Double High-Level Ozone and PM<sub>2.5</sub> Co-Pollution Episodes in Shanghai, China: Pollution Characteristics and Significant Role of Daytime HONO
In recent years, high fine particulate (PM<sub>2.5</sub>) pollution episodes with high ozone (O<sub>3</sub>) levels have been observed in Shanghai from time to time. However, their occurrence and characteristics remain poorly understood. Meanwhile, as a major precursor of tro...
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MDPI AG
2021-04-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/12/5/557 |
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| author | Kejing Yang Lingdong Kong Songying Tong Jiandong Shen Lu Chen Shengyan Jin Chao Wang Fei Sha Lin Wang |
| author_facet | Kejing Yang Lingdong Kong Songying Tong Jiandong Shen Lu Chen Shengyan Jin Chao Wang Fei Sha Lin Wang |
| author_sort | Kejing Yang |
| collection | DOAJ |
| description | In recent years, high fine particulate (PM<sub>2.5</sub>) pollution episodes with high ozone (O<sub>3</sub>) levels have been observed in Shanghai from time to time. However, their occurrence and characteristics remain poorly understood. Meanwhile, as a major precursor of tropospheric hydroxyl radical (OH) that initiates the formation of hydroperoxyl and organic peroxy radicals, HONO would inevitably affect the formation of O<sub>3</sub>, but its role in the formation of O<sub>3</sub> during the double high-level PM<sub>2.5</sub> and O<sub>3</sub> pollution episodes remains unclear. In this study, the characteristics of the double high pollution episodes and the role of HONO in O<sub>3</sub> formation in these episodes were investigated based on field observation in urban Shanghai from 2014 to 2016. Results showed that high PM<sub>2.5</sub> pollution and high O<sub>3</sub> pollution could occur simultaneously. The cases with data of double high O<sub>3</sub> and PM<sub>2.5</sub> concentrations accounted for about 1.0% of the whole sampling period. During the double high pollution episodes, there still existed active photochemical processes, while the active photochemical processes at high PM<sub>2.5</sub> concentration were conductive to the production and accumulation of O<sub>3</sub> under a VOC-limited regime and a calm atmospheric condition including high temperature, moderately high relative humidity, and low wind speed, which in turn enhanced the conversions of SO<sub>2</sub> and NO<sub>2</sub> and the formation and accumulation of secondary sulfate and nitrate aerosols and further promoted the increase of PM<sub>2.5</sub> concentration and the deterioration of air pollution. Further analysis indicated that the daytime HONO concentration could be strongly negatively correlated with O<sub>3</sub> concentration in most of the double high pollution episodes, revealing the dominant role of HONO in O<sub>3</sub> formation during these pollution episodes. This study provides important field measurement-based evidence for understanding the significant contribution of daytime HONO to O<sub>3</sub> formation, and helps to clarify the formation and coexistence mechanisms of the double high-level O<sub>3</sub> and PM<sub>2.5</sub> pollution episodes. |
| first_indexed | 2024-03-10T11:57:13Z |
| format | Article |
| id | doaj.art-99d96359482a4afda70879ced2277ad4 |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-10T11:57:13Z |
| publishDate | 2021-04-01 |
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| spelling | doaj.art-99d96359482a4afda70879ced2277ad42023-11-21T17:13:17ZengMDPI AGAtmosphere2073-44332021-04-0112555710.3390/atmos12050557Double High-Level Ozone and PM<sub>2.5</sub> Co-Pollution Episodes in Shanghai, China: Pollution Characteristics and Significant Role of Daytime HONOKejing Yang0Lingdong Kong1Songying Tong2Jiandong Shen3Lu Chen4Shengyan Jin5Chao Wang6Fei Sha7Lin Wang8Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, ChinaShanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, ChinaShanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, ChinaHangzhou Environmental Monitoring Center, Hangzhou 310007, ChinaShanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, ChinaShanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, ChinaShanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, ChinaPudong