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  • 1
    In: Environmental modelling & software, Amsterdam [u.a.] : Elsevier Science, 1997, 24(2009), 8, Seite 1012-1013, 1873-6726
    In: volume:24
    In: year:2009
    In: number:8
    In: pages:1012-1013
    Beschreibung / Inhaltsverzeichnis: The presented software application allows GUI-based access to the bubble dissolution model presented by McGinnis et al. [McGinnis, D.F., Greinert, J., Artemov, Y., Beaubien, S.E., Wüest, A., 2006. The fate of rising methane bubbles in stratified waters: what fraction reaches the atmosphere? Journal of Geophysical Research 111, C09007. doi:10.1029/2005JC003183]. It quantifies the dissolution of gas bubbles (containing any combination of CH4, CO2, O2, N2, and Ar) in marine or lacustrine environments based on the initial bubble size, free gas composition and environmental parameters (temperature, salinity, and dissolved gas concentrations). The software enables scientists and engineers to evaluate bubble dynamics in a simple way on Windows® PCs.
    Materialart: Online-Ressource
    ISSN: 1873-6726
    Sprache: Englisch
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    In: Limnology and oceanography, Oxford [u.a.] : Wiley-Blackwell, 1956, 55(2010), 2, Seite 950-964, 1939-5590
    In: volume:55
    In: year:2010
    In: number:2
    In: pages:950-964
    Materialart: Online-Ressource
    Seiten: graph. Darst
    ISSN: 1939-5590
    Sprache: Englisch
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    In: Environmental science & technology, Columbus, Ohio : American Chemical Society, 1967, 44(2010), 7, Seite 24192425, 1520-5851
    In: volume:44
    In: year:2010
    In: number:7
    In: pages:24192425
    Materialart: Online-Ressource
    Seiten: graph. Darst
    ISSN: 1520-5851
    Sprache: Englisch
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    In: Journal of geophysical research. C, Oceans, Hoboken, NJ : Wiley, 1978, 115(2010), 2169-9291
    In: volume:115
    In: year:2010
    In: extent:18
    Beschreibung / Inhaltsverzeichnis: Bubble transport of methane from shallow seep sites in the Black Sea west of the Crimea Peninsula between 70 and 112 m water depth has been studied by extrapolation of results gained through different hydroacoustic methods and direct sampling. Ship-based hydroacoustic echo sounders can locate bubble releasing seep sites very precisely and facilitate their correlation with geological or other features at the seafloor. Here, the backscatter strength of a multibeam system was integrated with single-beam data to estimate the amount of seeps/m2 for different backscatter intensities, resulting in 2709 vents in total. Direct flux measurements by submersible revealed methane fluxes from individual vents of 0.32-0.85 l/min or 14.5-37.8 mmol/min at ambient pressure and temperature conditions. A conservative estimate of 30 mmol/min per site was used to estimate the flux into the water to be 1219-1355 mmol/s. The flux to the atmosphere was calculated by applying a bubble dissolution model taking release depth, temperature, gas composition, and bubble size spectra into account. The flux into the atmosphere (3930-4533 mol/d) or into the mixed layer (6186-6899 mol/d) from the 21.8 km2 large study area is three times higher than independently measured fluxes of dissolved methane for the same area using geochemical methods (1030-2495 mol/d). The amount of methane dissolving in the mixed layer is 2256-2366 mol/d. This close match shows that the hydroacoustic approach for extrapolating the number of seeps/m2 and the applied bubble dissolution model are suitable to extrapolate methane fluxes over larger areas.
    Materialart: Online-Ressource
    Seiten: 18 , Ill., graph. Darst
    ISSN: 2169-9291
    Sprache: Englisch
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    In: Marine geology, Amsterdam [u.a.] : Elsevier Science, 1964, 272(2010), Seite 170-188, 1872-6151
    In: volume:272
    In: year:2010
    In: pages:170-188
    Materialart: Online-Ressource
    Seiten: graph. Darst
    ISSN: 1872-6151
    Sprache: Englisch
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    In: Journal of geophysical research. G, Biogeosciences, [Washington, DC] : [Verlag nicht ermittelbar], 2006, 115(2010), 2169-8961
    In: volume:115
    In: year:2010
    In: extent:9
    Beschreibung / Inhaltsverzeichnis: We determined methane (CH4) emissions in a field enclosure experiment in a littoral freshwater marsh under the influence of experimentally simulated warming and enhanced nitrogen deposition. Methane emissions by ebullition from the marsh composed of Phragmites australis were measured with funnel traps deployed in a series of enclosures for two 3 week periods. Diffusive fluxes were estimated on the basis of measured CH4 concentrations and application of Fick's law. Neither diffusive nor ebullitive fluxes of methane were significantly affected by warming or nitrate enrichment, possibly because variability both within and among replicate experimental enclosures was high. Average emission rates resulted primarily from ebullition (0.2-30.3 mmol CH4 m-2 d-1), which were 4 orders of magnitude higher than estimated diffusive fluxes and were of similar importance as the coarsely estimated advective methane transport through plants. Significant correlations between dissolved oxygen and dissolved methane and ebullition flux suggest that methane release from the sediment might feed back positively on methane production by reducing dissolved oxygen in the water column and oxygen flux into the sediment. Nitrate may have a similar effect. Extrapolation of our limited data indicates that total methane fluxes from vegetated littoral zones of temperate lakes may contribute 0.5%-7% of the global natural CH4 emissions. These results emphasize the importance of freshwater marshes as sources of methane emissions to the atmosphere, even when they occupy only relatively small littoral areas. More detailed investigations are clearly needed to assess whether global warming and nitrogen deposition can have climate feedbacks by altering methane fluxes from these wetlands.
