scholarly journals Insight Into Provenance and Variability of Atmospheric Dust in Antarctic Ice Cores During the Late Pleistocene From Magnetic Measurements

2020 ◽  
Vol 8 ◽  
Author(s):  
Luca Lanci ◽  
Barbara Delmonte ◽  
Maria Cristina Salvatore ◽  
Carlo Baroni
Author(s):  
Han Dolman

This chapter focuses on tools for climate research: biogeochemical observations and models. It discusses physical climate observations, such as temperature and humidity, and in situ observations of atmospheric composition. Turning these into reliable climate records appears to be non-trivial. The chapter describes how isotopes are used to get insight into biogeochemical processes. A special category of observations is biogeochemical proxy observations, used to gain insight into geological processes when no direct observations are possible. The example of climate proxy observations, such as those obtained via ice cores, is described. Models are increasingly used to gain insight into sensitivity of climate to changes in the forcing. Earth system modelling has become increasingly complex over the last two decades, including often detailed biogeochemical processes in the ocean and on land. The parametrization of these remains an important research subject. Inverse modelling is being used to identify sources and sinks of greenhouse gases.


1993 ◽  
Vol 18 ◽  
pp. 199-202 ◽  
Author(s):  
Chester C. Langway ◽  
Hitoshi Shoji ◽  
Atau Mitani ◽  
Henrik B. Clausen

The transformation of snow to ice under compressive stress is a very slow process unless meltwater is present. A qualitative measure of permeability variation with depth was continuously determined for various shallow-ice cores from the dry-snow zones in both Greenland and Antarctica to investigate this transformation process. Results of the study provide insight into snow densification mechanisms and generally characterize the pore close-off phenomena. Measurements show that bulk densities may be expressed as a function of overburden; pore close-off takes place when the overburden is approximately 3.0–4.5 bar.


1989 ◽  
Vol 151 ◽  
Author(s):  
R. L. Gunshor ◽  
L. A. Kolodziejski ◽  
M. Kobayashi ◽  
A. V. Nurmikko ◽  
N. Otsuka

ABSTRACTEpilayers of metastable zincblende MnSe and MnTe have been grown by molecular beam epitaxy. The MnSe structures have been used to study magnetic ordering in thin layers by means of optical and magnetic measurements. Preliminary optical reflectance measurements performed on samples of zincblende MnTe indicate a bandgap of approximately 3.15eV, while double barrier quantum structures demonstrate optical transitions corresponding to 2D electron and hole confinement. Optical measurements further provide insight into the band offsets existing between MnTe and CdTe, as well as between MnTe and ZnTe epilayers.


Author(s):  
ALEŠ KAPIČKA ◽  
EDUARD PETROVSKÝ ◽  
HANA GRISON ◽  
VILÉM PODRÁZSKÝ ◽  
PAVEL KŘÍŽEK

2019 ◽  
Vol 4 (3) ◽  
pp. 61 ◽  
Author(s):  
Giannantonio Cibin ◽  
Augusto Marcelli ◽  
Valter Maggi ◽  
Giovanni Baccolo ◽  
Dariush Hampai ◽  
...  

Airborne dust extracted from deep ice core perforations can provide chemical and mineralogical insight into the history of the climate and atmospheric conditions, with unrivalled temporal resolution, time span and richness of information. The availability of material for research and the natural complexity of the particulate, however, pose significant challenges to analytical methods. We present the developments undertaken to optimize the experimental techniques, materials and protocols for synchrotron radiation-based analysis, in particular for the acquisition of combined Synchrotron Radiation X-Ray Fluorescence and X-ray Absorption Spectroscopy data.


2017 ◽  
Vol 29 (3) ◽  
pp. 239-251 ◽  
Author(s):  
Kate M. Swanger

AbstractBuried glacier ice is common in the McMurdo Dry Valleys and under ideal climatic and geomorphological conditions may be preserved for multimillion-year timescales. This study focuses on the analysis of ~300 m2 of buried glacier ice in lower Kennar Valley, Quartermain Range. The mapped ice is clean,<10 m thick and covered by a~25 cm sandy drift. The mouth of Kennar Valley is occupied by a lobe of Taylor Glacier, an outlet glacier from Taylor Dome. Based on ice–sediment characteristics, air bubble concentrations and stable isotopic analyses from three ice cores, the lower Kennar Valley ice is glacial in origin. These data coupled with a previously reported exposure age chronology indicate that the buried ice was deposited by a late Pleistocene advance of Taylor Glacier, probably during an interglacial interval. The surface of the buried glacier ice exhibits a patterned ground morphology characterized by small, dome-shaped polygons with deep troughs. This shape possibly reflects the final stages of ice loss, as stagnant, isolated ice pinnacles sublimate in place. This study highlights how polygon morphology can be used to infer the thickness of clean buried ice and its geomorphological stability throughout Antarctica, as well as other in cold, arid landscapes.


2017 ◽  
Vol 89 (1) ◽  
pp. 333-351 ◽  
Author(s):  
Bram W. Langeveld ◽  
Dick Mol ◽  
Grant D. Zazula ◽  
Barbara Gravendeel ◽  
Marcel Eurlings ◽  
...  

AbstractMiddens (nests and caches) of Late Pleistocene arctic ground squirrels (Urocitellus parryii) that are preserved in the permafrost of Beringia archive valuable paleoecological data. Arctic ground squirrels selectively include the plant material placed in middens. To account for this selectivity bias, we used a multi-proxy approach that includes ancient DNA (aDNA) and macro- and microfossil analyses. Here, we provide insight into Pleistocene vegetation conditions using macrofossils, pollen, phytoliths and non-pollen palynomorphs, and aDNA collected from one such midden from the Yukon Territory (Canada), which was formed between 30,740 and 30,380 cal yr BP. aDNA confirmed the midden was constructed by U. parryii. We recovered 39 vascular plant and bryophyte genera and 68 fungal genera from the midden samples. Grass and other herbaceous families dominated vegetation assemblages according to all proxies. aDNA data yielded several records of vascular plants that are outside their current biogeographic range, while some of the recovered fungi yielded additional evidence for local occurrence of Picea trees during glacial conditions. We propose that future work on fossil middens should combine the study of macro- and microfossils with aDNA analysis to get the most out of these environmental archives.


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