Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter

Zhang, Jingwei; Guo, Yitian; Yu, Qian; Chen, Yong; Yu, Rui-Peng; Xue, Chaoyang; Yang, Rui; Zhang, Qiang; Liu, Xingang; Mu, Yujing; Wang, Jing; Ye, Can; Zhao, Hongying; Sun, Qiangqiang; Wang, Ziwen; An, Junling

doi:10.1016/j.jes.2020.03.039

Cited by 22 publications

(16 citation statements)

References 61 publications

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“…This result represents a combination of a relatively lower photolysis rate of acetone (~10 -7 s -1 ) and previously reported low MGLY concentration (~0.012 ppb) during autumn at the rural site (Qiu et al, 2020c). Our results are consistent with previous studies, in which they also confirm the dominant role of CH3CHO+OH in PA formation in eastern China (Zeng et al, 2019a;Zhang et al, 2020b) and even on global scale (Fischer, et al, 2014). CH3CHO could be directly emitted to the atmosphere and also formed through oxidations of alkenes, such as C3H6.…”

Section: Impacts Of Precursors On Rapid Increase Of Pansupporting

confidence: 93%

“…Despite several field campaigns and experiment analysis in recent years, the fast PAN formation mechanisms during cold days over the NCP region still have not been fully explored so far, especially over clean rural areas. Previously, HONO photolysis was tentatively considered as the cause of enhanced local photochemistry in winter of urban NCP region, thus contributing to increases in PAN concentrations (Liu et al, 2018;Zhang et al, 2020b). However, these studies neglect the impacts of carbonyl photolysis that may play a dominant role in PAN formation over the rural region where NOx emissions are rather low and could allow for fast photochemistry.…”

Section: Introductionmentioning

confidence: 99%

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Measurement report: Fast photochemical production of peroxyacetyl nitrate (PAN) over the rural North China Plain during cold-season haze events

Qiu

et al. 2021

Preprint

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Abstract. Photochemical pollution over the North China Plain (NCP) are attracting considerable concern. Peroxyacetyl nitrate (PAN) is usually viewed as the second most important photochemical pollutant featuring high mixing ratios during warm seasons. Our observations at a background site in the NCP identified high PAN concentrations even during cold-season haze events. The abrupt increasing rates of PAN by 244 % and 178 % over the morning hours (8:00–12:00) on 10/20 and 10/25, 2020 were 10.6 and 7.7 times those on clean days. The pollution days were characterized by higher temperature and humidity, accompanied by anomalous southerlies. Enhanced local photochemistry has been identified as the dominant factor that controls PAN increase in the morning at the rural site, as the time when prevailing wind turned to southerlies was too late to facilitate direct transport of PAN from the polluted urban region. By removing the effect of direct transport of PAN, we provide a quantitative assessment of net PAN chemical production rate of 0.45 ppb h−1 on the polluted morning, also demonstrating the strong local photochemistry. Using observations and calculated photolysis rates, we find that oxidation of acetaldehyde by hydroxyl radical (OH) is the primary pathway of peroxyacetyl radical formation at the rural site. Acetaldehyde concentrations and production rates of HOx (HOx = OH + HO2) radical on pollution days were 2.8 and 2 times that on clean days, respectively, leading to the abrupt increase of PAN in the morning. Formaldehyde (HCHO) photolysis dominates the daytime HOx production thus contributing to fast photochemistry of PAN. Our observational results fully explain the cause of rapid increase of PAN during cold days at a rural site of the NCP, as well as provide the evidence of important role of HCHO photolysis in secondary pollutants at lower nitrogen oxide emissions. This highlights the imperative to implement strict volatile organic compounds controls out of summer seasons over the NCP.

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Section: Impacts Of Precursors On Rapid Increase Of Pansupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Measurement report: Fast photochemical production of peroxyacetyl nitrate (PAN) over the rural North China Plain during cold-season haze events

Qiu

et al. 2021

Preprint

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“…In some model studies, larger γ were applied to better match the simulated HONO levels to measurements (e.g. [28,55,56]). Nighttime uptake coefficients of 5×10 -6 and 1×10 -5 on aerosol surface were used by Zhang et al [55] and Zhang et al [56], respectively, following the model setup in Li et al [57].…”

Section: Atmospheric Implication On Hono Unknown Sourcementioning

confidence: 99%

“…[28,55,56]). Nighttime uptake coefficients of 5×10 -6 and 1×10 -5 on aerosol surface were used by Zhang et al [55] and Zhang et al [56], respectively, following the model setup in Li et al [57]. Yet, the uptake coefficient in Li et al [57] was set as 1×10 -6 according to a laboratory experiment for the NO2 uptake on pure water and acidic solution [58].…”

