Anaerobic oxidation of methane (AOM) in marine sediments from the Skagerrak (Denmark): II. Reaction-transport modeling

Dale, Andy W.; Regnier, Pierre; Knab, N. J.; Jørgensen, Bo Barker; Cappellen, Philippe Van

doi:10.1016/j.gca.2007.11.039

Cited by 111 publications

(105 citation statements)

References 62 publications

(115 reference statements)

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“…A similar tailing of the methane profile was observed in other Black Sea sediments (Reeburgh et al, 1991;Jørgensen et al, 2001;Knab et al, 2009). These studies attributed methane tailing in the sulfate zone to incomplete AOM, which could, in turn, be attributed to the dynamics of reactive intermediates involved in AOM (Dale et al, 2006(Dale et al, , 2008Holmkvist et al, 2011).…”

Section: Depth Of the Sulfate-methane Transitionmentioning

confidence: 99%

Diagenetic barium cycling in Black Sea sediments – A case study for anoxic marine environments

Henkel¹,

Mogollón²,

Nöthen³

et al. 2012

Geochimica et Cosmochimica Acta

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High-resolution sedimentary records of major and minor elements (Al, Ba, Ca, Sr, Ti), total organic carbon (TOC), and profiles of pore water constituents (SO 2À 4 , CH 4 , Ca 2+ , Ba 2+ , Mg 2+ , alkalinity) were obtained for two gravity cores (core 755, 501 m water depth and core 214, 1686 m water depth) from the northwestern Black Sea. The records were examined in order to gain insight into the cycling of Ba in anoxic marine sediments characterized by a shallow sulfate-methane transition (SMT) as well as the applicability of barite as a primary productivity proxy in such a setting. The Ba records are strongly overprinted by diagenetic barite (BaSO 4 ) precipitation and remobilization; authigenic Ba enrichments were found at both sites at and slightly above the current SMT. Transport reaction modeling was applied to simulate the migration of the SMT during the changing geochemical conditions after the Holocene seawater intrusion into the Black Sea. Based on this, sediment intervals affected by diagenetic Ba redistribution were identified. Results reveal that the intense overprint of Ba and Ba xs (Ba excess above detrital average) strongly limits its correlation to primary productivity. These findings have implications for other modern and ancient anoxic basins, such as sections covering the Oceanic Anoxic Events which Ba is frequently used as a primary productivity indicator. Our study also demonstrates the limitations concerning the use of Ba xs as a tracer for downward migrations of the SMT: due to high sedimentation rates at the investigated sites, diagenetic barite fronts are buried below the SMT within a relatively short period. Thus, 'relict' barite fronts would only be preserved for a few thousands of years, if at all.

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Section: Depth Of the Sulfate-methane Transitionmentioning

confidence: 99%

Diagenetic barium cycling in Black Sea sediments – A case study for anoxic marine environments

Henkel¹,

Mogollón²,

Nöthen³

et al. 2012

Geochimica et Cosmochimica Acta

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“…Comparative AOM rates are not available for the different study pingos, but AOM occurs in concert with sulfate reduction, therefore sulfate fluxes can be used to make inferences about AOM rates. Sulfate reduction can and does take place in the absence of AOM as well (Dale et al, 2008;Hong et al, 2014;Wallmann et al, 2006), therefore it is important to differentiate between AOM and the breakdown of organic Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-540 Manuscript under review for journal Biogeosciences Discussion started: 11 January 2018 c Author(s) 2018. CC BY 4.0 License.…”

Section: Factors Controlling the Distribution Of Chemosynthesis Basedmentioning

confidence: 99%

Geophysical and geochemical controls on the megafaunal community of a high Arctic cold seep

