Winter photochemistry in Beijing: Observation and model simulation of OH and HO2 radicals at an urban site

Ma, Xuefei; Tan, Zhaofeng; Lu, Keding; Yang, Xinping; Liu, Yuhan; Li, Shule; Li, Xin; Chen, Shiyi; Novelli, Anna; Cho, Changmin; Zeng, Limin; Wahner, Andreas; Zhang, Yuanhang

doi:10.1016/j.scitotenv.2019.05.329

Cited by 106 publications

(104 citation statements)

References 51 publications

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“…concentrations measured during BEST-ONE (Tan et al, 2018) but these could not reproduce the OH 95 concentration observed when NO was above 1 ppbv or below 0.6 ppbv; consistent with previous campaigns when OH was measured and modelled under NO concentrations > 1 ppbv (Emmerson et al, 2005;Kanaya et al, 2007;Lu et al, 2013;Tan et al, 2017;Zhou et al, 2003). More recently, OH and HO2 were measured in central Beijing during winter-time at the Peking University (PKU) campus in November/December 2017 (Ma et al, 2019). The radical measurements were simulated using the 100 RACM2-LIM1 box model which highlighted an under-prediction of the OH concentration when NO exceeded 1 ppbv (Ma et al, 2019).…”

Section: Introduction 45supporting

confidence: 54%

“…As summarised in Table 4, previous winter campaigns, where the environment controlling peroxy 415 radicals is generally dominated by NO, have shown a similar underprediction of radical species at high levels of NOx (above 3 ppbv of NO) (Lu et al, 2013;Ma et al, 2019;Tan et al, 2017;Tan et al, 2018).…”

Section: Comparison Of Measured Oh Ho2 Ro2 Radical Concentrations Amentioning

confidence: 82%

“…During the photochemical cycle initiated by OH, NO can be oxidised to form NO2 via reaction with HO2 and organic peroxy radicals, RO2, and the subsequent photolysis of NO2 can lead to the net formation of ozone. It has been shown in previous field campaigns that measured mixing ratios of radicals have a strong dependence with j(O 1 D) (Ehhalt and Rohrer, 2000;Ma et al, 2019;Stone et al, 2012;Tan et al, 2018). Hence, the radical 65 concentrations measured during wintertime are typically expected to be lower than in the summertime due to lower photolysis rates of primary radical sources such as O3, HONO and HCHO.…”

Section: Introduction 45mentioning

confidence: 99%

“…More recently, OH and HO2 were measured in central Beijing during winter-time at the Peking University (PKU) campus in November/December 2017 (Ma et al, 2019). The radical measurements were simulated using the 100 RACM2-LIM1 box model which highlighted an under-prediction of the OH concentration when NO exceeded 1 ppbv (Ma et al, 2019). Two further campaigns have taken place in northern China during the summertime.…”

Section: Introduction 45mentioning

confidence: 99%

See 3 more Smart Citations

Elevated levels of OH observed in haze events during wintertime in central Beijing

Slater¹,

Whalley²,

Woodward-Massey³

et al. 2020

Preprint

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Abstract. Wintertime in situ measurements of OH, HO2 and RO2 radicals and OH reactivity were made in central Beijing during November and December 2016. Exceptionally elevated NO was observed on occasions, up to ~ 250 ppbv, believed to be the highest mole fraction for which there have then co-located radical observations. The daily maximum mixing ratios for radical species varied significantly day-to-day over the range 1–8 × 106 cm−3 (OH), 0.2–1.5 × 108 cm−3 (HO2) and 0.3–2.5 × 108 cm−3 (RO2). Averaged over the full observation period, the mean daytime peak in radicals was 2.7 × 106 cm−3, 0.39 × 108 cm−3 and 0.88 × 108 cm−3 for OH, HO2 and total RO2, respectively. The main daytime source of new radicals via initiation processes (primary production) was the photolysis of HONO (~ 83 %), and the dominant termination pathways were the reactions of OH with NO and NO2, particularly under polluted, haze conditions. The Master Chemical Mechanism (MCM) v3.3.1 operating within a box model was used to simulate the concentrations of OH, HO2 and RO2. The model underpredicted OH, HO2 and RO2, especially when NO mixing ratios were high (above 6 ppbv). The observation-to-model ratio of OH, HO2 and RO2 increased from ~ 1 (for all radicals) at 3 ppbv of NO to a factor of ~ 3, ~ 20 and ~ 91 for OH, HO2 and RO2, respectively, at ~ 200 ppbv of NO. The significant underprediction of radical concentrations by the MCM suggests a deficiency in the representation of gas-phase chemistry at high NOx. The OH concentrations were surprisingly similar (within 20 % during the day) inside and outside of haze events, despite j(O1D) decreasing by 50 % during haze periods. These observations provide strong evidence that gas-phase oxidation by OH can continue to generate secondary pollutants even under high pollution episodes, despite the reduction in photolysis rates within haze.

