scholarly journals Molecular characterization of organic aerosol in the Himalayas: insight from ultra-high-resolution mass spectrometry

2019 ◽  
Vol 19 (2) ◽  
pp. 1115-1128 ◽  
Author(s):  
Yanqing An ◽  
Jianzhong Xu ◽  
Lin Feng ◽  
Xinghua Zhang ◽  
Yanmei Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Chemical Composition ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Ion Cyclotron Resonance ◽  
Chemical Composition Of Water ◽  
High Fraction ◽  
Molecular Number

Abstract. An increased trend in aerosol concentration has been observed in the Himalayas in recent years, but the understanding of the chemical composition and sources of aerosol remains poorly understood. In this study, molecular chemical composition of water-soluble organic matter (WSOM) from two filter samples collected during two high aerosol loading periods (denoted as P1 and P2) at a high-altitude station (Qomolangma Station, QOMS; 4276 m a.s.l.) in the northern Himalayas was identified using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR MS). More than 4000 molecular formulas were identified in each filter sample which were classified into two compound groups (CHO and CHON) based on their elemental composition, with both accounting for nearly equal contributions in number (45 %–55 %). The relative abundance weighted mole ratio of O∕Cw for P1 and P2 was 0.43 and 0.39, respectively, and the weighted double bond equivalents (DBEw), an index for the saturation of organic molecules, were 7.12 and 7.87, respectively. Although the O∕Cw mole ratio was comparable for CHO and CHON compounds, the DBEw was significantly higher in CHON compounds than CHO compounds. More than 50 % molecular formulas in the Van Krevelen (VK) diagram (H∕C vs. O∕C) were located in 1–1.5 (H∕C) and 0.2–0.6 (O∕C) regions, suggesting potential lignin-like compounds. The distributions of CHO and CHON compounds in the VK diagram, DBE vs. number of C atoms, and other diagnostic diagrams showed high similarities among each other, suggesting their similar source and/or atmospheric processes. Many formulas formed from biogenic volatile organic compounds (e.g., ozonolysis of α-pinene products) and biomass-burning-emitted compounds (e.g., phenolic compounds) were found in the WSOM, suggesting the important contribution of these two sources in the Himalayas. The high DBE and high fraction of nitrogen-containing aerosol can potentially impact aerosol light absorption in this remote region. Further comprehensive study is needed due to the complexity of organic aerosol and limited molecular number identified in this study.

scholarly journals Molecular characterization of organic aerosol in Himalayas: insight from ultra-high resolution mass spectrometry

2018 ◽  
Author(s):  
Yanqing An ◽  
Jianzhong Xu ◽  
Lin Feng ◽  
Xinhua Zhang ◽  
Yanmei Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Chemical Composition ◽  
Relative Abundance ◽  
High Resolution Mass Spectrometry ◽  
Water Soluble ◽  
Ion Cyclotron Resonance ◽  
Chemical Composition Of Water ◽  
Molecular Information ◽  
The Common

Abstract. An increasing trend in aerosol concentration has been observed in Himalayas in recent years, but the understanding of the chemical composition and sources of aerosol remains poor. In this study, molecular chemical composition of water soluble organic matter (WSOM) from two filter samples (denoted as F30 and F43) collected during high aerosol loading periods at a high altitude station (Qomolangma Station, QOMS, 4276 m a.s.l.) in the northern Himalayas were identified by positive electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). More than 4500 molecular formulas were identified in each filter sample which were classified into two compound groups (CHO and CHON) based on their elemental composition with both accounting for nearly equal contributions in number (45 %–55 %). The relative abundance weighted mole ratio of O / Cw for F30 and F43 are 0.43 and 0.38, respectively, and the weighted double bond equivalent (DBEw), an index for the saturation of organic molecules, were 6.26 and 6.92, respectively, suggesting their medium oxidation and saturation degrees. Although the O / Cw mole ratio was comparable for CHO and CHON compounds, the DBEw was significant higher in CHON compounds than CHO compounds. More than 50 % molecular formulas in Van Krevelen (VK) diagram (H / C vs. O / C) located in 1–1.5 (H / C) and 0.2–0.6 (O / C) regions, suggesting potential lignin-like compounds. The distributions of CHO and CHON compounds in VK diagram, DBE vs. number of C atoms, and other diagnose diagrams showed highly similarities between each other suggesting their similar source and/or atmospheric processes. Detailed molecular information in the common formula of these two filters was explored. Many formulas with their homologous series of compounds formed from biogenic volatile organic compounds and biomass mass burning emitted compounds were found in the WSOM with high relative abundance suggesting the important contribution of these two sources in Himalayas. The high DBE and high nitrogen containing of aerosol would have important implication for aerosol light absorption and biogeochemical cycle in this remote region.

