Molecular alteration of marine dissolved organic matter under experimental hydrothermal conditions

Hawkes, Jeffrey A.; Hansen, Christian T.; Goldhammer, Tobias; Bach, Wolfgang; Dittmar, Thorsten

doi:10.1016/j.gca.2015.11.025

Cited by 80 publications

(110 citation statements)

References 92 publications

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“…In most cases works focused on small molecules (hydrocarbon gases, volatile fatty acids, and amino acids) and very few data are available on semivolatile organic compounds (SVOCs). Despite the growing interest for OM in the ocean and hydrothermal systems there is still a major lack in identification and quantification of organic compounds [10][11][12][13][14][15]. Notably numbers of studies agree on the major ligand role of organics in metal stabilisation, transportation, bioavailability, and ore-forming but there are hardly any clues on the nature of these ligands in hydrothermal environments [16][17][18][19][20][21][22][23][24][25].…”

Section: Geofluidsmentioning

confidence: 99%

“…Notably numbers of studies agree on the major ligand role of organics in metal stabilisation, transportation, bioavailability, and ore-forming but there are hardly any clues on the nature of these ligands in hydrothermal environments [16][17][18][19][20][21][22][23][24][25]. Organic compounds in hydrothermal fluids may come from marine dissolved organic matter (DOM) recycling [12,13], subsurface biomass degradation [26], entrainment of organic detritus from local recharge zones, and subsequent degradation, or abiotic formation in the deep subsurface [27][28][29][30]. The latter is supported by many theoretical [31][32][33] and experimental work summarised in two reviews [34,35].…”

Section: Geofluidsmentioning

confidence: 99%

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Organic, Gas, and Element Geochemistry of Hydrothermal Fluids of the Newly Discovered Extensive Hydrothermal Area in the Wallis and Futuna Region (SW Pacific)

et al. 2018

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Two newly discovered hydrothermal vent fields of the Wallis and Futuna region, Kulo Lasi and Fatu Kapa, were sampled for fluid geochemistry. A great geochemical diversity was observed and assigned to the diversity of lithologies as well as the occurrence of various processes. Kulo Lasi fluids likely formed by interaction with fresh volcanic rocks, phase separation, and mixing with magmatic fluid. Conversely, the geochemistry of the Fatu Kapa fluids would be mostly due to water/felsic lavas reactions. In terms of organic geochemistry, fluids from both fields were found to be enriched in formate, acetate, and semivolatile organic compounds (SVOCs): n-alkanes, n-fatty acids, and polyaromatic hydrocarbons (PAHs). Concentrations of SVOCs reached a few ppb at most. The distribution patterns of SVOCs indicated that several processes and sources, at once of biogenic, thermogenic, and abiogenic types, likely controlled organic geochemistry. Although the contribution of each process remains unknown, the mere presence of organics at the M level has strong implications for metal dispersion (cycles), deposition (ore-forming), and bioavailability (ecosystems), especially as our fluxes estimations suggest that back-arc hosted vent fields could contribute as much as MOR to the global ocean heat and mass budget.

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Section: Geofluidsmentioning

confidence: 99%

Section: Geofluidsmentioning

confidence: 99%

Organic, Gas, and Element Geochemistry of Hydrothermal Fluids of the Newly Discovered Extensive Hydrothermal Area in the Wallis and Futuna Region (SW Pacific)

et al. 2018

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“…In other words, the samples were normalized internally for total intensity and then externally to account for DOC concentration. This was done to correctly estimate the relative change in concentration over the course of incubation (Lechtenfeld et al, 2014;Seidel et al, 2015;Hawkes et al, 2016b;Mostovaya et al, 2017). The signal intensity we refer to further in the text (e.g., in the section FormulaSpecific Apparent Decay Coefficient k exp ) corresponds to DOC normalized intensity in undiluted sample.…”

Section: Ft-icr-ms Data Analysismentioning

confidence: 99%

“…This exemplifies that the exact chemical composition might be a more universal predictor of decay patterns than the degree of allochthony. With the increasing number of studies using the ultrahigh resolution mass spectrometry to understand the molecular drivers of DOM reactivity in a variety of systems (Gonsior et al, 2013;Sleighter et al, 2014;D'Andrilli et al, 2015;Kellerman et al, 2015;Hawkes et al, 2016b;Riedel et al, 2016;Kamjunke et al, 2017) a better understanding of the intrinsic controls of aquatic DOM reactivity becomes increasingly possible to achieve.…”

