Characterization of dicarboxylic acids, oxoacids, and α-dicarbonyls in PM2.5 within the urban boundary layer in southern China: Sources and formation pathways. (15th September 2021)

• Record Type: Journal Article
• Authors: Liu, Jianing; Zhou, Shengzhen; Zhang, Zhimin; Kawamura, Kimitaka; Zhao, Wanyu; Wang, Xuemei; Shao, Min; Jiang, Fan; Liu, Junwen; Sun, Xi; Hang, Jian; Zhao, Jun; Pei, Chenglei; Zhang, Jingpu; Fu, Pingqing
• Is Part Of: Environmental pollution. Volume 285(2021)
• Publication Date: 2021-09-15
• Subjects: Vertical distribution -- Organic aerosol -- Dicarboxylic acids -- Photochemical oxidation -- In-cloud process -- Sources; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2021.117185
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Low-molecular-weight dicarboxylic acids, which are important components of secondary organic aerosols, have been extensively studied in recent years. Many studies have focused on ground-level observations and literature reports on the vertical distribution of the organic aerosols within the urban boundary layer are limited. In this study, the vertical profiles of dicarboxylic acids and related organic compounds (DCRCs) in PM2.5 were investigated at altitudinal levels (ground level and 488 m above the ground level) at the Canton Tower in Guangzhou, southern China, to elucidate their primary sources and secondary formation processes. The concentrations of DCRCs at ground level were generally higher than those at 488 m. Oxalic acid (C2 ) was the most abundant species, followed by succinic acid (C4 ) and malonic acid (C3 ) at both heights. The higher ratio of DCRCs-bound carbon to organic carbon (i.e., DCRCs-C/OC) at 488 m (4.8 ± 1.2%) relative to that at ground level (2.7 ± 0.5%) indicated a higher degree of aerosol aging at 488 m. The abundance of C2 was increased and the conversion of C4 to C3 was enhanced due to the photochemical oxidation of its homologues during long-range transport periods. The increase in C2 was associated with in-cloud processes during pollution periods. Principal component analysis showed that DCRCs were mainly derived from atmospheric secondary processing and biomass burning was also an important source of long-chain carboxylic acids during autumn in Guangzhou. Our results illustrate that secondary processing and biomass burning play prominent roles in controlling the abundance of DCRCs. Furthermore, DCRCs are affected by air masses from regional areas, oxidation of their precursors via vertical transport and in-cloud processes. Graphical abstract: Image 1 Highlights: The vertical distribution of organic acids in PM2.5 was first displayed in South China. Oxidation of long-chain acids increased the abundance of short-chain diacids at 488 m. The increase in oxalic acid on the polluted days was related to in-cloud processes. Organic acids were mainly from secondary processes and biomass burning.