scholarly journals Modelling the impact of Siboglinids on the biogeochemistry of the Captain Arutyunov mud volcano (Gulf of Cadiz)

2012 ◽  
Vol 9 (6) ◽  
pp. 6683-6714
Author(s):  
K. Soetaert ◽  
D. van Oevelen ◽  
S. Sommer
Keyword(s):  
Transport Model ◽  
Sulfide Oxidation ◽  
Mud Volcano ◽  
Biogeochemical Model ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane ◽  
Sediment Biogeochemistry ◽  
Reaction Transport ◽  
The Impact

Abstract. A 2-Dimensional mathematical reaction-transport model was developed to study the impact of the mud-dwelling frenulate tubeworm Siboglinum sp. on the biogeochemistry of a sediment (MUC15) at the Captain Arutyunov mud volcano (CAMV). By explicitly describing the worm in its surrounding sediment, we are able to make budgets of processes occurring in- or outside of the worm, and to quantify how different worm densities and biomasses affect the anaerobic oxidation of methane (AOM) and sulfide reoxidation (HSox). The model shows that, at the observed densities, the presence of a thin worm body is sufficient to keep the upper 10 cm of sediment well homogenized with respect to dissolved substances, in agreement with observations. By this "bio-ventilation" activity, the worm pushes the sulfate-methane transition (SMT) zone downward to the posterior end of its body, and simultaneously physically separates the sulfide produced during the anaerobic oxidation of methane from oxygen. While there is little scope for the AOM to take place in the tubeworm's body, 70% of the sulfide that is produced by sulfate reduction processes or that is advected in the sediment is preferentially shunted via the organism where it is oxidised by endosymbionts providing the energy for the worm's growth. The process of sulfide reoxidation, occurring predominantly in the worm's body is thus very distinct from the anaerobic oxidation of methane, which is a diffuse process that takes place in the sediments in the methane-sulfate transition zone. We show how the sulfide oxidation process is affected by increasing densities and length of the frenulates, and by upward advection velocity. Our biogeochemical model is one of the first to describe tubeworms explicitly. It can be used to directly link biological and biogeochemical observations at seep sites, and to study the impacts of mud-dwelling frenulates on the sediment biogeochemistry under varying environmental conditions. Also, it provides a tool to explore the competition between bacteria and fauna for available energy resources.

scholarly journals Modelling the impact of Siboglinids on the biogeochemistry of the Captain Arutyunov mud volcano (Gulf of Cadiz)

2012 ◽  
Vol 9 (12) ◽  
pp. 5341-5352 ◽  
Author(s):  
K. Soetaert ◽  
D. van Oevelen ◽  
S. Sommer
Keyword(s):  
Transport Model ◽  
Sulfide Oxidation ◽  
Mud Volcano ◽  
Biogeochemical Model ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane ◽  
Sediment Biogeochemistry ◽  
Reaction Transport ◽  
The Impact

Abstract. A 2-Dimensional mathematical reaction-transport model was developed to study the impact of the mud-dwelling frenulate tubeworm Siboglinum sp. on the biogeochemistry of a~sediment (MUC15) at the Captain Arutyunov mud volcano (CAMV). By explicitly describing the worm in its surrounding sediment, we are able to make budgets of processes occurring in- or outside of the worm, and to quantify how different worm densities and biomasses affect the anaerobic oxidation of methane (AOM) and sulfide reoxidation (HSox). The model shows that, at the observed densities, the presence of a thin worm body is sufficient to keep the upper 10 cm of sediment well homogenised with respect to dissolved substances, in agreement with observations. By this "bio-ventilation" activity, the worm pushes the sulfate–methane transition (SMT) zone downward to the posterior end of its body, and simultaneously physically separates the sulfide produced during the anaerobic oxidation of methane from oxygen. While there is little scope for AOM to take place in the tubeworm's body, 70% of the sulfide that is produced by sulfate reduction processes or that is advected in the sediment is preferentially shunted via the organism where it is oxidised by endosymbionts providing the energy for the worm's growth. The process of sulfide reoxidation, occurring predominantly in the worm's body is thus very distinct from the anaerobic oxidation of methane, which is a diffuse process that takes place in the sediments in the methane-sulfate transition zone. We show how the sulfide oxidation process is affected by increasing densities and length of the frenulates, and by upward advection velocity. Our biogeochemical model is one of the first to describe tubeworms explicitly. It can be used to directly link biological and biogeochemical observations at seep sites, and to study the impacts of mud-dwelling frenulates on the sediment biogeochemistry under varying environmental conditions. Also, it provides a tool to explore the competition between bacteria and fauna for available energy resources.

