In situ acoustic scattering, attenuation, and dispersion measurements in marine sediments

2006 ◽  
Vol 120 (5) ◽  
pp. 3098-3098
Author(s):  
Altan Turgut ◽  
Roger Gauss ◽  
Charles Holand ◽  
Lisa Zurk
Keyword(s):  
Marine Sediments ◽  
Acoustic Scattering ◽  
Scattering Attenuation ◽  
Attenuation And Dispersion

A Chloroflexi bacterium dechlorinates polychlorinated biphenyls in marine sediments under in situ-like biogeochemical conditions

2012 ◽  
Vol 209-210 ◽  
pp. 449-457 ◽  
Author(s):  
Giulio Zanaroli ◽  
Annalisa Balloi ◽  
Andrea Negroni ◽  
Luigimaria Borruso ◽  
Daniele Daffonchio ◽  
...  
Keyword(s):  
Polychlorinated Biphenyls ◽  
Marine Sediments

The last interglacial–glacial cycle, Clyde foreland, Baffin Island, N.W.T.: stratigraphy, biostratigraphy, and chronology

1977 ◽  
Vol 14 (12) ◽  
pp. 2824-2857 ◽  
Author(s):  
G. H. Miller ◽  
J. T. Andrews ◽  
S. K. Short
Keyword(s):  
Amino Acid ◽  
Marine Sediments ◽  
Baffin Island ◽  
Buried Soils ◽  
Last Interglacial ◽  
Pollen Assemblage ◽  
Outlet Glacier ◽  
Radiocarbon Dates ◽  
Last Glaciation

A study of the stratigraphic sequence (14C and amino acid age control), marine bivalve faunal changes, and palynology of buried soils and organic-rich sediment collected from the Clyde Foreland Formation in the extensive cliff sections of the Clyde foreland, eastern Baffin Island, N.W.T., suggests the following last interglacial – Foxe (last glaciation) glacial – present interglacial sequence.(1) Cape Christian Member (ca. 130 000 years BP?)Consists of the Sledgepointer till overlain by the Cape Christian marine sediments. In situ molluscan fauna, collected from the marine sediments, contain a moderately warm bivalve assemblage. A well-developed soil that formed on the marine sediments (Cape Christian soil) contains an interglacial pollen assemblage dominated by dwarf birch. U-series dates of > 115 000 and ca. 130 000 years BP on molluscs from the Cape Christian marine sediments suggest that they were deposited during the last interglaciation, here termed the Cape Christian Interglaciation. The development of a subarctic pollen assemblage in the Cape Christian soil has not been duplicated during the present interglaciation, suggesting higher summer temperatures and perhaps a duration well in excess of 10 000 years for the last interglaciation.(2) Kuvinilk MemberConsists of fossiliferous marine sediments, locally divided by the Clyde till into upper and lower units. The Clyde till was deposited by the earliest and most extensive advance of the Foxe (last) Glaciation. Kuvinilk marine sediments both under- and overlying the Clyde till contain the pecten Chlamys islandicus, indicating that the outlet glacier advanced into a subarctic marine environment. Amino acid ratios from in situ pelecypod shells abovę and below the Clyde till are not statistically different, but contrast markedly with ratios obtained from the same species in the Cape Christian Member. Organic horizons within the Kuvinilk marine sediments contain a relatively rich pollen assemblage, although 'absolute' counts are low.(3) Kogalu Member (> 35 00014C years BP)Sediments of the Kogalu Member unconformably overlie those of the Kuvinilk Member, but are of a similar character. The dominant sediments are marine in origin, but in places are divided into upper and lower units by the Ayr Lake till. Amino acid ratios from in situ shells above and below the Ayr Lake till are indistinguishable, but substantially less than those in the Kuvinilk Member, suggesting the two members are separated by a considerable time interval. Radiocarbon dates on shells in the Kogalu marine sediments range from 33 000 to 47 700 years BP, but these may be only minimum estimates. The sea transgressed to a maximum level 70–80 m asl, coincident with the glacial maximum. Subarctic marine fauna of interstadial–interglacial character occur within the Kogalu marine sediments.(4) Eglinton Member (10 000 years BP to present)A major unconformity exists between the Kogalu and Eglinton Members. Ravenscraig marine sediments were deposited during an early Holocene marine transgression–regression cycle; the oldest dates on these sediments are ca. 10 000 years BP. Locally a vegetation mat occurs at the base or within the Ravenscraig unit. Pollen from these beds is sparse, but indicates a terrestrial vegetation assemblage as diverse as that of today. There is no evidence that Laurentide Ice reached the foreland during the last 30 000 years. Eolian sands that overlie a soil developed on the marine sediments record a late Holocene climatic deterioration. Pollen in organic-rich sediments at the base of, and within, the eolian sands record a vegetation shift in response to climatic change.

