Latitudinal difference in the molecular distributions of lipid compounds in the forest atmosphere in China

Donghuan Zhang; Hong Ren; Wei Hu; Libin Wu; Lujie Ren; Junjun Deng; Qiang Zhang; Yele Sun; Zifa Wang; Kimitaka Kawamura; Pingqing Fu

doi:10.1016/j.envpol.2021.118578

Latitudinal difference in the molecular distributions of lipid compounds in the forest atmosphere in China

Environ Pollut. 2022 Feb 1:294:118578. doi: 10.1016/j.envpol.2021.118578. Epub 2021 Nov 26.

Authors

Donghuan Zhang¹, Hong Ren², Wei Hu¹, Libin Wu¹, Lujie Ren¹, Junjun Deng¹, Qiang Zhang¹, Yele Sun³, Zifa Wang³, Kimitaka Kawamura⁴, Pingqing Fu⁵

Affiliations

¹ School of Earth System Science, Tianjin University, Tianjin, 300072, China.
² School of Earth System Science, Tianjin University, Tianjin, 300072, China; Air Environmental Modeling and Pollution Controlling Key Laboratory of Sichuan Higher Education Institute, Chengdu University of Information Technology, Chengdu, 610225, China.
³ State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
⁴ Chubu Institute for Advanced Studies, Chubu University, Kasugai, 487-8501, Japan.
⁵ School of Earth System Science, Tianjin University, Tianjin, 300072, China. Electronic address: fupingqing@tju.edu.cn.

PMID: 34843855
DOI: 10.1016/j.envpol.2021.118578

Abstract

Lipids are important biogenic markers to indicate the sources and chemical process of aerosol particles in the atmosphere. To better understand the influences of biogenic and anthropogenic sources on forest aerosols, total suspended particles (TSP) were collected at Mt. Changbai, Shennongjia, and Xishuangbanna that are located at different climatic zones in northeastern, central and southwestern China. n-Alkanes, fatty acids and n-alcohols were detected in the forest aerosols based on gas chromatography-mass spectrometry. The total concentrations of aliphatic compounds ranged from 15.3 ng m^-3 to 566 ng m^-3, and fatty acids were the most abundant (44-95%) followed by n-alkanes and n-alcohols. Low molecular weight- (LFAs) and unsaturated fatty acids (UnFAs) showed diurnal variation with higher concentrations during the nighttime in summer, indicating the potential impact from microbial activities on forest aerosols. The differences of oleic acid (C_18:1) and linoleic acid (C_18:2) concentrations between daytime and nighttime increased at lower latitude, indicating more intense photochemical degradation occurred at lower latitude regions. High levels of n-alkanes during daytime in summer with higher values of carbon preference indexes, combining the strong odd carbon number predominance with a maximum at C₂₇ or C₂₉, implied the high contributions of biogenic sources, e.g., higher plant waxes. In contrast, higher concentrations of low molecular weight n-alkanes were detected in winter forest aerosols. Levoglucosan showed a positive correlation (R² > 0.57) with high- and low molecular weight aliphatic compounds in Mt. Changbai, but such a correlation was not observed in Shennongjia and Xishuangbanna. These results suggest the significant influence of biomass burning in Mt. Changbai, and fossil fuel combustion might be another important anthropogenic source of forest aerosols. This study adds useful information to the current understanding of forest organic aerosols at different geographical locations in China.

Keywords: Aliphatic lipids; Fatty acids; Forest aerosols; Levoglucosan; Organic aerosols.

MeSH terms

Air Pollutants* / analysis
Atmosphere
China
Environmental Monitoring
Forests
Lipids / analysis
Particulate Matter* / analysis

Substances

Air Pollutants
Lipids
Particulate Matter