Insights into high concentrations of particle-bound imidazoles in the background atmosphere of southern China: Potential sources and influencing factors

He, Chao; Wang, Hao; Gong, Daocheng; Lv, Shaojun; Wu, Gengchen; Wang, Ruiwen; Chen, Yaqiu; Ding, Yaozhou; Li, Yanlei; Wang, Boguang

doi:10.1016/j.scitotenv.2021.150804

Cited by 9 publications

(9 citation statements)

References 45 publications

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“…Furthermore, the hourly detected particle number of the IMs-containing particles is also highly correlated with those of their precursors [ r > 0.5; p < 0.01 (Figure S6)]. A similar correlation between MIM and carbonyls such as glyoxal and methylglyoxal has also been reported . These results support the formation pathway of IMs from carbonyls and ammonium/amine, as identified by extensive laboratory studies. ,,, …”

Section: Resultssupporting

confidence: 80%

“…A similar correlation between MIM and carbonyls such as glyoxal and methylglyoxal has also been reported. 28 These results support the formation pathway of IMs from carbonyls and ammonium/ amine, as identified by extensive laboratory studies. 5,19,40,41 Diurnal Variation of IMs-Containing Particles.…”

Section: ■ Introductionsupporting

confidence: 84%

“…A few studies have investigated particulate IMs (PM 1 , PM 10 , and TSP) in the atmosphere in China, Germany, Italy, and Japan, most of which focused on their concentrations. The reported concentrations were in the range of 0.01–20.99 ng m –3 ; the most abundant was 4(5)-methylimidazole, followed by 2-ethylimidazole (EI), DMI, and IC. ,,,, Teich et al observed higher concentrations of IMs at night than during the day and attributed these observations to the photochemical process and boundary layer height. He et al showed that RH and salting effect may have an influence on the formation of secondary IMs.…”

Section: Introductionmentioning

confidence: 99%

“…The reported concentrations were in the range of 0.01–20.99 ng m –3 ; the most abundant was 4(5)-methylimidazole, followed by 2-ethylimidazole (EI), DMI, and IC. ,,,, Teich et al observed higher concentrations of IMs at night than during the day and attributed these observations to the photochemical process and boundary layer height. He et al showed that RH and salting effect may have an influence on the formation of secondary IMs. Recently, using a single-particle aerosol mass spectrometer (SPAMS), we first provided direct evidence for the formation of IMs from carbonyls and ammonium/amines in the ambient atmosphere and showed the facilitated formation of IMs under cloud conditions .…”

Section: Introductionmentioning

confidence: 99%

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Atmospheric Processing of Particulate Imidazole Compounds Driven by Photochemistry

Guo

Sun

et al. 2022

Environ. Sci. Technol. Lett.

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As a potential fraction of brown carbon, particulate imidazole compounds may initiate photosensitive reactions and have substantial radiative effects. However, our knowledge of the atmospheric processing of imidazole compounds is still in its nascent stage. On the basis of a single-particle aerosol mass spectrometer measurement, the mixing state of imidazole-containing particles and high-time-resolved variations of imidazole compounds were investigated in Qingdao, China, in November and December 2019. Five imidazole compounds (methylimidazole, ethylimidazole, dimethylimidazole, imidazole-2-carboxaldehyde, and 2,2′-biimidazole) were identified, overall accounting for ∼10% of all of the detected particles. They are tightly correlated and internally mixed with enhanced carbonyls, amines, and ammonium, supporting their secondary formation from these precursors. The number fraction of imidazole-containing particles exhibited predominant diurnal variations, especially on sunny days. A sharp decrease in the number fraction from morning to noon is most likely attributed to photochemical degradation. This is also confirmed by the reverse correlation (r = −0.77; p < 0.01) with photochemical indicators (temperature and O3) and our laboratory experiment by exposure of imidazole compounds to sunlight. Multiple linear regression and random forest analysis further support the hypothesis, with precursors (i.e., carbonyls and amines/ammonium) and O3 being the most important factors (∼70%) regulating the variations of imidazole compounds.

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Section: Resultssupporting

confidence: 80%

Section: ■ Introductionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Atmospheric Processing of Particulate Imidazole Compounds Driven by Photochemistry

Guo

Sun

et al. 2022

Environ. Sci. Technol. Lett.

