Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 12, 1865-1879, 2015
http://www.biogeosciences.net/12/1865/2015/
doi:10.5194/bg-12-1865-2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
20 Mar 2015
Multi-isotope labelling of organic matter by diffusion of 2H/18O-H2O vapour and 13C-CO2 into the leaves and its distribution within the plant
M. S. Studer1,2, R. T. W. Siegwolf2, M. Leuenberger3, and S. Abiven1 1Department of Geography, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland
2Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
3Climate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, University of Bern, Sidlerstr. 5, 3012 Bern, Switzerland
Abstract. Isotope labelling is a powerful tool to study elemental cycling within terrestrial ecosystems. Here we describe a new multi-isotope technique to label organic matter (OM).

We exposed poplars (Populus deltoides × nigra) for 14 days to an atmosphere enriched in 13CO2 and depleted in 2H218O. After 1 week, the water-soluble leaf OM (δ13C = 1346 ± 162‰) and the leaf water were strongly labelled (δ18O = −63 ± 8, δ2H = −156 ± 15‰). The leaf water isotopic composition was between the atmospheric and stem water, indicating a considerable back-diffusion of vapour into the leaves (58–69%) in the opposite direction to the net transpiration flow. The atomic ratios of the labels recovered (18O/13C, 2H/13C) were 2–4 times higher in leaves than in the stems and roots. This could be an indication of the synthesis of more condensed compounds in roots and stems (e.g. lignin vs. cellulose) or might be the result of O and H exchange and fractionation processes during phloem transport and biosynthesis.

We demonstrate that the three major OM elements (C, O, H) can be labelled and traced simultaneously within the plant. This approach could be of interdisciplinary interest in the fields of plant physiology, palaeoclimatic reconstruction or soil science.


Citation: Studer, M. S., Siegwolf, R. T. W., Leuenberger, M., and Abiven, S.: Multi-isotope labelling of organic matter by diffusion of 2H/18O-H2O vapour and 13C-CO2 into the leaves and its distribution within the plant, Biogeosciences, 12, 1865-1879, doi:10.5194/bg-12-1865-2015, 2015.
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We present a new technique to label organic matter (OM) at its place of formation by the application of 13C, 18O and 2H through the gaseous phase. The label diffused into leaves was incorporated into assimilates and was detected in plant tissues. This technique can be applied in soil sciences, e.g. to trace the decomposition pathways of soil OM inputs, or in plant physiology and palaeoclimatic reconstruction, e.g. to further investigate the origin of the 18O and 2H signal in tree ring cellulose.
We present a new technique to label organic matter (OM) at its place of formation by the...
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