Size distributions of molecular markers for biogenic secondary organic aerosol in urban Beijing

Di Liu; Shaofeng Xu; Yunchao Lang; Shengjie Hou; Lianfang Wei; Xiaole Pan; Yele Sun; Zifa Wang; Kimitaka Kawamura; Pingqing Fu

doi:10.1016/j.envpol.2023.121569

Size distributions of molecular markers for biogenic secondary organic aerosol in urban Beijing

Environ Pollut. 2023 Jun 15:327:121569. doi: 10.1016/j.envpol.2023.121569. Epub 2023 Apr 5.

Authors

Affiliations

¹ State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
² Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, 300072, China.
³ Chubu Institute for Advanced Studies, Chubu University, Kasugai, 487-8501, Japan.
⁴ Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, 300072, China. Electronic address: fupingqing@tju.edu.cn.

PMID: 37028792
DOI: 10.1016/j.envpol.2023.121569

Abstract

To understand the source, formation, and seasonality of biogenic secondary organic aerosol (BSOA), a nine-stage cascade impactor was utilized to collect size-segregated particulate samples from April 2017 to January 2018 in Beijing, China. BSOA tracers derived from isoprene, monoterpene, and sesquiterpene were measured with gas chromatography-mass spectrometry. Isoprene and monoterpene SOA tracers exhibited significant seasonal variations, with a summer maximum and a winter minimum. Dominance of 2-methyltetrols (isoprene SOA tracers) with a good correlation with levoglucosan (a biomass burning tracer), which was combined with the detection of methyltartaric acids (possible indicators for aged isoprene) in summer, implies possible biomass burning and long-range transport. In contrast, sesquiterpene SOA tracer (β-caryophyllinic acid) was dominant in winter and was probably associated with the local burning of biomass. Bimodal size distributions were observed for most isoprene SOA tracers, consistent with previous laboratory experiments and field studies showing that they can be formed not only in the aerosol phase but also in the gas phase. Monoterpene SOA tracers cis-pinonic acid and pinic acid showed a coarse-mode peak (5.8-9.0 μm) in four seasons due to their volatile nature. Sesquiterpene SOA tracer β-caryophyllinic acid showed a unimodal pattern with a major fine-mode peak (1.1-2.1 μm), which is linked to local biomass burning. The tracer-yield method was used to quantify the contributions of isoprene, monoterpene, and sesquiterpene to secondary organic carbon (SOC) and SOA. The highest isoprene SOC and SOA concentrations occurred in summer (2.00 μgC m^-3 and 4.93 μg m^-3, respectively), contributing to 1.61% of OC and 5.22% of PM_2.5, respectively. These results suggest that BSOA tracers are promising tracers for understanding the source, formation, and seasonality of BSOA.

Keywords: 2-Methyltetrols; Bimodal pattern; Biogenic secondary organic aerosols; Monoterpenes; Tracer-yield method.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Beijing
Environmental Monitoring / methods
Monoterpenes / analysis
Particulate Matter / analysis
Seasons
Sesquiterpenes* / analysis

Substances

Air Pollutants
isoprene
Monoterpenes
Sesquiterpenes
Aerosols
Particulate Matter