The Beaufort Sea continental shelf as a seasonal source of atmospheric methane

Kvenvolden, Keith A.; Lilley, Marvin D.; Lorenson, Thomas D.; Barnes, Peter W.; McLaughlin, Elizabeth A.

doi:10.1029/93gl02727

Cited by 57 publications

(52 citation statements)

References 20 publications

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“…These works assist in understanding the biological controls on oceanic methane and may contribute to establishing baselines to monitor change in marine sediments. This may be of particular importance in the Arctic Ocean due to its sensitivity to climate change and abundance of methane (Kvenvolden et al, 1993;McGuire et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…However, because planktonic prokaryotes are primarily free-living on the ABS, (Garneau et al, 2009) it is reasonable to propose that the stratified period provides an opportunity to observe hydrographic influences on sediment microbiomes. Another factor making the ABS a candidate for study is the abundant methane in shelf and slope sediments (Kvenvolden et al, 1993;McGuire et al, 2009), which permits examination of methane-containing sediments in contact with water of Atlantic or Pacific origin but in close geographic proximity. Because of these features, the influence of water dispersal, the physical environment and local geochemistry on microbiome structure can be parsed.…”

Section: Introductionmentioning

confidence: 99%

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Ocean currents shape the microbiome of Arctic marine sediments

et al. 2012

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Prokaryote communities were investigated on the seasonally stratified Alaska Beaufort Shelf (ABS). Water and sediment directly underlying water with origin in the Arctic, Pacific or Atlantic oceans were analyzed by pyrosequencing and length heterogeneity-PCR in conjunction with physicochemical and geographic distance data to determine what features structure ABS microbiomes. Distinct bacterial communities were evident in all water masses. Alphaproteobacteria explained similarity in Arctic surface water and Pacific derived water. Deltaproteobacteria were abundant in Atlantic origin water and drove similarity among samples. Most archaeal sequences in water were related to unclassified marine Euryarchaeota. Sediment communities influenced by Pacific and Atlantic water were distinct from each other and pelagic communities. Firmicutes and Chloroflexi were abundant in sediment, although their distribution varied in Atlantic and Pacific influenced sites. Thermoprotei dominated archaea in Pacific influenced sediments and Methanomicrobia dominated in methanecontaining Atlantic influenced sediments. Length heterogeneity-PCR data from this study were analyzed with data from methane-containing sediments in other regions. Pacific influenced ABS sediments clustered with Pacific sites from New Zealand and Chilean coastal margins. Atlantic influenced ABS sediments formed another distinct cluster. Density and salinity were significant structuring features on pelagic communities. Porosity co-varied with benthic community structure across sites and methane did not. This study indicates that the origin of water overlying sediments shapes benthic communities locally and globally and that hydrography exerts greater influence on microbial community structure than the availability of methane.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ocean currents shape the microbiome of Arctic marine sediments

et al. 2012

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“…(2012) reported methane supersaturation in Arctic surface waters and point to sediments as being the main source. Several studies have suggested that methane accumulates in Arctic waters underlying sea ice, where it can be subsequently oxidized (Kitidis et al, 2010;Kvenvolden et al, 1993;Savvivech et al, 2004;Shakova et al, 2010). While methane oxidation is one of the known sinks for methane, the future retreat of the Arctic sea-ice cover could limit the residence time of methane in the water column and the subsequent rates of methane oxidation.…”

Section: Introductionmentioning

confidence: 99%

CO<sub>2</sub> and CH<sub>4</sub> in sea ice from a subarctic fjord under influence of riverine input