scholarly journals Acoustic Detection of Oceanic Double-Diffusive Convection: A Feasibility Study

2010 ◽  
Vol 27 (3) ◽  
pp. 580-593 ◽  
Author(s):  
Tetjana Ross ◽  
Andone Lavery
Keyword(s):  
Acoustic Scattering ◽  
Double Diffusive Convection ◽  
Western Antarctic Peninsula ◽  
Acoustic Detection ◽  
Acoustic Backscattering ◽  
Diffusive Regime ◽  
Diffusive Convection ◽  
In Situ Observations ◽  
Double Diffusive

Abstract The feasibility of using high-frequency acoustic scattering techniques to map the extent and evolution of the diffusive regime of double-diffusive convection in the ocean is explored. A scattering model developed to describe acoustic scattering from double-diffusive interfaces in the laboratory, which accounted for much of the measured scattering in the frequency range from 200 to 600 kHz, is used in conjunction with published in situ observations of diffusive-convection interfaces to make predictions of acoustic scattering from oceanic double-diffusive interfaces. Detectable levels of acoustic scattering are predicted for a range of different locations in the world’s oceans. To corroborate these results, thin acoustic layers detected near the western Antarctic Peninsula using a multifrequency acoustic backscattering system are shown to be consistent with scattering from diffusive-convection interfaces.

Geoacoustic and Geological Characterization of Surficial Marine Sediments by In Situ Probe and Remote Sensing Techniques

2019 ◽  
pp. 295-350
Author(s):  
Richard H. Bennett ◽  
Huon Li ◽  
Michael D. Richardson ◽  
Peter Fleischer ◽  
Douglas N. Lambert ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Marine Sediments ◽  
Remote Sensing Techniques

scholarly journals Anaerobic bacterial degradation of protein and lipid macromolecules in subarctic marine sediment

2020 ◽  
Author(s):  
Claus Pelikan ◽  
Kenneth Wasmund ◽  
Clemens Glombitza ◽  
Bela Hausmann ◽  
Craig W. Herbold ◽  
...  
Keyword(s):  
Marine Sediments ◽  
Marine Sediment ◽  
Volatile Fatty Acids ◽  
Degradation Products ◽  
Stable Isotope Probing ◽  
Bacterial Degradation ◽  
Rrna Gene ◽  
Genomic Features ◽  
Carbon Processing

