Characterization of dissolved organic material in the interstitial brine of Lake Vida, Antarctica

Cawley, Kaelin M.; Murray, Alison E.; Doran, Peter T.; Kenig, Fabien; Stubbins, Aron; Chen, Hongmei; Hatcher, Patrick G.; McKnight, Diane M.

doi:10.1016/j.gca.2016.03.023

Cited by 18 publications

(19 citation statements)

References 69 publications

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“…The molecular signatures of whole water tree-DOM as revealed by negative mode electrospray ionization FT-ICR MS (Figure 2) share many features of whole water and extracted DOM from other aquatic environments (Mopper et al, 2007;Singer et al, 2012;Chen et al, 2014;Dittmar and Stubbins, 2014;Cawley et al, 2016). Shared features include a high diversity of elemental formulas distributed broadly in van Krevelen space (Figures 6A-C) and spanning a range of molecular classes ( Table 2).…”

Section: Molecular Signatures Of Tree-dommentioning

confidence: 96%

Molecular and Optical Properties of Tree-Derived Dissolved Organic Matter in Throughfall and Stemflow from Live Oaks and Eastern Red Cedar

et al. 2017

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Studies of dissolved organic matter (DOM) transport through terrestrial aquatic systems usually start at the stream. However, the interception of rainwater by vegetation marks the beginning of the terrestrial hydrological cycle making trees the headwaters of aquatic carbon cycling. Rainwater interacts with trees picking up tree-DOM, which is then exported from the tree in stemflow and throughfall. Stemflow denotes water flowing down the tree trunk, while throughfall is the water that drips through the leaves of the canopy. We report the concentrations, optical properties (light absorbance) and molecular signatures (ultrahigh resolution mass spectrometry) of tree-DOM in throughfall and stemflow from two tree species (live oak and eastern red cedar) with varying epiphyte cover on Skidaway Island, Savannah, Georgia, USA. Both stemflow and throughfall were enriched in DOM compared to rainwater, indicating trees were a significant source of DOM. The optical and molecular properties of tree-DOM were broadly consistent with those of DOM in other aquatic ecosystems. Stemflow was enriched in highly colored DOM compared to throughfall. Elemental formulas identified clustered the samples into three groups: oak stemflow, oak throughfall and cedar. The molecular properties of each cluster are consistent with an autochthonous aromatic-rich source associated with the trees, their epiphytes and the microhabitats they support. Elemental formulas enriched in oak stemflow were more diverse, enriched in aromatic formulas, and of higher molecular mass than for other tree-DOM classes, suggesting greater contributions from fresh and partially modified plant-derived organics. Oak throughfall was enriched in lower molecular weight, aliphatic and sugar formulas, suggesting greater contributions from foliar surfaces. While the optical properties and the majority of the elemental formulas within tree-DOM were consistent with vascular plant-derived organics, condensed aromatic formulas were also identified. As condensed aromatics are generally interpreted Stubbins et al.Optical and Molecular Signatures of Tree-DOM as deriving from partially combusted organics, some of the tree-DOM may have derived from the atmospheric deposition of thermogenic and other windblown organics. These initial findings should prove useful as future studies seek to track tree-DOM across the aquatic gradient from canopy roof, through soils and into fluvial networks.

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Section: Molecular Signatures Of Tree-dommentioning

confidence: 96%

Molecular and Optical Properties of Tree-Derived Dissolved Organic Matter in Throughfall and Stemflow from Live Oaks and Eastern Red Cedar

et al. 2017

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“…The overall goal of this study was to use spectroscopic techniques to evaluate the potential sources and sinks of DOM in these lakes and streams. Spectroscopic techniques that were used in this study, such as UV-vis spectroscopy and excitation-emission matrix spectroscopy (EEM), have been successful in studying concentrations, compositions, and dynamics of chromophoric (CDOM) and fluorescent DOM (FDOM) in aquatic systems including Antarctic lakes (Cawley et al, 2016McKnight et al, 1994). We hypothesized that DOM in the Antarctic lakes and streams has much larger compositional diversity than has been considered and such diversity is mostly introduced by external factors such as photodegradation because the simplicity of the sources would reduce the original DOM heterogeneity.…”

