由于甲醛在大气光化学反应中的重要性及其对环境、 气候和人类健康的危害, 监测、 有效控制甲醛浓度已经成为一件刻不容缓的要事。 目前传统的监测多局限于基于化学方法、 色谱法的室内监测, 或是室外较小范围的监测, 室外大范围的大气中的甲醛监测往往为人们所忽视。 为了有效监测大气中大范围的甲醛(HCHO)浓度, 建立了地基MAX-DOAS观测系统, 与主动DOAS观测系统相比, 该观测系统不受光源和反射装置限制, 平台搭建简单, 测量范围广。 2018年在合肥地区(117°17′E, 31°90′N)夏季开展了基于地基MAX-DOAS的外场连续观测实验, 结合新一代光谱处理软件QDOAS利用DOAS算法的非线性最小二乘拟合反演甲醛(HCHO)的斜柱浓度, 并通过大气质量因子(AMF)将甲醛(HCHO)的斜柱浓度转换为柱浓度, 并分析了7月份的观测数据, 结果表明, 低仰角下甲醛的差分斜柱浓的值较高, 说明, 对流层甲醛主要集中在接近地表的位置。 从实验数据还可以看到, 二氧化氮与甲醛的变化趋势基本一致, 说明大气中的甲醛与机动车排放或是工业排放出的的氮氧化物(NO2等)在大气的源与汇过程中具有一定的相关性。 通过地基MAX-DOAS测量数据与OMI观测值的比较发现, 二者的变化趋势具有良好的一致性, 且相关系数为0.518 9, 并分析了OMI观测值偏低的原因。 研究结果表明, 地基MAX-DOAS系统不仅可以对区域污染的演变进行研究, 也为甲醛的测量提供了一种实时、 快速的监测手段, 为分析大气甲醛的来源提供了一种新的解析手段, 为验证卫星观测数据提供了一种有效的手段。

Because of the importance of formaldehyde in atmospheric photochemical reaction and its harm to environment, climate and human health, it is urgent to control and monitor the concentration of formaldehyde. At present, traditional monitoring is mostly limited to indoor monitoring based on chemical methods and chromatographic methods or outdoor monitoring in a small range, while outdoor formaldehyde monitoring in a wide range of atmosphere is often ignored by people. In order to effectively monitor the concentration of formaldehyde (HCHO) in the atmosphere, the ground-based MAX - DOAS observation system was established. Compared with the active DOAS, the MAX - DOAS observation system was not limited by the light source and reflex attachment, with simple platform construction, wide measurement range. Based on this, continuous observation experiments were carried out based on MAX - DOAS observation system in the summer of 2018 at Hefei site, combined with the new generation of spectral processing software QDOAS, the nonlinear least squares fitting of DOAS algorithm was used to retrieve the differential slant column densities of formaldehyde (HCHO). Then the differential slant column densities of formaldehyde were converted to the vertical column densities by use of the atmospheric quality factor (AMF), and the observed data in July were analyzed, the result showed that the slant column densities of formaldehyde under low elevation angle are higher, therefore, tropospheric formaldehyde is mainly concentrated in the position near the earth’s surface. It can also be seen from the experimental data that the change trend of nitrogen dioxide and formaldehyde is basically consistent, indicating that the atmospheric formaldehyde is correlated with the nitrogen oxides (NO2, etc.) discharged by motor vehicles or industry in the process of atmospheric source and sink. It was found that the change trend of the two kinds of measurement data had a good consistency by the comparison between the ground-based MAX - DOAS measurement data and the OMI observation data, and the correlation coefficient was 0.518 9, and the reason why the OMI observation value was low was analyzed. The results showed that the ground-based MAX - DOAS system can not only study the evolution of regional pollution, but also provide a real-time and rapid monitoring method for formaldehyde measurement, a new analytical method for analyzing the source of atmospheric formaldehyde, and an effective method for verifying satellite observation data.