, Bambang H. Saharjo, Chelsea E. Stockwell, Erianto I. Putra, Thilina Jayarathne, Acep Akbar, Israr Albar, Donald R. Blake, Laura L. B. Graham, Agus Kurniawan, Simone Meinardi, Diah Ningrum, Ati D. Nurhayati, Asmadi Saad, Niken Sakuntaladewi, Eko Setianto, Isobel J. Simpson, Elizabeth A. Stone, Sigit Sutikno, Andri Thomas, Kevin C. Ryan, Mark A. Cochrane
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $1,725
Awards: Collaborative Research: Measurements of Selected Combustion Emissions in Nepal and Bhutan Integrated with Source Apportionment and Chemical Transport Modeling for South Asia, PROJECT SUMMARY: BECAUSE OF EPISODIC UNCONTROLLED FIRES WITHIN DRAINED PEAT-SWAMP FORESTS INDONESIA IS RANKED THE 4TH LARGEST CO2EMITTER OVER THE LAST HALF CENTURY. THE FORMER 1 MILLION HECTARE MEGA RICE PROJECT (MRP) DESIGNED TO CONVERT EXTENSIVE PEAT LANDSINTO FARM LANDS IS A MAJOR EMISSIONS SOURCE. DEEP ORGANIC SOILS STORING VAST AMOUNTS OF CARBON ARE NOW BEING LOST TO DECOMPOSITIONAND COMBUSTION. THE 120 000 HA KALIMANTAN FORESTS AND CLIMATE PARTNERSHIP (KFCP) REDUCED EMISSIONS FROM DEFORESTATIONAND FOREST DEGRADATION (REDD+) PROJECT IS WITHIN THE FORMER MRP. IN COLLABORATION WITH THE INDONESIAN GOVERNMENT S FORESTRYRESEARCH AND DEVELOPMENT AGENCY (FORDA) WE WILL DEVELOP A PROTOTYPE PEAT-FIRE EMISSIONS MODULE FOR KFCP TO INCORPORATE INTOTHE INDONESIAN NATIONAL CARBON ACCOUNTING SYSTEM (INCAS). THIS CAPACITY WILL ENABLE ANNUAL QUANTIFICATION OF FIRE-RELATED EMISSIONS.OUR RESEARCH PROJECT WILL UTILIZE LANDSAT AND MODIS DATA AND PRODUCTS TO QUANTIFY LAND COVER CHANGES BURNED AREA AND ESTIMATE THETIMING OF FIRE ACTIVITY. WE WILL INCORPORATE TRMM DATA FOR RELATING PRECIPITATION HISTORY TO THE TIMING OF OBSERVED WATER TABLE CHANGESTHAT IMPACT PEAT-FIRE ACTIVITY AT KFCP. WE WILL INTEGRATE SATELLITE DATA WITH EXISTING AERIAL KFCP LIDAR (2007&2010) AND PROPOSEA REPEAT LIDAR COLLECTION DURING THE STUDY TO PROVIDE QUANTIFIED TEMPORAL TOPOGRAPHIC CHANGE MAPS TO VALIDATE OUR MODELED RESULTSOF FIRE-RELATED PEAT CONSUMPTION. THIS PROJECT WILL LEVERAGE THE EXTENSIVE AND ONGOING DATA COLLECTION EFFORTS FOR HYDROLOGY FUELS LAND USES AND FIRE OCCURRENCE AT KFCP WITH OUR INITIAL FIELD WORK AND LABORATORY TESTING OF REGIONAL PEAT COMBUSTION AND EMISSIONCHARACTERISTICS TO PROVIDE GUIDED FIELD TESTING OF BACKGROUND AND FIRE-RELATED CARBON EMISSION RATES AND TYPES (E.G. METHANE CO2 CO PARTICULATES OTHER) DURING EL NINO AND NON-EL NINO YEARS AS AVAILABLE. THROUGH GROUNDBREAKING EMISSIONS FIELD SAMPLING OFIN-SITU SMOLDERING SURFACE SHALLOW (<20 CM) AND DEEP (>20 CM) PEAT FIRES WITH ON-SITE GAS CHROMATOGRAPHY FOR QUANTIFYING REACTIVESPECIES WHOLE AIR SAMPLING FOR PRECISE LAB MEASUREMENTS OF NON-REACTIVE GASES AND SIMULTANEOUS FILTER SAMPLING OF PARTICULATES WEWILL CREATE COMPREHENSIVE AND PERTINENT EMISSIONS FACTORS (EFS) THAT WILL BE CRITICALLY IMPORTANT FOR ASSESSING THE HEALTH IMPACTS ANDTOTAL GLOBAL WARMING POTENTIAL (GWP) OF THESE EMISSIONS. IN OUR INTERDISCIPLINARY RESEARCH WE WILL INVESTIGATE THE CHAINS OF SOCIALAND BIO-PHYSICAL EVENTS LEADING TO THESE DEEP-PEAT FIRES INTEGRATING FIRE SCENE ANALYSES WITH SOCIAL DATA TO DESCRIBE WHEN WHERE HOW AND UNDER WHAT CONDITIONS FIRES WITHIN KFCP HAVE OCCURRED SO THAT MORE EFFECTIVE MITIGATION STRATEGIES CAN BE DEVELOPED IN THEFUTURE. ACCURATE ACCOUNTING OF PEAT-FIRE CARBON EMISSIONS REQUIRES UNDERSTANDING HOW THEIR PRESENCE DEPTH OF BURNING AND SPREADRATES RELATE TO THE INTERPLAY OF CLIMATE WEATHER LAND USE LAND COVER DRAINAGE STATUS DISTURBANCE HISTORY FIRE TYPE PEAT DEPTH ANDCOMPOSITION. MODELING THIS PHENOMENON REQUIRES DEFINING 1) THE ANNUAL SURFACE AREA BURNED 2) THE AVAILABLE FUEL FRACTION (BURNABLE)AT EACH LOCATION THROUGH TIME AND 3) THE AMOUNT OF FUEL CONSUMED PER UNIT AREA. WE WILL IMPLEMENT A MODELING APPROACH THAT INITIALLYUSES EXISTING DATA ON THE PEAT HYDROLOGY CLIMATE LAND COVER BURNED AREA TIMING OF IGNITIONS AND FUEL LOADS TO STOCHASTICALLY PROVIDEPEAT FIRE PROBABILITY AND PARAMETERIZE DEPTH AND AREA BURNED FROM THE 2007 LIDAR DATA. THIS INITIAL MODEL WILL BE USED TO PROJECT THEEXPECTED AREA TYPE AND DEPTH OF BURNING FROM 2007-2011 AND THEN CHECKED AGAINST THE 2011 LIDAR DATA SET TO REFINE CALIBRATION OF THEMODELED PARAMETERS. THE THIRD MODELING PHASE WILL PROVIDE MONTE CARLO ESTIMATES OF TYPE DEPTH AND AREA OF BURNING WITH EMISSIONSQUANTITATIVELY WEIGHTED BY APPROPRIATE EFS DERIVED FOR SURFACE SHALLOW AND DEEP PEAT SMOKE AMOUNTS THAT WILL BE VALIDATED USING THEPROPOSED THIRD LIDAR DA, BIOMASS BURNING IS THE LARGEST GLOBAL SOURCE OF PRIMARY FINE ORGANIC AEROSOL (~50 TG/YR) AND THE SECOND LARGEST SOURCE OF REACTIVE NON-METHANE ORGANI, G8821539619
OpenAlex ID: W4292401805