scholarly journals Microbial Alkalinity Production and Silicate Alteration in Methane Charged Marine Sediments: Implications for Porewater Chemistry and Diagenetic Carbonate Formation

2022 ◽  
Vol 9 ◽  
Author(s):  
Patrick Meister ◽  
Gerhard Herda ◽  
Elena Petrishcheva ◽  
Susanne Gier ◽  
Gerald R. Dickens ◽  
...  
Keyword(s):  
Transport Model ◽  
Total Alkalinity ◽  
Anaerobic Oxidation Of Methane ◽  
Deep Biosphere ◽  
Ocean Drilling Program ◽  
Oxidation Of Methane ◽  
Carbonate Formation ◽  
Reaction Transport ◽  
The Stability ◽  
Fundamental Insight

A numerical reaction-transport model was developed to simulate the effects of microbial activity and mineral reactions on the composition of porewater in a 230-m-thick Pleistocene interval drilled in the Peru-Chile Trench (Ocean Drilling Program, Site 1230). This site has porewater profiles similar to those along many continental margins, where intense methanogenesis occurs and alkalinity surpasses 100 mmol/L. Simulations show that microbial sulphate reduction, anaerobic oxidation of methane, and ammonium release from organic matter degradation only account for parts of total alkalinity, and excess CO2 produced during methanogenesis leads to acidification of porewater. Additional alkalinity is produced by slow alteration of primary aluminosilicate minerals to kaolinite and SiO2. Overall, alkalinity production in the methanogenic zone is sufficient to prevent dissolution of carbonate minerals; indeed, it contributes to the formation of cemented carbonate layers at a supersaturation front near the sulphate-methane transition zone. Within the methanogenic zone, carbonate formation is largely inhibited by cation diffusion but occurs rapidly if cations are transported into the zone via fluid conduits, such as faults. The simulation presented here provides fundamental insight into the diagenetic effects of the deep biosphere and may also be applicable for the long-term prediction of the stability and safety of deep CO2 storage reservoirs.

A novel 1D thermo-hydro-biogeochemical hydrate model to assess the full benthic environmental impact of methane gas hydrate dissociation

2021 ◽  
Author(s):  
Maria De La Fuente ◽  
Sandra Arndt ◽  
Tim Minshul ◽  
Héctor Marín-Moreno
Keyword(s):  
Environmental Impact ◽  
Gas Hydrate ◽  
Transport Processes ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Microbial Oxidation ◽  
Saturation State ◽  
Hydrate Dissociation ◽  
Oxidation Of Methane ◽  
The Impact

