Coupling of Surface Layer Biological Processes and Vertical Flux in the Ross Sea

2000 ◽  
pp. 151-157
Author(s):  
W. O. Smith ◽  
H. J. Niebauer ◽  
V. L. Asper
Keyword(s):  
Surface Layer ◽  
Ross Sea ◽  
Vertical Flux ◽  
Biological Processes

Thermohaline structure and variability in the Terra Nova Bay polynya, Ross Sea

2000 ◽  
Vol 12 (4) ◽  
pp. 493-508 ◽  
Author(s):  
G. Budillon ◽  
G. Spezie
Keyword(s):  
Surface Layer ◽  
Cold Water ◽  
Ross Sea ◽  
Heat Budget ◽  
Salt Content ◽  
Heat Fluxes ◽  
Local Source ◽  
Near Surface ◽  
Terra Nova Bay ◽  
Terra Nova

Hydrological measurements from three cruises during the summers 1994/95, 1995/96 and 1997/98 in the western sector of the Ross Sea allow summer and year to year changes in heat and salt content in the Terra Nova Bay polynya to be analysed. Changes in the surface layer (upper pycnocline) followed the expected seasonal pattern of warming and freshening from the beginning to the end of the summer. These near-surface changes, expressed as net heating and salting rate, were about 11 W m−2 and -6 mg salt m−2 s−1. The heating changes were substantially lower than the estimated heat supplied by the atmosphere during the summer, which underlines the importance for this season of the advective component carried by the currents in the total heat budget. The year to year differences were about one or two orders of magnitude smaller than the seasonal changes in the surface layer. In the intermediate and deep layers, the summer heat and salt variability were of the same order as or one order higher than from one summer to the next. The differences in sign and magnitude for the heat change in the upper and in the lower pycnocline indicate a weak connection in the summer period between the surface heat fluxes and the deep waters. A local source of very cold water (with temperatures below the surface freezing point) of about 0.3 Sv has been detected close to the Terra Nova Bay coast. It arose out of the interaction of the shallow–intermediate layers of High Salinity Shelf Water with the coastal glaciers. The presence and the variability of this cold water point to the significant role of the thermohaline properties of Terra Nova Bay waters in controlling the floating glacier by governing the basal melting processes.

The vertical flux of biogenic and lithogenic material in the Ross Sea: moored sediment trap observations 1996–1998

2000 ◽  
Vol 47 (15-16) ◽  
pp. 3491-3520 ◽  
Author(s):  
Robert Collier ◽  
Jack Dymond ◽  
Susumu Honjo ◽  
Steven Manganini ◽  
Roger Francois ◽  
...  
Keyword(s):  
Sediment Trap ◽  
Ross Sea ◽  
Vertical Flux

Surface layer variability in the Ross Sea, Antarctica as assessed by in situ fluorescence measurements

2011 ◽  
Vol 88 (1-4) ◽  
pp. 28-45 ◽  
Author(s):  
Walker O. Smith ◽  
Vernon Asper ◽  
Sasha Tozzi ◽  
Xiao Liu ◽  
Sharon E. Stammerjohn
Keyword(s):  
Surface Layer ◽  
Ross Sea ◽  
Fluorescence Measurements

scholarly journals A balanced nitrogen budget of the surface layer of the southern Ross Sea, Antarctica

2000 ◽  
Vol 27 (17) ◽  
pp. 2721-2724 ◽  
Author(s):  
Walker O. Smith ◽  
Vernon A. Asper
Keyword(s):  
Surface Layer ◽  
Ross Sea ◽  
Nitrogen Budget

scholarly journals Dissolved oxygen dynamics during a phytoplankton bloom in the Ross Sea polynya

2015 ◽  
Vol 27 (4) ◽  
pp. 362-372 ◽  
Author(s):  
Bastien Y. Queste ◽  
Karen J. Heywood ◽  
Walker O. Smith ◽  
Daniel E. Kaufman ◽  
Timothy D. Jickells ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Primary Productivity ◽  
Ross Sea ◽  
Phytoplankton Bloom ◽  
Net Primary Production ◽  
Biological Processes ◽  
Carbon Export ◽  
Net Community Production ◽  
Spatio Temporal ◽  
The Difference

