Four- and Five-Carbon Dicarboxylic Acids Present in Secondary Organic Aerosol Produced from Anthropogenic and Biogenic Volatile Organic Compounds

Akihiro Fushimi,Sathiyamurthi Ramasamy,Yu Morino,Kimiyo Kumagai,Akihiro Iijima,Kei Sato,Fumikazu Ikemori

doi:10.3390/atmos12121703

Abstract

To better understand precursors of dicarboxylic acids in ambient secondary organic aerosol (SOA), we studied C4–C9 dicarboxylic acids present in SOA formed from the oxidation of toluene, naphthalene, α-pinene, and isoprene. C4–C9 dicarboxylic acids present in SOA were analyzed by offline derivatization gas chromatography–mass spectrometry. We revealed that C4 dicarboxylic acids including succinic acid, maleic acid, fumaric acid, malic acid, DL-tartaric acid, and meso-tartaric acid are produced by the photooxidation of toluene. Since meso-tartaric acid barely occurs in nature, it is a potential aerosol tracer of photochemical reaction products. In SOA particles from toluene, we also detected a compound and its isomer with similar mass spectra to methyltartaric acid standard; the compound and the isomer are tentatively identified as 2,3-dihydroxypentanedioic acid isomers. The ratio of detected C4–C5 dicarboxylic acids to total toluene SOA mass had no significant dependence on the initial VOC/NOx condition. Trace levels of maleic acid and fumaric acid were detected during the photooxidation of naphthalene. Malic acid was produced from the oxidation of α-pinene and isoprene. A trace amount of succinic acid was detected in the SOA produced from the oxidation of isoprene.

Highlights

Secondary organic aerosol (SOA) is a major component of atmospheric PM2.5 that affects climate [1] and human health [2,3,4]
We focused on experiments using anthropogenic volatile organic compounds (VOCs) because, as described later, target C4 and C5 dicarboxylic acid tracers were barely detected in SOA formed from biogenic VOCs
The saturation concentrations at 25◦C calculated by SPARC were 94 μg·m−3 for maleic acid, 720 μg·m−3 for succinic acid, 8.8 μg·m−3 for malic acid, 0.13 μg·m−3 for tartaric acid, 3.3 μg·m−3 for dihydroxy-4-oxopentanoic acid (DHOPA), 0.17 μg·m−3 for methyl tartaric acid, 0.012 μg·m−3 for DHPDA, 0.044 μg·m−3 for 2,4-dihydroxyglutaric acid, 8.3 μg·m−3 for phthalic acid, 0.18 μg·m−3 for pinic acid, 0.33 μg·m−3 for 3-hydroxyglutaric acid, and 26 μg·m−3 for

Summary

Introduction

Secondary organic aerosol (SOA) is a major component of atmospheric PM2.5 that affects climate [1] and human health [2,3,4]. An SOA tracer is defined as a compound that maintains its identity in the atmosphere with the SOA produced from a particular precursor. SOA tracers present in the aerosol are used to estimate the source and amount of SOA constituting the atmospheric aerosol [5]. Dicarboxylic acids detected in atmospheric aerosol have traditionally been believed to be SOA tracers. Azelaic acid (C9), adipic acid (C6), and oxalic acid (C2) are reported to be tracers of SOA derived from oleic acid [6], cyclohexene [7,8], and isoprene [9], respectively. The sources of dicarboxylic acids in atmospheric organic aerosols have not been fully characterized

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