Stable hydrogen isotope ratios in soil constituents: New insights into the formation of organic matter and clay minerals

土壤成分中的稳定氢同位素比率：对有机质和粘土矿物形成的新见解

基本信息

批准号：
318431048
负责人：
Professorin Dr. Yvonne Oelmann
金额：
--
依托单位：
Institut für Geographie und Geoökologie (IFGG)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/318431048?language=en
关键词：
Stable hydrogen isotope ratios soil

项目摘要

The use of stable hydrogen isotope ratios (delta2H values) in soils has up to now been limited, because part of the H pool in soil exchanges with ambient moisture and does not carry a meaningful isotope signal. This part needs to be separated from the nonexchangeable part which contains source and process information. For soil organic matter (SOM), steam equilibration of demineralized SOM with waters of known H isotope composition can be used while for clay minerals degassing at ca. 200°C under vacuum is common to separate exchangeable and nonexchangeable H. Previous work has suggested that SOM may be rapidly processed through the microorganisms during which C-bound H is exchanged in the glycolytic metabolism. Clay minerals conserve the delta2H value of ambient water at the time of formation in structural OH. We propose to study (i) the incorporation of ambient water H into the nonexchangeable H fraction (C-H bonds) in SOM and the associated isotopic fractionation during decomposition (ii) whether the soil clay fraction can be used to determine the origin of a soil sample and for relative dating of argillic B (Bt) horizons of recent soils and palaeosols. We will conduct laboratory and field incubations, establish steam equilibration for clay fractions, and analyze clay fractions of a global set of soils and of partly dated palaeo Bt horizons.

土壤中稳定的氢同位素比（Delta2h值）的使用已被限制，因为一部分H池在具有环境水分的土壤交换中，并且没有有意义的同位素信号。该部分需要与包含源和流程信息的不可汇合部分分开。对于土壤有机物（SOM），可以使用相当于已知的H同位素组成水的债务SOM的蒸汽，而粘土矿物质在ca的粘土中进行。真空下的200°C对于分离可交换和不可变的H是常见的。在结构OH中形成时，粘土矿物保留了环境水的delta2h值。我们建议研究（i）将环境水H掺入SOM中的不交换H部分（C-H键（C-H键）以及分解过程中相关的同位素分馏（ii）（ii）是否可以使用土壤粘土分数来确定土壤样品的起源和最近土壤和近期土壤和果汁质量的质量B（bt）水平的相对约定。我们将进行实验室和现场孵育，建立等效粘土分数的蒸汽，并分析一组全球土壤和部分日期的古BT视野的粘土分数。