菏泽市冬季PM_(2.5)中二元羧酸类SOA的昼夜变化特征  

Diurnal Variation of Dicarboxylic Acids and Related SOA in PM_(2.5) from Heze City in Winter

作　　者：孟静静[1,2] 刘晓迪[1] 侯战方 李静 魏本杰 邢继钊 MENG Jmg-jing 1,2, LIU Xiao-di1, HOU Zhan-fang1,2 LI Jing1 , WEI Ben-jie1, XING Jl-zhao1(1. School of Environment and Planning, Liaocheng University, Liaocheng 252000, China; 2. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi＇an 710061, China)

机构地区：[1]聊城大学环境与规划学院,聊城252000 [2]中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安710061

出　　处：《环境科学》2018年第11期4876-4884,共9页Environmental Science

基　　金：国家自然科学基金项目(41505112);山东省自然科学基金项目(BS2015HZ002);黄土与第四纪地质国家重点实验室开放基金项目(SKLLQG1504);大学生创新创业项目(26312161016);大学生创新创业项目(CXCY2017046)

摘　　要：为研究菏泽市冬季大气气溶胶中二元羧酸类化合物的昼夜变化特征与形成机制,于2017年冬季(12月)进行为期1个月的PM_(2.5)样品采集,并分析二元羧酸、酮羧酸、α-二羰基化合物及左旋葡聚糖等化学组分.结果表明,菏泽市冬季PM_(2.5)中白天二元羧酸与酮羧酸的总浓度均呈昼高夜低的变化特征,但α-二羰基化合物(二元羧酸的重要前体物)的变化特征却与之相反,表明白天气溶胶的氧化程度比夜晚强.无论在白天还是晚上,草酸(C_2)均是浓度最高的二元羧酸,其次是邻苯二甲酸(Ph)、丁二酸(C_4)和丙二酸(C_3),与其他城市地区的分子组成是相似的.由C_3/C_4的比值与温度(T)间的相关性分析可知,菏泽市冬季有机化合物主要受本地源的影响,而受远源输入的影响很小. C_2与SO_4^(2-)、气溶胶实际酸度(pHIS)的相关性分析表明,C_2主要是在液相中经酸催化的二次氧化反应形成的.因为主要的二元羧酸类化合物(C_2、Gly和mGly)与左旋葡聚糖(Levo)的相关性很强,且K^+/OC的平均比值为0. 06(范围为0. 03～0. 13),所以可以得出二元羧酸类化合物及K^+主要受生物质燃烧的影响.To identify the diurnal variation and formation mechanism of dicarboxylic acids and related compounds in PM（2.5） from Heze City,PM（2.5） samples were collected in the winter（ December） of 2017,which were subsequently analyzed for dicarboxylic acids,ketocarboxylic acids,α-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（ C2） is the dominant species during both day-and nighttime,followed by phahalic acid（ Ph）,succinic acid（ C4）,and malonic acid（ C3）,which is consistent with that in other urban regions. The mass ratios of C3/C4（ R^2 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. C2 correlated with in-situ pH and SO4^2-,suggesting that aqueous-phase oxidation was the major formation pathway of C2,which is driven by acid-catalyzed oxidation. Since the major SOA（ C2,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.

关 键 词：二元羧酸 昼夜变化特征 液相形成机制 PM2.5 菏泽市 

分 类 号：X513[环境科学与工程—环境工程]