scholarly journals Survey of Motile Microaerophilic Bacterial Morphotypes in the Oxygen Gradient above a Marine Sulfidic Sediment

2005 ◽  
Vol 71 (7) ◽  
pp. 3682-3691 ◽  
Author(s):  
Roland Thar ◽  
Tom Fenchel
Keyword(s):  
Oxygen Concentration ◽  
Free Swimming ◽  
Sediment Samples ◽  
Oxygen Gradient ◽  
Enrichment Cultures ◽  
Sulfidic Sediment ◽  
Bacterial Morphotypes

ABSTRACT Enrichment cultures for free-swimming microaerophilic bacteria were prepared from marine sulfidic sediment samples (Nivå Bay, Denmark). We observed nine different morphotypes; three of these morphotypes represented already-described species, i.e., Thiovulum majus, “Candidatus Ovobacter propellens,” and an as-yet-unnamed large vibrioid bacterium. In addition, we observed several morphotypes of spirilla and one vibrioid morphotype. A common feature of all investigated bacteria was that they aggregated chemotactically at the oxic-anoxic interface, whereas preferred oxygen concentration were in the range of 1 to 10 μM. The motile behavior and flagellar dynamics are analyzed in detail with an emphasis on spirilla.

OIL-DEGRADING POTENTIAL OF SURFICIAL SEDIMENTS NEAR OIL-PRODUCING PLATFORMS

1981 ◽  
Vol 1981 (1) ◽  
pp. 725-730
Author(s):  
L. R. Brown ◽  
K. L. Jeanes ◽  
W. F. Greenleaf ◽  
Geoff Frank
Keyword(s):  
Limiting Factor ◽  
Straight Chain ◽  
Sediment Samples ◽  
Enrichment Cultures ◽  
Pure Cultures ◽  
Laboratory Microcosm ◽  
Oil Concentration ◽  
Branched Chain ◽  
Microcosm Studies

ABSTRACT All surficial sediment samples were obtained either from areas near oil production platforms or from control areas some distance from these platforms during three separate cruises. All samples contained organisms capable of degrading crude oil in laboratory microcosm studies. Under conditions designed to test oil-degrading potential in situ, rate of degradation was not appreciably influenced by temperature fluctuations within a range of 15 to 27°C, or oil concentration, nor was it increased by added phosphorus or nitrogen. The maximum oil-degrading potential of the sediments was calculated to be 56 micrograms hydrocarbon carbon converted to carbon dioxide per milliliter of sediment per day. Oxygen diffusion into the sediments appeared to be the rate-limiting factor. Enrichment cultures prepared from platform sediments were more active than enrichment cultures prepared from control sediments. Studies with mixed and pure cultures revealed substrate preference for straight-chain hydrocarbons over the branched-chain compounds and aromatics. Some high molecular weight straight-chain aliphatics (about C30) and large amounts of branched-chain (C24 or C25) aliphatics were produced by some pure cultures isolated from sediment samples.

Experimental Study on Activated Sludge Form Sewage Treatment of Different Oxygen Gradient Reactor

2011 ◽  
Vol 374-377 ◽  
pp. 1054-1058
Author(s):  
Xi Tian ◽  
De Jun Bian ◽  
Qing Kai Ren ◽  
Hong Qu ◽  
Li Guo Wan ◽  
...  
Keyword(s):  
Experimental Study ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Oxygen Concentration ◽  
Concentration Gradient ◽  
Sewage Treatment ◽  
High Oxygen ◽  
Low Oxygen ◽  
Floc Size ◽  
Oxygen Gradient

It used dissolved oxygen meter to detect dissolved different oxygen concentration within wastewater treatment reactor and analysed reasons for the formation of oxygen concentration gradient. In order to learn more about activated sludge form of different oxygen gradient in the reactor, biological microscope operated in characteristics of microfauna and activated sludge floc in the reactor has been studied. The results showed that Vorticella and Rotifera could grow normally in the high and low regional areas; there are more abundant micro-fauna species in the area of low oxygen, and the microfauna was more mature than those in the area of high oxygen; activated sludge was brown and floc size was small in the areas of high oxygen, activated sludge was black and floc size was big.

High-resolution transmission electron microscopic study of highly oxygen doped silicon layer

1989 ◽  
Vol 47 ◽  
pp. 692-693
Author(s):  
H. Takaoka ◽  
M. Tomita ◽  
T. Hayashi
Keyword(s):  
High Resolution ◽  
Oxygen Concentration ◽  
Silicon Layer ◽  
Detailed Structure ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Doped Silicon ◽  
Argon Ion

High resolution transmission electron microscopy (HRTEM) is the effective technique for characterization of detailed structure of semiconductor materials. Oxygen is one of the important impurities in semiconductors. Detailed structure of highly oxygen doped silicon has not clearly investigated yet. This report describes detailed structure of highly oxygen doped silicon observed by HRTEM. Both samples prepared by Molecular beam epitaxy (MBE) and ion implantation were observed to investigate effects of oxygen concentration and doping methods to the crystal structure.The observed oxygen doped samples were prepared by MBE method in oxygen environment on (111) substrates. Oxygen concentration was about 1021 atoms/cm3. Another sample was silicon of (100) orientation implanted with oxygen ions at an energy of 180 keV. Oxygen concentration of this sample was about 1020 atoms/cm3 Cross-sectional specimens of (011) orientation were prepared by argon ion thinning and were observed by TEM at an accelerating voltage of 400 kV.

