Long-term changes of regional ozone in China: implications for human health and ecosystem impacts

Xu, Xiangde; Lin, Weili; Xu, Wanyun; Jin, Junli; Wang, Ying; Zhang, Gen; Zhang, Xiaochun; Ma, Zhiqiang; Dong, Yuanzhen; Ma, Qiang; Yu, Dajiang; Zou, Li; Wang, Dingding; Zhao, Huarong

doi:10.1525/elementa.409

Cited by 64 publications

(55 citation statements)

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“…It is inconsistent with satellite NO2 data shown in Fig 5 (and NOx emission inventory) which indicate gradual decrease in NOx emission after 2011. Recently reported surface measurements at two rural sites near Beijing (Shangdianzi and Gucheng) also did not observe sudden ozone drop around 2011/12 (Xu et al, 2020). I suggest comparing satellite observed tropospheric ozone to verify the sudden change observed in the present study.…”

Section: Major Commentssupporting

confidence: 81%

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Referee's comment

2020

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Section: Major Commentssupporting

confidence: 81%

“…. Please note that recent studies have shown levelling off/decrease in surface ozone levels in rural areas of eastern China and in outflow of eastern China air masses (Xu et al, 2020;Wang et al, 2019).…”

Section: Minor Commentsmentioning

confidence: 99%

Referee's comment

2020

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“…Table S1 also presents the observed HONO mixing ratios at two coastal sites in Hong Kong (Z. Y. Xu et al, 2015), but their levels were substantially underpredicted because capturing such coastal characteristics is challenging for the model, due to its low horizontal resolution (36 km).…”

Section: Comparison Of the Simulated And Observed Reactive Gasesmentioning

confidence: 99%

Worsening urban ozone pollution in China from 2013 to 2017 – Part 2: The effects of emission changes and implications for multi-pollutant control

2020

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Abstract. The Chinese government launched the Air Pollution Prevention and Control Action Plan in 2013, and various stringent measures have since been implemented, which have resulted in significant decreases in emissions and ambient concentrations of primary pollutants such as SO2, NOx, and particulate matter (PM). However, surface ozone (O3) concentrations have still been increasing in urban areas across the country. In a previous analysis, we examined in detail the roles of meteorological variation during 2013–2017 in the summertime surface O3 trend in various regions of China. In this study, we evaluated the effect of changes in multi-pollutant emissions from anthropogenic activities on O3 levels during the same period by using an up-to-date regional chemical transport model (WRF-CMAQ) driven by an interannual anthropogenic emission inventory. The Community Multiscale Air Quality (CMAQ) model was improved with regard to heterogeneous reactions of reactive gases on aerosol surfaces, which led to better model performance in reproducing the ambient concentrations of those gases. The model simulations showed that the maximum daily 8 h average (MDA8) O3 mixing ratio in urban areas increased by 0.46 ppbv per year (ppbv a−1) (p=0.001) from 2013 to 2017. In contrast, a slight decrease in MDA8 O3 by 0.17 ppbv a−1 (p=0.005) in rural areas was predicted, mainly attributable to the NOx emission reduction. The effects of changes in individual pollutant emissions on O3 were also simulated. The reduction of NOx emission increased the O3 levels in urban areas due to the nonlinear NOx and volatile organic compound (VOC) chemistry and decreasing aerosol effects; the slight increase in VOC emissions enhanced the O3 levels; the reduction of PM emissions increased the O3 levels by enhancing the photolysis rates and reducing the loss of reactive gases on aerosol surfaces; and the reduction of SO2 emissions resulted in a drastic decrease in sulfate concentrations, which increased O3 through aerosol effects. In contrast to the unfavorable effect of the above changes in pollutant emissions on efforts to reduce surface O3, the reduction of CO emissions did help to decrease the O3 level in recent years. The dominant cause of increasing O3 due to changes in anthropogenic emissions varied geographically. In Beijing, NOx and PM emission reductions were the two largest causes of the O3 increase; in Shanghai, the reduction of NOx and increase in VOC emissions were the two major causes; in Guangzhou, NOx reduction was the primary cause; in Chengdu, the PM and SO2 emission decreases contributed most to the O3 increase. Regarding the effects of decreasing concentrations of aerosols, the drop in heterogeneous uptake of reactive gases – mainly HO2 and O3 – was found to be more important than the increase in photolysis rates. The adverse effect of the reductions of NOx, SO2, and PM emissions on O3 abatement in Beijing, Shanghai, Guangzhou, and Chengdu would have been avoided if the anthropogenic VOCs emission had been reduced by 24 %, 23 %, 20 %, and 16 %, respectively, from 2013 to 2017. Our analysis revealed that the NOx reduction in recent years has helped to contain the total O3 production in China. However, to reduce O3 levels in major urban and industrial areas, VOC emission controls should be added to the current NOx-SO2-PM policy.