Sen¹,

Åström²,

Hong³

et al. 2018

Preprint

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Cold seep communities around gas hydrate mounds (pingos) in the Western Barents Sea (76°N, 16°E, ~400 m depth) were investigated with high resolution, geographically referenced images acquired with an ROV and towed camera. Four pingos associated with seabed methane release hosted diverse biological communities of mainly non-seep (background) species including commercially important fish and crustaceans, as well as a species new to this area (the snow crab Chionoecetes 15 opilio). We attribute the presence of most benthic community members to habitat heterogeneity and the occurrence of hard substrates (methane derived authigenic carbonates), particularly the most abundant phyla (Cnidaria and Porifera), though food availability and exposure to a diverse microbial community is also important for certain taxa. Only one chemosynthesis based species was confirmed, the siboglinid frenulate polychaete, Oligobrachia haakonmosbiensis. Overall, the pingo communities formed two distinct clusters, distinguished by the presence or absence of frenulates. Methane gas advection through sediments 20 was absent below the single pingo that lacked frenulates, while seismic profiles indicated gas saturated sediment below the other frenulate colonized pingos. The absence of frenulates could not be explained by sediment sulfide concentrations, despite these worms likely containing sulfide oxidizing symbionts. We propose that high levels of seafloor methane seepage linked to sub-surface gas reservoirs support an abundant and active sediment methanotrophic community that maintains high sulfide fluxes and serves as a carbon source for frenulate worms. The pingo currently lacking a sub-surface gas source and lower 25 methane concentrations has lower sulfide flux rates and limited amounts of carbon insufficient to support frenulates. Two previously undocumented behaviors were visible through the images: grazing activity of snow crabs on bacterial mats, and seafloor crawling of Nothria conchylega onuphid polychaetes.Biogeosciences Discuss., https://doi

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“…Non-local mixing due to bioirrigation has been previously included in models developed using the BRNS (e.g. Dale et al, 2008), and in the present application we assumed a profile for the bioirrigation rate of the type reported by Canavan et al (2006) for a coastal lake (formulation reported in Table 2). Organic matter oxidation is described by means of a multi-G model (Westrich and Berner, 1984) with three types of organic matter: labile (OM1), semi-refractory (OM2), and mussel biodeposits (faeces + pseudofaeces) (OM3), following the approach by Van Cappellen and Wang (1996).…”

Section: Model Theory: Mussel Farm Deposition Model and Early Diagenementioning

confidence: 99%

Modelling biogeochemical processes in sediments from the north-western Adriatic Sea: response to enhanced particulate organic carbon fluxes

et al. 2018

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Abstract. This work presents the result of a study carried out in the north-western Adriatic Sea, by combining two different types of biogeochemical models with field sampling efforts. A longline mussel farm was taken as a local source of perturbation to the natural particulate organic carbon (POC) downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment trap data, and its effects on sediment bioirrigation capacity and organic matter (OM) degradation pathways were investigated constraining an early diagenesis model by using original data collected in sediment porewater. The measurements were performed at stations located inside and outside the area affected by mussel farm deposition. Model-predicted POC fluxes showed marked spatial and temporal variability, which was mostly associated with the dynamics of the farming cycle. Sediment trap data at the two sampled stations (inside and outside of the mussel farm) showed average POC background flux of 20.0-24.2 mmol C m −2 d −1 . The difference of organic carbon (OC) fluxes between the two stations was in agreement with model results, ranging between 3.3 and 14.2 mmol C m −2 d −1 , and was primarily associated with mussel physiological conditions. Although restricted, these changes in POC fluxes induced visible effects on sediment biogeochemistry. Observed oxygen microprofiles presented a 50 % decrease in oxygen penetration depth (from 2.3 to 1.4 mm), accompanied by an increase in the O 2 influx at the station below the mussel farm (19-31 versus 10-12 mmol O 2 m −2 d −1 ) characterised by higher POC flux. Dissolved inorganic carbon (DIC) and NH + 4 concentrations showed similar behaviour, with a more evident effect of bioirrigation underneath the farm. This was confirmed through constraining the early diagenesis model, of which calibration leads to an estimation of enhanced and shallower bioirrigation underneath the farm: bioirrigation rates of 40 yr −1 and irrigation depth of 15 cm were estimated inside the shellfish deposition footprint versus 20 yr −1 and 20 cm outside. These findings were confirmed by independent data on macrofauna composition collected at the study site. Early diagenesis model results indicated a larger organic matter mineralisation below the mussel farm (11.1 versus 18.7 mmol m −2 d −1 ), characterised by similar proportions between oxic and anoxic degradation rates at the two stations, with an increase in the absolute values of oxygen consumed by OM degradation and reduced substances re-oxidation underneath the mussel farm.

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Anaerobic oxidation of methane (AOM) in marine sediments from the Skagerrak (Denmark): II. Reaction-transport modeling

Cited by 111 publications

References 62 publications

Diagenetic barium cycling in Black Sea sediments – A case study for anoxic marine environments

Diagenetic barium cycling in Black Sea sediments – A case study for anoxic marine environments

Geophysical and geochemical controls on the megafaunal community of a high Arctic cold seep

Modelling biogeochemical processes in sediments from the north-western Adriatic Sea: response to enhanced particulate organic carbon fluxes

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