scholarly journals Detailed Source-Specific Molecular Composition of Ambient Aerosol Organic Matter Using Ultrahigh Resolution Mass Spectrometry and 1H NMR

Atmosphere ◽  
2016 ◽  
Vol 7 (6) ◽  
pp. 79 ◽  
Author(s):  
Amanda Willoughby ◽  
Andrew Wozniak ◽  
Patrick Hatcher
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
1H Nmr ◽  
Molecular Composition ◽  
Ultrahigh Resolution ◽  
Ambient Aerosol ◽  
Resolution Mass ◽  
Aerosol Organic Matter

scholarly journals Molecular composition of biogenic secondary organic aerosols using ultrahigh-resolution mass spectrometry: comparing laboratory and field studies

2014 ◽  
Vol 14 (4) ◽  
pp. 2155-2167 ◽  
Author(s):  
I. Kourtchev ◽  
S. J. Fuller ◽  
C. Giorio ◽  
R. M. Healy ◽  
E. Wilson ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Boreal Forest ◽  
Laboratory Experiments ◽  
Field Studies ◽  
Molecular Composition ◽  
Forest Site ◽  
Ultrahigh Resolution ◽  
Urban Sample ◽  
Kendrick Mass Defect ◽  
Resolution Mass

Abstract. Numerous laboratory experiments have been performed in an attempt to mimic atmospheric secondary organic aerosol (SOA) formation. However, it is still unclear how close the aerosol particles generated in laboratory experiments resemble atmospheric SOA with respect to their detailed chemical composition. In this study, we generated SOA in a simulation chamber from the ozonolysis of α-pinene and a biogenic volatile organic compound (BVOC) mixture containing α- and β-pinene, Δ3-carene, and isoprene. The detailed molecular composition of laboratory-generated SOA was compared with that of background ambient aerosol collected at a boreal forest site (Hyytiälä, Finland) and an urban location (Cork, Ireland) using direct infusion nanoelectrospray ultrahigh-resolution mass spectrometry. Kendrick mass defect and van Krevelen approaches were used to identify and compare compound classes and distributions of the detected species. The laboratory-generated SOA contained a distinguishable group of dimers that was not observed in the ambient samples. The presence of dimers was found to be less pronounced in the SOA from the BVOC mixtures when compared to the one component precursor system. The molecular composition of SOA from both the BVOC mixture and α-pinene represented the overall composition of the ambient sample from the boreal forest site reasonably well, with 72.3 ± 2.5% (n = 3) and 69.1 ± 3.0% (n = 3) common ions, respectively. In contrast, large differences were found between the laboratory-generated BVOC samples and the ambient urban sample. To our knowledge this is the first direct comparison of molecular composition of laboratory-generated SOA from BVOC mixtures and ambient samples.

Tracking the formation of new brominated disinfection by-products during the seawater desalination process

2020 ◽  
Vol 6 (9) ◽  
pp. 2521-2541 ◽  
Author(s):  
Leanne C. Powers ◽  
Annaleise Conway ◽  
Carys L. Mitchelmore ◽  
Stephen J. Fleischacker ◽  
Mourad Harir ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Seawater Desalination ◽  
Ultrahigh Resolution ◽  
By Products ◽  
Resolution Mass

Ultrahigh resolution mass spectrometry revealed substantial dissolved organic matter changes and the formation of numerous bromine-containing disinfection by-products during the seawater desalination process.

scholarly journals Labilization and diversification of pyrogenic dissolved organic matter by microbes

2021 ◽  
Author(s):  
Aleksandar I. Goranov ◽  
Andrew S. Wozniak ◽  
Kyle W. Bostick ◽  
Andrew R. Zimmerman ◽  
Siddhartha Mitra ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
Microbial Biomass ◽  
Forest Fires ◽  
Ion Cyclotron Resonance ◽  
Exact Nature ◽  
Fluorescence Excitation ◽  
Ultrahigh Resolution ◽  
Rain Events ◽  
Resolution Mass

Abstract. With the increased occurrence of forest fires around the world, interest in the chemistry of pyrogenic organic matter (pyOM) and its fate in the environment has increased. Upon leaching from soils by rain events, significant amounts of dissolved pyOM (pyDOM) enter the aquatic environment and interact with microbial communities that are essential for cycling organic matter within the different biogeochemical cycles. To evaluate the bio-reactivity of pyDOM, aqueous extracts of laboratory-produced chars were incubated with soil microbes and the molecular changes to the composition of pyDOM were probed using ultrahigh resolution mass spectrometry (Fourier transform – ion cyclotron resonance – mass spectrometry). Given that photo-degradation also affects the composition and reactivity of pyDOM during terrigenous-to-marine export, the effects of photochemistry were also evaluated in the context of the bio-reactivity of pyDOM. Ultrahigh resolution mass spectrometry revealed that, after incubation, many different (both aromatic and aliphatic) compounds were degraded, and new labile compounds, 22–40 % of which were peptide-like, were produced. This indicated that a portion of pyDOM has been labilized into microbial biomass during the incubations. Fluorescence excitation-emission matrix spectra revealed that some fraction of these new molecules is associated with fluorophores from proteinaceous and/or autochthonous/microbial biomass origin. Two-dimensional 1H-1H total correlation NMR spectroscopy identified a peptidoglycan-like backbone within the microbially produced compounds. These results are consistent with previous observations of nitrogen from peptidoglycans within the soil and ocean nitrogen cycles. Interestingly, the exact nature of the bio-produced organic matter was found to vary drastically among samples indicating that the used microbial consortium may produce different exudates based on the composition of the initial pyDOM. Another potential explanation for the vast diversity of molecules is that microbes only consume low molecular weight compounds, but they also produce reactive oxygen species (ROS), which initiate oxidative and recombination reactions that produce new molecules. The observed microbially-mediated diversification of pyDOM suggests that pyDOM contributes to the observed large complexity of natural organic matter. More broadly, pyDOM can be substrate for microbial growth and be incorporated in environmental food webs.

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