Alpine snowpit profiles of polar organic compounds from Mt. Tateyama central Japan: Atmospheric transport of organic pollutants with Asian dust
Alpine snowpit profiles of polar organic compounds from Mt. Tateyama central Japan: Atmospheric transport of organic pollutants with Asian dust
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DOI：
10.1016/j.atmosenv.2020.117923
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发表时间：
2021-01
影响因子：
5
通讯作者：
Ambarish Pokhrel;K. Kawamura;E. Tachibana;B. Kunwar;Kazuma Aoki
中科院分区：
文献类型：
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作者：
Ambarish Pokhrel;K. Kawamura;E. Tachibana;B. Kunwar;Kazuma Aoki
2008年4月19日，从室户-平（36.58°N，137.60°E，海拔2450 m）的雪坑序列（深度6.60 m）中采集了雪坑样本（n = 10）。山立山（海拔3015米），日本中部。首次在该雪坑序列中测定了低分子量二元酸、ω-含氧酸、异辛酸和α-二羰基化合物。高浓度的短链二酸（C2-C5），观察到在尘土飞扬的雪比非尘土飞扬的雪样品。较长链的二元酸（C7-C12）在颗粒状和尘状雪样品中很重要。芳香族和脂肪族不饱和二元酸在冬季沉积的微尘层中浓度较高。除干净层外，二酸的分子分布的特征在于草酸（C2，平均值，20 ± 22 ng/g-雪）占主导地位，其次是琥珀酸（C4，7.2 ± 5.9 ng/g -雪）和丙二酸（C3，3.3 ± 2.9 ng/g -雪）。较低的C3/C4比值（0.46）表明，有机气溶胶是相当新鲜的，没有严重的光化学老化在日本中部的长距离传输。多尘雪中次生物种的浓度高于非多尘雪，这主要归因于非均相反应。异戊二烯、芳香酸和脂肪酸的云内氧化产物的强相关性表明，缩合、氧化和光解是形成二元酸的重要反应机制。中国的黄土（科萨颗粒）和蒙古戈壁沙漠的灰尘为极性有机化合物提供了表面积，在对流层低层中传播了数千公里，雪变质改变了二元酸和相关化合物的化学成分。
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/C4ratios (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.