Section: Introductionmentioning

confidence: 99%

Origin, distributions, and environmental significance of ubiquitous humic-like fluorophores in Antarctic lakes and streams

Kida

Kojima

Tanabe³

et al. 2019

Water Research

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“…Around 50% of the DOC of LVBr are in molecules larger than 1 kDa [ Cawley et al ., ]. Two other fractions of dissolved organic matter (DOM), representing 18% of DOC, have compounds with an average molecular weight of ~500 Da, as determined by Fourier transform ion cyclotron resonance mass spectrometry [ Cawley et al ., ]. As a result of the very limited carbon range of the SPME fibers and the large size of the constituents of the DOM of LVBr, the reduced‐carbon to oxychlorine ratio of the material adsorbed on the SPME fibers after DI sampling must have been much less than in the brine itself, although it cannot be quantified at this point.…”

Section: Discussionmentioning

confidence: 99%

“…LVBr has a DOC concentration 48.2 ± 9.7 mmol · L À1 , largely in excess of the molar abundance of perchlorate and chlorate (0.49 and 0.11 μmol · L À1 , respectively), but a vast majority of the DOC in LVBr is not amenable to DI-SPME as Carboxen®/PDMS (black) and PDMS/VDB (blue) fibers were designed for molecules in the C 2 -C 12 range [Mani, 1999]. Around 50% of the DOC of LVBr are in molecules larger than 1 kDa [Cawley et al, 2016]. Two other fractions of dissolved organic matter (DOM), representing 18% of DOC, have compounds with an average molecular weight of~500 Da, as determined by Fourier transform ion cyclotron resonance Journal of Geophysical Research: Planets 10.1002/2015JE004964 mass spectrometry [Cawley et al, 2016].…”

Section: Carbon Limitationmentioning

confidence: 99%

Perchlorate and volatiles of the brine of Lake Vida (Antarctica): Implication for the in situ analysis of Mars sediments

et al. 2016

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The cold (−13.4°C), cryoencapsulated, anoxic, interstitial brine of the >27 m thick ice of Lake Vida (Victoria Valley, Antarctica) contains 49 µg · L−1 of perchlorate and 11 µg · L−1 of chlorate. Lake Vida brine (LVBr) may provide an analog for potential oxychlorine‐rich subsurface brine on Mars. LVBr volatiles were analyzed by solid‐phase microextraction (SPME) gas chromatography–mass spectrometry (GC‐MS) with two different SPME fibers. With the exception of volatile organic sulfur compounds, most other volatiles observed were artifacts produced in the GC injector when the thermal decomposition products of oxychlorines reacted with reduced carbon derived from LVBr and the SPME fiber phases. Analysis of MilliQ water with perchlorate (40 µg · L−1) showed low level of organic artifacts, reflecting carbon limitation. In order to observe sample‐derived organic compounds, both in analog samples and on Mars, the molar abundance of reduced carbon in a sample must exceed those of O2 and Cl2 produced during decomposition of oxychlorines. This suggests that the abundance of compounds observed by the Sample Analysis at Mars (SAM) instruments in Sheepbed samples (CB‐3, CB5, and CB6) may be controlled by an increase in the reduced‐carbon/oxychlorine ratio of these samples. To increase chances of in situ detection of Martian organics during pyrolysis‐GC‐MS, we propose that the derivatization agents stored on SAM may be used as an external source of reduced carbon, increasing artificially the reduced‐carbon to perchlorate ratio during pyrolysis, allowing the expression of more abundant and perhaps more diverse Martian organic matter.

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Characterization of dissolved organic material in the interstitial brine of Lake Vida, Antarctica

Cited by 18 publications

References 69 publications

Molecular and Optical Properties of Tree-Derived Dissolved Organic Matter in Throughfall and Stemflow from Live Oaks and Eastern Red Cedar

Molecular and Optical Properties of Tree-Derived Dissolved Organic Matter in Throughfall and Stemflow from Live Oaks and Eastern Red Cedar

Origin, distributions, and environmental significance of ubiquitous humic-like fluorophores in Antarctic lakes and streams

Perchlorate and volatiles of the brine of Lake Vida (Antarctica): Implication for the in situ analysis of Mars sediments

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