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Section: Introduction 45supporting

confidence: 54%

Section: Comparison Of Measured Oh Ho2 Ro2 Radical Concentrations Amentioning

confidence: 82%

Section: Introduction 45mentioning

confidence: 99%

Section: Introduction 45mentioning

confidence: 99%

See 2 more Smart Citations

Elevated levels of OH observed in haze events during wintertime in central Beijing

Slater¹,

Whalley²,

Woodward-Massey³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…In Eq. (3), K t P is the theoretical value of the gas-aerosol partitioning coefficient (m 3 µg −1 ); MW OM is the estimated average molecular weight of organic compounds (200 g mol −1 ) (Williams et al, 2010;Xie et al, 2014); p 0 L is the vapour pressure of pure H 2 O 2 at the specified temperature, calculated by the extrapolation of the Antoine equation (Maass and Hiebert, 1924;Baum, 1998); ζ is the activity coefficient of H 2 O 2 , assumed to be unity (Pankow, 1994); f om is the weight fraction of the organic matter phase in total suspended particulate matter (TSP), also set to unity (Shen et al, 2018); R is the ideal gas constant (8.2×10 −5 atm m 3 mol −1 K −1 ); and T W is the mean temperature during BJ-2018Winter (270 ± 4 K for the whole observation period, 272 ± 4 K for daytime, and 269 ± 4 K for night-time). In Eq.…”

Section: Estimation Of Effective Partitioning Coefficientsmentioning

confidence: 99%

Partitioning of hydrogen peroxide in gas-liquid and gas-aerosol phases

et al. 2020

Self Cite

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Abstract. Hydrogen peroxide (H2O2) is a vital oxidant in the atmosphere and plays critical roles in the oxidation chemistry of both liquid and aerosol phases. The partitioning of H2O2 between the gas and liquid phases, or the aerosol phase, could affect its abundance in these condensed phases and eventually the formation of secondary components. However, the partitioning processes of H2O2 in gas-liquid and gas-aerosol phases are still unclear, especially in the ambient atmosphere. In this study, field observations of gas-, liquid-, and aerosol-phase H2O2 were carried out in the urban atmosphere of Beijing during the summer and winter of 2018. The effective field-derived mean value of Henry's law constant (HAm, 2.1×105 M atm−1) was 2.5 times of the theoretical value in pure water (HAt, 8.4×104 M atm−1) at 298±2 K. The effective derived gas-aerosol partitioning coefficient (KPm, 3.8×10-3 m3 µg−1) was 4 orders of magnitude higher on average than the theoretical value (KPt, 2.8×10-7 m3 µg−1) at 270±4 K. Beyond following Henry's law or Pankow's absorptive partitioning theory, the partitioning of H2O2 in the gas-liquid and gas-aerosol phases in the ambient atmosphere was also influenced by certain physical and chemical reactions. The average concentration of liquid-phase H2O2 in rainwater during summer was 44.12±26.49 µM. In 69 % of the collected rain samples, the measured level of H2O2 was greater than the predicted value in pure water calculated by Henry's law. In these samples, 41 % of the measured H2O2 was from gas-phase partitioning, while most of the rest may be from residual H2O2 in raindrops. In winter, the level of aerosol-phase H2O2 was 0.093±0.085 ng µg−1, which was much higher than the predicted value based on Pankow's absorptive partitioning theory. The contribution of partitioning of the gas-phase H2O2 to the aerosol-phase H2O2 formation was negligible. The decomposition/hydrolysis rate of aerosol-phase organic peroxides could account for 11 %–74 % of the consumption rate of aerosol-phase H2O2, and the value depended on the composition of organic peroxides in the aerosol particles. Furthermore, the heterogeneous uptake of HO2 and H2O2 on aerosols contributed to 22 % and 2 % of the aerosol-phase H2O2 consumption, respectively.

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Recent Progress in Atmospheric Chemistry Research in China: Establishing a Theoretical Framework for the “Air Pollution Complex”

et al. 2023

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Atmospheric chemistry research has been growing rapidly in China in the last 25 years since the concept of the “air pollution complex” was first proposed by Professor Xiaoyan TANG in 1997. For papers published in 2021 on air pollution (only papers included in the Web of Science Core Collection database were considered), more than 24 000 papers were authored or co-authored by scientists working in China. In this paper, we review a limited number of representative and significant studies on atmospheric chemistry in China in the last few years, including studies on (1) sources and emission inventories, (2) atmospheric chemical processes, (3) interactions of air pollution with meteorology, weather and climate, (4) interactions between the biosphere and atmosphere, and (5) data assimilation. The intention was not to provide a complete review of all progress made in the last few years, but rather to serve as a starting point for learning more about atmospheric chemistry research in China. The advances reviewed in this paper have enabled a theoretical framework for the air pollution complex to be established, provided robust scientific support to highly successful air pollution control policies in China, and created great opportunities in education, training, and career development for many graduate students and young scientists. This paper further highlights that developing and low-income countries that are heavily affected by air pollution can benefit from these research advances, whilst at the same time acknowledging that many challenges and opportunities still remain in atmospheric chemistry research in China, to hopefully be addressed over the next few decades.

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Winter photochemistry in Beijing: Observation and model simulation of OH and HO2 radicals at an urban site

Cited by 106 publications

References 51 publications

Elevated levels of OH observed in haze events during wintertime in central Beijing

Elevated levels of OH observed in haze events during wintertime in central Beijing

Partitioning of hydrogen peroxide in gas-liquid and gas-aerosol phases

Recent Progress in Atmospheric Chemistry Research in China: Establishing a Theoretical Framework for the “Air Pollution Complex”

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