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  • 1
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    In:  EPIC3Permafrost : proceedings of the 8th International Conference on Permafrost, 21-25 July 2003, Zurich, Switzerland / ed. by Marcia Phillips; Sarah M. Springman; Lukas U. Arenson. Lisse [u.a.] : Balkema, Vol. 1, pp. 645-650, ISBN: 90 5809 584 3
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 312 (1984), S. 148-150 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] There is some controversy over the rate of primary productivity in the world ocean. Values ranging from 20 Gton C yr'1 (refs 1,2) to 126 Gton C yr'1 (rf. 3) have been reported. In view of recent work which questions the validity of the 14C-technique4 and considers contributions from ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The carbon and nitrogen isotopic composition of 18 faunistic groups collected during the 39th cruise of the R.V. “Akademik Mstislav Keldysh” in September 1996 at the Broken Spur vent field, MAR, was studied. The trophic structure of the Broken Spur vent community is considered. All age stages of the shrimp Rimicaris exoculata living 5 m below the main aggregations at black smokers show higher δ15N and more depleted δ13C values than the same stages inhabiting the black smokers themselves. The shrimps R. exoculata and Chorocaris chacei demonstrate ontogenetic changes in δ13C (the former also in δ15N), with smaller individuals showing higher δ15N and more depleted δ13C values than larger shrimps. Benthopelagic and benthic components of the vent community differ significantly in δ13C and δ15N, the benthic fauna being less dependent upon chemosynthetic production.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1608-3237
    Keywords: microbial processes ; microbial count ; carbon cycle ; methane oxidation ; sulfate reduction ; Barents Sea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The total number of microorganisms and rates of microbial processes of the carbon cycle were determined in snow, sea ice, water, and seafloor sediments of the northern part of the Barents Sea from September to October, 1998. The explorations were carried out in two areas: along the transection from Franz Josef Land to Victoria Island and along the continental slope region covered with solid ice at latitude 81°–82° N and longitude 37°–39° E. At the time of study, the ice cover was represented by thick one-year old ice (up to 1.2 m), perennial ice (up to 1.85 m), and pack ice. The number of bacteria in the snow cover, sea ice, and seawater was 12 to 14, 50 to 110, and 10 to 240 × 103 cells/ml, respectively. Rates of dark CO2 assimilation, glucose utilization, and methane oxidation by bacteria were determined. The highest rate of microbial processes was found in samples of the lowermost newly formed sea ice. The lowest level of activity for all processes was observed in melted snow water. A direct relation was shown between the concentration of Corg, the bacterial biomass, and the values of δ13Corg in mixtures of melted snow and ice. The number of microorganisms and rates of microbial processes in seafloor sediments measured at the stations on the continental slope are comparable to those in the central part of the Barents Sea and the northern part of the Kara Sea.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1608-3237
    Keywords: carbon dioxide assimilation ; methane oxidation ; chemosynthesis ; hydrothermal fields ; Mid-Atlantic Ridge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rates of carbon dioxide assimilation and methane oxidation were determined in various zones of the Rainbow Hydrothermal Field (36°N) of the Mid-Atlantic Ridge. In the plume above the hydrothermal field, anomalously high methane content was recorded, the microbial population density (up to 105 cells/ml) was an order of magnitude higher than the background values, and the CO2 assimilation rate varied from 0.01 to 1.1 μg C/(l day). Based on the data on CO2 assimilation, the production of organic carbon due to bacterial chemosynthesis in the plume was calculated to be 930 kg/day or 340 tons/year (about 29% of the organic carbon production in the photic zone). In the black smoke above active smokers, the microbial population density was as high as 106 cells/ml, the rate of CO2 assimilation made up 5–10 μg C/(l day), the methane oxidation rate varied from 0.15 to 12.7 μl/(l day), and the methane concentration ranged from 1.05 to 70.6 μl/l. In bottom sediments enriched with sulfides, the rate of CO2 assimilation was at least an order of magnitude higher than in oxidized metal-bearing sediments. At the base of an active construction, whitish sediment was found, which was characterized by a high methane content (92 μl/dm3) and a high rate of methane oxidation (1.7 μl/(dm3 day)).
