Gas hydrate accumulation at the Håkon Mosby Mud Volcano

Ginsburg, G. D.; Milkov, Alexei V.; Soloviev, V. A.; Егоров, А. А.; Cherkashev, G. A.; Vogt, Peter R.; Crane, Kathleen; Lorenson, Thomas D.; Khutorskoy, M. D.

doi:10.1007/s003670050093

Cited by 119 publications

(66 citation statements)

References 8 publications

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“…Submarine mud volcanoes are conspicuous examples of focused flow regimes in sedimentary settings (Carson and Screaton, 1998) and have been associated with high thermal gradients (Henry et al, 1996), shallow gas hydrates (Ginsburg et al, 1999), and an abundance of high-molecular weight hydrocarbons (Roberts and Carney, 1997). Mud volcanoes are common seafloor features along continental shelves, continental slopes, and in the deeper portions of inland seas (e.g., the Caspian Sea, Milkov, 2000) along both active and passive margins.…”

Section: Introductionmentioning

confidence: 99%

Geophysical and geochemical signatures of Gulf of Mexico seafloor brines

et al. 2005

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Abstract. Geophysical, temperature, and discrete depthstratified geochemical data illustrate differences between an actively venting mud volcano and a relatively quiescent brine pool in the Gulf of Mexico along the continental slope. Geophysical data, including laser-line scan mosaics and subbottom profiles, document the dynamic nature of both environments. Temperature profiles, obtained by lowering a CTD into the brine fluid, show that the venting brine was at least 10 • C warmer than the bottom water. At the brine pool, thermal stratification was observed and only small differences in stratification were documented between three sampling times (1991, 1997 and 1998). In contrast, at the mud volcano, substantial temperature variability was observed, with the core brine temperature being slightly higher than bottom water (by 2 • C) in 1997 but substantially higher than bottom water (by 19 • C) in 1998. Detailed geochemical samples were obtained in 2002 using a device called the "brine trapper" and concentrations of dissolved gases, major ions and nutrients were determined. Both brines contained about four times as much salt as seawater and steep concentration gradients of dissolved ions and nutrients versus brine depth were apparent. Differences in the concentrations of calcium, magnesium and potassium between the two brine fluids suggest that the fluids are derived from different sources, have different dilution/mixing histories, or that brine-sediment reactions are more important at the mud volcano. Substantial concentrations of methane, ammonium, and silicate were observed in both brines, suggesting that fluids expelled from deep ocean brines are important sources of these constituents to the surrounding environment.

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Section: Introductionmentioning

confidence: 99%

Geophysical and geochemical signatures of Gulf of Mexico seafloor brines

et al. 2005

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“…The Haakon Mosby Mud Volcano (HMMV) is a submarine mud volcano and is the only one in a polar region which has been studied in great detail (8,16,18,25,38,47,61,62,68,80,81). Very recently, we showed that the HMMV hosts three key microbial communities ( Fig.…”

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Diversity and Abundance of Aerobic and Anaerobic Methane Oxidizers at the Haakon Mosby Mud Volcano, Barents Sea

Lösekann

Knittel

Nadalig

et al. 2007

Appl Environ Microbiol

359

368

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Submarine mud volcanoes are formed by expulsions of mud, fluids, and gases from deeply buried subsurface sources. They are highly reduced benthic habitats and often associated with intensive methane seepage. In this study, the microbial diversity and community structure in methane-rich sediments of the Haakon Mosby Mud Volcano (HMMV) were investigated by comparative sequence analysis of 16S rRNA genes and fluorescence in situ hybridization. In the active volcano center, which has a diameter of about 500 m, the main methaneconsuming process was bacterial aerobic oxidation. In this zone, aerobic methanotrophs belonging to three bacterial clades closely affiliated with Methylobacter and Methylophaga species accounted for 56% ؎ 8% of total cells. In sediments below Beggiatoa mats encircling the center of the HMMV, methanotrophic archaea of the ANME-3 clade dominated the zone of anaerobic methane oxidation. ANME-3 archaea form cell aggregates mostly associated with sulfate-reducing bacteria of the Desulfobulbus (DBB) branch. These ANME-3/DBB aggregates were highly abundant and accounted for up to 94% ؎ 2% of total microbial biomass at 2 to 3 cm below the surface. ANME-3/DBB aggregates could be further enriched by flow cytometry to identify their phylogenetic relationships. At the outer rim of the mud volcano, the seafloor was colonized by tubeworms (Siboglinidae, formerly known as Pogonophora). Here, both aerobic and anaerobic methane oxidizers were found, however, in lower abundances. The level of microbial diversity at this site was higher than that at the central and Beggiatoa species-covered part of the HMMV. Analysis of methyl-coenzyme M-reductase alpha subunit (mcrA) genes showed a strong dominance of a novel lineage, mcrA group f, which could be assigned to ANME-3 archaea. Our results further support the hypothesis of Niemann et al. (54), that high methane availability and different fluid flow regimens at the HMMV provide distinct niches for aerobic and anaerobic methanotrophs.Large amounts of methane are stored in the subsurface ocean as crystalline gas hydrate, dissolved in porewater, and as free gas. Most of the methane which rises from subsurface reservoirs is consumed by anaerobic microorganisms inhabiting sulfate-penetrated sediment layers before it reaches the seafloor (65). This microbially mediated anaerobic oxidation of methane (AOM) controls the emission of the greenhouse gas methane from the ocean to the atmosphere (see reference 23 and references therein).In marine habitats, the metabolic process of AOM is proposed to be a reversed methanogenesis coupled to the reduction of sulfate involving methanotrophic archaea (ANME archaea) and sulfate-reducing bacteria (SRB). ANME archaea and SRB are assumed to interact syntrophically (26) and form microbial consortia which oxidize methane with equimolar amounts of sulfate, yielding bicarbonate and sulfide (26, 51, 52). Sulfide produced as a by-product of AOM at cold seeps often supports chemosynthetic communities which derive energy from sulfide oxidation. ...

