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

2021 ◽  
Author(s):  
Friederike Gründger ◽  
David Probandt ◽  
Katrin Knittel ◽  
Vincent Carrier ◽  
Dimitri Kalenitchenko ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Arctic Shelf ◽  
Gas Seeps ◽  
Seasonal Shifts

scholarly journals Methane oxidizing seawater microbial communities from an Arctic shelf

2017 ◽  
Author(s):  
Christiane Uhlig ◽  
John B. Kirkpatrick ◽  
Steve D'Hondt ◽  
Brice Loose
Keyword(s):  
Sea Ice ◽  
Microbial Communities ◽  
Methane Oxidation ◽  
Methane Concentration ◽  
Oxidation Potential ◽  
Arctic Shelf ◽  
Natural Seawater ◽  
Methane Oxidizing Bacteria ◽  
High Concentrations ◽  
Methane Concentrations

Abstract. Microbial communities of the ocean can consume methane dissolved in seawater before it has a chance to escape to the atmosphere and contribute to greenhouse warming. Seawater over the shallow Arctic shelf is characterized by excess methane compared to the atmospheric equilibrium originating in sediments, permafrost and hydrates. Particularly high concentrations are found beneath sea ice. We studied the structure and methane oxidation potential of the microbial communities from seawater collected close to Utqiagvik, Alaska, in April 2016. The in situ methane concentrations were 16.3 ± 7.2 nmol L−1, approximately 4.8 times oversaturated compared to the atmospheric equilibrium. The group of methane oxidizing bacteria (MOB) in the natural seawater and seawater incubations was > 97 % dominated by Methylococcacales (γ-Proteobacteria). Incubations of seawater under a range of methane concentrations led to a loss of diversity in the bacterial community. The abundance of MOB was low with maximal fractions of 2.5 % at 200 times elevated methane concentration, while sequence reads of non-MOB methylotrophs were four times more abundant than MOB in most incubations. The abundances of MOB as well as non-MOB methylotrophs correlated tightly with the rate constant (kox) for methane oxidation, indicating that non-MOB methylotrophs might be coupled to MOB and involved in community methane oxidation. In sea ice, where methane concentrations of 82 ± 35.8 nmol kg−1 were found, Methylobacterium (α-Proteobacteria) was the dominant MOB with a relative abundance of 80 %. MOB abundances were very low in sea ice, with maximal fractions found at the ice-snow interface (0.1 %), while non-MOB-methlylotrophs were present in abundances compared to natural seawater communities. The differences in MOB taxa and an offset in methane concentration and stable isotope ratios between the ice and the water column point toward different methane cycling processes in both habitats.

scholarly journals Methane-oxidizing seawater microbial communities from an Arctic shelf

2018 ◽  
Vol 15 (11) ◽  
pp. 3311-3329 ◽  
Author(s):  
Christiane Uhlig ◽  
John B. Kirkpatrick ◽  
Steven D'Hondt ◽  
Brice Loose
Keyword(s):  
Sea Ice ◽  
Microbial Communities ◽  
Methane Oxidation ◽  
Oxidation Potential ◽  
Arctic Shelf ◽  
Natural Seawater ◽  
Methane Oxidizing Bacteria ◽  
High Concentrations ◽  
Marine Microbial Communities ◽  
Methane Concentrations

Abstract. Marine microbial communities can consume dissolved methane before it can escape to the atmosphere and contribute to global warming. Seawater over the shallow Arctic shelf is characterized by excess methane compared to atmospheric equilibrium. This methane originates in sediment, permafrost, and hydrate. Particularly high concentrations are found beneath sea ice. We studied the structure and methane oxidation potential of the microbial communities from seawater collected close to Utqiagvik, Alaska, in April 2016. The in situ methane concentrations were 16.3 ± 7.2 nmol L−1, approximately 4.8 times oversaturated relative to atmospheric equilibrium. The group of methane-oxidizing bacteria (MOB) in the natural seawater and incubated seawater was > 97 % dominated by Methylococcales (γ-Proteobacteria). Incubations of seawater under a range of methane concentrations led to loss of diversity in the bacterial community. The abundance of MOB was low with maximal fractions of 2.5 % at 200 times elevated methane concentration, while sequence reads of non-MOB methylotrophs were 4 times more abundant than MOB in most incubations. The abundances of MOB as well as non-MOB methylotroph sequences correlated tightly with the rate constant (kox) for methane oxidation, indicating that non-MOB methylotrophs might be coupled to MOB and involved in community methane oxidation. In sea ice, where methane concentrations of 82 ± 35.8 nmol kg−1 were found, Methylobacterium (α-Proteobacteria) was the dominant MOB with a relative abundance of 80 %. Total MOB abundances were very low in sea ice, with maximal fractions found at the ice–snow interface (0.1 %), while non-MOB methylotrophs were present in abundances similar to natural seawater communities. The dissimilarities in MOB taxa, methane concentrations, and stable isotope ratios between the sea ice and water column point toward different methane dynamics in the two environments.

