Photochemical production and loss of organic acids in high Arctic aerosols during long-range transport and polar sunrise ozone depletion events
Photochemical production and loss of organic acids in high Arctic aerosols during long-range transport and polar sunrise ozone depletion events
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DOI：
10.1016/j.atmosenv.2004.10.020
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发表时间：
2005-02
影响因子：
5
通讯作者：
K. Kawamura;Yoshie Imai;L. Barrie
中科院分区：
文献类型：
--
作者：
K. Kawamura;Yoshie Imai;L. Barrie
1992 年冬季到春季，对加拿大北极地区的 Alert 气溶胶中的水溶性有机物进行了独特的日常测量。这些测量可以深入了解极地日出后的远距离运输和臭氧消耗事件期间的光化学产生和有机物的损失。使用 GC 和 GC/MS 技术对 α, ω-二羧酸 (C2–C12)、ω-氧代羧酸 (C2–C9) 和 α-二羰基 (C2, C3) 以及丙酮酸和芳香族（邻苯二甲酸）二酸进行综合分析。草酸 (C2) 通常是细粒和粗粒馏分中的主要二酸种类，其次是丙二酸 (C3) 和琥珀酸 (C4)。细气溶胶部分 (0.2–64ngm−3) 中总二酸的浓度比粗气溶胶部分 (0.01–3ngm−3) 中的总二酸浓度高 5–60 倍。 3月初极地日出后，细气溶胶二酸的总浓度增加了3-5倍，而粗模式没有显着变化。从黑暗的冬天到阳光明媚的春天，同时测量的这些水溶性有机物与钒和硫酸盐的相关性和比率的时间变化表明，大气二酸和相关有机化合物在很大程度上受到冬季污染空气的长距离大气传输的控制，但它们受到光化学产生的显着影响。后者可能在阳光下发生，或者在运输到北极的过程中，或者在与春季阿勒特附近的地表臭氧消耗和溴化学相关的光化学事件期间发生。在极地日出时，通过光化学氧化将气态前体转化为颗粒物质的过程得到加强，导致总二酸与 V 的比率达到峰值。在臭氧消耗事件期间，光化学产生和损失的复杂模式取决于二酸化合物。不饱和（马来酸和邻苯二甲酸）二酸与颗粒 Br 呈负相关，而饱和二酸 (C2–C4) 与颗粒 Br 正相关。这些结果表明，与臭氧消耗相关的溴化学会导致不饱和二酸的降解并产生较小的饱和二酸。
Unique daily measurements of water-soluble organics in fine (<2μm) and coarse (>2μm) aerosols were conducted at Alert in the Canadian Arctic in winter to spring of 1992. They yield insight into photochemical production and loss of organics during long-range transport and ozone depletion events following polar sunrise. Comprehensive analyses of α, ω-dicarboxylic acids (C2–C12), ω-oxocarboxylic acids (C2–C9) and α-dicarbonyls (C2, C3) as well as pyruvic acid and aromatic (phthalic) diacid were conducted using GC and GC/MS techniques. Oxalic (C2) acid was generally the dominant diacid species in both fine and coarse fractions, followed by malonic (C3) and succinic (C4) acids. Concentrations of total diacids in the fine aerosol fraction (0.2–64ngm−3) were 5–60 times higher than those in the coarse fraction (0.01–3ngm−3). After polar sunrise in early-March, the total concentration of fine aerosol diacids increased by a factor of 3–5 while the coarse mode did not change significantly. From dark winter to sunlit spring, temporal changes in correlations and ratios of these water-soluble organics to vanadium and sulfate measured simultaneously suggest that atmospheric diacids and related organic compounds are largely controlled by long-range atmospheric transport of polluted air during winter, but they are significantly affected by photochemical production. The latter can occur in sunlight either during transport to the Arctic or during photochemical events associated with surface ozone depletion and bromine chemistry near Alert in spring. Conversion of gaseous precursors to particulate matter via photochemical oxidation was intensified at polar sunrise, resulting in a peak in the ratio of total diacids to V. During ozone depletion events, complex patterns are indicated in photochemical production and loss depending on the diacid compound. Unsaturated (maleic and phthalic) diacids were inversely correlated with particulate Br whereas saturated diacids (C2–C4) positively correlated with particulate Br. These results suggest that Br chemistry associated with ozone depletion leads to degradation of unsaturated diacids and to the production of smaller saturated diacids.