Timescales for the development of methanogenesis and free gas layers in recently-deposited sediments of Arkona Basin (Baltic Sea)

Mogollón, José M; Dale, Andrew W.; Fossing, Henrik; Regnier, Pierre

doi:10.5194/bg-9-1915-2012

Cited by 53 publications

(56 citation statements)

References 51 publications

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“…Microbial methanogenesis may lead to accumulation of free gas due to the soft, cohesive, low permeable sediments of the Witch Ground Basin instead of migrating out of the sediments (Boudreau et al, 2001;Boudreau et al, 2005). Such a scenario has been proposed for organic-rich sediments in the Arkona Basin, Baltic Sea, (Abegg & Anderson, 1997;Mogollón et al, 2012;Orsi et al, 1996), and Belfast Bay, Maine, USA (Brothers et al, 2012). There, pockmark formation is dependent on the sediment thickness, flux of organic matter, and sedimentation rates.…”

Section: Class 2 Pockmarks-timing and Controls Of Fluid Ventingmentioning

confidence: 99%

Pockmarks in the Witch Ground Basin, Central North Sea

Böttner

Berndt

Reinardy

et al. 2019

Geochem Geophys Geosyst

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Marine sediments host large amounts of methane (CH4), which is a potent greenhouse gas. Quantitative estimates for methane release from marine sediments are scarce, and a poorly constrained temporal variability leads to large uncertainties in methane emission scenarios. Here, we use 2‐D and 3‐D seismic reflection, multibeam bathymetric, geochemical, and sedimentological data to (I) map and describe pockmarks in the Witch Ground Basin (central North Sea), (II) characterize associated sedimentological and fluid migration structures, and (III) analyze the related methane release. More than 1,500 pockmarks of two distinct morphological classes spread over an area of 225 km2. The two classes form independently from another and are corresponding to at least two different sources of fluids. Class 1 pockmarks are large in size (>6 m deep, >250 m long, and >75 m wide), show active venting, and are located above vertical fluid conduits that hydraulically connect the seafloor with deep methane sources. Class 2 pockmarks, which comprise 99.5% of all pockmarks, are smaller (0.9–3.1 m deep, 26–140 m long, and 14–57 m wide) and are limited to the soft, fine‐grained sediments of the Witch Ground Formation and possibly sourced by compaction‐related dewatering. Buried pockmarks within the Witch Ground Formation document distinct phases of pockmark formation, likely triggered by external forces related to environmental changes after deglaciation. Thus, greenhouse gas emissions from pockmark fields cannot be based on pockmark numbers and present‐day fluxes but require an analysis of the pockmark forming processes through geological time.

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Section: Class 2 Pockmarks-timing and Controls Of Fluid Ventingmentioning

confidence: 99%

Pockmarks in the Witch Ground Basin, Central North Sea

Böttner

Berndt

Reinardy

et al. 2019

Geochem Geophys Geosyst

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“…Geochemical interactions were simulated using a one-dimensional reaction-transport model [Mewes et al, 2016] which discretizes the advection-diffusion-reaction equation [e.g., Berner, 1980;Boudreau, 1997;Mogollón et al, 2012]. The model consists of seven reactions (Table 1) and includes organic matter as the sole solid species (G, Tables 1 and 2), and four dissolved species (C, Tables 1 and 2).…”

Section: Model Setup and Reaction Networkmentioning

confidence: 99%

Quantifying manganese and nitrogen cycle coupling in manganese‐rich, organic carbon‐starved marine sediments: Examples from the Clarion‐Clipperton fracture zone

Mogollón

Mewes

Kasten

2016

Geophysical Research Letters

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Extensive deep‐sea sedimentary areas are characterized by low organic carbon contents and thus harbor suboxic sedimentary environments where secondary (autotrophic) redox cycling becomes important for microbial metabolic processes. Simulation results for three stations in the Eastern Equatorial Pacific with low organic carbon content (<0.5 dry wt %) and low sedimentation rates (10−1–100 mm ky−1) show that ammonium generated during organic matter degradation may act as a reducing agent for manganese oxides below the oxic zone. Likewise, at these sedimentary depths, dissolved reduced manganese may act as a reducing agent for oxidized nitrogen species. These manganese‐coupled transformations provide a suboxic conversion pathway of ammonium and nitrate to dinitrogen. These manganese‐nitrogen interactions further explain the presence and production of dissolved reduced manganese (up to tens of μM concentration) in sediments with high nitrate (>20 μM) concentrations.