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“…To the best of our knowledge, there has not been a study that have investigated the concentrations of imidazoles in atmospheric PM in Hong Kong. However, imidazoles have been detected in atmospheric PM in urban Guangzhou (another city in South China) (Lian et al, 2022) and at a background forest site in the Nanling Mountains of South China (He et al, 2022). Thus, future studies can focus on identifying other water-soluble BrC constituents and photosensitizers (e.g., imidazoles) in atmospheric PM in Hong Kong that can play potentially important roles in enhancing 1 O 2 and 3 C * production.…”

mentioning

confidence: 99%

Efficient production of singlet oxygen and organic triplet excited states in aqueous PM_2.5 in Hong Kong, South China

LYU

Hau

et al. 2023

Preprint

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Abstract. Photooxidants drive many atmospheric chemical processes. The photoexcitation of light-absorbing organic compounds (i.e., brown carbon (BrC)) in atmospheric waters can lead to the generation of reactive organic triplet excited states (3C∗), which can undergo further reactions to produce other photooxidants such as singlet oxygen (1O2). To determine the importance of these aqueous photooxidants in SOA formation and transformation, we must know their steady-state concentrations and quantum yields. However, there has been limited measurements of aqueous 3C∗ and 1O2 in atmospheric samples outside of North America and Europe. In this work, we report the first measurements of the steady-state concentrations and quantum yields of 3C∗ and 1O2 produced in aerosols in South China. We quantified the production of 3C∗ and 1O2 in illuminated aqueous extracts of PM2.5 collected in different seasons at two urban sites and one coastal semi-rural site during a year-round study conducted in Hong Kong, South China. The mass absorption coefficients at 300 nm for BrC in the aqueous PM2.5 extracts ranged from 0.49 × 104 to 2.01 × 104 cm2 g-C−1 for the three sites. Both 1O2 and 3C∗ were produced year-round. The steady-state concentrations of 1O2 ([1O2]ss) in the illuminated aqueous extracts spanned two orders of magnitude, ranging from 1.56 × 10−14 to 1.35 × 10−12 M, with a study average of (4.02 ± 3.52) × 10−13 M. The steady-state concentrations of 3C∗ ([3C∗]ss) in the illuminated aqueous extracts spanned two orders of magnitude, ranging from 2.93 × 10−16 to 8.08 × 10−14 M, with a study average of (1.09 ± 1.39) × 10−14 M. The [1O2]ss and [3C∗]ss correlated with the concentration and absorbance of BrC, thus implying that the amount of BrC drives the steady-state concentrations of these photooxidants. The locations (urban vs. semi-rural) did not have a significant effect on [3C∗]ss and [1O2]ss, which indicated that BrC from local sources did not have a significant influence on the year-round 3C∗ and 1O2 production. 3C∗ and 1O2 production were found to be the highest in winter and the lowest in summer for all three sites. The observed seasonal trends of 1O2 and 3C∗ production could be attributed to the seasonal variations in long-range air mass transport. Our analysis highlighted the key role that regional sources play in influencing the composition and concentrations of water-soluble BrC in winter PM2.5 in Hong Kong, which contributed to their highest 3C∗ and 1O2 production. The current results will be useful for modeling seasonal aqueous organic aerosol photochemistry in the South China region.

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Experimental study on the imidazoles of aqueous secondary organic aerosol formed from reaction of methylglyoxal and ammonium sulphate

Zhu

Huang

Lü

et al. 2022

Atmospheric Pollution Research

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Insights into high concentrations of particle-bound imidazoles in the background atmosphere of southern China: Potential sources and influencing factors

Cited by 9 publications

References 45 publications

Atmospheric Processing of Particulate Imidazole Compounds Driven by Photochemistry

Atmospheric Processing of Particulate Imidazole Compounds Driven by Photochemistry

Efficient production of singlet oxygen and organic triplet excited states in aqueous PM_2.5 in Hong Kong, South China

Experimental study on the imidazoles of aqueous secondary organic aerosol formed from reaction of methylglyoxal and ammonium sulphate

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Insights into high concentrations of particle-bound imidazoles in the background atmosphere of southern China: Potential sources and influencing factors

Cited by 9 publications

References 45 publications

Atmospheric Processing of Particulate Imidazole Compounds Driven by Photochemistry

Atmospheric Processing of Particulate Imidazole Compounds Driven by Photochemistry

Efficient production of singlet oxygen and organic triplet excited states in aqueous PM2.5 in Hong Kong, South China

Experimental study on the imidazoles of aqueous secondary organic aerosol formed from reaction of methylglyoxal and ammonium sulphate

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Efficient production of singlet oxygen and organic triplet excited states in aqueous PM_2.5 in Hong Kong, South China