Size-fractionated carbonaceous aerosols down to PM0.1 in southern Thailand: Local and long-range transport effects

Worradorn Phairuang; Muanfun Inerb; Masami Furuuchi; Mitsuhiko Hata; Surajit Tekasakul; Perapong Tekasakul

doi:10.1016/j.envpol.2020.114031

Size-fractionated carbonaceous aerosols down to PM_0.1 in southern Thailand: Local and long-range transport effects

Environ Pollut. 2020 May:260:114031. doi: 10.1016/j.envpol.2020.114031. Epub 2020 Jan 21.

Authors

Worradorn Phairuang¹, Muanfun Inerb², Masami Furuuchi³, Mitsuhiko Hata⁴, Surajit Tekasakul⁵, Perapong Tekasakul⁶

Affiliations

¹ Faculty of Environmental Management, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand; Air Pollution and Health Effect Research Center, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand. Electronic address: worradorn@gmail.com.
² Faculty of Environmental Management, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand.
³ Faculty of Environmental Management, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand; Faculty of Geoscience and Civil Engineering, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan.
⁴ Faculty of Geoscience and Civil Engineering, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan.
⁵ Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand.
⁶ Air Pollution and Health Effect Research Center, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand; Department of Mechanical Engineering, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand.

PMID: 32014745
DOI: 10.1016/j.envpol.2020.114031

Abstract

In this study, size-fractionated particulate matters (PM) down to ultrafine (PM_0.1) particles were collected using a cascade air sampler with a PM_0.1 stage, in Hat Yai city, Songkhla province, southern Thailand during the year 2018. The particle-bound carbonaceous aerosols (CA) as elemental carbon (EC) and organic carbon (OC) were quantified with the thermal/optical reflectance method following the IMPROVE_TOR protocol. The concentrations of different temperature carbon fractions (OC1-OC4, EC1-EC3 and PyO) in the size-fractionated PM were evaluated to discern OC and EC correlations as well as those between char-EC and soot-EC. The results showed that biomass burning, motor vehicle, and secondary organic aerosols (SOC) all contributed to the size-fractionated PM. The OC/EC ratios ranged from 2.90 to 4.30 over the year, with the ratios of PM_2.5-10 being the highest, except during the open biomass burning period. The concentration of CA was found to increase during the pre-monsoon season and had its peak value in the PM_0.5-1.0 fraction. The long-range transport of PMs from Indonesia, southwest of Thailand toward southern Thailand became more obvious during the pre-monsoon season. Transported plumes from biomass burning in Indonesia may increase the concentration of OC and EC both in the fine (PM_0.5-1.0 and PM_1.0-2.5) and coarse (PM_2.5-10 and PM_>10) fractions. The OC fraction in PM_0.1 was also shown to be significantly affected by the transported plumes during the pre-monsoon season. Good OC and EC correlations (R² = 0.824-0.915) in the fine particle fractions indicated that they had common sources such as fossil fuel combustion. However, the lower and moderate correlations (R² = 0.093-0.678) among the coarser particles suggesting that they have a more complex pattern of emission sources during the dry and monsoon seasons. This indicates the importance of focusing emission control strategies on different PM particle sizes in southern Thailand.

Keywords: Air mass; Biomass burning; Carbon; PM(0.1); Transboundary.

MeSH terms

Aerosols
Air Pollutants*
Biomass
Carbon
Cities
Environmental Monitoring*
Indonesia
Particle Size
Particulate Matter*
Seasons
Thailand

Substances

Aerosols
Air Pollutants
Particulate Matter
Carbon