et al. 2014

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Abstract. We present the CH 4 concentration [CH 4 ], the partial pressure of CO 2 (pCO 2 ) and the total gas content in bulk sea ice from subarctic, land-fast sea ice in the Kapisillit fjord, Greenland. Fjord systems are characterized by freshwater runoff and riverine input and based on δ 18 O data, we show that > 30 % of the surface water originated from periodic river input during ice growth. This resulted in fresher sea-ice layers with higher gas content than is typical from marine sea ice. The bulk ice [CH 4 ] ranged from 1.8 to 12.1 nmol L −1 , which corresponds to a partial pressure ranging from 3 to 28 ppmv. This is markedly higher than the average atmospheric methane content of 1.9 ppmv. Evidently most of the trapped methane within the ice was contained inside bubbles, and only a minor portion was dissolved in the brines. The bulk ice pCO 2 ranged from 60 to 330 ppmv indicating that sea ice at temperatures above −4 • C is undersaturated compared to the atmosphere (390 ppmv). This study adds to the few existing studies of CH 4 and CO 2 in sea ice, and we conclude that subarctic seawater can be a sink for atmospheric CO 2 , while being a net source of CH 4 .

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“…Of that marine contribution, 75 % is from coastal regions (Bange et al, 1994). CH 4 supersaturation relative to the atmosphere in estuaries (Borges and Abril, 2011;Upstill-Goddard et al, 2000) and coastal shelves (Kvenvolden et al, 1993;Savvichev et al, 2004;Shakhova et al, 2005Shakhova et al, , 2010 is indeed larger than that in the open ocean (Bates et al, 1996;Damm et al, 2007Damm et al, , 2008Damm et al, , 2010.…”

Section: Introductionmentioning

confidence: 99%

“…Many CH 4 measurements have been carried out in sediments and seawater throughout the coastal Arctic areas (Kvenvolden et al, 1993;Savvichev et al, 2004;Shakhova et al, 2005Shakhova et al, , 2010. These observations have led to speculations about potential CH 4 accumulation (Shakhova et al, 2010) and/or oxidation (Kitidis et al, 2010) under sea ice cover.…”

Section: Introductionmentioning

confidence: 99%

Physical controls on the storage of methane in landfast sea ice

et al. 2014

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Abstract. We report on methane (CH 4 ) dynamics in landfast sea ice, brine and under-ice seawater at Barrow in 2009. The CH 4 concentrations in under-ice water ranged from 25.9 to 116.4 nmol L −1 sw , indicating a supersaturation of 700 to 3100 % relative to the atmosphere. In comparison, the CH 4 concentrations in sea ice ranged from 3.4 to 17.2 nmol L −1 ice and the deduced CH 4 concentrations in brine from 13.2 to 677.7 nmol L −1 brine . We investigated the processes underlying the difference in CH 4 concentrations between sea ice, brine and under-ice water and suggest that biological controls on the storage of CH 4 in ice were minor in comparison to the physical controls. Two physical processes regulated the storage of CH 4 in our landfast ice samples: bubble formation within the ice and sea ice permeability. Gas bubble formation due to brine concentration and solubility decrease favoured the accumulation of CH 4 in the ice at the beginning of ice growth. CH 4 retention in sea ice was then twice as efficient as that of salt; this also explains the overall higher CH 4 concentrations in brine than in the under-ice water. As sea ice thickened, gas bubble formation became less efficient, CH 4 was then mainly trapped in the dissolved state. The increase of sea ice permeability during ice melt marked the end of CH 4 storage.

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The Beaufort Sea continental shelf as a seasonal source of atmospheric methane

Cited by 57 publications

References 20 publications

Ocean currents shape the microbiome of Arctic marine sediments

Ocean currents shape the microbiome of Arctic marine sediments

CO<sub>2</sub> and CH<sub>4</sub> in sea ice from a subarctic fjord under influence of riverine input

Physical controls on the storage of methane in landfast sea ice

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The Beaufort Sea continental shelf as a seasonal source of atmospheric methane

Cited by 57 publications

References 20 publications

Ocean currents shape the microbiome of Arctic marine sediments

Ocean currents shape the microbiome of Arctic marine sediments

CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; in sea ice from a subarctic fjord under influence of riverine input

Physical controls on the storage of methane in landfast sea ice

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CO<sub>2</sub> and CH<sub>4</sub> in sea ice from a subarctic fjord under influence of riverine input