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Forest fires in peatlands emit pollutants to the atmosphere, affecting public health. Though air quality data and epidemiology information are helpful in the management of the environment and public health, they are not always available. We aimed to reveal the utility of newspaper articles for estimating the public health concerns posed by air pollution. Using the database of a local newspaper, Riau Pos, in Riau Province of Sumatra, Indonesia, we have studied spatiotemporal correlations between publication frequency of newspaper articles mentioning search terms relevant to health issues and Fire Radiation Power (FRP) of peatland fires. FRP from one of the NASA satellite databases has been used as an index of air pollution caused by peatland fires. Visibility data for airport operation were also used as an index of particulate matter concentrations. The study regions are primarily the fire-prone Riau Province and nearby areas in the central area of Sumatra, Indonesia, from 2009 to 2018. Newspaper articles related to public health are found to be associated with FRP and visibility, or regional air pollution.

学位の種別: 課程博士, 審査委員会委員 : （主査）東京大学教授 戸野倉 賢一, 東京大学教授 大島 義人, 東京大学教授 徳永 朋祥, 東京大学准教授 井原 智彦, 京都大学准教授 甲山 治

Tropical peatlands in Indonesia have been disturbed over decades and are a source of carbon dioxide (CO2) into the atmosphere by peat respiration and peatland fire. With a portable solar spectrometer, we have performed measurements of column-averaged CO2 dry-air molar mixing ratios, XCO2, in Palangka Raya, Indonesia, and quantify the emission dynamics of the peatland with use of the data for weather, fire hotspot, ground water table, local airport operation visibility and weather radar images. Total emission of CO2 from surface and underground peat fires as well as from peatland ecosystem is evaluated by day-to-day variability of XCO2. We found that the peatland fire and the net ecosystem CO2 exchange contributed with the same order of magnitude to the CO2 emission during the non-El Niño Southern Oscillation year of July 2014-August 2015.

Smoke emitted from Indonesian peatland fires has caused dense haze and serious air pollution in Southeast Asia such as visibility impairment and adverse health impacts. To mitigate the Indonesian peatland fire aerosol impacts, an effective strategy and international framework based on the latest scientific knowledge needs to be established. Although several attempts have been made, limited data exist regarding the chemical characteristics of peatland fire smoke for the source apportionment. In order to identify the key organic compounds of peatland fire aerosols, we conducted intensive field studies based on ground-based and source-dominated sampling of PM 2.5 in Riau Province, Sumatra, Indonesia, during the peatland fire seasons in 2012. Levoglucosan was the most abundant compound among the quantified organic compounds at 8.98 ± 2.28% of the PM 2.5 mass, followed by palmitic acid at 0.782 ± 0.163% and mannosan at 0.607 ± 0.0861%. Potassium ion was not appropriate for an indicator of Indonesian peatland fires due to extremely low concentrations associated with smoldering fire at low temperatures. The vanillic/syringic acids ratio was 1.06 ± 0.155 in this study and this may be a useful signature profile for peatland fire emissions. Particulate n -alkanes also have potential for markers to identify impact of Indonesian peatland fire source at a receptor site.

Biomass burning is a significant source of fine particulate matter (PM2.5). Forest, bush, and peat fires in Kalimantan and Sumatra, Indonesia are major sources of transboundary haze pollution in Southeast Asia. However, limited data exist regarding the chemical characteristics of aerosols at sources. We conducted intensive field studies in Riau Province, Sumatra, Indonesia, during the peatland fire and non-burning seasons in 2012. We characterized PM2.5 carbonaceous aerosols emitted from peatland fire based on ground-based source-dominated sampling. PM2.5 aerosols were collected with two mini-volume samplers using Teflon and quartz fiber filters. Background aerosols were also sampled during the transition period between the non-burning and fire seasons. We analyzed the carbonaceous content (organic carbon (OC) and elemental carbon (EC)) by a thermal optical reflectance utilizing the IMPROVE_A protocol and the major organic components of the aerosols by a gas chromatography/mass spectrometry. PM2.5 aerosols emitted from peatland fire were observed in high concentrations of 7120 ± 3620 μg m−3 and were primarily composed of OC (71.0 ± 5.11% of PM2.5 mass). Levoglucosan exhibited the highest total ion current and was present at concentrations of 464 ± 183 μg m−3. The OC/EC ratios (36.4 ± 9.08), abundances of eight thermally-derived carbon fractions, OC/Levoglucosan ratios (10.6 ± 1.96), and Levoglucosan/Mannosan ratios (10.6 ± 2.03) represent a signature profile that is inherent in peatland fire. These data will be useful in identifying contributions from single or multiple species in atmospheric aerosol samples collected from peatland fires.

Evaluation of CO2 flux from peatland soil respiration is important to understand the effect of land use change on the global carbon cycle and climate change and particularly to support carbon emission reduction policies. However, quantitative estimation of emitted CO2 fluxes in Indonesia is constrained by existing field data. Current methods for CO2 measurement are limited by high initial cost, manpower, and the difficulties associated with construction issues. Measurement campaigns were performed using a newly developed nocturnal temperature-inversion trap method, which measures the amount of CO2 trapped beneath the nocturnal inversion layer, in the dry season of 2013 at a drained tropical peatland near Palangkaraya, Central Kalimantan, Indonesia. This method is cost-effective and data processing is easier than other flux estimation methods. We compared CO2 fluxes measured using this method with the published data from the existing eddy covariance and closed chamber methods. The maximum value of our measurement results was 10% lower than maximum value of eddy covariance method and average value was 6% higher than average of chamber method in drained tropical peatlands. In addition, the measurement results shows good correlation with groundwater table. The results of this comparison suggest that this methodology for the CO2 flux measurement is useful for field research in tropical peatlands.