Study on the daytime OH radical and implication for its relationship with fine particles over megacity of Shanghai, China

Nan, Jialiang; Wang, Shanshan; Guo, Yanlin; Xiang, Yajing; Zhou, Bin

doi:10.1016/j.atmosenv.2017.01.046

Cited by 38 publications

(20 citation statements)

References 60 publications

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“…These results agree well with the OH and HO 2 radical concentrations in Shanghai (1.02 × 10 7 molecules•cm −3 ) [24]. Shanghai was reported by previous studies to have respective values of (3-26) × 10 6 molecules•cm −3 and (2-25) × 10 8 molecules•cm −3 for OBM simulations and field observations [15,[24][25][26][27][28].…”

Section: Model Performance Evaluation: Oh and Ho 2 Simulationsupporting

confidence: 91%

O3 Sensitivity and Contributions of Different NMHC Sources in O3 Formation at Urban and Suburban Sites in Shanghai

et al. 2020

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Ground-level ozone (O3) pollution is still one of the priorities and challenges for air pollution control in the Yangtze River Delta (YRD) region of China. Understanding the relationship of O3 with its precursors and contributions of different sources in O3 formation is essential for the development of an O3 control strategy. This study analyzed O3 sensitivity to its precursors using a box model based on online observations of O3, non-methane hydrocarbons (NMHCs), nitrogen oxides (NOx), and carbon monoxide (CO) at an urban site and a suburban site in Shanghai in July 2017. Anthropogenic sources of NMHCs were identified using the positive matrix factorization (PMF) receptor model, and then contributions of different sources in O3 formation were estimated by the observation-based model (OBM). The relative incremental reactivity (RIR) values calculated by the OBM suggest that O3 formation at the urban site was in the NMHC-limited regime, while O3 formation at the suburban site tended between the transition regime and the NMHC-limited regime. Vehicular emission and liquefied petrochemical gas (LPG) use or aged air mass were found to be the two largest contributors at the urban and suburban sites in July, followed by paint and solvent use, and the petrochemical industry. However, from the perspective of O3 formation, vehicular emission and paint and solvent use were the largest two contributors at two sites due to the higher RIR values for paint and solvent use. In addition, the influence of transport on O3 sensitivity was identified by comparing O3 sensitivity at the suburban site across two days with different air mass paths. The result revealed that O3 formation in Shanghai is not only related to local emissions but also influenced by emissions from neighboring provinces. These findings on O3–NMHC–NOX sensitivity, contributions of different sources in O3 formation, and influence of transport could be useful for O3 pollution control in the YRD region. Nevertheless, more quantitative analyses on transport and further evaluation of the uncertainty of the OBM are still needed in future.

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Section: Model Performance Evaluation: Oh and Ho 2 Simulationsupporting

confidence: 91%

O3 Sensitivity and Contributions of Different NMHC Sources in O3 Formation at Urban and Suburban Sites in Shanghai

et al. 2020

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“…Lu et al () detected that daily concentration maximum of OH radical was in the range of (4–17) × 10 6 molecules cm −3 in Beijing. Nan et al () observed that the daytime OH radical concentration in Shanghai under steady state was averaged at 1.0 × 10 7 molecules cm −3 . The average OH level in the PRD during daytime in summer was about 1.0 × 10 7 molecules cm −3 (Hofzumahaus et al, ).…”

Section: Resultsmentioning

confidence: 99%

Secondary Organic Aerosol Formation From Isoprene Epoxides in the Pearl River Delta, South China: IEPOX‐ and HMML‐Derived Tracers

