摘要
Atmospheric O_(x)(nitrogen dioxide(NO_(2))+ozone(O_(3)))can better reflect the local and regional change character-istics of oxidants compared to O_(3)alone,so obtaining O_(x)accurately and rapidly is the basis for evaluating the O_(3)production rate.Furthermore,O_(x)has proved to be a more representative indicator and can serve as a reflection of pollution prevention efficacy.A portable instrument for measuring atmospheric O_(x)and NO_(2)based on cavity ring-down spectroscopy(O_(x)/NO_(2)-CRDS)was developed in this work.The NO_(2)concentration is accurately mea-sured according to its absorption characteristic at 407.86 nm.Ambient O_(3)is converted into NO_(2)by chemical titration of high concentrations of nitrogen oxide(NO),and the O_(3)conversion efficiencies obtained are nearly 99%.The detection limit of the O_(x)/NO_(2)-CRDS system for O_(x)is 0.024 ppbv(0.1 s),and the overall uncertainty of the instrument is±6%.Moreover,the Kalman filtering technique was applied to improve the measurement accuracy of O_(x)/NO_(2)-CRDS.The system was applied in a comprehensive field observation campaign at Hefei Sci-ence Island from 26 to 30 September 2022,and the time concentration series and change characteristics of O_(x)and NO_(2)were obtained for five days.The measured O_(x)concentrations were compared with those of two com-mercial instruments,and the consistency was good(R^(2)=0.98),indicating that this system can be deployed to accurately and rapidly obtain the concentrations of atmospheric O_(x)and NO_(2).It will be a useful tool for assessing the atmospheric oxidation capacity and controlling O_(3)pollution.
大气O_(x)(二氧化氮(NO_(2))+臭氧(O_(3)))相比于O_(3)能够更好的反应区域氧化剂的变化特征,O_(x)也是反应大气污染防治效果的一个关键指标.本研究基于腔衰荡光谱技术研发了一套大气O_(x)和NO_(2)同步测量系统(O_(x)/NO_(2)-CRDS).NO_(2)浓度是利用其在407.86 nm处的特征吸收获取,环境大气的O_(3)通过高浓度的NO被转化为NO_(2)进行间接测量,O_(3)转化效率高于99%,O_(x)/NO_(2)-CRDS的系统探测限为0.024 ppbv(0.1 s),系统总不确定度为±6%.该O_(x)/NO_(2)-CRDS系统成功应用于2022年9月26日-30日的合肥市科学岛综合外场观测中,获取了连续5天的NO_(2)和O_(x)的时间浓度序列和变化特征,并将O_(x)的测量结果与商业化的设备进行了对比验证,二者具有较好的一致性(R2=0.98),表明O_(x)/NO_(2)-CRDS能够被应用于大气O_(x)和NO_(2)的高灵敏探测.未来该系统也将会变成评估大气氧化性以及控制臭氧污染的重要工具.
基金
supported by the National Natural Science Foundation of China[grant number 62275250]
the Natural Science Foundation of Anhui Province[grant number 2008085J20]
the National Key R&D Program of China[grant number 2022YFC3700301]
the Anhui Provincial Key R&D Program[grant number 2022l07020022]。
作者简介
Corresponding authors:Renzhi Hu,E-mail addresses:rzhu@aiofm.ac.cn;Corresponding authors:Pinhua Xie,phxie@aiofm.ac.cn。