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“…CH 4 ) on the basis of the physicochemical properties of the gases (Wanninkhof et al, 2009). Although a variety of conceptual models have been introduced over the last decades, the parameterization of k is still under debate (Liss and Merlivat, 1986;Jähne et al, 1987;Wanninkhof, 1992;Nightingale et al, 2000, Sweeney et al, 2007Weiss et al, 2007;Wanninkhof et al, 2009). For this study, the most recent approximation of Wanninkhof et al (2009) was used.…”

Section: Sea-air Methane Flux Calculationsmentioning

confidence: 99%

“…Bottom water temperatures in the Arkona Basin, for example, show annual fluctuations between −0.32 • C (minimum) and 15.6 • C (maximum; ICES, 2011). In deeper basins the annual fluctuation of the surface sediment temperature can be expected to be much smaller than the fluctuations at the sea surface (Mogollón et al, 2011). The sediment temperature influences the solubility of methane in pore water and the depth of the shallow gas boundary layer (Wever et al, 2006).…”

Section: Water Temperaturementioning

confidence: 99%

One year of continuous measurements constraining methane emissions from the Baltic Sea to the atmosphere using a ship of opportunity

Gülzow¹,

Rehder²,

Deimling³

et al. 2012

Preprint

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Methane and carbon dioxide were measured with an autonomous and continuous running system on a ferry line crossing the Baltic Sea on a 2–3 day interval from the Mecklenburg Bight to the Gulf of Finland in 2010. Surface methane saturations show great seasonal differences in shallow regions like the Mecklenburg Bight (103–507%) compared to deeper regions like the Gotland Basin (96–161%). The influence of controlling parameters like temperature, wind, mixing depth and processes like upwelling, mixing of the water column and sedimentary methane emissions on methane oversaturation and emission to the atmosphere are investigated. Upwelling was found to influence methane surface concentrations in the area of Gotland significantly during the summer period. In February 2010, an event of elevated methane concentrations in the surface water and water column of the Arkona Basin was observed, which could be linked to a wind-derived water level change as a potential triggering mechanism. The Baltic Sea is a source of methane to the atmosphere throughout the year, with highest fluxes during the winter season. Stratification was found to intensify the formation of a methane reservoir in deeper regions like Gulf of Finland or Bornholm Basin, which leads to long lasting elevated methane concentrations and enhanced methane fluxes, when mixed to the surface during mixed layer deepening in autumn and winter. Methane concentrations and fluxes from shallow regions like the Mecklenburg Bight are rather controlled by sedimentary production and consumption of methane, wind events and the change in temperature-dependent solubility of methane in the surface water. Methane fluxes vary significantly in shallow regions (e.g. Mecklenburg Bight) and regions with a temporal stratification (e.g. Bornholm Basin, Gulf of Finland). On the contrary, areas with a permanent stratification like the Gotland Basin show only small seasonal fluctuations in methane fluxes

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Timescales for the development of methanogenesis and free gas layers in recently-deposited sediments of Arkona Basin (Baltic Sea)

Cited by 53 publications

References 51 publications

Pockmarks in the Witch Ground Basin, Central North Sea

Pockmarks in the Witch Ground Basin, Central North Sea

Quantifying manganese and nitrogen cycle coupling in manganese‐rich, organic carbon‐starved marine sediments: Examples from the Clarion‐Clipperton fracture zone

One year of continuous measurements constraining methane emissions from the Baltic Sea to the atmosphere using a ship of opportunity

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