Physical controls of dynamics of methane venting from a shallow seep area west of Svalbard

Silyakova, Anna; Jansson, Pär; Serov, Pavel; Férré, Bénédicte; Pavlov, Alexey K.; Hattermann, Tore; Graves, Carolyn A.; Platt, Stephen Matthew; Myhre, Cathrine Lund; Gründger, Friederike; Niemann, Helge

doi:10.1016/j.csr.2019.104030

Cited by 29 publications

(56 citation statements)

References 89 publications

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“…Rather than elevated methane concentrations, which were not entirely related to high MOx rates, the size of a MOB community may be the more relevant factor of an active MOB community (Steinle et al, 2015). Moreover, the succession of MOB communities depends largely on circulation patterns and water column hydrography (Steinle et al, 2015;Silyakova et al, 2020). In accordance with this, we observed in our study site-specific positive correlations between methane concentrations and MOx rates at PKF and SP ( Figure 4H).…”

Section: Effect Of Hydrography On Methane Concentrations and Methane supporting

confidence: 84%

“…Only a limited portion of the seeping methane reaches the atmosphere (Graves et al, 2015;Myhre et al, 2016;Steinle et al, 2016), while the major part remains in the water column as dissolved gas. Concentrations of methane may reach up to thousands times higher than background levels at seeps, yet decreases rapidly with the distance from the point source predominantly as a result of bacterial oxidation, lateral diffusion, and upward mixing (Graves et al, 2015;Silyakova et al, 2020). Microbial oxidation of methane (MOx), performed by methane oxidizing bacteria (MOB) which convert methane into methanol and formaldehyde, is the major removal mechanism of dissolved methane in ocean waters (Reeburgh, 2007;Murrell, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Compositional Differences in Dissolved Organic Matter Between Arctic Cold Seeps Versus Non-Seep Sites at the Svalbard Continental Margin and the Barents Sea

et al. 2020

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Dissociating gas hydrates, submerged permafrost, and gas bearing sediments release methane to the water column from a multitude of seeps in the Arctic Ocean. The seeping methane dissolves and supports the growth of aerobic methane oxidizing bacteria (MOB), but the effect of seepage and seep related biogeochemical processes on water column dissolved organic matter (DOM) dynamics is not well constrained. We compared dissolved methane, nutrients, chlorophyll, and particulate matter concentrations and methane oxidation (MOx) rates from previously characterized seep and non-seep areas at the continental margin of Svalbard and the Barents Sea in May and June 2017. DOM molecular composition was determined by Electrospray Ionization Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). We found that the chemical diversity of DOM was 3 to 5% higher and constituted more protein- and lipid-like composition near methane seeps when compared to non-seep areas. Distributions of nutrients, chlorophyll, and particulate matter however, were essentially governed by the water column hydrography and primary production. We surmise that the organic intermediates directly derived from seepage or indirectly from seep-related biogeochemical processes, e.g., MOx, modifies the composition of DOM leading to distinct DOM molecular-level signatures in the water column at cold seeps.

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Section: Effect Of Hydrography On Methane Concentrations and Methane supporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Compositional Differences in Dissolved Organic Matter Between Arctic Cold Seeps Versus Non-Seep Sites at the Svalbard Continental Margin and the Barents Sea

et al. 2020

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“…The hydrodynamics in our study area are complex (see also Silyakova et al 2020). The East Spitsbergen Current flows along the Svalbard islands southwards on the east side, following the coast around the island's southern tip and then turns northwards on the west side of the island (Nilsen et al 2008).…”

Section: Study Areamentioning

confidence: 96%

“…2L-M). The detailed hydrographic setting in May 2016 and July 2015 at the shelf west of Prins Karls Forland has been described by Silyakova et al (2020).…”

Section: Hydrographic Settingmentioning

confidence: 99%

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Seasonal shifts of microbial methane oxidation in Arctic shelf waters above gas seeps

Gründger

Probandt

Knittel

et al. 2021

Limnology & Oceanography

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The Arctic Ocean subseabed holds vast reservoirs of the potent greenhouse gas methane (CH 4 ), often seeping into the ocean water column. In a continuously warming ocean as a result of climate change an increase of CH 4 seepage from the seabed is hypothesized. Today, CH 4 is largely retained in the water column due to the activity of methane-oxidizing bacteria (MOB) that thrive there. Predicted future oceanographic changes, bottom water warming and increasing CH 4 release may alter efficacy of this microbially mediated CH 4 sink. Here we investigate the composition and principle controls on abundance and activity of the MOB communities at the shallow continental shelf west of Svalbard, which is subject to strong seasonal changes in oceanographic conditions. Covering a large area (364 km 2 ), we measured vertical distribution of microbial methane oxidation (MOx) rates, MOB community composition, dissolved CH 4 concentrations, temperature and salinity four times throughout spring and summer during three consecutive years. Sequencing analyses of the pmoA gene revealed a small, relatively uniform community mainly composed of type-Ia methanotrophs (deep-sea 3 clade). We found highest MOx rates (7 nM d −1 ) in summer in bathymetric depressions filled with stagnant Atlantic Water containing moderate concentrations of dissolved CH 4 (< 100 nM). MOx rates in these depressions during spring were much lower (< 0.5 nM d −1 ) due to lower temperatures and mixing of Transformed Atlantic Water flushing MOB with the Atlantic Water out of the depressions. Our results show that MOB and MOx in CH 4 -rich bottom waters are highly affected by geomorphology and seasonal conditions.

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Biogeochemistry and microbiology of high Arctic marine sediment ecosystems—Case study of Svalbard fjords

Jørgensen

Laufer

Michaud

et al. 2020

Limnology & Oceanography

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Fjord ecosystems of the high Arctic are distinct from fjords of temperate latitudes due to the influence of glaciers, icebergs, sea ice, and the permanently low temperatures. The sediment microbiology and biogeochemical processes were analyzed during an international research program with multiple field studies in Svalbard, situated between the Barents Sea and the Arctic Ocean. We here describe the physical and geochemical setting and the predominant microbiological processes in several fjords. Physiological studies of sediments and pure cultures show how the predominantly psychrophilic bacteria are adapted to the near‐zero temperature. The microbial communities include bacteria responsible for organic matter hydrolytic degradation, fermentation, and terminal oxidation to CO2. These processes drive the cycling of carbon, sulfur, iron, and manganese. The balance between the dominant sediment microbial processes changes along transects out through the fjords, reflecting the varying impact of the glacier‐derived rock flour, rich in metal oxides at the head, and the plankton‐derived, labile, marine organic matter at the mouth. Due to accelerated warming of Arctic ecosystems, glaciers are retreating with impacts on the physical, chemical, and biological functioning of the fjord sediment ecosystems.

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Physical controls of dynamics of methane venting from a shallow seep area west of Svalbard

Cited by 29 publications

References 89 publications

Compositional Differences in Dissolved Organic Matter Between Arctic Cold Seeps Versus Non-Seep Sites at the Svalbard Continental Margin and the Barents Sea

Compositional Differences in Dissolved Organic Matter Between Arctic Cold Seeps Versus Non-Seep Sites at the Svalbard Continental Margin and the Barents Sea

Seasonal shifts of microbial methane oxidation in Arctic shelf waters above gas seeps

Biogeochemistry and microbiology of high Arctic marine sediment ecosystems—Case study of Svalbard fjords

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