AbstractThe Ross Sea polynya is one of the most productive regions in the Southern Ocean. However, limited access and high spatio-temporal variability of physical and biological processes limit the use of conventional oceanographic methods to measure early season primary productivity. High-resolution observations from two Seagliders provide insights into the timing of a bloom in the southern Ross Sea polynya in December 2010. Changes in chlorophyll and oxygen concentrations are used to assess bloom dynamics. Using a ratio of dissolved oxygen to carbon, net primary production is estimated over the duration of the bloom showing a sensitive balance between net autotrophy and heterotrophy. The two gliders, observing spatially distinct regions during the same period, found net community production rates of -0.9±0.7 and 0.7±0.4 g C m-2 d-1. The difference highlights the spatial variability of biological processes and is probably caused by observing different stages of the bloom. The challenge of obtaining accurate primary productivity estimates highlights the need for increased observational efforts, particularly focusing on subsurface processes not resolved using surface or remote observations. Without an increased observational effort and the involvement of emerging technologies, it will not be possible to determine the seasonal trophic balance of the Ross Sea polynya and quantify the shelf’s importance in carbon export.

Short-term variations in particulate matter flux in Terra Nova Bay, Ross Sea

1997 ◽  
Vol 9 (2) ◽  
pp. 143-149 ◽  
Author(s):  
Mauro Fabiano ◽  
Mariachiara Chiantore ◽  
Paolo Povero ◽  
Riccardo Cattaneo-Vietti ◽  
Antonio Pusceddu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Sediment Trap ◽  
Biochemical Composition ◽  
Ross Sea ◽  
Early Summer ◽  
Biological Processes ◽  
Terra Nova Bay ◽  
Terra Nova ◽  
Matter Flux

As part of the Ross Sea Marginal Ice Zone Ecology Project (ROSSMIZE) the summer organic matter flux through the water column was measured at 40 m depth in Terra Nova Bay. Water samples and material from a sediment trap on the sea-bottom were analysed for their biochemical composition. A close coupling between biochemical composition of the organic matter in the water column and the material collected in the sediment trap was found, resulting from complex interactions between physical and biological processes. The physical processes are related to break-up and melting of the ice cover and occur mainly in the early summer season, whilst biological processes play a key role in mid summer and, from the evidence from faecal pellets, are related to the primary production and consumption processes.

The oxidation of Inconel alloy MA754 at low oxidation potential

1983 ◽  
Vol 41 ◽  
pp. 218-219
Author(s):  
D. N. Braski ◽  
P. D. Goodell ◽  
J. V. Cathcart ◽  
R. H. Kane
Keyword(s):  
Surface Layer ◽  
Oxidation Potential ◽  
Metal Interface ◽  
Elevated Temperature Strength ◽  
Surface Conditions ◽  
Inconel Alloy ◽  
Inco Alloy ◽  
Resistance To Oxidation ◽  
Oxide Particles ◽  
Cold Worked

It has been known for some time that the addition of small oxide particles to an 80 Ni—20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance is being studied collaboratively by ORNL and INCO Alloy Products Company.Initial experiments were performed using INCONEL alloy MA754, which is nominally: 78 Ni, 20 Cr, 0.05 C, 0.3 Al, 0.5 Ti, 1.0 Fe, and 0.6 Y2O3 (wt %).Small disks (3 mm diam × 0.38 mm thick) were cut from MA754 plate stock and prepared with two different surface conditions. The first was prepared by mechanically polishing one side of a disk through 0.5 μm diamond on a syntron polisher while the second used an additional sulfuric acid-methanol electropolishing treatment to remove the cold-worked surface layer. Disks having both surface treatments were oxidized in a radiantly heated furnace for 30 s at 1000°C. Three different environments were investigated: hydrogen with nominal dew points of 0°C, —25°C, and —55°C. The oxide particles and films were examined in TEM by using extraction replicas (carbon) and by backpolishing to the oxide/metal interface. The particles were analyzed by EDS and SAD.

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

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