scholarly journals High Sulfur Isotope Fractionation Associated with Anaerobic Oxidation of Methane in a Low-Sulfate, Iron-Rich Environment

2016 ◽  
Vol 4 ◽  
Author(s):  
Hannah S. Weber ◽  
Bo Thamdrup ◽  
Kirsten S. Habicht
Keyword(s):  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane ◽  
Sulfur Isotope Fractionation

scholarly journals Using kinetic isotope effect to evaluate the significance of the sequential and parallel steps: formation of microbial consortium during reversible anaerobic methane oxidation coupled with sulfate reduction

2019 ◽  
Vol 79 (11) ◽  
pp. 2056-2067
Author(s):  
Vasily Vavilin ◽  
Lyudmila Lokshina ◽  
Sergey Rytov
Keyword(s):  
Experimental Data ◽  
Sulfate Reduction ◽  
Methane Oxidation ◽  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Biomass Accumulation ◽  
Anaerobic Methane Oxidation ◽  
Anaerobic Oxidation Of Methane ◽  
Oxidation Of Methane ◽  
Sulfur Isotope Fractionation

Abstract The purpose of this study was to describe the dynamics of anaerobic oxidation of methane (AOM) coupled with sulfate reduction (SR) using experimental data from a continuous incubation experiments published earlier in order to show that formation of consortia of anaerobic archaea (ANME) and Desulfosarcina-like bacteria (DSS) may have a significant effect on sulfur isotope fractionation. The dynamic simulation of reversible AOM by ANME coupled with SR by DSS was performed. This simulation took into account biomass growth and fractionation of stable isotopes of sulfur. Two kinetic schemes with and without ANME + DSS consortium formation were tested. The respective models were applied at five influent methane concentrations. A good fit to experimental data was obtained only when assuming active ANME and DSS biomass accumulation. The assumption about incorporation of reversibility of anaerobic methane oxidation and sulfate reduction did not improve the model's fit to experimental data. In accordance with both the models, sulfur isotope fractionation was smallest for the highest influent methane concentration. The model considering the formation of consortia of ANME + DSS is proved to be more appropriate.

scholarly journals Theoretical Estimates of Equilibrium Carbon and Hydrogen Isotope Effects in Microbial Methane Production and Anaerobic Oxidation of Methane

2020 ◽  
Author(s):  
Jonathan Gropp ◽  
Mark Iron ◽  
Itay Halevy
Keyword(s):  
Isotopic Composition ◽  
Methane Production ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane ◽  
Production And Consumption ◽  
Fractionation Factors ◽  
Equilibrium Fractionation

Microbial production and consumption of methane are widespread in natural and artificial environments, with important economic and climatic implications. Attempts to use the isotopic composition of methane to constrain its sources are complicated by incomplete understanding of the mechanisms of variation in methane's isotopic composition. Knowledge of the equilibrium isotope fractionations among the large organic intracellular intermediates in the microbial pathways of methane production and consumption must form the basis of any exploration of the mechanisms of isotopic variation, but estimates of these equilibrium isotope fractionations are currently unavailable. To address this gap, we calculated the equilibrium isotopic fractionation of carbon (<sup>13</sup>C/<sup>12</sup>C) and hydrogen (D/H) isotopes among compounds in anaerobic methane metabolisms, as well as the abundance of multiple isotope substitutions ("clumping," e.g., <sup>13</sup>C--D) in these compounds. The Density Functional Theory calculations employed the M06-L/def2-TZVP level of theory and the SMD implicit solvation model, which we have recently optimized for large organic molecules and tested against measured equilibrium isotope fractionations. The computed <sup>13</sup>beta and <sup>2</sup>beta values decrease with decreasing average oxidation state of the carbon atom in the molecules, resulting in a preference for enrichment of the molecules with more oxidized carbon in <sup>13</sup>C and D. Using the computed $\beta$ values, we calculated the equilibrium isotope fractionation factors in the prominent methanogenesis pathways (hydrogenotrophic, methylotrophic and acetoclastic) and in the pathway for anaerobic oxidation of methane (AOM) over a temperature range of 0-700 degrees Celsius. Our calculated equilibrium fractionation factors compare favorably with experimental constrains, where available, and we used them to investigate the relation between the apparent isotope fractionation during methanogenesis and AOM and the thermodynamic drive for these reactions. We show that a detailed map of the equilibrium fractionation factors along these metabolic pathways allows an evaluation of the contribution of equilibrium and kinetic isotope effects to apparent isotope fractionations observed in laboratory, natural and artificial settings. The comprehensive set of equilibrium isotope fractionation factors calculated in this study provides a firm basis for future explorations of isotope effects in methane metabolism.

scholarly journals Theoretical Estimates of Equilibrium Carbon and Hydrogen Isotope Effects in Microbial Methane Production and Anaerobic Oxidation of Methane

