English
norskBlar i forfatter "Gründger, Friederike"
Viser treff 1-12 av 12
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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
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-07)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 ... -
Compositions of dissolved organic matter in the ice-covered waters above the Aurora hydrothermal vent system, Gakkel Ridge, Arctic Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-20)Hydrothermal vents modify and displace subsurface dissolved organic matter (DOM) into the ocean. Once in the ocean, this DOM is transported together with elements, particles, dissolved gases and biomass along with the neutrally buoyant plume layer. Considering the number and extent of actively venting hydrothermal sites in the oceans, their contribution to the oceanic DOM pool may be substantial. ... -
Development, productivity, and seasonality of living planktonic foraminiferal faunas and Limacina helicina in an area of intense methane seepage in the Barents Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-09)Although the plankton communities in the Barents Sea have been intensely studied for decades, little is known about the living planktonic foraminiferal (LPF) and pteropod faunas, especially those found at methane seep sites. Along a repeated transect in the “crater area” (northern Barents Sea, 74.9°N, 27.7°E) in spring and summer 2016 the flux of LPF and of the pteropod species <i>Limacina helicina</i> ... -
Distinct methane-dependent biogeochemical states in Arctic seafloor gas hydrate mounds
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-02)Archaea mediating anaerobic methane oxidation are key in preventing methane produced in marine sediments from reaching the hydrosphere; however, a complete understanding of how microbial communities in natural settings respond to changes in the flux of methane remains largely uncharacterized. We investigate microbial communities in gas hydrate-bearing seafloor mounds at Storfjordrenna, offshore ... -
Elevated methane alters dissolved organic matter composition in the Arctic Ocean cold seeps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-15)Cold seeps release methane (CH<sub>4</sub>) from the seafloor to the water column, which fuels microbially mediated aerobic methane oxidation (MOx). Methane-oxidising bacteria (MOB) utilise excess methane, and the MOB biomass serves as a carbon source in the food web. Yet, it remains unclear if and how MOx modifies the composition of dissolved organic matter (DOM) in cold seeps. We investigated MOx ... -
Fracture-controlled fluid transport supports microbial methane-oxidizing communities at Vestnesa Ridge
(Journal article; Peer reviewed, 2019-05-29)We report a rare observation of a mini-fracture in near-surface sediments (30 cm below the seafloor) visualized using a rotational scanning X-ray of a core recovered from the Lomvi pockmark, Vestnesa Ridge, west of Svalbard (1200 m water depth). Porewater geochemistry and lipid biomarker signatures revealed clear differences in the geochemical and biogeochemical regimes of this core compared with ... -
The Impact of Methane on Microbial Communities at Marine Arctic Gas Hydrate Bearing Sediment
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-24)Cold seeps are characterized by high biomass, which is supported by the microbial oxidation of the available methane by capable microorganisms. The carbon is subsequently transferred to higher trophic levels. South of Svalbard, five geological mounds shaped by the formation of methane gas hydrates, have been recently located. Methane gas seeping activity has been observed on four of them, ... -
Methane-fuelled biofilms predominantly composed of methanotrophic ANME-1 in Arctic gas hydrate-related sediments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-05)Sedimentary biofilms comprising microbial communities mediating the anaerobic oxidation of methane are rare. Here, we describe two biofilm communities discovered in sediment cores recovered from Arctic cold seep sites (gas hydrate pingos) in the north-western Barents Sea, characterized by steady methane fluxes. We found macroscopically visible biofilms in pockets in the sediment matrix at the depth ... -
Microbial methane formation in deep aquifers of a coal-bearing sedimentary basin, Germany
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-20)Coal-bearing sediments are major reservoirs of organic matter potentially available for methanogenic subsurface microbial communities. In this study the specific microbial community inside lignite-bearing sedimentary basin in Germany and its contribution to methanogenic hydrocarbon degradation processes was investigated. The stable isotope signature of methane measured in groundwater and coal-rich ... -
Physical controls of dynamics of methane venting from a shallow seep area west of Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-06)We investigate methane seepage on the shallow shelf west of Svalbard during three consecutive years, using discrete sampling of the water column, echosounder-based gas flux estimates, water mass properties, and numerical dispersion modelling. The results reveal three distinct hydrographic conditions in spring and summer, showing that the methane content in the water column is controlled by a combination ... -
Reduced methane seepage from Arctic sediments during cold bottom-water conditions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-13)Large amounts of methane are trapped within gas hydrate in subseabed sediments in the Arctic Ocean, and bottom-water warming may induce the release of methane from the seafloor. Yet the effect of seasonal temperature variations on methane seepage activity remains unknown as surveys in Arctic seas are conducted mainly in summer. Here we compare the activity of cold seeps along the gas hydrate stability ... -
Seasonal shifts of microbial methane oxidation in Arctic shelf waters above gas seeps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-07)The Arctic Ocean subseabed holds vast reservoirs of the potent greenhouse gas methane (CH<sub>4</sub>), often seeping into the ocean water column. In a continuously warming ocean as a result of climate change an increase of CH<sub>4</sub> seepage from the seabed is hypothesized. Today, CH<sub>4</sub> is largely retained in the water column due to the activity of methane-oxidizing bacteria (MOB) that ...
