Isotope ratios of nonexchangeable hydrogen in soils from different climate zones

Ruppenthal, Marc; Oelmann, Yvonne; Wilcke, Wolfgang

doi:10.1016/j.geoderma.2009.12.005

Cited by 24 publications

(56 citation statements)

References 46 publications

(102 reference statements)

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“…exchangeable bonded hydrogen (Meißner et al, 2014) in organic-rich soils on the extracted isotopic composition (Orlowski et al, 2016). The different existing exchangeable (labile) hydrogen fractions in environmental organic matter (O-, N-, and Sbonded or aromatic hydrogen) can easily interact with ambient water or water vapor (Ruppenthal et al, 2010) and thus are assumed to cause isotope effects. However, the effect of organic carbon content on isotope results obtained via extraction/equilibrium methods other than cryogenic extraction is still not known.…”

Section: Soil Type and Treatment Effects On Isotopic Signaturementioning

confidence: 99%

Intercomparison of soil pore water extraction methods for stable isotope analysis

Orlowski

Pratt

McDonnell

2016

Hydrological Processes

139

222

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Measurements of δ 2 H and δ 18 O composition of pore waters in saturated and unsaturated soil samples are routinely performed in hydrological studies. A variety of in-situ and lab-based pore water extraction methods for the analysis of the stable isotopes of water now exist.While some have been used for decades (e.g. cryogenic vacuum extraction) others are relatively new, such as direct vapor equilibration or the microwave extraction technique.Despite their broad range of application, a formal and comprehensive intercomparison of soil water extraction methods for stable isotope analysis is lacking and long overdue. Here we present an intercomparison among five commonly used lab-based pore water extraction techniques (high pressure mechanical squeezing, centrifugation, direct vapor equilibration, microwave extraction, and cryogenic extraction). We applied these extraction methods to two physicochemically different soil types that were dried and rewetted with water of known isotopic composition at three different water contents. Our results showed that the extraction approach can have a significant effect on pore water isotopic composition as all methods exhibited significant deviations from the spiked reference water, depending secondarily on the soil type and soil water content. Most pronounced, cryogenic water extraction showed large deviations from the spiked reference water, whereas mechanical squeezing and centrifugation provided results closest to the spiked water for both soil types. We also compared results for each extraction method -where liquid water was obtained -on both an OA-ICOS and IRMS. Differences between these two analytical instruments were negligible for these organic compound-free waters. We suggest that users of soil water extraction approaches carefully choose an extraction technique that is suitable for the specific research question, adapted to the dominant soil type and water content of the study.This article is protected by copyright. All rights reserved.

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Section: Soil Type and Treatment Effects On Isotopic Signaturementioning

confidence: 99%

Intercomparison of soil pore water extraction methods for stable isotope analysis

Orlowski

Pratt

McDonnell

2016

Hydrological Processes

139

222

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“…They have demonstrated that water is the main donor of hydrogen atoms in the non-exchangeable pool within the biosynthesis cycle (Baillif et al, 2009). Ruppenthal and colleagues have shown as well that precipitation contributes up to 80 % of the isotopic composition of non-exchangeable hydrogen (Ruppenthal et al, 2010). Moreover, the incorporation of water hydrogen is favored by the strength of the C-H bond breakage.…”

Section: Preservation Of the Organic Substrate Hydrogen In Biosynthesesmentioning

confidence: 99%

“…The isotopic composition of the NEH preserves the initial composition of the plant and registers the rain isotopic composition (Sessions et al, 2004;Schimmelmann et al, 2006;Ruppenthal et al, 2010). The δ 2 H of water and exchangeable hydrogen is not stable.…”

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confidence: 96%

Hydrogen dynamics in soil organic matter as determined by <sup>13</sup>C and <sup>2</sup>H labeling experiments

et al. 2016

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Abstract. Understanding hydrogen dynamics in soil organic matter is important to predict the fate of 3 H in terrestrial environments. One way to determine hydrogen fate and to point out processes is to examine the isotopic signature of the element in soil. However, the non-exchangeable hydrogen isotopic signal in soil is complex and depends on the fate of organic compounds and microbial biosyntheses that incorporate water-derived hydrogen. To decipher this complex system and to understand the close link between hydrogen and carbon cycles, we followed labeled hydrogen and labeled carbon throughout near-natural soil incubations. We performed incubation experiments with three labeling conditions: 1 -13 C 2 H double-labeled molecules in the presence of 1 H 2 O; 2 -13 C-labeled molecules in the presence of 2 H 2 O; 3 -no molecule addition in the presence of 2 H 2 O. The preservation of substrate-derived hydrogen after 1 year of incubation (ca. 5 % in most cases) was lower than the preservation of substrate-derived carbon (30 % in average). We highlighted that 70 % of the C-H bonds are broken during the degradation of the molecule, which permits the exchange with water hydrogen. Added molecules are used more for trophic resources. The isotopic composition of the non-exchangeable hydrogen was mainly driven by the incorporation of water hydrogen during microbial biosynthesis. It is linearly correlated with the amount of carbon that is degraded in the soil. The quantitative incorporation of water hydrogen in bulk material and lipids demonstrates that nonexchangeable hydrogen exists in both organic and mineralbound forms. The proportion of the latter depends on soil type and minerals. This experiment quantified the processes affecting the isotopic composition of non-exchangeable hydrogen, and the results can be used to predict the fate of tritium in the ecosystem or the water deuterium signature in organic matter.