    Materialart: Online-Ressource
    Seiten: 9 , Ill., graph. Darst
    ISSN: 2169-8961
    Sprache: Englisch
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    In: Marine geology, Amsterdam [u.a.] : Elsevier Science, 1964, 272(2010), Seite 170-188, 1872-6151
    In: volume:272
    In: year:2010
    In: pages:170-188
    Beschreibung / Inhaltsverzeichnis: In situ methane emission measurements from sediments are combined with water column backscatter anomalies recorded with an Acoustic Doppler Current Profiler (ADCP) integrated on a benthic observatory. During cruise SO191 to the Hikurangi Margin (New Zealand), the Fluid Flux Observatory (FLUFO) was deployed at a cold seep site at Omakere Ridge. The sediments incubated in the two benthic chambers of FLUFO contained seep-associated fauna, including small and larger tubeworms, juvenile bivalves of the genus Acharax and some juvenile clams. The first 26 h of in situ incubation revealed low to moderate methane fluxes of 0.01 to 0.4 mmol m- 2 d- 1 into the overlying water of the backup and flux chamber, respectively. In the following sampling sequence, however, the methane concentration in the flux chamber reached 3-fold higher concentrations whereas the methane concentration in the backup chamber remained low and unchanged. Simultaneous to the sudden methane increase, a significant backscatter anomaly was recorded and persisted for 30 min and covered the entire depth range (100 m) of the upward looking ADCP. Data analyses revealed that a single-phase plume (no bubbles) outburst likely occurred during this time. While bubbles appeared to be present during some periods, plume simulations revealed that the volume of gas required (rate of 8 ton/day) does not support a bubble plume. A second data set was obtained during lander deployments at Rock Garden where visual observations by ROV confirmed the transient pattern of free gas injection into the water column. Acoustic flares and methane concentration increase in the bottom water hint towards a pressure (tidal) induced discharge mechanism. The presented data demonstrate the temporal and spatial variability of seabed methane emission, and very short methane signal lifetime in the water column (hours to a few days) due to turbulent diffusion. Both have to be considered when methane budgets are extrapolated from single methane emission rates.
    Materialart: Online-Ressource
    Seiten: Ill., graph. Darst
    ISSN: 1872-6151
    Sprache: Englisch
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Publikationsdatum: 2014-06-18
    Materialart: Conference or Workshop Item , NonPeerReviewed
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 49 (2004), S. 0 
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: 1. In this paper we test the usefulness of acoustic backscatter measurements from a 614 kHz Acoustic Doppler Current Profiler (ADCP) for the qualitative and quantitative characterisation of zooplankton distributions in lakes. ADCP-based backscatter estimates were compared with frequent net hauls obtained during a calibration experiment in which the acoustic backscatter was strongly dominated by vertical migrating Chaoborus flavicans larvae.2. The correlation between backscatter estimates and the C. flavicans concentration was very good. Vertical swimming speed of larvae, measured directly by the ADCP, was up to a maximum of 5 mm s−1 and agreed very well with the observed vertical movement of the backscatter contour lines. Although the strong backscatter from C. flavicans overwhelmed the signal from the remaining zooplankton, a good correlation between backscatter strength and the total remaining zooplankton concentration, dominated by Cyclops spp., was found for the depth and time intervals where no C. flavicans were present.3. In addition to the calibration experiment, longer-term ADCP measurements from different lakes revealed a strong temporal correlation between the onset of the up- and downward migration of zooplankton and the local sunset and sunrise.4. We conclude that ADCPs can be used to monitor plankton distributions both temporally and spatially. It also seems possible to estimate plankton densities after appropriate calibration.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Publikationsdatum: 2023-12-06
    Schlagwort(e): Center for Marine Environmental Sciences; EXP; Experiment; Flow velocity, water; Flume_Eddy_2013_EXP_15op; MARUM; Oxygen; Oxygen optode (PyroScience GmbH, Germany); Particle image velocimetry (PIV)
    Materialart: Dataset
    Format: text/tab-separated-values, 8880 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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