New Area Environmental Monitoring Station, No. 51 Lingshan Road, Shanghai 200135, ChinaShanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, ChinaIn recent years, high fine particulate (PM<sub>2.5</sub>) pollution episodes with high ozone (O<sub>3</sub>) levels have been observed in Shanghai from time to time. However, their occurrence and characteristics remain poorly understood. Meanwhile, as a major precursor of tropospheric hydroxyl radical (OH) that initiates the formation of hydroperoxyl and organic peroxy radicals, HONO would inevitably affect the formation of O<sub>3</sub>, but its role in the formation of O<sub>3</sub> during the double high-level PM<sub>2.5</sub> and O<sub>3</sub> pollution episodes remains unclear. In this study, the characteristics of the double high pollution episodes and the role of HONO in O<sub>3</sub> formation in these episodes were investigated based on field observation in urban Shanghai from 2014 to 2016. Results showed that high PM<sub>2.5</sub> pollution and high O<sub>3</sub> pollution could occur simultaneously. The cases with data of double high O<sub>3</sub> and PM<sub>2.5</sub> concentrations accounted for about 1.0% of the whole sampling period. During the double high pollution episodes, there still existed active photochemical processes, while the active photochemical processes at high PM<sub>2.5</sub> concentration were conductive to the production and accumulation of O<sub>3</sub> under a VOC-limited regime and a calm atmospheric condition including high temperature, moderately high relative humidity, and low wind speed, which in turn enhanced the conversions of SO<sub>2</sub> and NO<sub>2</sub> and the formation and accumulation of secondary sulfate and nitrate aerosols and further promoted the increase of PM<sub>2.5</sub> concentration and the deterioration of air pollution. Further analysis indicated that the daytime HONO concentration could be strongly negatively correlated with O<sub>3</sub> concentration in most of the double high pollution episodes, revealing the dominant role of HONO in O<sub>3</sub> formation during these pollution episodes. This study provides important field measurement-based evidence for understanding the significant contribution of daytime HONO to O<sub>3</sub> formation, and helps to clarify the formation and coexistence mechanisms of the double high-level O<sub>3</sub> and PM<sub>2.5</sub> pollution episodes.https://www.mdpi.com/2073-4433/12/5/557O<sub>3</sub>PM<sub>2.5</sub>HONOdouble high pollutionsecondary aerosol |
| spellingShingle | Kejing Yang Lingdong Kong Songying Tong Jiandong Shen Lu Chen Shengyan Jin Chao Wang Fei Sha Lin Wang Double High-Level Ozone and PM<sub>2.5</sub> Co-Pollution Episodes in Shanghai, China: Pollution Characteristics and Significant Role of Daytime HONO Atmosphere O<sub>3</sub> PM<sub>2.5</sub> HONO double high pollution secondary aerosol |
| title | Double High-Level Ozone and PM<sub>2.5</sub> Co-Pollution Episodes in Shanghai, China: Pollution Characteristics and Significant Role of Daytime HONO |
| title_full | Double High-Level Ozone and PM<sub>2.5</sub> Co-Pollution Episodes in Shanghai, China: Pollution Characteristics and Significant Role of Daytime HONO |
| title_fullStr | Double High-Level Ozone and PM<sub>2.5</sub> Co-Pollution Episodes in Shanghai, China: Pollution Characteristics and Significant Role of Daytime HONO |
| title_full_unstemmed | Double High-Level Ozone and PM<sub>2.5</sub> Co-Pollution Episodes in Shanghai, China: Pollution Characteristics and Significant Role of Daytime HONO |
| title_short | Double High-Level Ozone and PM<sub>2.5</sub> Co-Pollution Episodes in Shanghai, China: Pollution Characteristics and Significant Role of Daytime HONO |
| title_sort | double high level ozone and pm sub 2 5 sub co pollution episodes in shanghai china pollution characteristics and significant role of daytime hono |
| topic | O<sub>3</sub> PM<sub>2.5</sub> HONO double high pollution secondary aerosol |
| url | https://www.mdpi.com/2073-4433/12/5/557 |
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