Alpine snowpit profiles of polar organic compounds from Mt. Tateyama central Japan: Atmospheric transport of organic pollutants with Asian dust. (1st January 2021)

• Record Type: Journal Article
• Authors: Pokhrel, Ambarish; Kawamura, Kimitaka; Tachibana, Eri; Kunwar, Bhagawati; Aoki, Kazuma
• Is Part Of: Atmospheric environment. Volume 244(2021)
• Publication Date: 2021-01-01
• Subjects: Diacids -- Incloud isoprene oxidation -- Snowpit -- Asian dust -- Transboundary pollution; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2020.117923
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: Snowpit samples (n = 10) were collected (19 April 2008) from the snowpit sequences (depth 6.60 m) at the Murodo-Daira site (36.58°N, 137.60°E, elevation of 2450 m a.s.l.) of Mt. Tateyama (3015 m a.s.l.), central Japan. The first time, low molecular weight diacids, ω-oxoacids, pyruvic acid, and α-dicarbonyls were measured for this snowpit sequence. Higher concentrations of short-chain diacids (C2 –C5 ) are observed in dusty snow than non-dusty snow samples. Longer chain diacids (C7 –C12 ) are significant in granular and dusty snow samples. Aromatic and aliphatic unsaturated diacids showed higher concentrations in the slightly dusty layer deposited in winter. Except for a clean layer, molecular distributions of diacids are characterized by the predominance of oxalic acid (C2, ave, 20 ± 22 ng/g-snow) followed by succinic (C4, 7.2 ± 5.9 ng/g -snow), and malonic acids (C3, 3.3 ± 2.9 ng/g -snow) for all the snow layers. Lower C3 /C4 ratios (0.46) suggest that organic aerosols are rather fresh without serious photochemical aging during the long-range transport over central Japan. The higher concentrations of the secondary species in dusty snow than non-dusty samples were mainly attributed to the heterogeneous reaction. The strong correlations of incloud oxidation products of isoprene, aromatic acids, and fatty acids suggest that condensation, oxidation, and photolysis are important reaction mechanisms for the formation of diacids. Chinese Loess (Kosa particles) and Mongolian Gobi desert's dust provided the surface area for polar organic compounds, traveled to several thousand kilometers in the lower troposphere, and snow metamorphism altered the chemical composition of diacids and related compounds. Graphical abstract: Image 1 Highlights: Bacteria and Incloud isoprene oxidation results in the end product of dicarboxylic acids. Organic compounds are attributed to heterogeneous reactions. Atmospheric transport of diacids and oxoacids with Asian dust is important. Asian dust is not responsible for the atmospheric photochemical processing of organics. Snow metamorphism may play an important role in these organic compounds (fresh organic compounds are well captured).