- Dona Paula, Goa, India.
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Abstract Submission No. | ABS-2022-08-0044 |
Title of Abstract | Biomass burning derived organic aerosols over the Arabian Sea: insights from the molecular distributions and relative abundances of sugar compounds |
Authors | Poonam Bikkina*, Kimitaka Kawamura |
Organisation | CSIR-National Institute of Oceanography, Goa |
Address | ptyagi@nio.org North Goa, Goa, India Pincode: 4.03004 Mobile: 7675015797 E-mail: ptyagi@nio.org |
Country | India |
Presentation | Oral |
Abstract | Biomass burning (BB) is a significant source of atmospheric organic aerosols (OA) over the marine basins that are downwind of the continental outflows. To assess the impact of BB, we measured three classes of BB organic aerosols (BBOA) including anhydrosugars (levoglucosan: Lev, galactosan: Gal, and mannosan: Man), sugars (glucose, fructose, sucrose, and trehalose) and sugar alcohols (arabitol, mannitol, erythritol and inositol) in wintertime aerosols collected over the Arabian Sea (SS379: 6-25 December 2018). Molecular distributions of anhydrosugars showed the predominance of Lev (av. 121 ng m-3) followed by Man (7.5 ng m-3) and Gal (2.3 ng m-3). Besides, Lev strongly correlated with Man (r = 0.80), Gal (r = 0.91), sugar alcohols (r = 0.86) and elemental carbon (r = 0.72), indicating their common origin from biomass burning emissions. The backward air mass trajectories intercepted by the satellite-based fire counts over the Indo-Gangetic Plain and southern India together with the presence of Lev, confirming the impact of BBOA. A comparison of diagnostic mass ratios of anhydrosugars (Lev/Man ~16 vs. Lev/K+ ~0.27) in the TSP samples with those of source-emissions revealed their origin from crop-residue/hardwood burning (Lev/Man>10; Lev/K+<1). Sucrose (a tracer of atmospheric pollen particles) is the second most abundant sugar compound, whose concentration sometimes dominates the Lev levels. Arabitol strongly correlated with mannitol, erythritol and trehalose, suggesting their contribution from airborne fungal spores. Glucose correlated well with the fructose, likely because of their origin from leaf fragments, fruits and pollen particles. High mass contribution of Lev-C in organic carbon (0.2 20%) along with other primary sugars over the neritic waters of the Arabian Sea during the winter cruise further strengthen the impact of biomass burning emissions. Furthermore, basin-wide estimate of atmospheric dry-deposition of total saccharides to the Arabian Sea (25 Gg-C yr-1) is comparable with that of riverine supply (30 Gg-C yr-1). All these results emphasize the significance of atmospheric anthropogenic sugar compounds from the South Asian outflow. |