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“…Map of the Håkon Mosby Mud Volcano (HMMV) located at the continental slope of the western Barents Sea. Mud flows, observations of gas hydrates, and distribution of bacterial mats and tube worms are indicated according to studies by Eldholm et al (1999), Ginsburg et al (1999), Milkov et al (2004), Smirnov (2000), and Vogt et al (1999).…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution of mud flows, chemoautotrophic communities, and biogeochemical habitats at Håkon Mosby Mud Volcano

et al. 2007

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Marine mud volcanoes are significant source locations contributing to the marine methane cycle. Enhanced heat flow, unique chemoautotrophic communities, occurrence of massive gas hydrates and large gas plumes are direct evidences of elevated methane concentrations and the dynamic environment of mud volcanoes. Related to the high concentrations and large inventories of CH 4 in surface sediments only a fraction of the methane is exported to the bottom water. This is mainly due to chemoautotrophic communities oxidizing methane and proving a "microbial filter" reducing CH 4 fluxes. Although these processes were studied for several mud volcanoes still little is known about the spatial pattern and the areas covered by chemoautotrophic communities or by present mud flows.For this purposes the Håkon Mosby Mud Volcano (HMMV), which is located at the continental slope of the Barents Sea, was studied by several dives with the Remotely Operated Vehicle Victor6000. During these dives a high resolution microbathymetric map, with a footprint of 25 × 25 cm and a vertical resolution of better than 10 cm was derived. Furthermore, video streams of the bottom camera were converted into georeferenced mosaics, providing a detailed image about the spatial distribution of seafloor features as bacterial mats, pogonophorans, both indicating methane oxidation, or mud flows. Based on visual inspection of 2310 georeferenced mosaics covering an area of 46,160 m 2 , different biogeochemical habitats were identified and quantified on a m 2 -basis. By application of geostatistic techniques as indicator kriging the distribution of different biogeochemical habitats was quantified and mapped for the entire HMMV.Considering the flat and hummocky area of HMMV, approximately 16% (115,165 m 2 ) of the flat centre is nearly void of any benthic communities. This area is considered as a region of high methane discharge into bottom water. An area of 5% (38,244 m 2 ), located in the south-eastern part, is densely inhabited by Beggiatoa. The hummocky outer part is colonised dominantly by pogonophoran tube worms (37.3%; 276,121 m 2 ) and only occasional by Beggiatoa. Source locations and drainage directions for current mud flows were identified by computation of trend surfaces and consideration of temperature data. This suggests that present mud flow ascend close to the northern edge of the flat unit of HMMV, and that the drainage pattern of mud flows shifted from a westward to a south-south-eastern direction.

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Gas hydrate accumulation at the Håkon Mosby Mud Volcano

Cited by 119 publications

References 8 publications

Geophysical and geochemical signatures of Gulf of Mexico seafloor brines

Geophysical and geochemical signatures of Gulf of Mexico seafloor brines

Diversity and Abundance of Aerobic and Anaerobic Methane Oxidizers at the Haakon Mosby Mud Volcano, Barents Sea

Spatial distribution of mud flows, chemoautotrophic communities, and biogeochemical habitats at Håkon Mosby Mud Volcano

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