scholarly journals A molecular-level approach for characterizing water-insoluble components of ambient organic aerosol particulates using ultra-high resolution mass spectrometry

2014 ◽  
Vol 14 (7) ◽  
pp. 10393-10427
Author(s):  
A. S. Willoughby ◽  
A. S. Wozniak ◽  
P. G. Hatcher
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosols ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Proton Nuclear Magnetic Resonance ◽  
Aerosol Sample ◽  
Resonance Spectroscopy ◽  
Ion Cyclotron Resonance

Abstract. The chemical composition of organic aerosols in the atmosphere is strongly influenced by human emissions, and the effect these have on the environment, human health, and climate change is determined by the molecular nature of these chemical species. The complexity of organic aerosol samples limits the ability to study the chemical composition, and, therefore, the associated properties and the impacts they have. Many studies address the water-soluble fraction of organic aerosols, and have had much success in identifying specific molecular formulas for thousands of compounds present. However, little attention is given to the water-insoluble portion, which can contain most of the fossil material that is emitted through human activity. Here we compare the organic aerosols present in water extracts and organic solvent extracts (pyridine and acetonitrile) of an ambient aerosol sample collected in a rural location that is impacted by natural and anthropogenic emission sources. A semi-quantitative method was developed using proton nuclear magnetic resonance spectroscopy to determine that the amount of organic matter extracted by pyridine is comparable to that of water. Electrospray ionization Fourier transform ion cyclotron resonance mass spectra show that pyridine extracts a molecularly unique fraction of organic matter compared to water or acetonitrile, which extract chemically similar organic matter components. The molecular formulas unique to pyridine were less polar, more aliphatic, and reveal formulas containing sulfur to be an important component of insoluble aerosol organic matter.

scholarly journals Secondary Organic Aerosol from Atmospheric Photooxidation of Indole

2017 ◽  
Author(s):  
Julia Montoya ◽  
Jeremy R. Horne ◽  
Mallory L. Hinks ◽  
Lauren T. Fleming ◽  
Veronique Perraud ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Air Quality ◽  
Chemical Composition ◽  
High Resolution ◽  
Secondary Organic Aerosol ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosol ◽  
Scanning Mobility Particle Sizer ◽  
High Resolution Mass ◽  
Resolution Mass

Abstract. Indole is a heterocyclic compound emitted by various plant species under stressed conditions or during flowering events. The formation, optical properties, and chemical composition of secondary organic aerosol (SOA) formed by low-NOx photooxidation of indole were investigated. The SOA yield (1.1 ± 0.3) was estimated from measuring the particle mass concentration with a scanning mobility particle sizer (SMPS) and correcting it for the wall loss effects. The SOA particles were collected on filters and analysed offline with UV-Vis spectrophotometry to measure the mass absorption coefficient (MAC) of the bulk sample. The samples were visibly brown and had MAC values of ~7 m2/g at λ = 300 nm and ~2 m2/g at λ = 400 nm, comparable to strongly absorbing brown carbon emitted from biomass burning. The chemical composition of SOA was examined with several mass spectrometry methods. The direct analysis in real time mass spectrometry (DART-MS) and nanospray desorption electrospray high resolution mass spectrometry (nano-DESI-HRMS) were used to provide information about the overall distribution of SOA compounds. High performance liquid chromatography, coupled to photodiode array spectrophotometry and high resolution mass spectrometry (HPLC-PDA-HRMS) was used to identify chromophoric compounds. Indole derivatives, such as tryptanthrin, indirubin, indigo dye, and indoxyl red were found to contribute significantly to the visible absorption spectrum of indole SOA. The potential effect of indole SOA on air quality was explored with the airshed model, which found elevated concentrations of indole SOA during the afternoon hours contributing considerably to the total organic aerosol under selected scenarios. Because of its high MAC values, indole SOA can contribute to decreased visibility and poor air quality.