Methane Oxidation on a Coverage Layer Study

2008 ◽  
Author(s):  
Juliana L. Rose ◽  
Pedro Paulo F. Gouvêa ◽  
Cláudio F. Mahler
Keyword(s):  
Methane Oxidation

GEOINFORMATION SUPPORT OF HYDROCARBONS TRANSPORT FROM ARCTIC SHELF

2017 ◽  
Vol 12 ◽  
pp. 14-20
Author(s):  
S.S. Kubrin ◽  
◽  
S.N. Reshetnyak ◽  
A.A. Aleshin ◽  
◽  
...  
Keyword(s):  
Arctic Shelf

Ultra-Low Amounts of Palladium (0.005-0.05 Wt% Pd) Supported on Titania: Remarkable Low-Temperature Activity for NO Reduction with CO and Structure-Function Property Relationships in Methane Oxidation

2020 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Libor Kovarik ◽  
Nicholas R. Jaegers ◽  
János Szanyi ◽  
Yong Wang
Keyword(s):  
Nitric Oxide ◽  
Carbon Monoxide ◽  
Methane Oxidation ◽  
Steam Reforming ◽  
Methane Steam Reforming ◽  
Oxide Reduction ◽  
Water Steam ◽  
Methane Steam ◽  
Anatase Titania ◽  
Nitric Oxide Reduction

<p>Atomically dispersed Pd +2 cations with ultra-dilute loading of palladium (0.005-0.05 wt%) were anchored on anatase titania and characterized with FTIR, microscopy and catalytic tests. CO infrared adsorption produces a sharp, narrow mono-carbonyl Pd(II)-CO band at ~2,130 cm<sup>-1</sup> indicating formation of highly uniform and stable Pd+2 ions on anatase titania. The 0.05 wt% Pd/TiO<sub>2</sub> sample was evaluated for methane combustion under dry and wet (industrially relevant) conditions in the presence and absence of carbon monoxide. Notably, we find the isolated palladium atoms respond dynamically upon oxygen concentration modulation (switching-on and switching off). When oxygen is removed from the wet methane stream, palladium ions are reduced to metallic state by methane and catalyze methane steam reforming instead of complete methane oxidation. Re-admission of oxygen restores Pd<sup>+2</sup> cations and switches off methane steam reforming activity. Moreover, 0.05 wt% Pd/TiO<sub>2</sub> is a competent CO oxidation catalyst in the presence of water steam with 90% CO conversion and TOF ~ 4,000 hr<sup>-1</sup> at 260 ⁰C. </p><p>More importantly, we find that diluting 0.05 wt% Pd/titania sample with titania to ultra-low 0.005 wt% palladium loading produces a remarkably active material for nitric oxide reduction with carbon monoxide under industrially relevant conditions with >90% conversion of nitric oxide at 180 ⁰C (~460 ppm NO and 150 L/g*hr flow rate in the presence of >2% water steam) and TOF ~6,000 hr<sup>-1</sup>. Pd thus outperforms state-of-the-art rhodium containing catalysts with (15-20 times higher rhodium loading; rhodium is ~ 3 times more expensive than palladium). Furthermore, palladium catalysts are more selective towards nitrogen and produce significantly less ammonia relative to the more traditional rhodium catalysts due to lower Pd amount nd lower water-gas-shift activity. Our study is the first example of utilizing ultra-low (0.05 wt% and less) noble metal (Pd) amounts to produce heterogeneous catalysts with extraordinary activity for nitric oxide reduction. This opens up a pathway to study other Pd, Pt and Rh containing materials with ultra-low loadings of expensive noble metals dispersed on titania or titania-coated oxides for industrially relevant nitric oxide abatement.</p>

РRINCIPLES OF ONSHORE FACILITIES DESIGN FOR THE OBJECTS OF OIL AND GAS COMPLEX IN THE ARCTIC SHELF

2018 ◽  
pp. 62-68
Author(s):  
M.A. Magomedgadzhieva ◽  
◽  
G.S. Oganov ◽  
I.B. Mitrofanov ◽  
A.M. Karpov ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Arctic Shelf ◽  
The Arctic ◽  
Facilities Design
Sign in / Sign up

Export Citation Format

Share Document