Recently, the team led by Researcher Jiang Ling and Associate Researcher Li Gang from the Cluster Spectroscopy and Dynamics Research Group (Group 2506) of the State Key Laboratory of Molecular Reaction Dynamics used a self-developed aerosol mass spectrometry experimental method based on the Dalian Coherent Light source to study the photo-oxidation reaction process of α -pinene with NOx and NH3, revealing the formation mechanism of secondary organic aerosols (SOA).
NOx is an important inorganic pollutant that forms SOA and has always been regarded as a key pollution control substance. However, recent studies have found that NH3 is closely related to the peak level of secondary particulate matter pollution. Experimental studies show that biogenic volatile organic compounds (BVOCs) with a relatively high emission rate in the atmosphere interact with inorganic pollutants (NOx and NH3) emitted from anthropogenic sources, forming a high concentration of SOA. However, the synergistic mechanism of NOx and NH3 on the oxidation of BVOCs to form SOA is unclear. Precisely studying the chemical composition of aerosols, the quantitative and mass concentrations of particulate matter, and the mechanism of their effects on SOA has long been the goal pursued by atmospheric chemistry researchers.
The terpenes released by plants mainly include isoprene, monoterpenes, sesquiterpenes, etc. Their atmospheric oxidation reactions are the main way to produce SOA. Among them, the monoterpene with the highest content in the atmosphere is α -pinene. In this study, Jiang Ling's team utilized the self-developed DICP-CAS smoke chamber and aerosol mass spectrometry based on Dalian Coherent light source (Phys. Chem.Chem. Phys., 2022; Atmos. Environ., 2024), the influence laws of NOx and NH3 on the photo-oxidation of α -pinene to form SOA were studied. The results show that the inhibitory effects of NO and NO2 on the photo-oxidation of α -pinene show monotonic and parabolic trends respectively, and NH3 increases the number concentration of particulate matter generated during the photo-oxidation process of α -pinene with NOx through the reaction with organic acids. Furthermore, based on the online aerosol mass spectrometry analysis of the Dalian Coherent Light Source and combined with quantum chemistry theoretical calculations, the team characterized the molecular structure and formation pathway of the products of the photo-oxidation reaction of α -pinene. These research results reveal the influence mechanism of NOx and NH3 on the photo-oxidation process of BVOCs, providing a scientific basis for establishing predictive SOA formation networks and improving atmospheric models.
the relevant research results are titled "Effects of NOxand NH3on the secondary organic aerosol formation fromα-pinene photooxidation". Published in "Atmospheric Environment". The first author of the above-mentioned achievements is Zhao Yingqi, a doctoral student from Group 2506 of Dalian Institute of Chemical Physics. The above-mentioned work was supported by the National Natural Science Foundation of China's "Frontier Research in Dynamic Chemistry" Science Center project, the Major Project of Science and Technology Innovation 2030 of the Ministry of Science and Technology, the Dalian Coherent Light Source Special Fund, and other projects. (Written and photographed by Zhao Yingqi
The article links: https://doi.org/10.1016/j.atmosenv.2024.120778
