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Compound-specific oxygen isotope analysis of carbohydrates as a novel tool in ecophysiology and climate research

Applicant Saurer Matthias
Number 150003
Funding scheme Project funding (Div. I-III)
Research institution Labor für Atmosphärenchemie Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Climatology. Atmospherical Chemistry, Aeronomy
Start/End 01.08.2014 - 31.07.2016
Approved amount 222'529.00
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All Disciplines (3)

Discipline
Climatology. Atmospherical Chemistry, Aeronomy
Geochemistry
Environmental Research

Keywords (5)

tree physiology; biochemistry; stable isotopes; tree rings; climate

Lay Summary (German)

Lead
Das Verhältnis von schweren und leichten Sauerstoffisotopen in der Natur ist nicht konstant, sondern variiert auf Grund von leicht unterschiedlichen physikalischen und chemischen Eigenschaften der Isotope. Die Isotopenanalytik gerade auch von Sauerstoff wird deshalb schon länger als vielseitige Methode zur Untersuchung von Veränderungen in Atmosphäre und Biosphäre eingesetzt. Zur Verfeinerung der Methodik ist nun geplant, die Isotopenverhältnisse in einzelnen Kohlenhydraten zu bestimmen.
Lay summary

Inhalt und Ziel des Forschungsprojekts

Im vorliegenden Projekt soll eine Methodik entwickelt werden, mit der Sauerstoffisotope von unterschiedlichen Komponenten eines aus Pflanzen extrahierten Konzentrats bestimmt werden können, wie z.B. Sucrose oder Glucose. Dabei wird nach der Extraktion und Reinigung des Pflanzensafts dieser chemisch so verändert, dass er bei hohen Temperaturen flüchtig wird, und in einem Gas-Chromatographen in seine Bestandteile aufgetrennt werden kann. Anschliessend erfolgt die massenspektrometrische Bestimmung der einzelnen Komponenten bezüglich Sauerstoffisotopen. Nach Entwicklung und Testen der Methode werden Pflanzen aus einem Wald in Sibirien näher untersucht, wo es darum geht, den Kohlenstoff- und Wasserhaushalt dieser empfindlichen Ökosysteme zu untersuchen, wo die Bäume (Lärchen) auf Permafrost gedeihen, der nur in den Sommermonaten in den obersten Schichten auftaut.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Mit der neuen Methode können verschiedenste Forschungsfragen in Ökophysiologie und Klimaforschung genauer beantwortet werden, bei denen bisher statt einzelner Komponenten nur das Gesamtmaterial untersucht wurde. Wir erwarten, dass so in Zukunft neue Erkenntnisse zur Reaktion von Pflanzen auf den Klimawandel gefunden werden.

Direct link to Lay Summary Last update: 29.11.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Oxygen isotope fractionations across individual leaf carbohydrates in grass and tree species δ18O of individual leaf carbohydrates
Lehmann Marco M., Gamarra Bruno, Kahmen Ansgar, Siegwolf Rolf T.W., Saurer Matthias (2017), Oxygen isotope fractionations across individual leaf carbohydrates in grass and tree species δ18O of individual leaf carbohydrates, in Plant, Cell & Environment, 40(8), 1658-1670.
A novel methylation derivatization method for δ18O analysis of individual carbohydrates with GC-Pyrolysis-IRMS
Lehmann Marco, Fischer Maria, Blees Jan, Zech Michael, Siegwolf Rolf, Saurer Matthias (2016), A novel methylation derivatization method for δ18O analysis of individual carbohydrates with GC-Pyrolysis-IRMS, in Rapid Communications in Mass Spectrometry, 30, 221-229.
The impact of an inverse climate-isotope relationship in soil water on the oxygen-isotope composition of Larix gmelinii in Siberia
Saurer Matthias, Kirdyanov Alexander, Prokushkin Anatoly, Rinne Katja, Siegwolf Rolf (2015), The impact of an inverse climate-isotope relationship in soil water on the oxygen-isotope composition of Larix gmelinii in Siberia, in New Phytologist, 209, 955-964.

