Comprehensive observations of the nocturnal atmospheric oxidation of NO3 and N2O5 were conducted at a suburban site in Changzhou in the YRD using cavity ring-down spectroscopy(CRDS)from 27 May to 24 June,2019.High concentrations of NO3 precursors were observed,and the nocturnal production rate of NO3 was determined to be 1.7±1.2 ppbv/hr.However,the nighttime NO3 and N2O5 concentrations were relatively low,with maximum values of 17.7 and 304.7 pptv,respectively,illustrating the rapid loss of NO3 and N2O5.It was found that NO3 dominated the nighttime atmospheric oxidation,accounting for 50.7％,while O3 and OH only contributed 34.1％and 15.2％,respectively.For the reactions of NO3 with volatile organic compounds(VOCs),styrene was found to account for 60.3％,highlighting its dominant role in the NO3 reactivity.In general,the contributions of the reactions between NO3 and VOCs and the N2O5 uptake to NO3 loss were found to be about 39.5％and 60.5％,respectively,indicating that N2O5 uptake also played an important role in the loss of NO3 and N2O5,especially under the high humidity conditions in China.The formation of nitrate at night mainly originated from N2O5 uptake,and the maximum production rate of NO3-reached 6.5 ppbv/hr.The average NOx consumption rate via NO3 and N2O5 chemistry was found to be 0.4 ppbv/h,accounting for 47.9％of the total NOx removal.The predominant roles of NO3 and N2O5 in nitrate formation and NOx removal in the YRD region was highlighted in this study.

Chuan Lin;Renzhi Hu;Pinhua Xie;Shengrong Lou;Guoxian Zhang;Jinzhao Tong;Jianguo Liu;Wenqing Liu

Key Laboratory of Environmental Optics and Technology,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;University of Science and Technology of China,Hefei 230026,China;CAS Center for Excellence in Regional Atmospheric Environment,Institute of Urban Environment,Chinese Academy of Sciences,Xiamen 361000,China;State Environmental Protection Key Laboratory of the Formation and Prevention of Urban Air Pollution Complex,Shanghai Academy of Environmental Sciences,Shanghai 200233,China

环境科学学报（英文版）

[1]Chuan Lin;Renzhi Hu;Pinhua Xie;Shengrong Lou;Guoxian Zhang;Jinzhao Tong;Jianguo Liu;Wenqing Liu-.Nocturnal atmospheric chemistry of NO3 and N2O5 over Changzhou in the Yangtze River Delta in China)[J].环境科学学报（英文版）,2022(04):376-390

Nocturnal,Changzhou,pptv

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