ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2014-07-22
    Description: Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene epoch. However, the same thermokarst lakes can also sequester carbon, and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. Although methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial timescales. We assess thermokarst-lake carbon feedbacks to climate with an atmospheric perturbation model and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000 years ago. High rates of Holocene carbon accumulation in 20 lake sediments (47 +/- 10 grams of carbon per square metre per year; mean +/- standard error) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160 petagrams of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 per cent (ref. 6). The carbon in perennially frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears, potentially negating the climate stabilization provided by thermokarst lakes during the late Holocene.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Anthony, K M Walter -- Zimov, S A -- Grosse, G -- Jones, M C -- Anthony, P M -- Chapin, F S 3rd -- Finlay, J C -- Mack, M C -- Davydov, S -- Frenzel, P -- Frolking, S -- England -- Nature. 2014 Jul 24;511(7510):452-6. doi: 10.1038/nature13560. Epub 2014 Jul 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Water and Environmental Research Center, University of Alaska, Fairbanks, Alaska 99775-5860, USA. ; Northeast Scientific Station, Pacific Institute for Geography, Far-East Branch, Russian Academy of Sciences, Cherskii 678830, Russia. ; 1] Geophysical Institute, University of Alaska, Fairbanks, Alaska 99775-7320, USA [2] Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam 14473, Germany. ; 1] Water and Environmental Research Center, University of Alaska, Fairbanks, Alaska 99775-5860, USA [2] US Geological Survey, Reston, Virginia 20192, USA. ; Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775-7000, USA. ; Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, Minnesota 55108, USA. ; Department of Biology, University of Florida, Gainesville, Florida 32611, USA. ; Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany. ; Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire 03824-3525, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25043014" target="_blank"〉PubMed〈/a〉
    Keywords: Alaska ; Atmosphere/chemistry ; Canada ; Carbon Dioxide/analysis ; *Carbon Sequestration ; Climate ; Freezing ; Geologic Sediments/chemistry ; Greenhouse Effect ; History, Ancient ; Lakes/*chemistry ; Methane/analysis ; Siberia ; Soil/chemistry ; Temperature
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2004-11-30
    Description: The widespread extinctions of large mammals at the end of the Pleistocene epoch have often been attributed to the depredations of humans; here we present genetic evidence that questions this assumption. We used ancient DNA and Bayesian techniques to reconstruct a detailed genetic history of bison throughout the late Pleistocene and Holocene epochs. Our analyses depict a large diverse population living throughout Beringia until around 37,000 years before the present, when the population's genetic diversity began to decline dramatically. The timing of this decline correlates with environmental changes associated with the onset of the last glacial cycle, whereas archaeological evidence does not support the presence of large populations of humans in Eastern Beringia until more than 15,000 years later.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shapiro, Beth -- Drummond, Alexei J -- Rambaut, Andrew -- Wilson, Michael C -- Matheus, Paul E -- Sher, Andrei V -- Pybus, Oliver G -- Gilbert, M Thomas P -- Barnes, Ian -- Binladen, Jonas -- Willerslev, Eske -- Hansen, Anders J -- Baryshnikov, Gennady F -- Burns, James A -- Davydov, Sergei -- Driver, Jonathan C -- Froese, Duane G -- Harington, C Richard -- Keddie, Grant -- Kosintsev, Pavel -- Kunz, Michael L -- Martin, Larry D -- Stephenson, Robert O -- Storer, John -- Tedford, Richard -- Zimov, Sergei -- Cooper, Alan -- New York, N.Y. -- Science. 2004 Nov 26;306(5701):1561-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Henry Wellcome Ancient Biomolecules Centre, Oxford University, South Parks Road, Oxford OX13PS, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15567864" target="_blank"〉PubMed〈/a〉
    Keywords: Alaska ; Animals ; Bayes Theorem ; *Bison/classification/genetics ; Canada ; China ; *Climate ; DNA, Mitochondrial/genetics ; Environment ; *Fossils ; Genetic Variation ; Genetics, Population ; Human Activities ; Humans ; North America ; Phylogeny ; Population Dynamics ; Sequence Analysis, DNA ; Time
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2012-03-03
    Description: High-latitude northern rivers export globally significant quantities of dissolved organic carbon (DOC) to the Arctic Ocean. Climate change, and its associated impacts on hydrology and potential mobilization of ancient organic matter from permafrost, is likely to modify the flux, composition, and thus biogeochemical cycling and fate of exported DOC in the Arctic. This study examined DOC concentration and the composition of dissolved organic matter (DOM) across the hydrograph in Siberia's Kolyma River, with a particular focus on the spring freshet period when the majority of the annual DOC load is exported. The composition of DOM within the Kolyma basin was characterized using absorbance-derived measurements (absorbance coefficient a330, specific UV absorbance (SUVA254), and spectral slope ratio SR) and fluorescence spectroscopy (fluorescence index and excitation-emission matrices (EEMs)), including parallel factor analyses of EEMs. Increased surface runoff during the spring freshet led to DOM optical properties indicative of terrestrial soil inputs with high humic-like fluorescence, SUVA254, and low SR and fluorescence index (FI). Under-ice waters, in contrast, displayed opposing trends in optical properties representing less aromatic, lower molecular weight DOM. We demonstrate that substantial losses of DOC can occur via biological (∼30% over 28 days) and photochemical pathways (〉29% over 14 days), particularly in samples collected during the spring freshet. The emerging view is therefore that of a more dynamic and labile carbon pool than previously thought, where DOM composition plays a fundamental role in controlling the fate and removal of DOC at a pan-Arctic scale.
    Print ISSN: 0148-0227
    Topics: Biology , Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1573-8973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1573-8922
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A feasibility study is made of the use of electrical models in a seismoacoustic study of the failure process of fibers (rods). Specific models are proposed for the case of the failure of a thin glass rod. The output signal of the electrical model is compared with the experimentally recorded elastic pulse produced upon the failure of the glass specimen. The close correspondence between the seismoacoustic pulse and the output signal of the electrical model is pointed out.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1573-8922
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The dispersion equation is derived for axisymmetric (longitudinal and torsional) normal vibrations in oriented glass-reinforced plastics. The low-frequency case is examined in detail. The frequency limits of applicability of the method of substituting a homogeneous medium for the composite (GRP) are estimated. The dependence of the vibration propagation velocity on glass content is calculated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Metal science and heat treatment 23 (1981), S. 620-625 
    ISSN: 1573-8973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1573-8973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1573-9120
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Russian physics journal 25 (1982), S. 902-905 
    ISSN: 1573-9228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the quasiharmonic approximation, the phonon Green's function of crystal deformation is determined and the dependence of the frequency on the deformation is found. The results obtained are applied to the description of isothermal and adiabatic elastic moduli.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...