G01_09

Quantitative evaluation of OC aerosol sources and aging processes: insights from a comprehensive method of dual-carbon isotopes and tracers

Jiang F^1,6, Liu J¹, Cheng Z^2,7, Ding P^3,7, Zhu S^2,7, Yuan X¹, Zhang Z⁴, Zong Z⁵, Tian C⁵, Hu W^2,7, Zheng J¹, Szidat S⁶, Li J^2,7, Zhang G^2,7

¹Institute for Environmental and Climate Research, Jinan University, Guangzhou, China, ²State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China, ³State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China, ⁴South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou, China, ⁵Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China, ⁶Department of Chemistry, Biochemistry and Pharmaceutical Sciences and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland, ⁷CAS Center for Excellence in Deep Earth Science, Guangzhou, China

Organic carbon aerosol (OC) is a pivotal component of PM₂.₅ in the atmospheric environment, yet its emission sources and atmospheric behaviors remain poorly constrained. In this study, a comprehensive method based on the combination of dual-carbon isotopes (¹³C and ¹⁴C) and macro tracers was employed in the PRDAIO campaign performed in the megacity Guangzhou, China. The ¹⁴C analysis showed that ~60 % of OC during the sampling campaign was associated with non-fossil sources such as biomass burning activities and biogenic emissions. It should be noted that this non-fossil contribution in OC would significantly decrease when the air masses came from the eastern cities. Overall, non-fossil secondary OC was the largest contributor (~39 %) to OC, followed by fossil secondary OC (~26 %), non-fossil primary OC (~21 %), and fossil primary OC (~14 %). Also, we established the dynamic variation of ¹³C as a function of aged OC and VOCs oxidized OC to explore the aging processes of OC. Our pilot results showed that a large fraction (average: ~53 %) of OC was not from the gaseous oxidation but the aging formation. This study confirmed that non-fossil sources played an important role in the loading of organic aerosol in this megacity and the aging processes were probably highly involved in the formation of organic aerosol.