Ding

et al. 2018

JGR Atmospheres

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Atmospheric photooxidation of isoprene forms isoprene epoxydiols (IEPOX) and hydroxymethel-methyl-α-lactone (HMML) via hydroperoxyl radical (HO 2 ) channel and NO/NO 2 channel, respectively. Reactive uptake of these epoxides onto particles produces isoprene secondary organic aerosols (iSOA). Currently, there is little information regarding these two epoxides during iSOA formation in polluted regions. In this study, iSOA tracers from IEPOX and HMML were measured from summer to fall in the heavily polluted Pearl River Delta (PRD) region. The total concentration of the iSOA tracers ranged from 5.77 to 466 ng m À3 . Isoprene SOA tracers correlated well with sulfate (p < 0.01), indicating that the abundant sulfate in the PRD plays an important role in iSOA formation. A kinetic model of IEPOX loss showed that 58% of IEPOX could undergo ring-opening reactions under the polluted PRD conditions in summer. This leads to high levels of IEPOX-derived SOA tracers in the PRD. High temperature in the PRD (>22°C) suppresses the production of HMML, likely as a result of fast decomposition of HMML's precursor under high temperatures. Thus, the HMML-derived tracers had lower levels than the IEPOX-derived SOA tracers during the whole campaign. The ratios of the IEPOX-derived tracers to the HMML-derived SOA tracers in summer were~3 times higher than those in fall. This seasonal trend may be explained by the relative high isoprene/NO x ratio, temperature, and fast heterogeneous reaction of IEPOX in summer. Our study shows that in highly polluted regions like PRD, reduction in SO 2 emission can significantly reduce iSOA formation. HE ET AL. 6999

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“…Second, the concentrations of atmospheric oxidant such as ozone are higher at SORPES (Table 1). Moreover, the concentrations of OH and NO 3 radicals in the Yangtze River Delta urban area of China are higher than in the clean area (S. Nan et al, 2017). Third, the concentrations of anthropogenic pollutants and biogenic VOCs are distinctly different at the two stations.…”

Section: Comparisons Of Npf At Smear II and Sorpesmentioning

confidence: 95%

Modelling studies of HOMs and their contributions to new particle formation and growth: comparison of boreal forest in Finland and a polluted environment in China

Ding

Roldin

et al. 2018

Atmos. Chem. Phys.

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Abstract. Highly oxygenated multifunctional compounds (HOMs) play a key role in new particle formation (NPF), but their quantitative roles in different environments of the globe have not been well studied yet. Frequent NPF events were observed at two "flagship" stations under different environmental conditions, i.e. a remote boreal forest site (SMEAR II) in Finland and a suburban site (SORPES) in polluted eastern China. The averaged formation rate of 6 nm particles and the growth rate of 6-30 nm particles were 0.3 cm −3 s −1 and 4.5 nm h −1 at SMEAR II compared to 2.3 cm −3 s −1 and 8.7 nm h −1 at SORPES, respectively. To explore the differences of NPF at the two stations, the HOM concentrations and NPF events at two sites were simulated with the MALTE-BOX model, and their roles in NPF and particle growth in the two distinctly different environments are discussed. The model provides an acceptable agreement between the simulated and measured concentrations of sulfuric acid and HOMs at SMEAR II. The sulfuric acid and HOM organonitrate concentrations are significantly higher but other HOM monomers and dimers from monoterpene oxidation are lower at SORPES compared to SMEAR II. The model simulates the NPF events at SMEAR II with a good agreement but underestimates the growth of new particles at SORPES, indicating a dominant role of anthropogenic processes in the polluted environment. HOMs from monoterpene oxidation dominate the growth of ultrafine particles at SMEAR II while sulfuric acid and HOMs from aromatics oxidation play a more important role in particle growth. This study highlights the distinct roles of sulfuric acid and HOMs in NPF and particle growth in different environmental conditions and suggests the need for molecular-scale measurements in improving the understanding of NPF mechanisms in polluted areas like eastern China.

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Study on the daytime OH radical and implication for its relationship with fine particles over megacity of Shanghai, China

Cited by 38 publications

References 60 publications

O3 Sensitivity and Contributions of Different NMHC Sources in O3 Formation at Urban and Suburban Sites in Shanghai

O3 Sensitivity and Contributions of Different NMHC Sources in O3 Formation at Urban and Suburban Sites in Shanghai

Secondary Organic Aerosol Formation From Isoprene Epoxides in the Pearl River Delta, South China: IEPOX‐ and HMML‐Derived Tracers

Modelling studies of HOMs and their contributions to new particle formation and growth: comparison of boreal forest in Finland and a polluted environment in China

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