Stable isotope and hydrogeochemical studies of Beaver Lake and Radok Lake, MacRobertson Land, East Antarctica

AbstractObservations of the water level in Beaver Lake, an epishelf lake in East Antarctica, show a regular tidal signal that is lagged and attenuated from the tides beneath the adjacent Amery Ice Shelf. The phase lag and amplitude attenuation can be created by a narrow inlet connection between Beaver Lake and the cavity beneath the Amery Ice Shelf. A forced linear damped oscillator is used to determine the inlet dimensions that are required to produce the observed phase lag and amplitude attenuation. The model shows that the observations are consistent with a tidal flow that is restricted by the drag created by flow in the narrow inlet. Analysis shows that the phase lag and amplitude attenuation of the tides in Beaver Lake has increased over the years 1991-2002, probably due to a thickening of the overlying ice shelf. The response is sensitive to subtle variations in the dimensions of the inlet.

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Temporal and spatial variation of stable-isotope ratios and accumulation rates in the hinterland of Neumayer station, East Antarctica

Journal of Glaciology ◽

10.3189/002214310793146296 ◽

2010 ◽

Vol 56 (198) ◽

pp. 673-687 ◽

Cited By ~ 31

Author(s):

Francisco Fernandoy ◽

Hanno Meyer ◽

Hans Oerter ◽

Frank Wilhelms ◽

Wolfgang Graf ◽

...

Keyword(s):

Stable Isotope ◽

Isotope Composition ◽

Regional Climate ◽

Isotope Analysis ◽

East Antarctica ◽

Accumulation Rates ◽

Tritium Content ◽

Air Temperatures ◽

Isotope Record ◽

Dronning Maud Land

AbstractFour firn cores were retrieved in 2007 at two ridges in the area of the Ekström Ice Shelf, Dronning Maud Land, coastal East Antarctica, in order to investigate the recent regional climate variability and the potential for future extraction of an intermediate-depth core. Stable water-isotope analysis, tritium content and electrical conductivity were used to date the cores. For the period 1981–2006 a strong and significant correlation between the stable-isotope composition of firn cores in the hinterland and mean monthly air temperatures at Neumayer station was (r = 0.54−0.71). No atmospheric warming or cooling trend is inferred from our stable-isotope data for the period 1962–2006. The stable-isotope record of the ice/firn cores could expand well beyond the meteorological record of the region. No significant temporal variation of accumulation rates was detected. However, decreasing accumulation rates were found from coast to hinterland, as well as from east (Halvfarryggen) to west (Søråsen). The deuterium excess (d) exhibits similar differences (higher d at Søråsen, lower d at Halvfarryggen), with a weak negative temporal trend on Halvfarryggen (0.04‰ a−1), probably implying increasing oceanic input. We conclude that Halvfarryggen acts as a natural barrier for moisture-carrying air masses circulating in the region from east to west.

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A review of the bipolar see–saw from synchronized and high resolution ice core water stable isotope records from Greenland and East Antarctica

Quaternary Science Reviews ◽

10.1016/j.quascirev.2015.01.031 ◽

2015 ◽

Vol 114 ◽

pp. 18-32 ◽

Cited By ~ 43

Author(s):

A. Landais ◽

V. Masson-Delmotte ◽

B. Stenni ◽

E. Selmo ◽

D.M. Roche ◽

...

Keyword(s):

High Resolution ◽

Stable Isotope ◽

Ice Core ◽

East Antarctica ◽

Water Stable Isotope

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Sedimentology of the Permian Radok Conglomerate in the Beaver Lake area of MacRobertson Land, East Antarctica

Geological Magazine ◽

10.1017/s0016756800011420 ◽

1995 ◽

Vol 132 (1) ◽

pp. 51-63 ◽

Cited By ~ 12

Author(s):

C. R. Fielding ◽

J. A. Webb

Keyword(s):

Sediment Accumulation ◽

East Antarctica ◽

Upper Permian ◽

Rift System ◽

Flow Sheet ◽

Lake Area ◽

Organic Sediment ◽

Sediment Gravity Flow ◽

Beaver Lake ◽

Coal Measures

AbstractThe mid- to Upper Permian Radok Conglomerate, the lowermost formation of the Permo-Triassic Amery Group, crops out in the Beaver Lake area of the northern Prince Charles Mountains, East Antarctica. Outcrop is confined to a north-south elongate, fault-bounded corridor interpretedas a remnant of a continental extensional basin formed during Late Palaeozoic times. This basinforms a small part of the much larger Lambert Graben, a major continental rift system. The RadokConglomerate consists of interbedded conglomerates, argillaceous sandstones, siltstones, and minor, thin carbonaceous siltstones and coals. Textural, petrographic, palaeocurrent and other data suggestlocal derivation from Precambrian massifs to the immediate west, during a period of fault activity.The unit is a minimum of 400 m thick, the base being unexposed, and grossly fines upward. It isabruptly overlain by quartzo-feldspathic sandstone-dominated rocks of the Upper Permian Bainmedart Coal Measures. Seven recurrent lithofacies have been recognized with the Radok Conglomerate, and are interpreted as the products of poorly-confined stream flow, sheet flow and sediment gravity flow processes, suspension fallout in shallow standing water, and organic sediment accumulation in peat-forming wetlands. The unit as a whole is interpreted as having accumulated as a coarse alluvial apron along the western margin of a ?graben extensional trough. Similar, though poorly exposed, facies are exposed on the eastern margin of the basin and may reflect similar depositional systems. Towards the top of the Radok Conglomerate, typical Radok lithologies are interbedded with quartzo-feldspathic sandstones derived from the south, precursors of the overlying Bainmedart Coal Measures. Interference between transverse (Radok) and axial (Bainmedart) drainage is possibly related to progressive infilling of extensional topography, thereby allowing axially flowing rivers to avulse increasingly into the Beaver Lake region from the main Lambert Graben.

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Indications of Holocene sea-level rise in Beaver Lake, East Antarctica

Antarctic Science ◽

10.1017/s095410200700017x ◽

2007 ◽

Vol 19 (1) ◽

pp. 125-128 ◽

Cited By ~ 6

Author(s):

Bernd Wagner ◽

Nadja Hultzsch ◽

Martin Melles ◽

Damian B. Gore

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

East Antarctica ◽

Relative Sea Level ◽

The Holocene ◽

Isostatic Uplift ◽

Beaver Lake ◽

Holocene Sea Level

A 100 cm long sediment sequence was recovered from Beaver Lake in Amery Oasis, East Antarctica, using gravity and piston corers. Sedimentological and mineralogical analyses and the absence of micro and macrofossils indicate that the sediments at the base of the sequence formed under glacial conditions, probably prior to c. 12 500 cal. yr BP. The sediments between c. 81 and 31 cm depth probably formed under subaerial conditions, indicating that isostatic uplift since deglaciation has been substantially less than eustatic sea-level rise and that large areas of the present-day floor of Beaver Lake must have been subaerially exposed following deglaciation. The upper 31 cm of the sediment sequence were deposited under glaciomarine conditions similar to those of today, supporting geomorphic observations that the Holocene was a period of relative sea-level highstand in Amery Oasis.

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Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831/a000183 ◽

2014 ◽

Vol 84 (Supplement 1) ◽

pp. 25-29 ◽

Cited By ~ 7

Author(s):

Guangwen Tang

Keyword(s):

Stable Isotope ◽

Vitamin A ◽

Provitamin A ◽

Animal Origin ◽

Plant Food ◽

Plant Foods ◽

A Value ◽

Provitamin A Carotenoids ◽

Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

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