Vodyanitskii mud volcano, Sorokin trough, Black Sea: Geological characterization and quantification of gas bubble streams

Sahling, Heiko; Bohrmann, Gerhard; Artemov, Yu. G.; Bahr, André; Brüning, Markus; Klapp, Stephan A; Klaucke, Ingo; Kozlova, Elena; Nikolovska, Aneta; Pape, Thomas; Reitz, Anja; Wallmann, Klaus

doi:10.1016/j.marpetgeo.2009.01.010

Cited by 102 publications

(91 citation statements)

References 68 publications

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“…This approach is advantageous because it is relatively simple and straight forward, providing order-of-magnitude estimations for gas bubble fluxes. Similar methodologies were recently applied in other settings characterized by gas bubble emissions (Römer et al, 2012a(Römer et al, , b, 2014Sahling et al, 2009).…”

Section: Quantification Of Gas Bubble Emissionsmentioning

confidence: 91%

Gas emissions at the continental margin west of Svalbard: mapping, sampling, and quantification

et al. 2014

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Abstract. We mapped, sampled, and quantified gas emissions at the continental margin west of Svalbard during R/V Heincke cruise He-387 in late summer 2012. Hydroacoustic mapping revealed that gas emissions were not limited to a zone just above 396 m water depth. Flares from this depth have gained significant attention in the scientific community in recent years because they may be caused by bottom-water warming-induced hydrate dissolution in the course of global warming and/or by recurring seasonal hydrate formation and decay. We found that gas emissions occurred widespread between about 80 and 415 m water depth, which indicates that hydrate dissolution might only be one of several triggers for active hydrocarbon seepage in that area. Gas emissions were remarkably intensive at the main ridge of the Forlandet moraine complex in 80 to 90 m water depths, and may be related to thawing permafrost.Focused seafloor investigations were performed with the remotely operated vehicle (ROV) "Cherokee". Geochemical analyses of gas bubbles sampled at about 240 m water depth as well as at the 396 m gas emission sites revealed that the vent gas is primarily composed of methane (> 99.70 %) of microbial origin (average δ 13 C = −55.7 ‰ V-PDB).Estimates of the regional gas bubble flux from the seafloor to the water column in the area of possible hydrate decomposition were achieved by combining flare mapping using multibeam and single-beam echosounder data, bubble stream mapping using a ROV-mounted horizontally looking sonar, and quantification of individual bubble streams using ROV imagery and bubble counting. We estimated that about 53 × 10 6 mol methane were annually emitted at the two areas and allow for a large range of uncertainty due to our method (9 to 118 × 10 6 mol yr −1 ). First, these amounts show that gas emissions at the continental margin west of Svalbard were on the same order of magnitude as bubble emissions at other geological settings; second, they may be used to calibrate models predicting hydrate dissolution at present and in the future; and third, they may serve as a baseline (year 2012) estimate of the bubble flux that will potentially increase in the future due to ever-increasing global-warming-induced bottom water warming and hydrate dissociation.

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Section: Quantification Of Gas Bubble Emissionsmentioning

confidence: 91%

Gas emissions at the continental margin west of Svalbard: mapping, sampling, and quantification

et al. 2014

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“…Seep (r e ) have been measured by video (Leifer, 2010;Römer et al, 2012;Sahling et al, 2009;Sauter et al, 2006) and passive acoustics. Passive acoustic (r e ) measurement has only been demonstrated for low-flow bubble plumes where the individual bubble acoustic signatures can be identified (Leifer and Tang, 2006;Maksimov et al, 2016).…”