scholarly journals Linking biogenic hydrocarbons to biogenic aerosol in the Borneo rainforest

2013 ◽  
Vol 13 (7) ◽  
pp. 18113-18141
Author(s):  
J. F. Hamilton ◽  
M. R. Alfarra ◽  
N. Robinson ◽  
M. W. Ward ◽  
A. C. Lewis ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Tropical Rainforest ◽  
Ion Trap ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Ion Cyclotron Resonance ◽  
Aerosol Formation ◽  
Chemical Structures

Abstract. Emissions of biogenic volatile organic compounds are though to contribute significantly to secondary organic aerosol formation in the tropics, but understanding the process of these transformations has proved difficult, due to the complexity of the chemistry involved and very low concentrations. Aerosols from above a South East Asian tropical rainforest in Borneo were characterised using liquid chromatography-ion trap mass spectrometry, high resolution aerosol mass spectrometry and fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) techniques. Oxygenated compounds were identified in ambient organic aerosol that could be directly traced back to isoprene, monoterpenes and sesquiterpene emissions, by combining field data on chemical structures with mass spectral data generated from synthetically produced products created in a simulation chamber. Eighteen oxygenated species of biogenic origin were identified in the rainforest aerosol from the precursors isoprene, α-pinene, limonene, α-terpinene and β-caryophyllene. The observations provide the unambiguous field detection of monoterpene and sesquiterpene oxidation products in SOA above a pristine tropical rainforest. The presence of 2-methyltetrol organosulfates and an associated sulfated dimer provides direct evidence that isoprene in the presence of sulfate aerosol can make a contribution to biogenic organic aerosol above tropical forests. High-resolution mass spectrometry indicates that sulfur can also be incorporated into oxidation products arising from monoterpene precursors in tropical aerosol.

scholarly journals Linking biogenic hydrocarbons to biogenic aerosol in the Borneo rainforest

2013 ◽  
Vol 13 (22) ◽  
pp. 11295-11305 ◽  
Author(s):  
J. F. Hamilton ◽  
M. R. Alfarra ◽  
N. Robinson ◽  
M. W. Ward ◽  
A. C. Lewis ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Tropical Rainforest ◽  
Ion Trap ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Ion Cyclotron Resonance ◽  
Aerosol Formation ◽  
Chemical Structures

Abstract. Emissions of biogenic volatile organic compounds are though to contribute significantly to secondary organic aerosol formation in the tropics, but understanding these transformation processes has proved difficult, due to the complexity of the chemistry involved and very low concentrations. Aerosols from above a Southeast Asian tropical rainforest in Borneo were characterised using liquid chromatography–ion trap mass spectrometry, high-resolution aerosol mass spectrometry and Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) techniques. Oxygenated compounds were identified in ambient organic aerosol that could be directly traced back to isoprene, monoterpenes and sesquiterpene emissions, by combining field data on chemical structures with mass spectral data generated from synthetically produced products created in a simulation chamber. Eighteen oxygenated species of biogenic origin were identified in the rainforest aerosol from the precursors isoprene, α-pinene, limonene, α-terpinene and β-caryophyllene. The observations provide the unambiguous field detection of monoterpene and sesquiterpene oxidation products in SOA above a pristine tropical rainforest. The presence of 2-methyl tetrol organosulfates and an associated sulfated dimer provides direct evidence that isoprene in the presence of sulfate aerosol can make a contribution to biogenic organic aerosol above tropical forests. High-resolution mass spectrometry indicates that sulfur can also be incorporated into oxidation products arising from monoterpene precursors in tropical aerosol.

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