The maximum carbonyl ratio (MCR) as a new index for the structural classification of secondary organic aerosol components

Zhang, Yun; Wang, Kai; Tong, Haijie; Huang, Ru‐Jin; Hoffmann, Thorsten

doi:10.1002/rcm.9113

Cited by 24 publications

(57 citation statements)

References 81 publications

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“…The regions marked in (a) and (b) were obtained from Zhang et al. (2021) to describe oxidation state of CHON compounds. It should be noted that this comparison can be biased by the extraction method and instruments used for analysis.…”

Section: Resultsmentioning

confidence: 99%

“…To compare the chemical characteristics of CHON compounds detected in this study with the chemical characteristics of source and ambient aerosol samples reported in previous studies, a modified van Krevelen diagram based on the maximum carbonyl ratio was constructed (Figure 3 and Tables S7 and S8 in Supporting Information ; Zhang et al., 2021). The diagram was divided into five areas, which describe the oxidation states of very highly oxidized organic compounds, highly oxidized organic compounds, intermediately oxidized organic compounds, oxidized unsaturated organic compounds, and highly unsaturated organic compounds (Zhang et al., 2021). The CHON+ and CHON– compounds were located in areas that corresponded to oxidized unsaturated compounds and intermediately oxidized organic compounds, respectively.…”

Section: Resultsmentioning

confidence: 99%

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Factors Influencing the Molecular Compositions and Distributions of Atmospheric Nitrogen‐Containing Compounds

et al. 2022

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NOCs deposition from atmospheric particles considerably affects the global nitrogen cycle and can have substantial effects on aquatic and terrestrial ecosystems (Altieri Abstract Atmospheric nitrogen-containing organic compounds (NOCs) are critical components of global nitrogen deposition and light-absorption species. The sources and compositions of NOCs are complex and remain largely unknown. Here, NOCs in 55 ambient aerosol samples collected in Guangzhou, South China, were analyzed via ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry in negative-ion and positive-ion electrospray ionization (ESI) modes. The molecular compositions of NOCs measured via ESI-and ESI+ exhibited considerable differences. NOCs detected in the negative mode were mainly composed of highly oxygenated organic nitrates (O/N = 6), whereas NOCs detected in the positive mode were mainly composed of reduced nitrogen-containing compounds (e.g., amides and amino acids). CHN compounds potentially corresponding to amines and alkaloids showed low abundance in the detection modes. Non-metric multidimensional scaling and individual compound correlation analyses showed that the molecular compositions of NOCs were mainly affected by anthropogenic activities and meteorological parameters. For example, anthropogenic activities such as biomass burning and secondary nitrogen-chemistry processes led to the accumulation of aromatic and highly oxygenated NOCs during winter. During summer, higher OH radical concentrations and temperatures will result in more prevalent or persistent reduced aliphatic NOCs, particularly lipid-like amines. Some variables (e.g., relative humidity) have distinct effects on the variation of different types of NOCs. More research is needed to reveal the influencing mechanisms. This study clarifies the molecular compositions of NOCs and the mechanisms by which various factors influence the molecular variations. The findings can guide the assessment of NOCs evolution and deposition.Plain Language Summary Negative and positive electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to characterize the molecular composition of nitrogen-containing organic compounds (NOCs) from aerosol samples in Guangzhou. It was determined that a large amount of various NOCs are present in the samples, with NOCs in highly oxidative and reduced states can be roughly identified by distinct ionization modes. By combining the ESI-FT-ICR-MS results and statistical analysis, the factors that associated with the distribution of NOCs and how these factors worked were identified. Anthropogenic activities and meteorological parameters (e.g., temperature and oxidation levels) are the two important drivers that led to the variations of NOCs, resulting to inverse molecular patterns with different response to aromatic/highly unsaturated and saturated structures, respectively. This study provides a useful clue for studying NOCs in complex system, bridges the links between t...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Factors Influencing the Molecular Compositions and Distributions of Atmospheric Nitrogen‐Containing Compounds

et al. 2022

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“…The majority of compounds in Cluster D (Figure D) are CHOn compounds, present in the region of 1.1 < H/C < 2 and 0.2 < O/C < 0.9. Previous studies suggest that in this region oxidation products of biogenic emissions appear. ,, We confirm this cluster as partly biogenic as we detect the compounds MBTCA (C 8 H 12 O 6 ) and pinic acid (C 9 H 14 O 4 ), which are widely used as oxidation tracers of α-pinene (Figure S9D,E). − However, we cannot exclude the contribution of anthropogenic compounds in this cluster.…”

Section: Results and Discussionmentioning

confidence: 98%

Nontarget Screening Exhibits a Seasonal Cycle of PM_2.5 Organic Aerosol Composition in Beijing

Ungeheuer

Zheng

et al. 2022

Environ. Sci. Technol.

