Insights into the day-night sources and optical properties of coastal organic aerosols in southern China

Qian Zhang; Ziyi Li; Peng Wei; Qiyuan Wang; Jie Tian; Ping Wang; Zhenxing Shen; Jianjun Li; Hongmei Xu; Youzhi Zhao; Xiaoqing Dang; Junji Cao

doi:10.1016/j.scitotenv.2022.154663

Insights into the day-night sources and optical properties of coastal organic aerosols in southern China

Sci Total Environ. 2022 Jul 15:830:154663. doi: 10.1016/j.scitotenv.2022.154663. Epub 2022 Mar 19.

Authors

Qian Zhang¹, Ziyi Li¹, Peng Wei², Qiyuan Wang³, Jie Tian⁴, Ping Wang⁵, Zhenxing Shen⁶, Jianjun Li⁴, Hongmei Xu⁶, Youzhi Zhao⁴, Xiaoqing Dang¹, Junji Cao⁷

Affiliations

¹ Key Laboratory of Northwest Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China.
² School of Geography and Environment, Shandong Normal University, Jinan 250358, PR China; Division of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong, China.
³ State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China. Electronic address: wangqy@ieecas.cn.
⁴ State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
⁵ Hainan Tropical Ocean University, Sanya 572022, China. Electronic address: wpalong@hntou.edu.cn.
⁶ Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
⁷ Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China. Electronic address: jjcao@mail.iap.ac.cn.

PMID: 35318062
DOI: 10.1016/j.scitotenv.2022.154663

Abstract

Organic aerosols (OAs) in particulate matter with an aerodynamic diameter of smaller than 2.5 μm (PM_2.5) can affect the atmospheric radiation balance through varying molecular structure and light absorption of the aerosols. In this study, daytime and nighttime PM_2.5 mass, and contents of OA including nitrated aromatic compounds (NACs), polycyclic aromatic hydrocarbons (PAHs), n-alkanes, and hopanes were measured from April 11th to May 15th, 2017, at the coastal Sanya, China. The average concentration of 18 total quantified PAHs (∑PAHs) was 2.08 ± 1.13 ng·m^-3, which was 2.8 and 12 times higher than that of ∑NACs and hopanes, while was 7.5 times lower that of n-alkanes. Combustion-derived PAHs contributed 74% to the ∑PAHs. This finding, in addition to a high benzo[a]pyrene/(benzo[a]pyrene+benzo[e]pyrene) ratio, indicates that the PAHs mainly derived from fresh fuel combustion during the sampling periods. Furthermore, dramatic day-night differences were observed in the loadings of total NACs, PAHs, and n-alkanes, which had a high coefficient of divergence values of 0.67, 0.47, and 0.32, respectively. Moreover, hopanes exhibited similar variation as well. The proportion of dimethyl-nitrophenol (DM-NP), dinitrophenol (DNP), and nitrosalicylic acid (NSA) in PM_2.5 were higher in the daytime than at nighttime, suggesting the co-influence of primary emissions and secondary formation related to biomass combustion. The positive matrix factorization (PMF) model revealed that motor vehicle and biomass burning emissions were the two main pollution sources in the daytime, contributing 51.7% and 24.6%, respectively, of the total quantified OAs. The proportion of industrial coal combustion emissions was higher at nighttime (20.6%) than in daytime (10%). Both the PAHs and NACs displayed light absorbing capacities among OAs compounds over Sanya City, and thus their influence on solar radiation must be considered in the future control policies.

Keywords: Coastal city; Day and night variation; Optical properties; Organic aerosols; Sources.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Alkanes / analysis
Benzo(a)pyrene
China
Environmental Monitoring
Particulate Matter / analysis
Pentacyclic Triterpenes
Polycyclic Aromatic Hydrocarbons* / analysis
Seasons
Vehicle Emissions

Substances

Aerosols
Air Pollutants
Alkanes
Particulate Matter
Pentacyclic Triterpenes
Polycyclic Aromatic Hydrocarbons
Vehicle Emissions
Benzo(a)pyrene