2020 ◽  
Author(s):  
Jonathan Gropp ◽  
Mark Iron ◽  
Itay Halevy
Keyword(s):  
Isotopic Composition ◽  
Methane Production ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane ◽  
Production And Consumption ◽  
Fractionation Factors ◽  
Equilibrium Fractionation

Microbial production and consumption of methane are widespread in natural and artificial environments, with important economic and climatic implications. Attempts to use the isotopic composition of methane to constrain its sources are complicated by incomplete understanding of the mechanisms of variation in methane's isotopic composition. Knowledge of the equilibrium isotope fractionations among the large organic intracellular intermediates in the microbial pathways of methane production and consumption must form the basis of any exploration of the mechanisms of isotopic variation, but estimates of these equilibrium isotope fractionations are currently unavailable. To address this gap, we calculated the equilibrium isotopic fractionation of carbon (<sup>13</sup>C/<sup>12</sup>C) and hydrogen (D/H) isotopes among compounds in anaerobic methane metabolisms, as well as the abundance of multiple isotope substitutions ("clumping," e.g., <sup>13</sup>C--D) in these compounds. The Density Functional Theory calculations employed the M06-L/def2-TZVP level of theory and the SMD implicit solvation model, which we have recently optimized for large organic molecules and tested against measured equilibrium isotope fractionations. The computed <sup>13</sup>beta and <sup>2</sup>beta values decrease with decreasing average oxidation state of the carbon atom in the molecules, resulting in a preference for enrichment of the molecules with more oxidized carbon in <sup>13</sup>C and D. Using the computed $\beta$ values, we calculated the equilibrium isotope fractionation factors in the prominent methanogenesis pathways (hydrogenotrophic, methylotrophic and acetoclastic) and in the pathway for anaerobic oxidation of methane (AOM) over a temperature range of 0-700 degrees Celsius. Our calculated equilibrium fractionation factors compare favorably with experimental constrains, where available, and we used them to investigate the relation between the apparent isotope fractionation during methanogenesis and AOM and the thermodynamic drive for these reactions. We show that a detailed map of the equilibrium fractionation factors along these metabolic pathways allows an evaluation of the contribution of equilibrium and kinetic isotope effects to apparent isotope fractionations observed in laboratory, natural and artificial settings. The comprehensive set of equilibrium isotope fractionation factors calculated in this study provides a firm basis for future explorations of isotope effects in methane metabolism.

scholarly journals Anaerobic oxidation of methane by Mn oxides in sulfate-poor environments

Geology ◽  
2021 ◽  
Author(s):  
Chunfang Cai ◽  
Kaikai Li ◽  
Dawei Liu ◽  
Cedric M. John ◽  
Daowei Wang ◽  
...  
Keyword(s):  
Isotope Fractionation ◽  
Junggar Basin ◽  
Early Diagenesis ◽  
Geochemical Data ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Authigenic Carbonates ◽  
Oxidation Of Methane ◽  
Kinetic Isotope ◽  
Mn Oxides

Strongly 13C-depleted authigenic carbonates (e.g., δ13CVPDB &lt;−30‰; VPDB—Vienna Peedee belemnite) in nature are generally believed to form by sulfate-dependent anaerobic oxidation of methane (AOM). However, we demonstrate using geochemical data and thermodynamic calculation that such calcites are most likely derived from biogenic oxidation of methane in sulfate-poor, nonmarine environments during early diagenesis, as observed in the Triassic sandy conglomerates from the Junggar Basin, northwestern China. This process operated through preferential oxidation of 13C-depleted methane by Mn oxides in closed conditions, producing calcites with higher Mn contents and δ13C values in association with more 13C-enriched residual methane as a result of kinetic isotope fractionation. Thus, the Mn-rich and 13C-depleted carbonates are proposed as tracers of Mn-dependent AOM, which should have served as an important sink of greenhouse methane in low-sulfate early Earth’s oceans.

scholarly journals Triple sulfur isotope relationships during sulfate-driven anaerobic oxidation of methane

2018 ◽  
Vol 504 ◽  
pp. 13-20 ◽  
Author(s):  
Shanggui Gong ◽  
Yongbo Peng ◽  
Huiming Bao ◽  
Dong Feng ◽  
Xiaobin Cao ◽  
...  
Keyword(s):  
Sulfur Isotope ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane

scholarly journals Theoretical Estimates of Equilibrium Carbon and Hydrogen Isotope Effects in Microbial Methane Production and Anaerobic Oxidation of Methane

2020 ◽  
Author(s):  
Jonathan Gropp ◽  
Mark Iron ◽  
Itay Halevy
Keyword(s):  
Isotopic Composition ◽  
Methane Production ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane ◽  
Production And Consumption ◽  
Fractionation Factors ◽  
Equilibrium Fractionation

