High N2O5 Concentrations Observed in Urban Beijing: Implications of a Large Nitrate Formation Pathway

Wang, Haichao; Lu, Keding; Chen, Hong; Zhu, Qindan; Chen, Qi; Guo, Song; Jiang, Mingming; Li, Xin; Shang, Dongjie; Tan, Zhaofeng; Wu, Yusheng; Wu, Zhijun; Zou, Qi; Zheng, Yan; Zeng, Limin; Zhu, Tong; Hu, Min; Zhang, Yuanhang

doi:10.1021/acs.estlett.7b00341

Cited by 183 publications

(176 citation statements)

References 38 publications

(61 reference statements)

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“…(3) and (5), high S a , high NO x , low k NO 3 , or low temperature allow the N 2 O 5 uptake to more easily be located in the γ N 2 O 5 -insensitive region. Here, the critical value of the N 2 O 5 uptake coefficient (2 × 10 −3 ) was relatively low com- pared with that recommended for the surface of mineral dust (0.013, 290-300 K; Crowley et al, 2010b;Tang et al, 2017) or determined in many field experiments (e.g., S. S. Brown et al, 2006bBrown et al, , 2009Wagner et al, 2013;Morgan et al, 2015;Phillips et al, 2016;Brown et al, 2016;Wang et al, 2017b;. This suggests that the NO x loss and pNO − 3 formation by N 2 O 5 uptake were easily maximized in the pollution episode and further worsened the PM pollution.…”

Section: Sensitivity Studiesmentioning

confidence: 63%

“…Particulate nitrate formation via N 2 O 5 heterogeneous hydrolysis in summer was proved efficient by ground-based observation in North China (Wang et al, 2017b; and found comparable to or even higher than the daytime formation. Several studies showed that N 2 O 5 hydrolysis is responsible for nocturnal pNO − 3 enhancement in summer in Beijing (Pathak et al, 2009(Pathak et al, , 2011Wang et al, 2017a).…”

Section: Introductionmentioning

confidence: 83%

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Fast particulate nitrate formation via N2O5 uptake aloft in winter in Beijing

Wang

Chen

et al. 2018

Atmos. Chem. Phys.

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Abstract. Particulate nitrate (pNO − 3 ) is an important component of secondary aerosols in urban areas. Therefore, it is critical to explore its formation mechanism to assist with the planning of haze abatement strategies. Here we report vertical measurements of NO x and O 3 by in situ instruments on a movable carriage on a tower during a winter heavy-haze episode (18 to 20 December 2016) in urban Beijing, China. Based on the box model simulation at different heights, we found that pNO − 3 formation via N 2 O 5 heterogeneous uptake was negligible at ground level due to N 2 O 5 concentrations of near zero controlled by high NO emissions and NO concentration. In contrast, the contribution from N 2 O 5 uptake was large at high altitudes (e.g., > 150 m), which was supported by the lower total oxidant (NO 2 + O 3 ) level at high altitudes than at ground level. Modeling results show the specific case that the nighttime integrated production of pNO − 3 for the high-altitude air mass above urban Beijing was estimated to be 50 µg m −3 and enhanced the surface-layer pNO − 3 the next morning by 28 µg m −3 through vertical mixing. Sensitivity tests suggested that the nocturnal NO x loss by NO 3 -N 2 O 5 chemistry was maximized once the N 2 O 5 uptake coefficient was over 2 × 10 −3 on polluted days with S a at 3000 µm 2 cm −3 in wintertime. The case study provided a chance to highlight the fact that pNO − 3 formation via N 2 O 5 heterogeneous hydrolysis may be an important source of particulate nitrate in the urban airshed during wintertime.

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Section: Sensitivity Studiesmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 83%

Fast particulate nitrate formation via N2O5 uptake aloft in winter in Beijing

Wang

Chen

et al. 2018

Atmos. Chem. Phys.

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“…S1), likely suggesting the effects of SO 2 emission control over China in the recent years (Sun et al, 2015b). Previous studies also showed nitrates dominating the secondary inorganic species of aerosols (Sun et al, 2015b;Zheng et al, 2015;Wang et al, 2017 (Fig. S1), which made these elements difficult to emit into the air (Tian et al, 2014).…”

Section: Chemical Properties Of Aerosols At Different Pollution Levelsmentioning

confidence: 77%

Variations of Chemical Composition and Source Apportionment of PM2.5 during Winter Haze Episodes in Beijing

Tao

et al. 2017

Aerosol Air Qual. Res.

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PM 2.5 samples were collected in Beijing between February 24 and March 12 of 2014, and analyzed to examine chemical compositions and origins of the PM 2.5 at pollution levels of clean (PM 2.5 < 75 µg m -3 ), light-medium (75-150 µg m -3 ), heavy (150-250 µg m -3 ) and severe (> 250 µg m -3 ). The mean PM 2.5 concentration was 137.7 ± 124.8 µg m -3 during the observation period, accounting for 66% of PM 10. As all aerosol species concentrations increased with the pollution level, the contributions of secondary inorganic aerosols (SIA) to PM 2.5 continuously increased while the contributions of OC and EC decreased, indicating a substantial contribution from secondary formation to the elevation of PM 2.5 pollution. The acidity of PM 2.5 , the ratio of anion microequivalent concentration to cation, increased from 0.96 to 1.08 as pollution levels increased. Using a PMF model, secondary inorganic aerosols, industrial emissions, soil dust, traffic emissions, and coal combustion and biomass burning were identified as contributors to the PM 2.5 , and on average accounted 46%, 20%, 10%, 6% and 18% of the PM 2.5 , respectively, in the observation period. Industrial emissions were the dominant PM 2.5 source during the clean period (60%). Except for traffic emission, sources of PM 2.5 at the light-medium level were consistent, accounting for 17%-29%. Secondary inorganic aerosols were the largest origin of PM 2.5 at heavy and severe pollution levels, accounting for 40% and 78%, respectively. In addition, the 48 h transport distances of air masses decreased from 2000 km (clean) to 300 km (severe level) and the proportion of air masses from south pollution areas in the total air masses at each pollution level increased from 0% to 97%, indicating that the stability of near surface air and the northerly transport of pollutants from the south at local and regional scales played a the key role in the PM 2.5 elevation.