<p>Large quantities of methane (CH<sub>4</sub>) are stored in gas hydrates at shallow depths within marine sediments. These reservoirs are highly sensitive to ocean warming and if destabilized could lead to significant CH<sub>4</sub> release and global environmental impacts. However, the existence of such a positive feedback loop has recently been questioned as efficient CH<sub>4 </sub>sinks within the sediment-ocean continuum likely mitigate the impact of gas hydrate-derived CH<sub>4</sub> emissions on global climate. In particular, benthic anaerobic oxidation of methane (AOM) represents an important CH<sub>4 </sub>sink capable of completely consuming CH<sub>4</sub> fluxes before they reach the seafloor. However, the efficiency of this benthic biofilter is controlled by a complex interplay of multiphase methane transport and microbial oxidation processes and is thus highly variable (0-100%). In addition, AOM potentially enhances benthic alkalinity fluxes with important, yet largely overlooked implications for ocean pH, saturation state and CO<sub>2</sub> emissions. As a consequence, the full environmental impact of hydrate-derived CH<sub>4</sub> release to the ocean-atmosphere system and its feedbacks on global biogeochemical cycles and climate still remain poorly quantified. To the best our knowledge, currently available modelling tools to assess the benthic CH<sub>4</sub> sink and its environmental impact during hydrate dissociation do not account for the full complexity of the problem. Available codes generally do not explicitly resolve the dynamics of the microbial community and thus fail to represent transient changes in AOM biofilter efficiency and windows of opportunity for CH<sub>4</sub> escape. They also highly simplify the representation of  multiphase CH<sub>4 </sub>transport processes and gas hydrate dynamics and rarely assess the influence of hydrate-derived CH<sub>4</sub> fluxes on benthic-pelagic alkalinity and dissolved inorganic carbon fluxes. To overcome these limitations, we have developed a novel 1D thermo-hydro-biogeochemical hydrate model that improve the quantitative understanding of the benthic CH<sub>4</sub> sink and benthic carbon cycle-climate feedbacks in response to methane hydrate dissociation caused by temperature and sea-level perturbations. Our mathematical model builds on previous thermo-hydraulic hydrate simulators, expanding them to include the dominant microbial processes affecting CH<sub>4</sub> fluxes in a consistent and coupled mathematical formulation. The micro-biogeochemical reaction network accounts for the main redox reactions (i.e., aerobic degradation, organoclastic sulphate reduction (OSR), methanogenesis and aerobic-anaerobic oxidation of methane (AeOM-AOM)), carbonate dissolution/precipitation and equilibrium reactions that drive biogeochemical dynamics in marine hydrate-bearing sediments . In particular, the AOM rate is expressed as a bioenergetic rate law that explicitly accounts for biomass dynamics. Finally, the model allows tracking the carbon isotope signatures of all dissolved and solid carbon species. In this talk we will present the model structure for the multiphase-multicomponent hydrate system, describe the specific constitutive and reaction equations used in the formulation, discuss the numerical strategy implemented and illustrate the potential capabilities of the model.</p>

scholarly journals Coupled Dynamics of Iron and Phosphorus in Sediments of an Oligotrophic Coastal Basin and the Impact of Anaerobic Oxidation of Methane

PLoS ONE ◽  
2013 ◽  
Vol 8 (4) ◽  
pp. e62386 ◽  
Author(s):  
Caroline P. Slomp ◽  
Haydon P. Mort ◽  
Tom Jilbert ◽  
Daniel C. Reed ◽  
Bo G. Gustafsson ◽  
...  
Keyword(s):  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Coupled Dynamics ◽  
Oxidation Of Methane ◽  
The Impact ◽  
Coastal Basin

scholarly journals Anaerobic Oxidation of Methane in Freshwater Sediments of Rzeszów Reservoir

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 398
Author(s):  
Dorota Szal ◽  
Renata Gruca-Rokosz
Keyword(s):  
Electron Acceptors ◽  
Small Scale ◽  
Anaerobic Oxidation Of Methane ◽  
Sediment Layer ◽  
Anaerobic Oxidation ◽  
Freshwater Sediments ◽  
Oxidation Rates ◽  
Oxidation Of Methane ◽  
Dam Reservoirs ◽  
The Impact

The anaerobic oxidation of methane (AOM) is an important sink of methane that plays a significant role in global warming. However, evidence for the AOM in freshwater habitats is rare, especially in dam and weir (small-scale dam) reservoirs. Here, the AOM process was examined in freshwater sediments of a small-scale dam reservoir located in Rzeszów, SE Poland. The AOM rate was determined in the main experiment with the addition of the 13CH4 isotope marker (He+13CH4). Sediments were collected three times: in spring (in May, 15 °C), in summer (in July, 20 °C) and in autumn (in September, 10 °C). Further analysis considers the impact on AOM rate of potential electron acceptors present in pore-water (NO2−, NO3−, SO42−, and Fe3+ ions). The work suggests that an AOM process does take place in the studied reservoir sediments, with this evidenced by the presence in the headspace of an increased 13CO2 concentration deemed to derive from 13CH4 oxidation. Rates of AOM noted were of 0.36–1.42 nmol·g−1·h−1, with the most intensive oxidation in each sediment layer occurring at 20 °C. While none of the potential electron acceptors considered individually were found to have had a statistically significant influence on the AOM rate, their significance to the dynamics of the AOM process was not precluded.