Collaboration

Group / person Country
Types of collaboration
Kerstin Treydte, Swiss Federal Research Insitute WSL Birmensdorf Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Markus Leuenberger, Physics Institute, University of Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Alexander Kirdyanov, Anastasia Knorre, Anatoly Prokushkin, Institute of Forest SB RAS, Krasnoyarsk Russia (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
AGU Annual meeting Poster A new derivatization method for δ18O analysis of individual carbohydrates with GC-Pyrolysis-IRMS. 14.12.2015 San Francisco, United States of America Lehmann Marco; Saurer Matthias;
Annual Meeting of the German Association for Stable Isotope Research Talk given at a conference δ18O analysis of individual carbohydrates – a new method for GC/Pyrolysis-IRMS 28.09.2015 Heidelberg, Germany Saurer Matthias; Lehmann Marco;
EGU General Assembly Talk given at a conference 18O analysis of individual carbohydrates – a new method for GC-pyrolysis-IRMS 13.04.2015 Wien, Austria Lehmann Marco; Saurer Matthias;
Annual Meeting of the German Association for Stable Isotope Research Poster Progress in compound-specific oxygen isotope analysis of sugars 15.10.2014 München, Germany Saurer Matthias; Lehmann Marco;


Associated projects

Number Title Start Funding scheme
130112 Isotope pathway from atmosphere to the tree ring along a humidity gradient in Switzerland 01.09.2010 Project funding (Div. I-III)
128035 Tree growth and forest ecosystem functioning in Eurasia under changing climate 01.11.2009 SCOPES
136295 iTREE-Long-term variability of tree growth in a changing environment - identifying physiological mechanisms using stable C and O isotopes in tree rings. 01.04.2012 Sinergia
166162 Compound-specific dual isotope analysis for the investigation of plant response to environmental change 01.08.2016 Project funding (Div. I-III)
134864 Understanding the isotope signal of trees growing on continuous permafrost in northern Siberia 01.08.2011 Project funding (Div. I-III)

Abstract

Oxygen isotope variations in different compartments of the atmosphere, hydrosphere and the ecosystem have long been recognized as valuable source of information about current and past environmental changes. In plants, fractionation effects of the heaver 18O versus the lighter 16O have been studied in controlled and field experiments and resulted in models describing the fractionations at leaf level and within the plant as a function of exogenous and endogenous factors. This enabled valuable applications of d18O analysis in plant physiology and climate research via tree-ring analysis. To advance this technique further, however, it is necessary to better understand processes within the plant related to biochemistry, to know, for instance, how much of the isotope enrichment observed during transpiration is transferred via sucrose to the cellulose in the stem. The next important step is therefore to move from bulk analysis or analysis of total soluble carbohydrates to compound-specific isotope analysis (CSIA), as is already well implemented for stable carbon isotopes. It has proved challenging, however, to apply CSIA to oxygen isotope analysis, via GC-pyrolysis, and only very few data exist so far. Recently, we have developed a method that looks promising to obtain results at least for sucrose, using tri-methyl-silyation derivatization to make the sugars volatile and thus GC-amenable. In the work proposed here, we want (1) to improve the precision of the method to be able to resolve natural d18O variability by optimizing analytical conditions and testing alternative derivatizing reagents (2) to evaluate the method for other sugars than sucrose, mainly glucose, fructose, and raffinose, and the sugar-alcohols pinitol and myo-inositol and (3) to apply the method to samples from two experiments: a) a field study in Siberia with larch trees (Larix) and b) a lab experiment, where we will grow small larch trees under controlled conditions. From the field study, we have available already extracted and purified needle carbohydrates that were analysed for d13C with liquid chromatography within the current SNF-funded project. This unique sample set of bi-weekly collected needles, together with available d18O data from water extracted from soil of different depths, stem and needles, will enable the interpretation of d18O of sugars in the context of microclimatic conditions and source d18O variations. In the lab experiment, samples from leaves of plants grown under different relative air humidity will show the sensitivity of the isotope signal in individual sugars compared to total carbohydrates and the transfer of the isotope signal into stem cellulose.With this project, we want to provide the research community with a novel, easy-to-apply method for the oxygen isotope analysis of individual sugars. The method may potentially find wide-spread application in diverse research fields and provide new insights into plant functioning under varying environmental conditions and climate change.
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