Aqueous-phase formation of N-containing secondary organic compounds affected by the ionic strength  

作　　者：Yuqi Gan Xiaohui Lu Shaodong Chen Xinghua Jiang Shanye Yang Xiewen Ma Mei Li Fan Yang Yewen Shi Xiaofei Wang 

机构地区：[1]Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention,Department of Environmental Science and Engineering,Fudan University,Shanghai 200433,China [2]Shanghai Institute of Pollution Control and Ecological Security,Shanghai 200092,China [3]Guangdong Provincial Observation and Research Station for Coastal Atmosphere and Climate of the Great Bay Area,Southern University of Science and Technology,Shenzhen 518055,China [4]Institute of Mass Spectrometry and Atmospheric Environment,Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution,Jinan University,Guangzhou,China [5]Environmental Monitoring Station of Pudong New District,Shanghai 201200,China [6]Shanghai Municipal Center for Disease Control&Prevention,Shanghai 200336,China

出　　处：《Journal of Environmental Sciences》2024年第4期88-101,共14页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.21976034,42077193,92044301,and21906024);the Shanghai Municipal Health Commission Science and Research Fund(No.202040185);the Shanghai Pudong New District Bureau of Ecology and Environment Research Project(No.PDHJ20210008);the Guangdong Provincial Observation and Research Station for Coastal Atmosphere and Climate of the Great Bay Area(No.2021B1212050024)。

摘　　要：The reaction of carbonyl-to-imine/hemiaminal conversion in the atmospheric aqueous phase is a critical pathway to produce the light-absorbing N-containing secondary organic compounds(SOC).The formation mechanism of these compounds has been wildly investigated in bulk solutions with a low ionic strength.However,the ionic strength in the aqueous phase of the polluted atmosphere may be higher.It is still unclear whether and to what extent the inorganic ions can affect the SOC formation.Here we prepared the bulk solution with certain ionic strength,in which glyoxal and ammonium were mixed to mimic the aqueous-phase reaction.Molecular characterization by High-resolution Mass Spectrometry was performed to identify the N-containing products,and the light absorption of the mixtures was measured by ultraviolet-visible spectroscopy.Thirty-nine N-containing compounds were identified and divided into four categories(N-heterocyclic chromophores,high-molecular-weight compounds with N-heterocycle,aliphatic imines/hemiaminals,and the unclassified).It was observed that the longer reaction time and higher ionic strength led to the formation of more N-heterocyclic chromophores and the increasing of the lightabsorbance of the mixture.The added inorganic ions were proposed to make the aqueous phase somewhat viscous so that the molecules were prone to undergo consecutive and intramolecular reactions to form the heterocycles.In general,this study revealed that the enhanced ionic strength and prolonged reaction time had the promotion effect on the lightabsorbing SOC formation.It implies that the aldehyde-derived aqueous-phase SOC would contribute more light-absorbing particulate matter in the industrial or populated area where inorganic ions are abundant.

关 键 词：Ionic strength Carbonyl-to-imine/hemiaminal HETEROCYCLIC Brown carbon Mass spectrometry Aqueous-phase reaction 

分 类 号：X51[环境科学与工程—环境工程]