Comprehensive PM2.5 Organic Molecular Composition and Stable Carbon Isotope Ratios at Sonla, Vietnam: Fingerprint of Biomass Burning Components

Abstract

This study presents measurements of aerosol chemical properties at Sonla, northern Vietnam (675 m a.s.l.) during spring time, when biomass burning (BB) was very active in the northern Indochina Peninsula, as part of the 7-SEAS (Seven South East Asian Studies) campaign in 2013. The gas chromatography-mass spectrometry (GC-MS) analysis of BB markers in 14 selected samples indicated that mixed softwood, hardwood, grass, and non-woody vegetation were burned. More than 50 organic compounds including levoglucosan, lignin and resin products, sugar and sugar alcohol compounds, fatty acids, phthalate esters, aromatic acids, poly-acids, and biogenic oxidation products (e.g., 2-methyltetrols, alkene triols, 3-hydroxyglutaric acid) were measured in PM 2.5 . Levoglucosan, a BB tracer, was the predominant species among aerosol sugars, with an average concentration of 1.62 ± 0.89 µg m -3 , comprising 2.23 ± 0.5% of PM 2.5 mass. For the collection period of the selected samples, backward air mass trajectories were classified into the source regions of Indochina (BBIC), southern China (BBSC), and the South China Sea (BBSS). All resolved molecular compounds show their dominance on the trajectory from BBIC, verifying the BB smoke origin of that region. Trajectory classification provides additional information, such as higher level of diethyl phthalate associated with BBSC trajectory, revealing urban or industrial influence, and more low-molecular-weight than high-molecular-weight fatty acids, indicating distributions with more microbial and lesser plant wax/vegetation burning contributions along the BBSC trajectory. In addition, we report, for the first time, stable carbon isotopic data (δ 13 C) for PM 2.5 aerosols in northern Vietnam, which ranged from -26.6 to -25.4‰ in PM 2.5 , indicating contributions from burning of C 3 plants and fossil fuel combustion.

Satellite-Surface Perspectives of Air Quality and Aerosol-Cloud Effects on the Environment: An Overview of 7-SEAS/BASELInE

“…Nguyen et al (2016) comprehensively investigated the PM 2.5 organic molecular composition and stable carbon isotope ratios of biomass-burning smoke for the first time at SL site, by using gas chromatography-mass spectrometry (GC-MS). Fourteen representative PM 2.5 samples were collected in spring of 2013 and analyzed for more than 50 organic compounds including primary (i.e., anhydrosugars, lignin and resin products, sugars, sugar alcohols, fatty acids, and phthalate esters) and secondary (i.e., aromatic acids, polyacids, and biogenic oxidation products, such as 2-methyltetrols, alkenes triols, and 3-hydroxyglutaric acid) organic aerosol components.…”

Carbonaceous aerosol composition in air masses influenced by large-scale biomass burning: a case-study in Northwestern Vietnam

“…i.e. photochemical conversion of biogenic VOC emissions (Nguyen et al, 2016). During days with medium BB influence, levoglucosan levels increased up to 1000 ng m -3 , and the excess ratio slightly decreased while being more variable.…”

“…cloud-radiation interactions prior to entering the receptor areas of Hong Kong, southeastern Tibetan Plateau or central Taiwan 45 Yen et al, 2013;Chan, 2003;Engling et al, 2011;Nguyen et al, 2016;Lee et al, 2016).…”

“…However, the source apportionment was only based on light-absorbing carbon and levoglucosan concentrations. So far, very few studies (Nguyen et al, 2016;Popovicheva et al, 2016;Popovicheva et al, 2017;Pham et al, 2019) investigated the organic chemical composition of aerosol samples collected in Northwestern Vietnam during BB events in detail. We complement the analysis by Bukowiecki et al (2019) and present results from the chemical analysis of PM2.5 samples and trace gas measurements collected during the BB season in 65 2015 at PDI.…”

Influences of the Long-Range Transport of Biomass-Burning Pollutants on Surface Air Quality during 7-SEAS Field Campaigns

“…Additional supersites for 7-SEAS/BASELInE were located near the BB source region in Doi Angkhang, Thailand, and along the SEA BB transport pathway in Son La and Yen Bai in Vietnam . Observational data from this campaign has been used in recent studies focused on aerosols and chemistry near BB source regions Nguyen et al, 2016;Popovicheva et al, 2016), long-range transport issues Chen et al, 2016;Chuang et al, 2016) and even cloud condensation nuclei comparisons between BB source regions over Thailand and downwind receptor areas in Taiwan . In this paper, we report on the possible unique mechanism to bring the long-range transport of SEA BB pollutants down to the surface using data collected during 7-SEAS/BASELInE.…”