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Multi-isotope labeling (¹³C, ¹⁸O, ²H) of fresh assimilates to trace organic matter dynamics in the plant-soil system


Studer, Mirjam S; Siegwolf, R T W; Leuenberger, M; Abiven, Samuel (2014). Multi-isotope labeling (¹³C, ¹⁸O, ²H) of fresh assimilates to trace organic matter dynamics in the plant-soil system. Biogeosciences Discussions, 11:15911-15943.

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 x nigra) for 14 days to an atmosphere enriched in ¹³CO₂ and depleted in ²H₂¹⁸O. After one 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 diffusion of vapour into the leaves (58–69%). 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 either indicates the synthesis of more condensed compounds (lignin vs. cellulose) in roots and stems, or be the result of O and H exchange and fractionation processes during 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 for the fields of plant physiology, paleoclimatic reconstruction or soil science.

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 x nigra) for 14 days to an atmosphere enriched in ¹³CO₂ and depleted in ²H₂¹⁸O. After one 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 diffusion of vapour into the leaves (58–69%). 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 either indicates the synthesis of more condensed compounds (lignin vs. cellulose) in roots and stems, or be the result of O and H exchange and fractionation processes during 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 for the fields of plant physiology, paleoclimatic reconstruction or soil science.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Geography
Dewey Decimal Classification:910 Geography & travel
Language:English
Date:2014
Deposited On:28 Nov 2014 15:51
Last Modified:08 Dec 2017 08:28
Publisher:Copernicus Publications
ISSN:1810-6285
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.5194/bgd-11-15911-2014

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