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1608-3237
    Keywords: methane seeps ; bacterial mats ; filamentous bacteria ; sulfate reduction ; methanogenesis ; methane oxidation ; pogonophoras ; methanotrophic endosymbiotic bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Functioning of microbial communities in surface sediments of the Haakon Mosby underwater mud volcano (lat. 72°N) and in gas seepage fields of the Vestnesa Ridge was investigated using Mir-1 and Mir-2 deep-sea submersibles during the 40th voyage of the research vessel Academician Mstislav Keldysh. Large areas of sedimentary deposits of the Haakon Mosby mud volcano (HMMV) and pockmarks of the Vestnesa Ridge (VR) are covered with bacterial mats 0.1 to 0.5 cm thick. The microbial community making up bacterial mats of the HMMV was dominated by large filamentous bacteria with filaments measuring up to 100 μm in length and 2 to 8 μm in width. The occurrence of rosettes allowed the observed filamentous bacteria to be referred to the morphologically similar genera Leucothrix or Thiothrix. Three morphological types of filamentous bacteria were identified in bacterial mats covering VR pockmarks. Filaments of type one are morphologically similar with representatives of the genera Thioploca or Desmanthos. Type two filaments had numerous inclusions of sulfur and resembled representatives of the genus Thiothrix. The third morphological type was constituted by single filaments made up of tightly connected disk-like cells and can be assigned to the genus Beggiatoa. The rates of methane oxidation (up to 1570 μl C/(dm3 day)) and sulfate reduction (up to 17 mg S/(dm3day)) measured in the surface sediments of HMMV and VR were close to the maximum rates of these processes observed in heavily polluted regions of the northwestern shelf of the Black Sea. High rates of microbiological processes correlated with the high number of bacteria. The rate of methane production in sediments studied was notably lower and ranged from 0.1 to 3.5 μ CH4/(dm3 day). Large areas of the HMMV caldera were populated by pogonophoras, represented by the two species Sclerolinum sp. and Oligobrachia sp. The mass development of Sclerolinum sp. in the HMMV caldera was by the activity of aerobic methane-oxidizing bacteria localized inside the cells of these animals. Bacterial cells were also found in the trophosome tissue of Oligobrachia sp., but in cells of these bacteria, we did not observe the membrane structures typical of methanotrophs. The localization pattern of pogonophoras on the surface of reduced sediments suggests that the predominant bacteria in Oligobrachia tissues are sulfur-oxidizing endosymbionts.
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 2018-01-19
    Description: Two genetically different types of authigenic carbonate mounds are studied: those within an active hydrothermal field related to serpentinite protrusions in the zone of intersection of a transform fracture zone and the Mid-Atlantic Ridge, and those in an active field of methane seepings in the Dnieper canyon of the Black sea. The general geochemical conditions under which authigenic carbonate formation occurs in the two fields considered were found. They include the presence of reduced H2S, H2, and CH4 gases at the absence of free oxygen; the high alkalinity of the waters participating in the carbonate formation; the similarity of the textural and structural features of authigenic aragonite, which represents the initial mineral of the carbonate matter of the mounds; the paragenesis of aragonite with sulfide minerals; and the close relation of carbonate mounds with communities of sulfate-reducing and methane-oxidizing microorganisms. A new mechanism of formation of hydrothermal authigenic carbonates is suggested; it implies their microbial sulfate reduction over the hydrogen of the fluid in the subsurface zone (biosphere) of mixing between the hydrothermal solution and the adjacent seawater.
    Type: Article , PeerReviewed
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  • 8
    Publication Date: 2015-09-30
    Description: Paragenetic mineral assemblages have been established based on mineralogical, chemical, and isotope (S, Pb) studies, and the sequence of deposition has been defined in hydrothennal sulfide structures in a typical back-arc basin. The ores in the Manus basin have a prominent Zn specialization (sphalerite, würtzite, and fe-sphalerite). An association of Fe-spbalerite and galena with Ag sulfosalts is noted that is not characteristic of typical midocean ridge hydrothennal systems. The average 34S in the sulfide minerals is 3.5%o, which corresponds to the medium-temperature sphalerite stage in hydrothermal mineral fonnation. It is suggested that the metal source is located in the relatively acid rocks of the island-arc tholeiitic series and possibly in sediments.
    Type: Article , PeerReviewed
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