Probing molecular-level transformations of dissolved organic matter: insights on photochemical degradation and protozoan modification of DOM from electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

Kujawinski, Elizabeth B.; Vecchio, Rossana Del; Blough, Neil V.; Klein, Geoffrey C.; Marshall, Alan G.

doi:10.1016/j.marchem.2004.06.038

Cited by 264 publications

(241 citation statements)

References 59 publications

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“…Longer WRT allows for a greater proportion of DOM to be derived from autochthonous sources 21,26 and increases photo-exposure. Accordingly, as aromatic compounds are particularly sensitive to photodegradation 11 , we found a decreased abundance of polyphenols with increasing WRT (Fig. 3b).…”

Section: Molecular Associations With Precipitation and Residence Timementioning

confidence: 64%

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Chemodiversity of dissolved organic matter in lakes driven by climate and hydrology

et al. 2014

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Despite the small continental coverage of lakes, they are hotspots of carbon cycling, largely due to the processing of terrestrially derived dissolved organic matter (DOM). As DOM is an amalgam of heterogeneous compounds comprising gradients of microbial and physicochemical reactivity, the factors influencing DOM processing at the molecular level and the resulting patterns in DOM composition are not well understood. Here we show, using ultrahigh-resolution mass spectrometry to unambiguously identify 4,032 molecular formulae in 120 lakes across Sweden, that the molecular composition of DOM is shaped by precipitation, water residence time and temperature. Terrestrially derived DOM is selectively lost as residence time increases, with warmer temperatures enhancing the production of nitrogen-containing compounds. Using biodiversity concepts, we show that the molecular diversity of DOM, or chemodiversity, increases with DOM and nutrient concentrations. The observed molecular-level patterns indicate that terrestrially derived DOM will become more prevalent in lakes as climate gets wetter.

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Section: Molecular Associations With Precipitation and Residence Timementioning

confidence: 64%

“…The burgeoning use of mass spectrometry in DOM studies has tremendously advanced our molecular-level understanding of DOM dynamics [11][12][13][14][15] . Recent developments in data processing now enable us to analyze the detailed molecular composition of DOM as a function of environmental gradients over a large number of samples.…”

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confidence: 99%

Chemodiversity of dissolved organic matter in lakes driven by climate and hydrology

et al. 2014

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“…Despite these challenges, much has been learned by tracking changes in DOC concentration and DOM composition during incubation experiments, including the variation in biomineralization rates as a function of DOM source (e.g., Moran and Zepp, 1997;Obernosterer and Benner, 2004), the relationship of microbial activity to the production of labile (e.g., Kawasaki and Benner, 2006) and refractory (e.g., Ogawa et al, 2001;Jiao et al, 2010;Lechtenfeld et al, 2015) DOM, and how bacterial-derived refractory material compares structurally to refractory DOM in the ocean (e.g., Osterholz et al, 2015). Studies using ultrahigh resolution mass spectrometry have revealed additional molecular-level transformations in DOM as a result of microorganism activity (Kujawinski et al, 2004), including a significant decrease in the molecular diversity of terrigenous DOM (Seidel et al, 2015) and a preferential degradation of oxygen-rich molecules on a time scale of several days (Kim et al, 2006;Medeiros et al, 2015c;Seidel et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Microbially-Mediated Transformations of Estuarine Dissolved Organic Matter

et al. 2017

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Microbially-mediated transformations of dissolved organic matter (DOM) in a marsh-dominated estuarine system were investigated at the molecular level using ultrahigh resolution mass spectrometry. In addition to observing spatial and temporal variability in DOM sources in the estuary, multiple incubations with endogenous microorganisms identified the influence of DOM composition on biodegradation. A clear microbial preference for degradation of compounds associated with marine DOM relative to those of terrestrial origin was observed, resulting in an overall shift of the remaining DOM toward a stronger terrigenous signature. During short, 1-day long incubations of samples rich in marine DOM, the molecular formulae that were enriched had slightly smaller mass (20-30 Da) and number of carbon atoms compared to the molecular formulae that were depleted. Over longer time scales (70 days), the mean differences in molecular mass between formulae that were depleted and enriched were substantially larger (∼270 Da). The differences in elemental composition over daily time scales were consistent with transformations in functional groups; over longer time scales, the differences in elemental composition may be related to progressive transformations of functional groups of intermediate products and/or other reactions. Our results infused new data toward the understanding of DOM processing by bacterioplankton in estuarine systems.

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“…Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), due to its ultrahigh resolution and mass accuracy, can provide molecular elemental information about NOM without chromatographic separation [5,6], and has been used for accurate characterization of NOM [7][8][9]. Electrospray ionization (ESI) is the most commonly used ionization method for FT-ICR-MS characterization of NOM because it is one of the softest ionization methods and can be easily coupled with FT-ICR-MS [10,11]. However, during ESI analysis, only some polar and moderately polar molecules of NOM can be ionized by ESI, and most of non-polar compounds cannot be detected [11].…”

Section: Introductionmentioning

confidence: 99%

Comprehensive characterization of natural organic matter by MALDI- and ESI-Fourier transform ion cyclotron resonance mass spectrometry

Cao

Huang

et al. 2015

Analytica Chimica Acta

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A B S T R A C TNatural organic matter (NOM) is a complex and non-uniform mixture of organic compounds which plays an important role in environmental processes. Due to the complexity, it is challenging to obtain fully detailed structural information about NOM. Although Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) has been demonstrated to be a powerful tool for providing molecular information about NOM, multiple ionization methods are needed for comprehensive characterization of NOM at the molecular level considering the ionizing selectivity of different ionization methods. This paper reports the first use of matrix assisted laser desorption/ionization (MALDI) method coupled with FT-ICR-MS for molecular characterization of NOM within a mass range of 200-800 Da. The mass spectral data obtained by MALDI were systematically compared with data generated by electrospray ionization (ESI). It showed that complementary molecular information about NOM which could not be detected by ESI, were provided by MALDI. More unsaturated and aromatic constituents of NOM with lower O/C ratio (O/C ratio < 0.5) were preferentially ionized in MALDI negative mode, whereas more polar constituents of NOM with higher O/C ratio were preferentially ionized in ESI negative mode. Molecular anions of NOM appearing at even m/z in MALDI negative ion mode were detected. The results show that NOM molecules with aromatic structures, moderate O/C ratio (0.7 > O/C ratio > 0.25) and lower H/C ratio were liable to form molecular anions at even m/z, whereas those with higher H/C ratio are more likely to form deprotonated ions at odd m/z. It is speculated that almost half of the NOM molecules identified by MALDI may be aromatic or condensed aromatic compounds with

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Probing molecular-level transformations of dissolved organic matter: insights on photochemical degradation and protozoan modification of DOM from electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

Cited by 264 publications

References 59 publications

Chemodiversity of dissolved organic matter in lakes driven by climate and hydrology

Chemodiversity of dissolved organic matter in lakes driven by climate and hydrology

Microbially-Mediated Transformations of Estuarine Dissolved Organic Matter

Comprehensive characterization of natural organic matter by MALDI- and ESI-Fourier transform ion cyclotron resonance mass spectrometry

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