Section: Sonar Seep Bubble Observationsmentioning

confidence: 99%

Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea

et al. 2017

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Abstract. Sonar surveys provide an effective mechanism for mapping seabed methane flux emissions, with Arctic submerged permafrost seepage having great potential to significantly affect climate. We created in situ engineered bubble plumes from 40 m depth with fluxes spanning 0.019 to 1.1 L s −1 to derive the in situ calibration curve (Q(σ )). These nonlinear curves related flux (Q) to sonar return (σ ) for a multibeam echosounder (MBES) and a single-beam echosounder (SBES) for a range of depths. The analysis demonstrated significant multiple bubble acoustic scattering -precluding the use of a theoretical approach to derive Q(σ ) from the product of the bubble σ (r) and the bubble size distribution where r is bubble radius. The bubble plume σ occurrence probability distribution function ( (σ )) with respect to Q found (σ ) for weak σ well described by a power law that likely correlated with small-bubble dispersion and was strongly depth dependent. (σ ) for strong σ was largely depth independent, consistent with bubble plume behavior where large bubbles in a plume remain in a focused core.(σ ) was bimodal for all but the weakest plumes. Q(σ ) was applied to sonar observations of natural arctic Laptev Sea seepage after accounting for volumetric change with numerical bubble plume simulations. Simulations addressed different depths and gases between calibration and seep plumes. Total mass fluxes (Q m ) were 5.56, 42.73, and 4.88 mmol s −1 for MBES data with good to reasonable agreement (4-37 %) between the SBES and MBES systems. The seepage flux occurrence probability distribution function ( (Q)) was bimodal, with weak (Q) in each seep area well described by a power law, suggesting primarily minor bubble plumes. The seepage-mapped spatial patterns suggested subsurface geologic control attributing methane fluxes to the current state of subsea permafrost.

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“…In recent years, much attention has been paid to the long-term in-situ and on-line observations of the methane flux and the spatio-temporal variability at various hydrocarbon seep locations, e.g., Bush Hill of Mexico, Coal Oil Point seep field of the Santa Barbara channel, Hydrate Ridge, the Black Sea and Hikurangi Margin of New Zealand (Roberts et al 1999;Brown 2001, 2004;Boles et al 2001;Torres et al 2002;Tryon et al 2002;Leifer and Boles 2005a, b;MacDonald et al 2005;Vardaro et al 2006;Solomon et al 2008;Sahling et al 2009;Krabbenhoeft et al 2010;Leifer et al 2010;Linke et al 2010;Römer et al 2012a, b;Etiope et al 2013). The preliminary results indicate that the flux and material associated with hydrocarbon seeps are both spatial and temporal in nature Tryon and Brown 2004;Leifer and Boles 2005b;Solomon et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Temporal Variation in Natural Gas Seep Rate and Influence Factors in the Lingtou Promontory Seep Field of the Northern South China Sea

Di¹,

Dong²,

Chen

2014

Terr. Atmos. Ocean. Sci.

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Natural hydrocarbon seeps in marine environment are important sources of methane and other greenhouse gases into the ocean and the atmosphere. This greenhouse gas seepage influences the global methane budget and global climate change. Hydrocarbon seeps on the shallow seabed produce a near-shore gas bubble zone along the western coast of Hainan Island, in the northern South China Sea. However, few studies on the quantitative value of the methane flux and on temporal variation and influence factors of hydrocarbon seeps have been conducted until now. This study describes the results of continuous gas vent measurements for 420 hours on the seabed of the Lingtou promontory shore. The amount of gas released from a single gas vent was 30.5 m 3 during the measurement period. The gas flow rate ranged from 22 -72 L h -1 , with an average rate of 53.4 L h -1 . The time series analyses of the 420-hour record clearly show three principal tidal components with periods of 5.4, 4.6, and 2.4 hours, which are the main factors controlling the gas flow rate. Low flow rates were associated with high tide and high flow rates associated with low tide. A 1-m increase in seawater height results in a decrease of 20 -30 L h -1 or 35 -56% of the hourly flow rate. Therefore, the changes in gas volume escape from the pore could be attributed to the hydrostatic pressure effect induced by water depth. This dominant mechanism controlled pore activation as well as the gas flow rate, suggesting that in the marine environment, especially the shallow-water shelf area, sea level changes may result in great variations in methane release into the ocean and atmosphere.

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Vodyanitskii mud volcano, Sorokin trough, Black Sea: Geological characterization and quantification of gas bubble streams

Cited by 102 publications

References 68 publications

Gas emissions at the continental margin west of Svalbard: mapping, sampling, and quantification

Gas emissions at the continental margin west of Svalbard: mapping, sampling, and quantification

Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea

Temporal Variation in Natural Gas Seep Rate and Influence Factors in the Lingtou Promontory Seep Field of the Northern South China Sea

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