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Equilibrium isotope fractionation factors of H exchange between steam and soil clay fractions

Merseburger, Stefan ORCID iD icon 1; Kessler, Arnim; Oelmann, Yvonne; Wilcke, Wolfgang ORCID iD icon 1
1 Institut für Geographie und Geoökologie (IFGG), Karlsruher Institut für Technologie (KIT)

Abstract:

Rationale

Steam equilibration overcomes the problem of the traditional measurements of H isotope compositions, which leave an arbitrary amount of adsorbed water in the sample, by controlling for the entire exchangeable H pool, including adsorbed water and hydroxyl-H. However, the use of steam equilibration to determine nonexchangeable stable H isotope compositions in environmental media (expressed as δ2Hn values) by mathematically eliminating the influence of exchangeable H after sample equilibration with waters of known H-isotopic composition requires the knowledge of the equilibrium isotope fractionation factor between steam-H and exchangeable H of the sample (αex-w), which is frequently unknown.
Methods

We developed a new method to determine the αex-w values for clay minerals, topsoil clay fractions, and mica by manipulating the contributions of exchangeable H to the total H pool via different degrees of post-equilibration sample drying. We measured the δ2H values of steam-equilibrated mineral and soil samples using elemental analyzer-pyrolysis-isotope ratio mass spectrometry.
Results

The αex-w values of seven clay minerals ranged from 1.071 to 1.140, and those of 19 topsoil clay fractions ranged from 0.885 to 1.216. ... mehr

Zugehörige Institution(en) am KIT Institut für Geographie und Geoökologie (IFGG)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 30.05.2023
Sprache Englisch
Identifikator ISSN: 0951-4198, 1097-0231
KITopen-ID: 1000157307
Erschienen in Rapid Communications in Mass Spectrometry
Verlag John Wiley and Sons
Band 37
Heft 10
Seiten Art.-Nr. e9499
Vorab online veröffentlicht am 27.02.2023
Nachgewiesen in Web of Science
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Scopus
Dimensions
Relationen in KITopen
Globale Ziele für nachhaltige Entwicklung Ziel 15 – Leben an Land

Verlagsausgabe §
DOI: 10.5445/IR/1000157307
Veröffentlicht am 27.03.2023
Seitenaufrufe: 92
seit 27.03.2023
Downloads: 86
seit 07.08.2023
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