Modeling the carbon isotope signatures of methane and dissolved inorganic carbon to unravel mineralization pathways in boreal lake sediments

Clayer, François; Moritz, Anja; Gélinas, Yves; Tessier, André; Gobeil, Charles

doi:10.1016/j.gca.2018.02.012

Cited by 17 publications

(11 citation statements)

References 98 publications

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“…Indeed, the values of δ 13 C-CH4 which are lower than -70 ‰ over the whole profiles in the two lake basins, and the large difference (67 to 92 ‰) between the δ 13 C of gaseous CO2 (δ 13 C-CO2) and δ 13 C-CH4, strongly contrast with the typical δ 13 C-CH4 values (−68 to −50 ‰) and with the difference between δ 13 C-CO2 and δ 13 C-CH4 (39 to 58 ‰) reported for acetoclasty (Whiticar, 1999). The δ 13 C results reported previously for another basin of Lake Tantaré (Basin B; Clayer et al, 2018) show also in the hydrogenotrophy domain in Fig. S2.…”

Section: The δ 13 C Profiles 240contrasting

confidence: 61%

“…12 the COS for the Z2 of Lake Bédard since we had to assume a COS value to estimate R2 and the COS has no influence of the modelled δ 13 C profiles (section S2.2.2.3 of the SI). Negative COS values between −0.9 370 and −1.1 suggest that fermenting OM in the sediments of the two lake basins would be better represented by a mixture of fatty acids and fatty alcohols than by carbohydrates, as suggested by Clayer et al (2018) for the sporadically anoxic Lake Tantaré Basin B. For its part, the highly negative COS value of −3.2 calculated for the Z1 of Lake Tantaré Basin A is unreasonable, and the inaccuracy of the COS determination in this lake basin is discussed in section 4.3.…”

Section: Organic Substrates For Methanogenesis At the Sampling Sitesmentioning

confidence: 87%

“…Concentrations and carbon isotopic composition of CH4 and DIC were measured as described by Clayer et al (2018). Briefly, the concentrations were analyzed within 24 h of peeper retrieval by gas chromatography with a precision better than 4 % and 105 detection limits (DL) of 2 µM and 10 µM for CH4 and DIC, respectively.…”

Section: Analysesmentioning

confidence: 99%

“…Lipids such as fatty acids and fatty alcohols with similar COS are naturally abundant in sediments to sustain the estimated rates of CH4 and DIC production during fermentation (Hedges and Oades, 1997;Cranwell, 400 1981;Matsumoto, 1989;Burdige, 2006). As discussed by Clayer et al (2018) the most labile organic compounds (i.e., proteins and carbohydrates) can be rapidly degraded during their transport through the water column and in the uppermost sediment layer, leaving mainly lipids as metabolizable substrates at depths where fermentation and methanogenesis occurs. This interpretation is consistent with thermodynamic and kinetic evidences that proteins and carbohydrates are more labile and are degraded faster than lipids (LaRowe and Van Cappellen, 2011).…”

Section: Reduced Organic Compounds As Methanogenic Substrates In Lakementioning

confidence: 99%

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Mineralization of organic matter in boreal lake sediments: Rates, pathways and nature of the fermenting substrates

Clayer¹,

Gélinas²,

Tessier³

et al. 2020

Preprint

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Abstract. The complexity of organic matter (OM) degradation mechanisms represents a significant challenge for developing biogeochemical models to quantify the role of aquatic sediments in the climate system. The common representation of OM by carbohydrates formulated as CH2O in models comes with the assumption that its degradation by fermentation produces equimolar amounts of methane (CH4) and dissolved inorganic carbon (DIC). To test the validity of this assumption, we modeled using reaction-transport equations vertical profiles of the concentration and isotopic composition (&#948;13C) of CH4 and DIC in the top 25&#8201;cm of the sediment column from two lake basins, one whose hypolimnion is perennially oxygenated and one with seasonal anoxia. Our results reveal that methanogenesis only occurs via hydrogenotrophy in both basins. Furthermore, we calculate, from CH4 and DIC production rates associated with methanogenesis, that the fermenting OM has an average carbon oxidation state (COS) below &#8722;0.9. Modeling solute porewater profiles reported in the literature for four other seasonally anoxic lake basins also yields negative COS values. Collectively, the mean (&#177;SD) COS value of &#8722;1.4&#8201;&#177;&#8201;0.3 for all the seasonally anoxic sites is much lower than the value of zero expected from carbohydrates fermentation. We conclude that carbohydrates do not adequately represent the fermenting OM and that the COS should be included in the formulation of OM fermentation in models applied to lake sediments. This study highlights the need to better characterize the labile OM undergoing mineralization to interpret present-day greenhouse gases cycling and predict its alteration under environmental changes.