Section: Atmospheric Implication On Hono Unknown Sourcementioning

confidence: 99%

Measurement of heterogeneous uptake of NO2 on inorganic particles, sea water and urban grime

Wang

et al. 2021

Journal of Environmental Sciences

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Heterogeneous reactions of NO2 on different surfaces play an important role in atmospheric NOx removal and HONO formation, having profound impacts on photochemistry in polluted urban areas. Previous studies have suggested that the NO2 uptake on the ground or aerosol surfaces could be a dominant source for elevated HONO during daytime. However, the uptake behavior of NO2 varies with different surfaces, and different uptake coefficients were used or derived in different studies. To obtain a more holistic picture of heterogeneous NO2 uptake on different surfaces, a series of laboratory experiments using different flow tube reactors was conducted, and the NO2 uptake coefficient (γ) were determined on inorganic particles, sea water and urban grime. The results showed that heterogeneous reactions on those surfaces were generally weak in dark condition, with the measured γ varied from <10 -8 to 3.2×10 -7 under different humidity.A photo-enhanced uptake of NO2 on urban grime were observed, with obvious formation of HONO and NO from the heterogeneous reaction. The photo-enhanced γ was measured to be 1.9×10 -6 to at 5% RH and 5.8×10 -6 at 70% RH on urban grime, showing a positive RH dependence for both NO2 uptake and HONO formation. The results demonstrate an important role of urban grime in the daytime NO2-to-HONO conversion, and could be helpful to explain the unknown daytime HONO source in the polluted urban area.

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“…In a conventional view, the winter PAN levels are low due to weak solar radiation (G. Zhang et al, 2014), and in summer, observed PAN pollution events are usually accompanied by O 3 pollution episodes (B. Zhang et al, 2017). However, recent studies in China found that PAN concentrations on winter haze days could be as high as those observed in summer photochemical smog (Liu et al, 2018; Qiu, Ma, et al, 2019; G. Zhang, Xia, et al, 2020; B. Zhang et al, 2019), suggesting potential contributions from unfavorable meteorological conditions and local photochemical reactions (Qiu, Ma, et al, 2019; J. Zhang, Guo, et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Markedly Enhanced Levels of Peroxyacetyl Nitrate (PAN) During COVID‐19 in Beijing

Qiu

et al. 2020

Geophysical Research Letters

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High levels of secondary air pollutants during COVID-19 in China have aroused great concern. In Beijing, measured daily mean peroxyacetyl nitrate (PAN) concentrations reached 4 ppb over the lockdown period (24 January to 15 February), whose averages were 2-3 times that before lockdown (1-23 January). The lockdown PAN levels also reached a high historical record based on our long-term measurements (2016-2019). Unlike ozone and PM 2.5 , PAN formation depends on less complex photochemistry between NO x and volatile organic compounds (VOCs), providing a novel approach to investigate the wintertime photochemistry during COVID-19. The GEOS-Chem simulations suggest a markedly enhanced photochemistry by a factor of 2 during the lockdown. Change of meteorology featuring with anomalous wind convergence under higher temperatures is the main reason for enhanced photochemical formation of PAN, while chemically nonlinear feedbacks also play a role. Our results suggest implementing targeted VOC emission controls in the context of increasing photochemical pollution over this complex polluted region. Plain Language Summary Outbreaks of the COVID-19 pandemic caused immediate implementation of lockdown policy in China, which drastically decreased emissions of primary air pollutants. Peroxyacetyl nitrate (PAN), as an important photochemical product, is controlled by reactions between NO x and volatile organic compounds (VOCs) that were reduced substantially due to the lockdown. However, observed PAN levels in Beijing during the lockdown were markedly enhanced and were even much higher than the concentrations during the same periods in 2016-2019. Modeling results prove that this increase in PAN is driven by enhanced photochemistry, resulting from anomalous wind convergence under higher temperature and enhanced radical level in response to NO x reduction. Our results suggest the necessity of reducing VOC emissions in controlling photochemical pollution even in the wintertime over China.

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Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter

Cited by 22 publications

References 61 publications

Measurement report: Fast photochemical production of peroxyacetyl nitrate (PAN) over the rural North China Plain during cold-season haze events

Measurement report: Fast photochemical production of peroxyacetyl nitrate (PAN) over the rural North China Plain during cold-season haze events

Measurement of heterogeneous uptake of NO2 on inorganic particles, sea water and urban grime

Markedly Enhanced Levels of Peroxyacetyl Nitrate (PAN) During COVID‐19 in Beijing

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