氮氧化物是大气中一种重要的痕量气体, 影响大气的氧化性, 危害人和动物的生理健康、 导致光化学烟雾、 灰霾、 酸沉降等环境问题。 近年来随着我国经济的迅速发展, 能源消耗量的不断增加, 氮氧化物的排放量居高不下, 因此研究氮氧化物在大气中的含量及其化学性质具有非常重要的意义。 氮氧化物(NOx)的探测方式非常多样, 但总活性氮氧化物(NOy)的测量方式一直以来以催化转化化学发光法(CL)为主, 本文介绍了一种热解双通道腔衰荡光谱技术(TD-CRDS)同步测量大气中NO2和NOy浓度的方法。 优化了热解装置的性妮, 确定了NO2的有效吸收截面, 分析了系统可能存在的干扰(H2O、 乙二醛、 NH3、 N2O等), 探讨了系统的探测限(NO2腔: 8.72×108 molecules·cm-3; NOy腔: 9.71×108 molecules·cm-3)及误差(NO2的测量误差: 5%, NOy的测量误差: 12%)。 另外, 为了验证系统的性能, 将CRDS与长光程差分吸收光谱(LP-DOAS)同步测量了环境气体NO2浓度, 相关性系数r为0.960; 与Model 42i-NOy分析仪开展环境大气NOy的对比测量, 相关性系数r为0.968, 均具有较好的一致性。 在合肥科学岛综合楼顶楼开展了为期一周的外场观测, 测量期间NO2和NOy的平均浓度分别为0.411×1012和0.773×1012 molecules·cm-3 , 通过平均日变化图发现NO2与NOy浓度具有相似的变化趋势, 一般于10:00开始下降, 15:00达到最低值。 CRDS技术因其高灵敏度、 高时间分辨率已成为一种新型简便地测量环境大气中总活性氮氧化物的方法。

Nitrogen oxide, being one of an important trace gas in the atmosphere, may affect the oxidation of the atmosphere, harm the physiological health of the human beings and the animals, and cause photochemical smog, haze, acid depositions and other environmental problems. In recent years, with the rapid development of the economy and the continuous increase of energy consumption in our country, the nitrogen oxide emissions have been remaining at a high level. Therefore, it is of great significance to study the content and chemical properties of the nitrogen oxides in the atmosphere. The methods for determining NOx has tended to become diversified. However, the methods for determining the total reactive nitrogen oxide (NOy) have always been dominated by the catalytic conversion chemiluminescence (CL). In this paper, a method of simultaneous measurement of NO2 and NOy concentration in the ambient air by the thermal dissociation cavity ring down spectrometer (TD-CRDS) is introduced. The performance of the pyrolysis device was optimized, the effective absorption cross section of NO2 was determined, the interferences which may possibly exist in the system (H2O, glyoxal, NH3, N2O and etc. ) was analyzed, and the detection limit (NO2 chamber: 8.72×108 molecules·cm-3; NOy chamber: 9.71×108 molecules·cm-3) and the errors (NO2 measurement: 5%; NOy measurement: 12%) were discussed. In order to verify the performance of the system, the concentration of NO2 was determined by comparing the CRDS and the long-path differential optical absorption spectroscopy (LP-DOAS) synchronously, with a linear correlation factor r=0.960. The concentration of NOy in the atmosphere was determined through comparing with the model Model 42i-NOy analyzer synchronously, with a linear correlation factor r=0.968. Both consistencies is good. A field experiment was performed for a week at Hefei Science Island. During the measurement, the average concentrations of NO2 and NOy were 4.11×1012 molecules·cm-3 and 7.73×1012 molecules·cm-3, respectively. According to the average daily variation diagram, it is found that there is a similar trend in the concentration of NO2 and NOy, and it usually starts to decline at 10:00 and the lowest value occurs at 15:00. Because of its high sensitivity and high time resolution, the CRDS has become a new and simple method for determining the total reactive nitrogen oxide in the ambient air.