The time course of calcium deposition in shells of the barnacle (Balanus amphititre amphititre) during cyprid-juvenile metamorphosis

1994 ◽  
Vol 52 ◽  
pp. 178-179
Author(s):  
Nancy R. Wallace ◽  
Craig C. Freudenrich ◽  
Karl Wilbur ◽  
Peter Ingram ◽  
Ann LeFurgey
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Time Course ◽  
Vertical Plane ◽  
Mantle Cavity ◽  
Qualitative Assessment ◽  
Calcium Deposition ◽  
Free Swimming ◽  
Freeze Dried ◽  
Scanning Electron

The morphology of balanomorph barnacles during metamorphosis from the cyprid larval stage to the juvenile has been examined by light microscopy and scanning electron microscopy (SEM). The free-swimming cyprid attaches to a substrate, rotates 90° in the vertical plane, molts, and assumes the adult shape. The resulting metamorph is clad in soft cuticle and has an adult-like appearance with a mantle cavity, thorax with cirri, and incipient shell plates. At some time during the development from cyprid to juvenile, the barnacle begins to mineralize its shell, but it is not known whether calcification occurs before, during, or after ecdysis. To examine this issue, electron probe x-ray microanalysis (EPXMA) was used to detect calcium in cyprids and juveniles at various times during metamorphosis.Laboratory-raised, free-swimming cyprid larvae were allowed to settle on plastic coverslips in culture dishes of seawater. The cyprids were observed with a dissecting microscope, cryopreserved in liquid nitrogen-cooled liquid propane at various times (0-24 h) during metamorphosis, freeze dried, rotary carbon-coated, and examined with scanning electron microscopy (SEM). EPXMA dot maps were obtained in parallel for qualitative assessment of calcium and other elements in the carapace, wall, and opercular plates.

I3S Pattern as a mark-recapture tool to identify captured and free-swimming sea turtles: an assessment

2018 ◽  
Vol 589 ◽  
pp. 263-268 ◽  
Author(s):  
B Calmanovici ◽  
D Waayers ◽  
J Reisser ◽  
J Clifton ◽  
M Proietti
Keyword(s):  
Sea Turtles ◽  
Free Swimming ◽  
Mark Recapture

Holocene diatom assemblages from Dunderbukhta sediments, West Svalbard

2019 ◽  
pp. 242-245
Author(s):  
Ksenya V. Poleshchuk ◽  
Zinaida V. Pushina ◽  
Sergey R. Verkulich
Keyword(s):  
Environmental Changes ◽  
Ecological Groups ◽  
Diatom Assemblages ◽  
Diatom Analysis ◽  
Diatom Flora ◽  
Sediment Samples ◽  
Ecological Zones ◽  
Middle Holocene ◽  
Temperature Trends

The diatom analysis results of sediment samples from Dunderbukta area (Wedel Jarlsberg Land, West Svalbard) are presented in this paper. The diatom flora consists of four ecological groups, which ratio indicates three ecological zones. These zones show environmental changes of the area in early–middle Holocene that is demonstrating periods of regression and temperature trends.

ANALYSIS OF ACCUMULATION AND DISTRIBUTION OF LEAD IN THE SYSTEM WATER-BOTTOM SEDIMENTS IN THE BACH DANG ESTUARY (VIETNAM)

2017 ◽  
pp. 62-66
Author(s):  
Truong Van Tuan ◽  
Irina Vladimirovna Volkova
Keyword(s):  
Bottom Sediment ◽  
Bottom Sediments ◽  
Water Samples ◽  
Suspended Solids ◽  
Natural Habitat ◽  
Bottom Layer ◽  
Sediment Samples ◽  
Natural Breeding ◽  
System Water ◽  
Water Bottom

Research was held in the estuary of the river Bach Dang (Dongbay community, Rakhtay district, Hai Phong, Vietnam) in June, 2012 - May, 2013. Concentration of lead was studied in water, suspended solids and bottom sediment. Clam beach (natural breeding environment of Meretrix lyrata ) was inspected regularly, every month. Water samples were taken 6 times from the bottom layer 10 cm down the bottom, once per 3 hours in each of 12 investigated zones. Bottom sediment samples were taken at the depth 2 cm. The findings show that lead accumulates mainly in suspended solids (23.3 mg/kg) and in bottom sediment (14.31 mg/kg), in water it is in small quantities (0.003 mg/kg). Analysis of bottom sediment samples taken in different places showed that they have even leadcontent, lead is distributed uniformly, localization of contaminations is not found. The results obtained can be assumed as the basis for investigating lead accumulation and its excretion by clam Meretrix lyrata organisms in the natural habitat.

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