Microbial production and consumption of methane are widespread in natural and artificial environments, with important economic and climatic implications. Attempts to use the isotopic composition of methane to constrain its sources are complicated by incomplete understanding of the mechanisms of variation in methane's isotopic composition. Knowledge of the equilibrium isotope fractionations among the large organic intracellular intermediates in the microbial pathways of methane production and consumption must form the basis of any exploration of the mechanisms of isotopic variation, but estimates of these equilibrium isotope fractionations are currently unavailable. To address this gap, we calculated the equilibrium isotopic fractionation of carbon (<sup>13</sup>C/<sup>12</sup>C) and hydrogen (D/H) isotopes among compounds in anaerobic methane metabolisms, as well as the abundance of multiple isotope substitutions ("clumping," e.g., <sup>13</sup>C--D) in these compounds. The Density Functional Theory calculations employed the M06-L/def2-TZVP level of theory and the SMD implicit solvation model, which we have recently optimized for large organic molecules and tested against measured equilibrium isotope fractionations. The computed <sup>13</sup>beta and <sup>2</sup>beta values decrease with decreasing average oxidation state of the carbon atom in the molecules, resulting in a preference for enrichment of the molecules with more oxidized carbon in <sup>13</sup>C and D. Using the computed $\beta$ values, we calculated the equilibrium isotope fractionation factors in the prominent methanogenesis pathways (hydrogenotrophic, methylotrophic and acetoclastic) and in the pathway for anaerobic oxidation of methane (AOM) over a temperature range of 0-700 degrees Celsius. Our calculated equilibrium fractionation factors compare favorably with experimental constrains, where available, and we used them to investigate the relation between the apparent isotope fractionation during methanogenesis and AOM and the thermodynamic drive for these reactions. We show that a detailed map of the equilibrium fractionation factors along these metabolic pathways allows an evaluation of the contribution of equilibrium and kinetic isotope effects to apparent isotope fractionations observed in laboratory, natural and artificial settings. The comprehensive set of equilibrium isotope fractionation factors calculated in this study provides a firm basis for future explorations of isotope effects in methane metabolism.

scholarly journals Theoretical Estimates of Equilibrium Carbon and Hydrogen Isotope Effects in Microbial Methane Production and Anaerobic Oxidation of Methane

2020 ◽  
Author(s):  
Jonathan Gropp ◽  
Mark Iron ◽  
Itay Halevy
Keyword(s):  
Isotopic Composition ◽  
Methane Production ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane ◽  
Production And Consumption ◽  
Fractionation Factors ◽  
Equilibrium Fractionation

Microbial production and consumption of methane are widespread in natural and artificial environments, with important economic and climatic implications. Attempts to use the isotopic composition of methane to constrain its sources are complicated by incomplete understanding of the mechanisms of variation in methane's isotopic composition. Knowledge of the equilibrium isotope fractionations among the large organic intracellular intermediates in the microbial pathways of methane production and consumption must form the basis of any exploration of the mechanisms of isotopic variation, but estimates of these equilibrium isotope fractionations are currently unavailable. To address this gap, we calculated the equilibrium isotopic fractionation of carbon (<sup>13</sup>C/<sup>12</sup>C) and hydrogen (D/H) isotopes among compounds in anaerobic methane metabolisms, as well as the abundance of multiple isotope substitutions ("clumping," e.g., <sup>13</sup>C--D) in these compounds. The Density Functional Theory calculations employed the M06-L/def2-TZVP level of theory and the SMD implicit solvation model, which we have recently optimized for large organic molecules and tested against measured equilibrium isotope fractionations. The computed <sup>13</sup>beta and <sup>2</sup>beta values decrease with decreasing average oxidation state of the carbon atom in the molecules, resulting in a preference for enrichment of the molecules with more oxidized carbon in <sup>13</sup>C and D. Using the computed $\beta$ values, we calculated the equilibrium isotope fractionation factors in the prominent methanogenesis pathways (hydrogenotrophic, methylotrophic and acetoclastic) and in the pathway for anaerobic oxidation of methane (AOM) over a temperature range of 0-700 degrees Celsius. Our calculated equilibrium fractionation factors compare favorably with experimental constrains, where available, and we used them to investigate the relation between the apparent isotope fractionation during methanogenesis and AOM and the thermodynamic drive for these reactions. We show that a detailed map of the equilibrium fractionation factors along these metabolic pathways allows an evaluation of the contribution of equilibrium and kinetic isotope effects to apparent isotope fractionations observed in laboratory, natural and artificial settings. The comprehensive set of equilibrium isotope fractionation factors calculated in this study provides a firm basis for future explorations of isotope effects in methane metabolism.

Sign in / Sign up

Export Citation Format

Share Document