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2 results on '"Chaiyoth Sresawasd"'

1. Influence of Meteorological Conditions and Fire Hotspots on PM0.1 in Northern Thailand during Strong Haze Episodes and Carbonaceous Aerosol Characterization

Author

Chaiyoth Sresawasd, Thaneeya Chetiyanukornkul, Phuchiwan Suriyawong, Surajit Tekasakul, Masami Furuuchi, Mitsuhiko Hata, Rachane Malinee, Perapong Tekasakul, and Racha Dejchanchaiwong

Subjects
Ultrafine particles, Carbonaceous aerosols, Forest fire, Source identification, ASEAN haze, Science
Abstract

Abstract Northern Thailand has long been severely affected by haze from biomass burning containing fine and ultrafine aerosols in the dry period. The carbonaceous PM0.1 comprising elemental carbon (EC) and organic carbon (OC) collected during the haze and non-haze periods in Chiang Mai, Thailand was investigated. The PM0.1 levels during the haze periods were about 3 times higher than the non-haze periods, a significant increase. PM0.1 concentration was strongly correlated with atmospheric relative humidity and the number of forest fire hotspots. Carbonaceous aerosol characteristics in PM0.1 were analyzed with the thermal/optical transmittance (TOT) method following the IMPROVE protocol. The concentrations of OC and EC, distribution of OC and EC and OC/EC ratios in PM0.1 were evaluated. Average OC and EC mass concentrations in PM0.1 were 6.8 ± 2.7 and 1.4 ± 0.5 µg m−3 during the haze periods, significantly higher than those during the non-haze periods; 1.9 ± 0.9 and 0.5 ± 0.2 µg m−3. The OC/EC ratio increased linearly with the number of hotspots. This indicated significant contribution from biomass burning to the PM0.1. This was strongly supported by the 48-hr backward trajectory simulation, that indicated both domestic and transboundary aerosol transports. Because both organic and elemental carbon are the light-absorbing carbonaceous aerosols, the increase during the haze periods contributed to regional air quality and climate. This study enhances the understanding of PM0.1 behavior in Chiang Mai, Thailand, during the haze periods in upper southeast Asia.

Published
2021
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2. Impact of transport of fine and ultrafine particles from open biomass burning on air quality during 2019 Bangkok haze episode

Author

Racha Dejchanchaiwong, Kunchira Thongboon, Thunyapat Thongyen, Chaiyoth Sresawasd, Worradorn Phairuang, Panwadee Suwattiga, Surajit Tekasakul, Nobchonnee Nim, and Perapong Tekasakul

Subjects
Environmental Engineering, Haze, 010504 meteorology & atmospheric sciences, 010501 environmental sciences, 01 natural sciences, chemistry.chemical_compound, Air Pollution, Ultrafine particle, Humans, Environmental Chemistry, Biomass, Particle Size, Air quality index, 0105 earth and related environmental sciences, General Environmental Science, Morning, Aerosols, Total organic carbon, Air Pollutants, General Medicine, Particulates, Thailand, Carbon, Aerosol, chemistry, Environmental chemistry, Pyrene, Environmental science, Particulate Matter, Seasons, Environmental Monitoring
Abstract

Transboundary and domestic aerosol transport during 2018–2019 affecting Bangkok air quality has been investigated. Physicochemical characteristics of size-segregated ambient particles down to nano-particles collected during 2017 non-haze and 2018–2019 haze periods were analyzed. The average PM2.5 concentrations at KU and KMUTNB sites in Bangkok, Thailand during the haze periods were about 4 times higher than in non-haze periods. The highest average organic carbon and elemental carbon concentrations were 4.6 ± 2.1 µg/m3 and 1.0 ± 0.4 µg/m3, respectively, in PM0.5–1.0 range at KU site. The values of OC/EC and char-EC/soot-EC ratios in accumulation mode particles suggested the significant influence of biomass burning, while the nuclei and coarse mode particles were from mixed sources. PAH concentrations during 2018–2019 haze period at KU and KMUTNB were 3.4 ± 0.9 ng/m3 and 1.8 ± 0.2 ng/m3, respectively. The PAH diagnostic ratio of PM2.5 also suggested the main contributions were from biomass combustion. This is supported by the 48-hrs backward trajectory simulation. The higher PM2.5 concentrations during 2018–2019 haze period are also associated with the meteorological conditions that induce thermal inversions and weak winds in the morning and evening. Average values of benzo(a)pyrene toxic equivalency quotient during haze period were about 3–6 times higher than during non-haze period. This should raise a concern of potential human health risk in Bangkok and vicinity exposing to fine and ultrafine particulate matters in addition to regular exposure to traffic emission.

Published
2020
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