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“…HO 2 and RO 2 concentrations were detected as OH after chemical conversion by adding excess NO in another two separated cells. Detailed information of this instrument can be found in the paper by Tan et al (2017) and the references therein. Only a brief description of the radical 20 instrument is presented here.…”

Section: Oh Ho 2 and Ro 2 Measurementsmentioning

confidence: 99%

“…Also for this environment, there is a tendency of underestimating OH for conditions when NO was less than 300 pptv. Additionally, a missing peroxy radical source was found for the high NO x regime showing a severe underestimation of local ozone production (Tan et al, 2017).…”

mentioning

confidence: 96%

Wintertime photochemistry in Beijing: Observations of ROx radical concentrations in the North China Plain during the BEST-ONE campaign

Tan¹,

Rohrer²,

Lu³

et al. 2018

Preprint

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Abstract. The first wintertime in-situ measurements of hydroxyl (OH), hydroperoxy (HO 2 ) and organic peroxy (RO 2 ) 15 radicals (RO x =OH+HO 2 +RO 2 ) in combination with observations of total reactivity of OH radicals, k OH in Beijing are presented. The field campaign "Beijing winter finE particle STudy -Oxidation, Nucleation and light Extinctions" (BEST-ONE) was conducted at the suburban site Huairou near Beijing from January to March 2016. It aimed to understand oxidative capacity during wintertime and to elucidate the secondary pollutants formation mechanism in the North China Plain (NCP). OH radical concentrations at noontime ranged from 2.4×10 6 cm -3 in severely polluted 20 air (k OH ~ 27 s -1 ) to 3.6×10 6 cm -3 in relatively clean air (k OH ~ 5 s -1). These values are nearly two-fold larger than OH concentrations observed in previous winter campaign in Birmingham, Tokyo, and New York City. During this campaign, the total primary production rate of RO x radicals was dominated by the photolysis of nitrous acid accounting for 46% of the identified primary production pathways for RO x radicals. Other important radical sources were alkene ozonolysis (28%) and photolysis of oxygenated organic compounds (24%). A box model was used to 25 simulate the OH, HO 2 and RO 2 concentrations based on the observations of their long-lived precursors. The model was capable of reproducing the observed diurnal variation of the OH and peroxy radicals during clean days with a factor of 1.5. However, it largely underestimated HO 2 and RO 2 concentrations by factors up to 5 during pollution episodes. The HO 2 and RO 2 observed-to-modeled ratios increased with increasing NO concentrations, indicating a deficit in our understanding of the gas-phase chemistry in the high NO x regime. The OH concentrations observed in 30 the presence of large OH reactivities indicate that atmospheric trace gas oxidation by photochemical processes can be highly effective even during wintertime, thereby facilitating the vigorous formation of secondary pollutants.

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High N₂O₅ Concentrations Observed in Urban Beijing: Implications of a Large Nitrate Formation Pathway

Cited by 183 publications

References 38 publications

Fast particulate nitrate formation via N<sub>2</sub>O<sub>5</sub> uptake aloft in winter in Beijing

Fast particulate nitrate formation via N<sub>2</sub>O<sub>5</sub> uptake aloft in winter in Beijing

Variations of Chemical Composition and Source Apportionment of PM2.5 during Winter Haze Episodes in Beijing

Wintertime photochemistry in Beijing: Observations of RO<sub>x</sub> radical concentrations in the North China Plain during the BEST-ONE campaign

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High N2O5 Concentrations Observed in Urban Beijing: Implications of a Large Nitrate Formation Pathway

Cited by 183 publications

References 38 publications

Fast particulate nitrate formation via N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; uptake aloft in winter in Beijing

Fast particulate nitrate formation via N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; uptake aloft in winter in Beijing

Variations of Chemical Composition and Source Apportionment of PM2.5 during Winter Haze Episodes in Beijing

Wintertime photochemistry in Beijing: Observations of RO&lt;sub&gt;x&lt;/sub&gt; radical concentrations in the North China Plain during the BEST-ONE campaign

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High N₂O₅ Concentrations Observed in Urban Beijing: Implications of a Large Nitrate Formation Pathway

Fast particulate nitrate formation via N<sub>2</sub>O<sub>5</sub> uptake aloft in winter in Beijing

Fast particulate nitrate formation via N<sub>2</sub>O<sub>5</sub> uptake aloft in winter in Beijing

Wintertime photochemistry in Beijing: Observations of RO<sub>x</sub> radical concentrations in the North China Plain during the BEST-ONE campaign