Preprints
https://doi.org/10.5194/acp-2022-707
https://doi.org/10.5194/acp-2022-707
 
01 Nov 2022
01 Nov 2022
Status: this preprint is currently under review for the journal ACP.

Fates of secondary organic aerosols in the atmosphere identified from compound-specific dual-carbon isotope analysis of oxalic acid

Buqing Xu1,2, Jiao Tang1,2, Tiangang Tang1,3, Shizhen Zhao1,2, Guangcai Zhong1,2, Sanyuan Zhu1,2, Jun Li1,2, and Gan Zhang1,2 Buqing Xu et al.
  • 1State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
  • 2CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
  • 3Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China

Abstract. Secondary organic aerosols (SOAs) are important components of fine particulates in the atmosphere. However, the sources of SOA precursor and atmospheric processes affecting SOAs are poorly understood. This limits our abilities to improve air quality and model aerosol-mediated climate forcing. Here, we use novel compound-specific dual-carbon isotope fingerprints (Δ14C and δ13C) for dominant SOA tracer molecules (oxalic acid and related polar compounds) to investigate the fates of SOAs in the atmosphere at five emission hotspots in China. Coal combustion and vehicle exhausts accounted for ~55 % of the sources of carbon in oxalic acid in Beijing and Shanghai, but biomass-burning and biogenic emissions accounted for ~70 % of the sources of carbon in oxalic acid in Chengdu, Guangzhou, and Wuhan. The dual-carbon isotope signatures of SOA molecules and bulk organic carbon pools (e.g., water-soluble organic carbon) were compared to investigate the fates of SOAs in the atmosphere. Photochemical aging of organic aerosols was dominant in summer, but fresh SOA formation from precursor volatile organic compounds was dominant in winter. The results indicated that SOA carbon sources and chemical processes producing SOAs vary spatially and seasonally and these variations need including in Chinese climate projection models and air quality management practices.

Buqing Xu et al.

Status: open (until 25 Dec 2022)

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Buqing Xu et al.

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Short summary
We analyzed compound-specific dual-carbon isotope signatures (Δ14C and δ13C) of dominant secondary organic aerosol (SOA) tracer molecules (oxalic acid and related polar compounds) to investigate the fates of SOAs in the atmosphere at five emission hotspots in China. The results indicated that SOA carbon sources and chemical processes producing SOAs vary spatially and seasonally and these variations need including in Chinese climate projection models and air quality management practices.
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