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

Tan, Zhaofeng; Rohrer, Franz; Lu, Keding; Ma, Xin; Bohn, Birger; Broch, Sebastian; Dong, Huabin; Fuchs, Hendrik; Gkatzelis, Georgios I.; Hofzumahaus, A.; Holland, F.; Li, Xin; Liu, Ying; Liu, Yuhan; Novelli, Anna; Shao, Mingan; Wang, Haichao; Wu, Yusheng; Zeng, Limin; Hu, Min; Kiendler‐Scharr, Astrid; Wahner, Andreas; Zhang, Yuanhang

doi:10.5194/acp-2018-359

Cited by 30 publications

(73 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…OOA is also correlated with O x during daytime ( r 2 = 0.71 and 0.62), a tracer for the extent of photochemical processing in urban atmosphere (Herndon et al, ). Results here highlight the strong photochemical production of SOA in winter, consistent with a recent finding of high OH radical concentrations in winter in Beijing (Tan et al, ). In contrast, OPOA correlates the best with CO 2 + ( r 2 = 0.60–0.84), yet moderately correlates with O x during daytime ( r 2 = 0.44–0.69).…”

Section: Resultssupporting

confidence: 92%

Changes in Aerosol Chemistry From 2014 to 2016 in Winter in Beijing: Insights From High‐Resolution Aerosol Mass Spectrometry

et al. 2019

View full text Add to dashboard Cite

Air quality has been continuously improved in recent years in Beijing, yet severe haze episodes still frequently occur in winter. Here we deployed an Aerodyne high‐resolution aerosol mass spectrometer in two winter seasons during the same period to investigate the changes in aerosol chemistry from 2014 to 2016 in Beijing. Compared to 2014, submicron aerosol (PM1) species showed ubiquitous increases in mass concentrations by 10–130% in winter 2016, of which nitrate showed the largest increase among all aerosol species leading to a much higher NO3/SO4 ratio in 2016 (1.36 ± 0.90) than 2014 (0.72 ± 0.59). This result highlights an increasing role of nitrate in particulate matter pollution in recent years in Beijing. Aerosol composition and size distributions also changed significantly. Secondary inorganic species showed elevated contributions by ~10% in winter 2016 associated with corresponding decreases in organic aerosol (OA). Positive matrix factorization of OA illustrated the significant changes in both primary emissions and secondary production. While cooking OA decreased substantially from 25% in 2014 to 15% in 2016, the contribution of biomass burning OA slightly increased instead. Although secondary OA contributed similarly to OA in the two winters (49% vs. 53%), we observed ubiquitous increases (~50%) in photochemically related oxygenated OA and oxidized primary OA, and oxygen‐to‐carbon ratios of OA, indicating the enhanced photochemical production in winter 2016. Aqueous‐phase production of secondary OA however was relatively similar in the two winters. Further analysis demonstrated that the changes in aerosol and OA composition varied differently across different pollution and relative humidity levels.

show abstract

Section: Resultssupporting

confidence: 92%

Changes in Aerosol Chemistry From 2014 to 2016 in Winter in Beijing: Insights From High‐Resolution Aerosol Mass Spectrometry

et al. 2019

View full text Add to dashboard Cite

show abstract

“…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).…”

Section: Introduction 45supporting

confidence: 50%

“…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%

“…The first measurements were made during the BEST-ONE campaign (Tan et al, 2017) that took place in January 2016 in Huairou, which is a suburban site 60 km northeast from Beijing. The average 85 daytime maximum concentrations observed during the BEST-ONE campaign for OH, HO2 and RO2 were 2.5 x 10 6 cm -3 , 0.8 x 10 8 cm -3 (3.2 pptv) and 0.6 x 10 8 cm -3 (2.4 pptv) respectively.…”

Section: Introduction 45mentioning

confidence: 99%

See 1 more Smart Citation

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

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.

show abstract

“…Detailed information about the sampling site was described in Tan et al (2018). A weather station (Met one Instrument Inc., USA) was performed to measure meteorological parameters (ambient RH, temperature, wind speed, wind direction) and detailed aerosol particle physical and chemical properties were recorded using a suite of state-of-the-science instrumentation.…”

Section: Location and Instrumentationmentioning

confidence: 99%

Mutual promotion effect between aerosol particle liquid water and nitrate formation lead to severe nitrate-dominated particulate matter pollution and low visibility

Wang¹,

Chen²,

Wu³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. As has been the case in North America and Western Europe, the SO2 emissions substantially reduced in North China Plain (NCP) in recent years. A dichotomy of reductions in SO2 and NOx concentrations result in the frequent occurrences of nitrate (pNO3&#8722;)-dominated particulate matter pollution over NCP. In this study, we observed a polluted episode with the nitrate mass fraction in non-refractory PM1 (NR-PM1) up to 44&#8201;% during wintertime in Beijing. Based on this typical pNO3&#8722;-dominated haze event, the linkage between aerosol water uptake and pNO3&#8722; formation, further impacting on visibility degradation, have been investigated based on field observations and theoretical calculations. During haze development, as ambient relative humidity (RH) increased from ~&#8201;10&#8201;% up to 70&#8201;%, the aerosol particle liquid water increased from ~&#8201;1&#8201;&#956;g/m3 at the beginning to ~&#8201;75&#8201;&#956;g/m3 at the fully-developed haze period. Without considering the water uptake, the particle surface area and the volume concentrations increased by a factor of 4.1 and 4.8, respectively, during the development of haze event. Taking water uptake into account, the wet particle surface area and volume concentrations enhanced by a factor of 4.7 and 5.8, respectively. As a consequence, the hygroscopic growth of particles facilitated the condensational loss of dinitrogen pentoxide (N2O5) and nitric acid (HNO3) to particles contributing pNO3&#8722;. From the beginning to the fully-developed haze, the condensational loss of N2O5 increased by a factor of 20 when only considering aerosol surface area and volume of dry particles, while increasing by a factor of 25 considering extra surface area and volume due to water uptake. Similarly, the condensational loss of HNO3 increased by a factor of 2.7~2.9 and 3.1~3.5 for dry and wet aerosol surface area and volume from the beginning to the fully-developed haze period. Above results demonstrated that the pNO3&#8722; formation is further enhanced by aerosol water uptake with elevated ambient RH during haze development, in turn, facilitating the aerosol taking up water due to the hygroscopicity of nitrate salt. Such mutual promotion effect between aerosol particle liquid water and nitrate formation can rapidly degrade air quality and halve visibility within one day. Reduction of nitrogen-containing gaseous precursors, e.g., by control of traffic emissions, is essential in mitigating severe haze events in NCP.

show abstract

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

Cited by 30 publications

References 38 publications

Changes in Aerosol Chemistry From 2014 to 2016 in Winter in Beijing: Insights From High‐Resolution Aerosol Mass Spectrometry

Changes in Aerosol Chemistry From 2014 to 2016 in Winter in Beijing: Insights From High‐Resolution Aerosol Mass Spectrometry

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

Mutual promotion effect between aerosol particle liquid water and nitrate formation lead to severe nitrate-dominated particulate matter pollution and low visibility

Contact Info

Product

Resources

About