High daytime abundance of primary organic aerosols over Mt. Emei, Southwest China in summer

Yue Zhao; Hong Ren; Junjun Deng; Linjie Li; Wei Hu; Lujie Ren; Siyao Yue; Yanbing Fan; Libin Wu; Jie Li; Yele Sun; Zifa Wang; Hajime Akimoto; Xin Zeng; Yi Cheng; Shaofei Kong; Hang Su; Yafang Cheng; Kimitaka Kawamura; Pingqing Fu

doi:10.1016/j.scitotenv.2019.134475

High daytime abundance of primary organic aerosols over Mt. Emei, Southwest China in summer

Sci Total Environ. 2020 Feb 10:703:134475. doi: 10.1016/j.scitotenv.2019.134475. Epub 2019 Nov 3.

Authors

Yue Zhao¹, Hong Ren¹, Junjun Deng¹, Linjie Li², Wei Hu¹, Lujie Ren¹, Siyao Yue², Yanbing Fan¹, Libin Wu¹, Jie Li², Yele Sun², Zifa Wang², Hajime Akimoto³, Xin Zeng⁴, Yi Cheng⁴, Shaofei Kong⁴, Hang Su⁵, Yafang Cheng⁵, Kimitaka Kawamura⁶, Pingqing Fu⁷

Affiliations

¹ Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China.
² State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
³ Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Japan.
⁴ Department of Atmospheric Science, School of Environmental Sciences, China University of Geosciences, Wuhan 430074, China.
⁵ Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany.
⁶ Chubu Institute for Advanced Studies, Chubu University, Kasugai 487-8501, Japan.
⁷ Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China. Electronic address: fupingqing@tju.edu.cn.

PMID: 31759721
DOI: 10.1016/j.scitotenv.2019.134475

Abstract

Organic molecular composition of fine aerosols in the free troposphere is poorly understood. Here, PM_2.5 (particles with aerodynamic diameters ≤ 2.5 μm) samples were collected at the summit of Mt. Emei (3080 m a.s.l.) in the Southwestern China on a daytime and nighttime basis during summer 2016 (June-July). The samples were analyzed by solvent-extraction followed by derivatization and gas chromatography/mass spectrometry (GC/MS). Four classes of organic compounds, i.e. n-alkanes, fatty acids, saccharides and lignin/resin acids were measured quantitatively. Fatty acids were found to be the most abundant species with an average concentration of 401 ± 419 ng m^-3 (range 25.7-1490 ng m^-3) in the daytime, similar to the average concentration at night (399 ± 447 ng m^-3, 19.6-1970 ng m^-3). However, the concentrations of biomass burning tracers (e.g., levoglucosan), primary biological aerosol tracers (e.g., mannitol and arabitol) and low molecular weight n-alkanes derived from fossil fuel combustion in daytime samples were obviously higher than those in nighttime samples. The results suggest that valley breezes transported a large number of aerosols and their precursors from the ground surface to the summit of Mt. Emei in the daytime. Estimated with tracer-based methods, the contributions of biogenic primary sources (plant debris, fungal spore, and biomass burning) to organic carbon was in the range of 3.28-83.5% (22.0 ± 17.5%) in the daytime and 3.45-37.4% (10.9 ± 8.97%) at night. As the largest contributor, biomass burning was an important anthropogenic/natural source of aerosol particles in the free troposphere over Mt. Emei. CAPSULE: Valley/mountain breeze is an important constraint to the temporal variations in organic aerosols over Mt. Emei.

Keywords: Fatty acids; Lignin/resin acids; Mt. Emei; Primary organic aerosols; Saccharides; n-Alkanes.