Sökning: "tree-ring cellulose."

Hittade 4 avhandlingar innehållade orden tree-ring cellulose..

  1. 1. Intramolecular isotope analysis reveals plant ecophysiological signals covering multiple timescales

    Författare :Thomas Wieloch; Jürgen Schleucher; Mats Nilsson; Gerd Gleixner; Lisa Wingate; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NMR spectroscopy; tree ring; isotope ratio; isotope effect; intramolecular 13C 12C signal; carbon allocation; acclimation; plant performance; climate reconstruction; plant ecophysiology;

    Sammanfattning : Our societies' wellbeing relies on stable and healthy environments. However, our current lifestyles, growth-oriented economic policies and the population explosion are leading to potentially catastrophic degradation of ecosystems and progressive disruption of food chains. LÄS MER

  3. 2. Monitoring climate and plant physiology using deuterium isotopomers of carbohydrates

    Författare :Angela Augusti; Jürgen Schleucher; Vaughan Hurry; Howard Griffiths; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Climate reconstruction; deuterium; elevated CO2; isotopomer; nuclear magnetic resonance; photorespiration; tree-ring cellulose.; Plant physiology; Växtfysiologi;

    Sammanfattning : Climate is changing and it is certain that this change is due to human activities. Atmospheric greenhouse gases have been rising in an unprecedented way during the last two centuries, although the land biosphere has dampened their increase by absorbing CO2 emitted by anthropogenic activities. LÄS MER

  4. 3. Deuterium isotopomers as a tool in environmental research

    Författare :Tatiana Betson; Jürgen Schleucher; Peter Högberg; Richard Robins; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; deuterium; NMR; isotopomers; CO2 response; climate reconstruction; persistent pollutants; stable isotopes; Environmental chemistry; Miljökemi;

    Sammanfattning : This thesis describes the development and the use of quantitative deuterium Nuclear Magnetic Resonance spectroscopy (NMR) as a tool in two areas of environmental research: the study of long term climate-plant interactions and the source tracking of persistent organic pollutant. Long-term interactions between plants and climate will influence climate change during this century and beyond, but cannot be studied in manipulative experiments. LÄS MER

  5. 4. Holocene climate and environmental change in high latitudes as recorded by stable isotopes in peat deposits

    Författare :Päivi Kaislahti Tillman; Steffen Holzkämper; Stefan Wastegård; Peter Kuhry; Thomas W. D. Edwards; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stable isotopes; Holocene; subarctic; climate; Sphagnum fuscum; kvartärgeologi; Quarternary Geology;

    Sammanfattning : In this thesis, stable carbon and oxygen isotopes in α-cellulose isolated from Sphagnum fuscum moss remains were used as climate proxies. The main focus was to implement the methods in records from high latitude peatlands in the Northern Hemisphere (west-central Canada and north-eastern European Russia), reconstruct palaeoclimate of the studied regions during the Holocene, and evaluate the compatibility of results with other proxy records, especially tree-ring isotope time-series. LÄS MER