Identification of ozone sensitivity for NO2 and secondary HCHO based on MAX-DOAS measurements in northeast China. (February 2022)

• Record Type: Journal Article
• Authors: Xue, Jiexiao; Zhao, Ting; Luo, Yifu; Miao, Congke; Su, Pinjie; Liu, Feng; Zhang, Guohui; Qin, Sida; Song, Youtao; Bu, Naishun; Xing, Chengzhi
• Is Part Of: Environment international. Volume 160(2022)
• Publication Date: 2022-02
• Subjects: MAX-DOAS -- Formaldehyde -- Secondary source -- HCHO/NO2 -- Ozone production sensitivity; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2021.107048
• Languages: English
• ISSNs: 0160-4120

Abstract

Graphical abstract: Highlights: HCHO VCDs peaked in summer affected by oxidation of BVOCs in Shenyang. The contribution of primary and secondary sources of HCHO were 8.36% and 73.74%, respectively. The accuracy of O3 sensitivity was improved 12% by using HCHOsec /NO2 in summer. The hourly O3 sensitivities were mainly VOC-limited during the whole year. Abstract: In this study, tropospheric formaldehyde (HCHO) vertical column densities (VCDs) were measured using multi-axis differential optical absorption spectroscopy (MAX-DOAS) from January to November 2019 in Shenyang, Northeast China. The maximum HCHO VCD value appeared in the summer (1.74 × 10 16 molec/cm 2 ), due to increased photo-oxidation of volatile organic compounds (VOCs). HCHO concentrations increased from 08:00 and peaked near 13:00, which was mainly attributed to the increased release of isoprene from plants and enhanced photolysis at noon. The HCHO VCDs observed by MAX-DOAS and OMI have a good correlation coefficient (R) of 0.78, and the contributions from primary and secondary HCHO sources were distinguished by the multi-linear regression model. The anthropogenic emissions showed unobvious seasonal variations, and the primary HCHO was relatively stable in Shenyang. Secondary HCHO contributed 82.62%, 83.90%, 78.90%, and 41.53% to the total measured ambient HCHO during the winter, spring, summer, and autumn, respectively. We also found a good correlation (R = 0.78) between enhanced vegetation index (EVI) and HCHO VCDs, indicating that the oxidation of biogenic volatile organic compounds (BVOCs) was the main source of HCHO. The ratio of secondary HCHO to nitrogen dioxide (NO2 ) was used as the tracer to analyze O3 -NOx -VOC sensitivities. We found that the VOC-limited, VOC-NOx -limited, and NOx -limited regimes made up 93.67%, 6.23%, 0.11% of the overall measurements, respectively. In addition, summertime ozone (O3 ) sensitivity changed from VOC-limited in the morning to VOC-NOx -limited in the afternoon. Therefore, this study offers information on HCHO sources and corresponding O3 production sensitivities to support strategic management decisions.