GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 65 (1996), S. 131-136 
    ISSN: 0268-2575
    Schlagwort(e): acidity poisoning ; isopropanol dehydration ; lithium-doped alumina catalysts ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effect of lithium addition to γ-Al2O3 on the acidity and on the catalytic behaviour in the isopropanol dehydration reaction is studied. Results show that there is an important blocking or poisoning effect of lithium on the Lewis Al3+ sites of the alumina surface; these sites play an important role in the isopropanol dehydration reaction to di-isopropylether and propylene. The di-isopropylether formation is drastically reduced by lithium addition, while the propylene formation can be maintained, even at a high lithium content, by increasing the reaction temperature. Results are interpreted by considering that the ether would be produced by a concerted mechanism (E2), and the olefin formation could be carried out by both E2 or E1 mechanisms.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Publikationsdatum: 2024-03-19
    Beschreibung: Forests are a substantial terrestrial carbon sink, but anthropogenic changes in land \nuse and climate have considerably reduced the scale of this system1 \n. Remote-sensing \nestimates to quantify carbon losses from global forests2\xe2\x80\x935 \n are characterized by \nconsiderable uncertainty and we lack a comprehensive ground-sourced evaluation to \nbenchmark these estimates. Here we combine several ground-sourced6 \n and satellitederived approaches2,7,8 \n to evaluate the scale of the global forest carbon potential \noutside agricultural and urban lands. Despite regional variation, the predictions \ndemonstrated remarkable consistency at a global scale, with only a 12% diference \nbetween the ground-sourced and satellite-derived estimates. At present, global forest \ncarbon storage is markedly under the natural potential, with a total defcit of 226\xe2\x80\x89Gt \n(model range\xe2\x80\x89=\xe2\x80\x89151\xe2\x80\x93363\xe2\x80\x89Gt) in areas with low human footprint. Most (61%, 139\xe2\x80\x89Gt\xe2\x80\x89C) \nof this potential is in areas with existing forests, in which ecosystem protection can \nallow forests to recover to maturity. The remaining 39% (87\xe2\x80\x89Gt\xe2\x80\x89C) of potential lies in \nregions in which forests have been removed or fragmented. Although forests cannot \nbe a substitute for emissions reductions, our results support the idea2,3,9 \n that the \nconservation, restoration and sustainable management of diverse forests ofer \nvaluable contributions to meeting global climate and biodiversity targets.
    Schlagwort(e): Multidisciplinary
    Repository-Name: National Museum of Natural History, Netherlands
    Materialart: info:eu-repo/semantics/article
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Publikationsdatum: 2024-03-06
    Beschreibung: Understanding what controls global leaf type variation in trees is crucial for \ncomprehending their role in terrestrial ecosystems, including carbon, water \nand nutrient dynamics. Yet our understanding of the factors infuencing \nforest leaf types remains incomplete, leaving us uncertain about the global \nproportions of needle-leaved, broadleaved, evergreen and deciduous \ntrees. To address these gaps, we conducted a global, ground-sourced \nassessment of forest leaf-type variation by integrating forest inventory \ndata with comprehensive leaf form (broadleaf vs needle-leaf) and habit \n(evergreen vs deciduous) records. We found that global variation in leaf \nhabit is primarily driven by isothermality and soil characteristics, while leaf \nform is predominantly driven by temperature. Given these relationships, \nwe estimate that 38% of global tree individuals are needle-leaved evergreen, \n29% are broadleaved evergreen, 27% are broadleaved deciduous and \n5% are needle-leaved deciduous. The aboveground biomass distribution \namong these tree types is approximately 21% (126.4\xe2\x80\x89Gt), 54% (335.7\xe2\x80\x89Gt), 22% \n(136.2\xe2\x80\x89Gt) and 3% (18.7\xe2\x80\x89Gt), respectively. We further project that, depending \non future emissions pathways, 17\xe2\x80\x9334% of forested areas will experience \nclimate conditions by the end of the century that currently support a \ndiferent forest type, highlighting the intensifcation of climatic stress on \nexisting forests. By quantifying the distribution of tree leaf types and their \ncorresponding biomass, and identifying regions where climate change will \nexert greatest pressure on current leaf types, our results can help improve \npredictions of future terrestrial ecosystem functioning and carbon cycling.
    Repository-Name: National Museum of Natural History, Netherlands
    Materialart: info:eu-repo/semantics/article
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...