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Section: The δ 13 C Profiles 240contrasting

confidence: 61%

Section: Organic Substrates For Methanogenesis At the Sampling Sitesmentioning

confidence: 87%

Section: Analysesmentioning

confidence: 99%

Section: Reduced Organic Compounds As Methanogenic Substrates In Lakementioning

confidence: 99%

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Mineralization of organic matter in boreal lake sediments: Rates, pathways and nature of the fermenting substrates

Clayer¹,

Gélinas²,

Tessier³

et al. 2020

Preprint

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“…Отметим, что это основной путь образования CH 4 в наземных болотистых экосистемах. В озерных осадках, где механизм сульфат-редукции не проявляется в приповерхностных осадках, так же как и в болотах, доминирует путь генерации CH 4 посредством ферментации ацетата, но в более погруженных озерных осадках преобладающей становится реакция восстановления СО 2 водородом, так же как и в морских осадках (Clayer et al, 2018).…”

Section: результаты и обсуждениеunclassified

Isotopic and geochemical study of marine sediments organic matter from delta of Indigirka river to the ice shelf border of the East-Siberian sea

et al. 2019

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Various hydrocarbon gases (СН4, С2Н4, С2Н6, С3Н6, С3Н8, С4Н8, н-С4Н10) and CO2 have been obtained with very low concentration from different layers of marine sediments with thickness up to 2 m on the continental shelf of the East Siberian Sea in the section from the mouth of Indigirka river to the ice shelf border. A freshwater complex, carried by Indigirka river and other rivers, has the dominant influence on composition of organic matter (OM) in almost entire studied area of the East Siberian Sea. It was shown that concentration of the most common gases CH4 and CO2 increases with increasing depth of sediment sampling for the core of sediments selected at station 5602-2, and the carbon isotope composition of CO2 decreases, reaching a value of -24‰. A sulfate reduction area was found at sediment depth of 48–70 cm. For the first time it was shown that a regular change in isotopic fractional characteristics (IFC) occurs as a result of diagenesis of OM. IFC was obtained for low maturation OM, OM for sulfate reduction area, and for high maturation OM. For low horizons of the sediment (below 77 cm from the surface), the OM is significantly matured along the path of geochemical evolution compared with the immature sediments of the upper horizons.

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An empirical model to predict methane production in inland water sediment from particular organic matter supply and reactivity

Grasset

Moras

Isidorova

et al. 2021

Limnology & Oceanography

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The highest CH 4 production rates can be found in anoxic inland water surface sediments however no model quantifies CH 4 production following fresh particular organic matter (POM) deposition on anoxic sediments. This limits our capability of modeling CH 4 emissions from inland waters to the atmosphere. To generate such a model, we quantified how the POM supply rate and POM reactivity control CH 4 production in anoxic surface sediment, by amending sediment at different frequencies with different quantities of aquatic and terrestrial POM. From the modeled CH 4 production, we derived parameters related to the kinetics and the extent of CH 4 production. We show that the extent of CH 4 production can be well predicted by the quality (i.e., C/N ratio) and the quantity of POM supplied to an anoxic sediment. In particular, within the range of sedimentation rates that can be found in aquatic systems, we show that CH 4 production increases linearly with the quantity of phytoplankton-derived and terrestrially derived POM. A high frequency of POM addition, which is a common situation in natural systems, resulted in higher peaks in CH 4 production rates. This suggests that relationships derived from earlier incubation experiments that added POM only once, may result in underestimation of sediment CH 4 production. Our results quantitatively couple CH 4 production in anoxic surface sediment to POM sedimentation flux, and are therefore useful for the further development of mechanistic models of inland water CH 4 emission.

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Modeling the carbon isotope signatures of methane and dissolved inorganic carbon to unravel mineralization pathways in boreal lake sediments

Abstract: the carbon isotope signatures of methane and dissolved inorganic carbon to unravel mineralization pathways in boreal lake sediments,

Cited by 17 publications

References 98 publications

Mineralization of organic matter in boreal lake sediments: Rates, pathways and nature of the fermenting substrates

Mineralization of organic matter in boreal lake sediments: Rates, pathways and nature of the fermenting substrates

Isotopic and geochemical study of marine sediments organic matter from delta of Indigirka river to the ice shelf border of the East-Siberian sea

An empirical model to predict methane production in inland water sediment from particular organic matter supply and reactivity

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