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“…Ozone concentrations from the Earth's surface up to ∼ 30 km were measured over Beijing using an ozonesonde developed by the Key Laboratory of Middle Atmosphere and Global Environment Observation of the Institute of Atmospheric Physics (IAP) (Zhang et al, 2014). The IAP ozonesonde is based on an electrochemical method which is well documented in previous studies (Wang et al, 2003;Xuan et al, 2004;Zheng and Li, 2005). The ozonesonde has previously been compared with the widely used electrochemical concentration cell (ECC) developed by Komhyr (1969) and the Brewer spectrophotometer (Zhang et al, 2014) and was able to capture the ozone profile.…”

Section: Ozonesondementioning

confidence: 99%

“…Air quality controls have been implemented in China as a result of the recent increases in atmospheric pollutants, especially in the North China Plain, and the emissions of SO 2 and NO x have been successfully reduced in recent years (Ma et al, 2016;van der A et al, 2017;Li et al, 2017). Recent studies have shown a levelling off/decrease in surface ozone levels in rural areas of eastern China and in the outflow of eastern China air masses (Xu et al, 2020;. Using the Infrared Atmospheric Sounding Interferometer (IASI) on board the European Space Agency's (ESA) MetOp series of polar orbiting satellites, together with surface and ozonesonde measurements, Dufour et al (2018) reported the trend in tropospheric ozone concentrations over the North China Plain for the time period 2008-2016.…”

Section: Introductionmentioning

confidence: 99%

Long-term variations in ozone levels in the troposphere and lower stratosphere over Beijing: observations and model simulations

et al. 2020

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Abstract. Tropospheric ozone is both a major pollutant and a short-lived greenhouse gas and has therefore caused much concern in recent years. The ozone profile in the troposphere and lower stratosphere over Beijing has been observed since 2002 by ozonesondes developed by the Institute of Atmospheric Physics. Increasing concentrations of tropospheric ozone from 2002 to 2010 measured by these balloon-based observations have been reported previously. As more observations are now available, we used these data to analyse the long-term variability of ozone over Beijing during the whole period from 2002 to 2018. The ozonesondes measured increasing concentrations of ozone from 2002 to 2012 in both the troposphere and lower stratosphere. There was a sudden decrease in observed ozone between 2011 and 2012. After this decrease, the increasing trend in ozone concentrations slowed down, especially in the mid-troposphere, where the positive trend became neutral. We used the Chemical Lagrangian Model of the Stratosphere (CLaMS) to determine the influence of the transport of ozone from the stratosphere to the troposphere on the observed ozone profiles. CLaMS showed a weak increase in the contribution of stratospheric ozone before the decrease in 2011–2012 and a much more pronounced decrease after this time. Because there is no tropospheric chemistry in CLaMS, the sudden decrease simulated by CLaMS indicates that a smaller downward transport of ozone from the stratosphere after 2012 may explain a significant part of the observed decrease in ozone in the mid-troposphere and lower stratosphere. However, the influence of stratospheric ozone in the lower troposphere is negligible in CLaMS, and the hiatus in the positive trend after 2012 can be attributed to a reduction in ozone precursors as a result of stronger pollution control measures in Beijing.

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Long-term changes of regional ozone in China: implications for human health and ecosystem impacts

Cited by 64 publications

References 65 publications

Referee's comment

Referee's comment

Worsening urban ozone pollution in China from 2013 to 2017 – Part 2: The effects of emission changes and implications for multi-pollutant control

Long-term variations in ozone levels in the troposphere and lower stratosphere over Beijing: observations and model simulations

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