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The molecular composition of atmospheric particulate matter (PM) in the urban environment is complex, and it remains a challenge to identify its sources and formation pathways. Here, we report the seasonal variation of the molecular composition of organic aerosols (OA), based on 172 PM 2.5 filter samples collected in Beijing, China, from February 2018 to March 2019. We applied a hierarchical cluster analysis (HCA) on a large nontargetscreening data set and found a strong seasonal difference in the OA chemical composition. Molecular fingerprints of the major compound clusters exhibit a unique molecular pattern in the Van Krevelen-space. We found that summer OA in Beijing features a higher degree of oxidation and a higher proportion of organosulfates (OSs) in comparison to OA during wintertime, which exhibits a high contribution from (nitro-)aromatic compounds. OSs appeared with a high intensity in summer-haze conditions, indicating the importance of anthropogenic enhancement of secondary OA in summer Beijing. Furthermore, we quantified the contribution of the four main compound clusters to total OA using surrogate standards. With this approach, we are able to explain a small fraction of the OA (∼11−14%) monitored by the Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM). However, we observe a strong correlation between the sum of the quantified clusters and OA measured by the ToF-ACSM, indicating that the identified clusters represent the major variability of OA seasonal cycles. This study highlights the potential of using nontarget screening in combination with HCA for gaining a better understanding of the molecular composition and the origin of OA in the urban environment.

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“…The maximum carbonyl ratio (MCR) was used to estimate the contribution of carbonyl equivalent groups in the molecule with oxygen number greater than or equal to DBE (Zhang et al, 2021). The value of MCR is calculated as Eq.…”

Section: Molecular Formula Assignmentmentioning

confidence: 99%

“…The maximum carbonyl ratio (MCR) index is suggested as a tool for a better characterization of the sources and the processing of atmospheric OA components (Zhang et al, 2021). Figure 3 As shown in Figure 4, the identified HOMs mainly exist as dimers with m/z of 350∼450 Da.…”

Section: Effects Of Ozone Concentration On Size Distribution and Oxid...mentioning

confidence: 99%

Large differences of highly oxygenated organic molecules (HOMs) and low volatile species in SOA formed from ozonolysis of β-pinene and limonene

Liu

Zhang

Zhong

et al. 2022

Preprint

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Abstract. Secondary organic aerosols (SOA) play a key role in climate change and public health. However, the oxidation state and volatility of SOA are still not well understood. Here, we investigated the highly oxygenated organic molecules (HOMs) in SOA formed from ozonolysis of β-pinene and limonene. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize HOMs, and a scanning mobility particle sizer (SMPS) was used to measure the concentration and size distribution of SOA particles. The abundance of HOMs in limonene SOA was 5–13 % higher than in β-pinene SOA (3–13 %) exhibiting different trends with increasing ozone concentrations. β-pinene oxidation-derived HOMs prefer to stabilize at high ozone concentration, accompanied by substantial formation of ultra-low-volatility organic compounds (ULVOCs). Limonene-oxidation-derived HOMs prefer to stabilize at moderate ozone concentrations, with semi-, low-, and extremely low-volatility organic compounds (SVOCs, LOVCs, and ELVOCs) play a major role. Combined experimental evidence and theoretical analysis indicate that oxygen-increasing-based peroxy radical chemistry is a plausible mechanism for the formation of compounds with 10 carbon atoms. Our findings show that HOMs and low volatile species in β-pinene and limonene SOA are largely different. The ozone concentration-driven SOA formation and evolution mechanism of monoterpenes is suggested to be considered in future climate or exposure risk models, which may enable more accurate air quality prediction and management.

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The maximum carbonyl ratio (MCR) as a new index for the structural classification of secondary organic aerosol components

Cited by 24 publications

References 81 publications

Factors Influencing the Molecular Compositions and Distributions of Atmospheric Nitrogen‐Containing Compounds

Factors Influencing the Molecular Compositions and Distributions of Atmospheric Nitrogen‐Containing Compounds

Nontarget Screening Exhibits a Seasonal Cycle of PM_2.5 Organic Aerosol Composition in Beijing

Large differences of highly oxygenated organic molecules (HOMs) and low volatile species in SOA formed from ozonolysis of β-pinene and limonene

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The maximum carbonyl ratio (MCR) as a new index for the structural classification of secondary organic aerosol components

Cited by 24 publications

References 81 publications

Factors Influencing the Molecular Compositions and Distributions of Atmospheric Nitrogen‐Containing Compounds

Factors Influencing the Molecular Compositions and Distributions of Atmospheric Nitrogen‐Containing Compounds

Nontarget Screening Exhibits a Seasonal Cycle of PM2.5 Organic Aerosol Composition in Beijing

Large differences of highly oxygenated organic molecules (HOMs) and low volatile species in SOA formed from ozonolysis of β-pinene and limonene

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Nontarget Screening Exhibits a Seasonal Cycle of PM_2.5 Organic Aerosol Composition in Beijing