The Aggravation of Summertime Nocturnal Ozone Pollution in China and Its Potential Impact on the Trend of Nitrate Aerosols

Abstract

Tropospheric ozone (O3) concentration continued to increase over past years, thereby becoming a growing environmental concern in China. Most studies have focused on the analysis of daily maximum 8‐hr O3 concentration, while there is still a dearth of investigations of nocturnal O3. Here, by analyzing the data of 1,313 sites from the China National Environmental Monitoring Center, we show a remarkable increase in the nocturnal O3 concentration during summertime of 2015–2019 in most regions of China, revealing an aggravation of nocturnal O3 pollution. Combining with a GeoDetector model and statistical analysis, we clarify that the aggravation of nocturnal O3 pollution is mainly caused by reduction in both ambient nitrogen dioxide (NO2) concentration and wet scavenging in recent years. We further reveal that the increasing O3 may have enhanced the nocturnal particulate nitrate (NO3− ${{\mathrm{N}\mathrm{O}}_{3}}^{-}$) formation through N2O5 heterogeneous hydrolysis, and thereby driving the variation and long‐term trend of nocturnal NO3− ${{\mathrm{N}\mathrm{O}}_{3}}^{-}$.

A Comparative Investigation on the Characteristics of Nocturnal Ozone Enhancement Events and Their Effects on Ground-level Ozone and PM2.5 in the Central City of the Yellow River Delta, China, in 2022 and 2023

“…It can be seen that the high and middle percentile of nocturnal ozone concentration increased most significantly in Dongying from 2022 to 2023. The increase in nocturnal ozone concentrations in Dongying is similar to the results of Li et al, who found that nocturnal ozone concentrations increased significantly in most regions of China in the summer of 2019 compared to 2015 [15]. From 2022 to 2023, the monthly variation of nocturnal ozone concentration in Dongying showed an unimodal distribution, with the peak occurring in June (Figure 2).…”

“…Due to the synthetic effects of photochemical generation, dry depositions and boundary layer entrainment, the diurnal variation of ozone concentration usually presents a unimodal distribution, that is, the concentration is higher during the daytime and lower at nighttime, which has been confirmed by a large number of field observations [6][7][8][9][10][11]. However, in recent years, many studies have found that the nocturnal ozone concentrations are surging rather than falling, and the nocturnal ozone peak occurs, which has been widely observed in the United States, Europe, and China [12][13][14][15][16][17][18][19]. Studies reported that higher nocturnal ozone concentrations may have an impact on atmospheric chemical processes, human health, and vegetation growth [15,[20][21][22].…”

“…However, in recent years, many studies have found that the nocturnal ozone concentrations are surging rather than falling, and the nocturnal ozone peak occurs, which has been widely observed in the United States, Europe, and China [12][13][14][15][16][17][18][19]. Studies reported that higher nocturnal ozone concentrations may have an impact on atmospheric chemical processes, human health, and vegetation growth [15,[20][21][22]. Wang et al [21] suggested that the increase in nocturnal ozone concentrations in China in recent years has led to an increase in the nocturnal atmospheric oxidation capacity in China.…”

A Comparative Investigation of the Characteristics of Nocturnal Ozone Enhancement Events and Their Effects on Ground-Level Ozone and PM2.5 in the Central City of the Yellow River Delta, China, in 2022 and 2023

“…Due to the synthetic effects of photochemical generation, dry depositions, and boundary layer entrainment, the diurnal variation in ozone concentration usually presents a unimodal distribution; that is, the concentration is higher during the daytime and lower at nighttime, which has been confirmed by a large number of field observations [6][7][8][9][10][11]. However, in recent years, many studies have demonstrated that nocturnal ozone concentrations are surging and that a nocturnal ozone peak occurs, which has been widely observed in the United States, Europe, and China [12][13][14][15][16][17][18][19]. Studies have reported that higher nocturnal ozone concentrations may have an impact on atmospheric chemical processes, human health, and vegetation growth [15,[20][21][22].…”

Unexpected Trade-Offs of Fossil Fuel Reduction on PM2.5 and O3 Pollution Regulation Can Be Offset by Synergistic Control of VOCs Source

“…Air pollution is a global environmental concern that can pose substantial adverse impacts on climate change and human health. − In China, severe PM 2.5 pollution has been considerably alleviated due to rigorous emission control measures but remains a significant concern. − This is especially evident in the North China Plain (NCP), where severe PM 2.5 pollution events continue to occur frequently. − Additionally, O 3 levels have continued to show a steady upward trend on a global scale in recent years, gradually replacing PM 2.5 as the most important air pollutant. − The frequent occurrence of double-high level pollution events, where both PM 2.5 and O 3 concentrations exceeded the national air quality standards simultaneously, have been observed in the NCP. − Hence, there is an urgent need to address such pollution issues by reducing both PM 2.5 and O 3 pollution synergistically.…”