Quantification of Atmospheric Total Reactive Nitrogen Oxides by Thermal Decomposition-Broadband Cavity Enhanced Absorption Spectroscopy
10.19756/j.issn.0253-3820.241380
- VernacularTitle:热解-宽带腔增强吸收光谱技术对大气总活性氮氧化物的定量研究
- Author:
Dou SHAO
1
;
Min QIN
;
Wu FANG
;
Bao-Bin HAN
;
Ke TANG
;
Jian-Ye XIE
;
Xia-Dan ZHAO
;
Zhi-Tang LIAO
;
En-Bo REN
Author Information
1. 中国科学院合肥物质科学研究院安徽光学精密机械研究所,中国科学院环境光学与技术重点实验室,合肥 230031;中国科学技术大学,合肥 230026
- Keywords:
Reactive nitrogen oxides;
Thermal decomposition;
Broadband cavity enhanced absorption spectroscopy
- From:
Chinese Journal of Analytical Chemistry
2025;53(3):387-396
- CountryChina
- Language:Chinese
-
Abstract:
Nitrogen oxides(NOx=NO+NO2)are important precursors of ozone(O3),and NOx and its oxides together constitute reactive nitrogen oxides(NOy)in the atmosphere.A comprehensive understanding of the total NOy level in the atmosphere is of great significance for a deeper understanding of the atmospheric nitrogen cycle and oxidation,as well as for formulating strategies for air pollution prevention and control.In this work,a thermal decomposition-broadband cavity enhanced absorption spectroscopy(TD-BBCEAS)technique for online measurement of total NOy in the atmosphere was developed.With this method,the NOy was efficiently converted into NO2,and the total NOy concentration in the atmosphere was indirectly obtained by measuring NO2.Focusing on the key factors affecting the measurement of total NOy,the influence of NO titration efficiency and other NOy component TD efficiency on measurement accuracy was emphasized.By changing the oxygen(O2)flow rate through the mercury lamp to alter the O3 concentration for titrating NO,the conversion efficiency of NO was evaluated.At O2 flow rate of 6 mL/min,the conversion efficiency of NO was greater than 99%.TD efficiency testing and analysis on NO2,peroxyacetyl nitrate(PAN),nitric acid(HNO3),and nitrous acid(HONO),which account for a large proportion of atmospheric NOy components,was carried out using 680℃as the optimal TD temperature for efficient conversion of NOy.With NO and HONO sample gases as typical verification gases,the conversion efficiency of NOy and the accuracy of NOy measurement by TD-BBCEAS system were verified by switching the on and off modes of mercury lamp and TD device.At integration time of 60 s,the detection limit of the system for NOy was 2.83×1010 molecules/cm3(60 s,2σ).A comparative measurement of actual atmospheric NOy was conducted between the TD-BBCEAS system and the NOy analyzer.The observation results showed a correlation coefficient(R2)of 0.98 and a slope of 0.93,further verifying the feasibility and accuracy of applying the TD-BBCEAS system to measurement of total NOy.