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“…organic matter. An interesting approach to overcome this problem may therefore be the sample equilibration method proposed by Schimmelmann [65] and Ruppenthal et al [14], which allows determining δ 2 H values for the non-exchangeable hydrogen soil pools only. Second, distinct organic pools have different δ 2 H values, for example, lipids are relatively 2 H-depleted, whereas carbohydrates are relatively 2 H-enriched.…”

Section: Bulk δ 2 H Values Of the O-layers And The A H -Horizons Showmentioning

confidence: 99%

“…The application of these proxies to bulk plant, soil or sediment samples [13,14] is, however, limited or at least complicated because bulk material is composed of many different organic and inorganic pools characterised by different isotope values, resulting in a mixed isotope signal. Furthermore, certain pools are prone to post-sedimentary hydrogen exchange reactions [15,16].…”

Section: Introductionmentioning

confidence: 99%

Don-alkane biomarkers in soils/sediments reflect theδ²H isotopic composition of precipitation? A case study from Mt. Kilimanjaro and implications for paleoaltimetry and paleoclimate research

Zech

Różański

et al. 2015

Isotopes in Environmental and Health Studies

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During the last decade compound-specific deuterium ((2)H) analysis of plant leaf wax-derived n-alkanes has become a promising and popular tool in paleoclimate research. This is based on the widely accepted assumption that n-alkanes in soils and sediments generally reflect δ(2)H of precipitation (δ(2)H(prec)). Recently, several authors suggested that δ(2)H of n-alkanes (δ(2)H(n-alkanes)) can also be used as a proxy in paleoaltimetry studies. Here, we present results from a δ(2)H transect study (∼1500 to 4000 m above sea level [a.s.l.]) carried out on precipitation and soil samples taken from the humid southern slopes of Mt. Kilimanjaro. Contrary to earlier suggestions, a distinct altitude effect in δ(2)H(prec) is present above ∼2000 m a.s.l., that is, δ(2)H(prec) values become more negative with increasing altitude. The compound-specific δ(2)H values of nC27 and nC29 do not confirm this altitudinal trend, but rather become more positive both in the O-layers (organic layers) and the Ah-horizons (mineral topsoils). Although our δ(2)H(n-alkane) results are in agreement with previously published results from the southern slopes of Mt. Kilimanjaro [Peterse F, van der Meer M, Schouten S, Jia G, Ossebaar J, Blokker J, Sinninghe Damsté J. Assessment of soil n-alkane δD and branched tetraether membrane lipid distributions as tools for paleoelevation reconstruction. Biogeosciences. 2009;6:2799-2807], a re-interpretation is required given that the δ(2)H(n-alkane) results do not reflect the δ(2)H(prec) results. The theoretical framework for this re-interpretation is based on the evaporative isotopic enrichment of leaf water associated with the transpiration process. Modelling results show that relative humidity, decreasing considerably along the southern slopes of Mt. Kilimanjaro (from 78% in ∼2000 m a.s.l. to 51% in 4000 m a.s.l.), strongly controls δ(2)H(leaf water). The modelled (2)H leaf water enrichment along the altitudinal transect matches well the measured (2)H leaf water enrichment as assessed by using the δ(2)H(prec) and δ(2)H(n-alkane) results and biosynthetic fractionation during n-alkane biosynthesis in leaves. Given that our results clearly demonstrate that n-alkanes in soils do not simply reflect δ(2)H(prec) but rather δ(2)H(leaf water), we conclude that care has to be taken not to over-interpret δ(2)H(n-alkane) records from soils and sediments when reconstructing δ(2)H of paleoprecipitation. Both in paleoaltimetry and in paleoclimate studies changes in relative humidity and consequently in δ(2)H(n-alkane) values can completely mask altitudinally or climatically controlled changes in δ(2)H(prec).

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Isotope ratios of nonexchangeable hydrogen in soils from different climate zones

Cited by 24 publications

References 46 publications

Intercomparison of soil pore water extraction methods for stable isotope analysis

Intercomparison of soil pore water extraction methods for stable isotope analysis

Hydrogen dynamics in soil organic matter as determined by <sup>13</sup>C and <sup>2</sup>H labeling experiments

Don-alkane biomarkers in soils/sediments reflect theδ²H isotopic composition of precipitation? A case study from Mt. Kilimanjaro and implications for paleoaltimetry and paleoclimate research

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Isotope ratios of nonexchangeable hydrogen in soils from different climate zones

Cited by 24 publications

References 46 publications

Intercomparison of soil pore water extraction methods for stable isotope analysis

Intercomparison of soil pore water extraction methods for stable isotope analysis

Hydrogen dynamics in soil organic matter as determined by &lt;sup&gt;13&lt;/sup&gt;C and &lt;sup&gt;2&lt;/sup&gt;H labeling experiments

Don-alkane biomarkers in soils/sediments reflect theδ2H isotopic composition of precipitation? A case study from Mt. Kilimanjaro and implications for paleoaltimetry and paleoclimate research

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Product

Resources

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Hydrogen dynamics in soil organic matter as determined by <sup>13</sup>C and <sup>2</sup>H labeling experiments

Don-alkane biomarkers in soils/sediments reflect theδ²H isotopic composition of precipitation? A case study from Mt. Kilimanjaro and implications for paleoaltimetry and paleoclimate research