scholarly journals Constraints on mechanisms and rates of anaerobic oxidation of methane by microbial consortia: process-based modeling of ANME-2 archaea and sulfate reducing bacteria interactions

2008 ◽  
Vol 5 (3) ◽  
pp. 1933-1967 ◽  
Author(s):  
B. Orcutt ◽  
C. Meile
Keyword(s):  
Sulfate Reducing Bacteria ◽  
Substrate Affinity ◽  
Main Process ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Intermediate Species ◽  
Sulfate Reducing ◽  
Oxidation Of Methane ◽  
Reducing Bacteria ◽  
The Impact

Abstract. Anaerobic oxidation of methane (AOM) is the main process responsible for the removal of methane generated in Earth's marine subsurface environments. However, the biochemical mechanism of AOM remains elusive. By explicitly resolving the observed spatial arrangement of methanotrophic archaea and sulfate reducing bacteria found in consortia mediating AOM, potential intermediates involved in the electron transfer between the methane oxidizing and sulfate reducing partners were investigated via a consortium-scale reaction transport model that integrates the effect of diffusional transport with thermodynamic and kinetic controls on microbial activity. Model simulations were used to assess the impact of poorly constrained microbial characteristics such as minimum energy requirements to sustain metabolism, substrate affinity and cell specific rates. The role of environmental conditions such as the influence of methane levels on the feasibility of H2, formate and acetate as intermediate species, and the impact of the abundance of intermediate species on pathway reversal was examined. The results show that higher production rates of intermediates via AOM lead to increased diffusive fluxes from the methane oxidizing archaea to sulfate reducing bacteria, but the build-up of the exchangeable species causes the energy yield of AOM to drop below that required for ATP production. Comparison to data from laboratory experiments shows that under the experimental conditions of Nauhaus et al. (2007), neither hydrogen nor formate is exchanged fast enough between the consortia partners to achieve measured rates of metabolic activity, but that acetate exchange might support rates that approach those observed.

scholarly journals Constraints on mechanisms and rates of anaerobic oxidation of methane by microbial consortia: process-based modeling of ANME-2 archaea and sulfate reducing bacteria interactions

2008 ◽  
Vol 5 (6) ◽  
pp. 1587-1599 ◽  
Author(s):  
B. Orcutt ◽  
C. Meile
Keyword(s):  
Sulfate Reducing Bacteria ◽  
Energy Yield ◽  
Main Process ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Intermediate Species ◽  
Sulfate Reducing ◽  
Oxidation Of Methane ◽  
Reducing Bacteria ◽  
The Impact

Abstract. Anaerobic oxidation of methane (AOM) is the main process responsible for the removal of methane generated in Earth's marine subsurface environments. However, the biochemical mechanism of AOM remains elusive. By explicitly resolving the observed spatial arrangement of methanotrophic archaea and sulfate reducing bacteria found in consortia mediating AOM, potential intermediates involved in the electron transfer between the methane oxidizing and sulfate reducing partners were investigated via a consortium-scale reaction transport model that integrates the effect of diffusional transport with thermodynamic and kinetic controls on microbial activity. Model simulations were used to assess the impact of poorly constrained microbial characteristics such as minimum energy requirements to sustain metabolism and cell specific rates. The role of environmental conditions such as the influence of methane levels on the feasibility of H2, formate and acetate as intermediate species, and the impact of the abundance of intermediate species on pathway reversal were examined. The results show that higher production rates of intermediates via AOM lead to increased diffusive fluxes from the methane oxidizing archaea to sulfate reducing bacteria, but the build-up of the exchangeable species can cause the energy yield of AOM to drop below that required for ATP production. Comparison to data from laboratory experiments shows that under the experimental conditions of Nauhaus et al. (2007), none of the potential intermediates considered here is able to support metabolic activity matching the measured rates.

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