Meng Jing-Jing, Liu Xiao-di, Hou Zhan-Fang, Li Jing, Wei Ben-Jie, Xing Ji-Zhao
School of Environment and Planning, Liaocheng University, Liaocheng 252000, China.
State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
Huan Jing Ke Xue. 2018 Nov 8;39(11):4876-4884. doi: 10.13227/j.hjkx.201804042.
To identify the diurnal variation and formation mechanism of dicarboxylic acids and related compounds in PM from Heze City, PM samples were collected in the winter (December) of 2017, which were subsequently analyzed for dicarboxylic acids, ketocarboxylic acids, -dicarbonyls, and levoglucosan (Levo). The results showed that the total concentrations of dicarboxylic and ketocarboxylic acids were higher during daytime than those during nighttime. In contrast to the diurnal variation of dicarboxylic and ketocarboxylic acids, the total concentrations of α-dicarbonyls exhibited higher concentrations in nighttime than in daytime. Because α-dicarbonyls are the major precursors of dicarboxylic acids, the opposing patterns suggest that the photochemical oxidation in daytime is stronger than that in nighttime. Oxalic acid (C) is the dominant species during both day-and nighttime, followed by phahalic acid (Ph), succinic acid (C), and malonic acid (C), which is consistent with that in other urban regions. The mass ratios of C/C (>0.7) correlated strongly with temperature, indicating that organic compounds in the atmosphere of Heze City are mainly derived from the photochemical oxidation of local emissions rather than long-range transport in winter. C correlated with in-situ pH and SO, suggesting that aqueous-phase oxidation was the major formation pathway of C, which is driven by acid-catalyzed oxidation. Since the major SOA (C, glyoxal, and methyglyoxal, secondary organic aerosol) correlated with Levo and the average mass rations of K/organic carbon was 0.06 (ranging from 0.03 to 0.13), it can be concluded that the dicarboxylic acids and related SOA and K in Heze City were significantly influenced by biomass burning in winter.
为确定菏泽市大气颗粒物（PM）中二元羧酸及相关化合物的日变化特征和形成机制，于2017年冬季（12月）采集了PM样本，随后对其进行二元羧酸、酮羧酸、α - 二羰基化合物和左旋葡聚糖（Levo）分析。结果表明，二元羧酸和酮羧酸的总浓度白天高于夜间。与二元羧酸和酮羧酸的日变化相反，α - 二羰基化合物的总浓度夜间高于白天。由于α - 二羰基化合物是二元羧酸的主要前体，这种相反的模式表明白天的光化学氧化比夜间更强。草酸（C₂）在白天和夜间均为主要成分，其次是邻苯二甲酸（Ph）、琥珀酸（C₄）和丙二酸（C₃），这与其他城市地区一致。C₂/C₃的质量比（>0.7）与温度密切相关，表明菏泽市冬季大气中的有机化合物主要来源于本地排放的光化学氧化，而非长距离传输。C₂与原位pH值和SO₂相关，表明水相氧化是C₂的主要形成途径，由酸催化氧化驱动。由于主要的二次有机气溶胶（SOA，C₂、乙二醛和甲基乙二醛）与Levo相关，且K⁺/有机碳的平均质量比为0.06（范围为0.03至0.13），可以得出结论，菏泽市冬季的二元羧酸及相关SOA和K⁺受生物质燃烧的显著影响。