Section: General Trends In Reactivity Among Major Compound Groupsmentioning

confidence: 99%

Molecular Determinants of Dissolved Organic Matter Reactivity in Lake Water

et al. 2017

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Lakes in the boreal region have been recognized as the biogeochemical hotspots, yet many questions regarding the regulators of organic matter processing in these systems remain open. Molecular composition can be an important determinant of dissolved organic matter (DOM) fate in freshwater systems, but many aspects of this relationship remain unclear due to the complexity of DOM and its interactions in the natural environment. Here, we combine ultrahigh resolution mass spectrometry (FT-ICR-MS) with kinetic modeling of decay of >1,300 individual DOM molecular formulae identified by mass spectrometry, to evaluate the role of specific molecular characteristics in decomposition of lake water DOM. Our data is derived from a 4 months microbial decomposition experiment, carried out on water from three Swedish lakes, with the set-up including natural lake water, as well as the lake water pretreated with UV light. The relative decay rate of every molecular formula was estimated by fitting a single exponential model to the change in FT-ICR-MS signal intensities over decomposition time. We found a continuous range of exponential decay coefficients (k exp ) within different groups of compounds and show that for highly unsaturated and phenolic compounds the distribution of k exp was shifted toward the lowest values. Contrary to this general trend, plant-derived polyphenols and polycondensed aromatics were on average more reactive than compounds with an intermediate aromaticity. The decay rate of aromatic compounds increased with increasing nominal oxidation state of carbon, and molecular mass in some cases showed an inverse relationship with k exp in the UV-manipulated treatment. Further, we observe an increase in formulae-specific k exp as a result of the UV pretreatment. General trends in reactivity identified among major compound groups emphasize the importance of the intrinsic controllers of lake water DOM decay. However, we additionally indicate that each compound group contained a wide spectrum of reactivities, suggesting that high resolution is needed to further ascertain the complex reasons behind DOM reactivity in lake water.

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“…In recent hydrothermal fields, however, organic matter becomes thermally altered and redistributed (Simoneit, 1993;Delacour et al, 2008;Konn et al, 2009). Laboratory experiments using marine DOM indicate that thermal alteration 10 already occurs at temperatures >68-100°C, and efficient removal of organic molecules at 212-401°C (Hawkes et al, 2015(Hawkes et al, , 2016. It has been argued, however, that such DOM removal may also be due to transformation into immiscible material through, for example, condensation (Castello et al, 2014) and/or defunctionalisation reactions (Hawkes et al, 2016).…”

mentioning

confidence: 99%

Ideas and perspectives: Hydrothermally driven redistribution and sequestration of early Archaean biomass – the hydrothermal pump hypothesis

Duda¹,

Thiel²,

Bauersachs³

et al. 2017

Preprint

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Abstract. Archaean hydrothermal chert veins commonly contain abundant organic carbon of uncertain origin (abiotic vs. biotic). In this study, we analysed kerogen contained in a hydrothermal chert vein from the ca. 3.5 Ga old Dresser Formation 20 (Pilbara Craton, Western Australia). Catalytic hydropyrolysis (HyPy) of this kerogen yielded n-alkanes up to n-C 22 , with a sharp decrease in abundance beyond n-C 18 . A very similar distribution (≤ n-C 18 ) was observed in HyPy products of preextracted recent bacterial biomass, while abiotic compounds synthesised via Fischer-Tropsch-type synthesis exhibited a modal distribution. We therefore propose that the original organic matter in the Archaean chert veins has a primarily microbial origin. We hypothesise that the microbially-derived organic matter accumulated in different aquatic and 25 subsurface Dresser environments, and was then assimilated, redistributed and sequestered by hydrothermal fluids ('hydrothermal pump hypothesis').

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Molecular alteration of marine dissolved organic matter under experimental hydrothermal conditions

Cited by 80 publications

References 92 publications

Organic, Gas, and Element Geochemistry of Hydrothermal Fluids of the Newly Discovered Extensive Hydrothermal Area in the Wallis and Futuna Region (SW Pacific)

Organic, Gas, and Element Geochemistry of Hydrothermal Fluids of the Newly Discovered Extensive Hydrothermal Area in the Wallis and Futuna Region (SW Pacific)

Molecular Determinants of Dissolved Organic Matter Reactivity in Lake Water

Ideas and perspectives: Hydrothermally driven redistribution and sequestration of early Archaean biomass – the hydrothermal pump hypothesis

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