AbstractMicroorganisms in marine sediments play major roles in marine biogeochemical cycles by mineralizing substantial quantities of organic matter from decaying cells. Proteins and lipids are abundant components of necromass, yet the taxonomic identities of microorganisms that actively degrade them remain poorly resolved. Here, we revealed identities, trophic interactions, and genomic features of bacteria that degraded 13C-labeled proteins and lipids in cold anoxic microcosms containing sulfidic subarctic marine sediment. Supplemented proteins and lipids were rapidly fermented to various volatile fatty acids within 5 days. DNA-stable isotope probing (SIP) suggested Psychrilyobacter atlanticus was an important primary degrader of proteins, and Psychromonas members were important primary degraders of both proteins and lipids. Closely related Psychromonas populations, as represented by distinct 16S rRNA gene variants, differentially utilized either proteins or lipids. DNA-SIP also showed 13C-labeling of various Deltaproteobacteria within 10 days, indicating trophic transfer of carbon to putative sulfate-reducers. Metagenome-assembled genomes revealed the primary hydrolyzers encoded secreted peptidases or lipases, and enzymes for catabolism of protein or lipid degradation products. Psychromonas species are prevalent in diverse marine sediments, suggesting they are important players in organic carbon processing in situ. Together, this study provides new insights into the identities, functions, and genomes of bacteria that actively degrade abundant necromass macromolecules in the seafloor.

scholarly journals IN SITU ACTIVATION ANALYSIS OF MARINE SEDIMENTS WITH $sup 252$Cf

1972 ◽  
Author(s):  
N A Wogman ◽  
Jr, H G Rieck ◽  
J R Kosorok ◽  
R W Perkins
Keyword(s):  
Activation Analysis ◽  
Marine Sediments ◽  
In Situ Activation

scholarly journals Supplementary material to "The fate of fixed nitrogen in oligotrophic marine sediments: an in situ study"

2016 ◽  
Author(s):  
Stefano Bonaglia ◽  
Astrid Hylén ◽  
Jayne E. Rattray ◽  
Mikhail Y. Kononets ◽  
Nils Ekeroth ◽  
...  
Keyword(s):  
Marine Sediments ◽  
Fixed Nitrogen ◽  
In Situ Study ◽  
Supplementary Material

scholarly journals Temperature response of denitrification and anammox reveals the adaptation of microbial communities to in situ temperatures in permeable marine sediments that span 50° in latitude

2013 ◽  
Vol 10 (9) ◽  
pp. 14595-14626 ◽  
Author(s):  
A. Canion ◽  
J. E. Kostka ◽  
T. M. Gihring ◽  
M. Huettel ◽  
J. E. E. van Beusekom ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Marine Sediments ◽  
Metabolic Response ◽  
Anammox Bacteria ◽  
Advective Flow ◽  
Permeable Sediments ◽  
N Removal ◽  
In Situ Conditions ◽  
Wide Range

Abstract. Despite decades of research on the physiology and biochemistry of nitrate/nitrite-respiring microorganisms, little is known regarding their metabolic response to temperature, especially under in situ conditions. The temperature regulation of microbial communities that mediate anammox and denitrification was investigated in near shore permeable sediments at polar, temperate, and subtropical sites with annual mean temperatures ranging from −5 to 23 °C. Total N2 production rates were determined using the isotope pairing technique in intact core incubations under diffusive and simulated advection conditions and ranged from 2 to 359 μmol N m−2 d−1. For the majority of sites studied, N2 removal was 2 to 7 times more rapid under advective flow conditions. Anammox comprised 6 to 14% of total N2 production at temperate and polar sites and was not detected at the subtropical site. Potential rates of denitrification and anammox were determined in anaerobic slurries in a temperature gradient block incubator across a temperature range of −1 to 42 °C. The highest optimum temperature (Topt) for denitrification was 36 °C and was observed in subtropical sediments, while the lowest Topt of 21 °C was observed at the polar site. Seasonal variation in the Topt was observed at the temperate site with values of 26 and 34 °C in winter and summer, respectively. The Topt values for anammox were 9 and 26 °C at the polar and temperate sites, respectively. The results demonstrate adaptation of denitrifying communities to in situ temperatures in permeable marine sediments across a wide range of temperatures, whereas marine anammox bacteria may be predominately psychrophilic to psychrotolerant. To our knowledge, we provide the first rates of denitrification and anammox from permeable sediments of a polar permanently cold ecosystem. The adaptation of microbial communities to in situ temperatures suggests that the relationship between temperature and rates of N removal is highly dependent on community structure.

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