Validation and application of a cryogenic vacuum extraction system for soil and plant water extraction for isotope analysis
Validation and application of a cryogenic vacuum extraction system for soil and plant water extraction for isotope analysis
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DOI：
10.5194/jsss-2-179-2013
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发表时间：
2013-11
影响因子：
1
通讯作者：
N. Orlowski;H. Frede;N. Brüggemann;L. Breuer
中科院分区：
文献类型：
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作者：
N. Orlowski;H. Frede;N. Brüggemann;L. Breuer
抽象的。在植物、土壤和水文学研究中，水的稳定同位素分析通常需要从植物或土壤样品中提取水。低温真空提取是获得此类水样的最广泛使用和最准确的提取方法之一。在这里，我们提出了一种新的设计，低温真空提取系统与18个提取槽和创新的机制，以通风的真空系统后提取。这种移动的和可扩展的多端口提取系统通过提供每天同时提取大量样品的可能性，克服了捕获未分级提取的水样品所需的时间瓶颈。通风系统通过用高纯度氮气吹扫每个样品来防止在干燥过程中水蒸气的损失或混合。一组系统功能测试表明，萃取装置保证了稳定的萃取条件，萃取水样的同位素组成没有变化。令人惊讶的是，干燥和再水化土壤的提取物显示出添加的水和提取物的同位素组成的显着差异。这一观察结果挑战了低温提取系统完全提取土壤水的假设。此外，在植物吸水研究中，氢和氧同位素数据得到了不同的结果，在植物真正吸水的深度的定义方面提出了问题。结果质疑是否可以使用一个标准的统一的方法，固定提取时间，因为它是经常做的，建立和广泛使用的低温真空蒸馏法。
Abstract. Stable isotopic analysis of water in plant, soil, and hydrological studies often requires the extraction of water from plant or soil samples. Cryogenic vacuum extraction is one of the most widely used and accurate extraction methods to obtain such water samples. Here, we present a new design of a cryogenic vacuum extraction system with 18 extraction slots and an innovative mechanism to aerate the vacuum system after extraction. This mobile and extendable multi-port extraction system overcomes the bottleneck of time required for capturing unfractionated extracted water samples by providing the possibility to extract a larger number of samples per day simultaneously. The aeration system prevents the loss or mixture of water vapor during defrosting by purging every sample with high-purity nitrogen gas. A set of system functionality tests revealed that the extraction device guarantees stable extraction conditions with no changes in the isotopic composition of the extracted water samples. Surprisingly, extractions of dried and rehydrated soils showed significant differences of the isotopic composition of the added water and the extracts. This observation challenges the assumption that cryogenic extraction systems to fully extract soil water. Furthermore, in a plant water uptake study different results for hydrogen and oxygen isotope data were obtained, raising problems in the definition from which depths plants really take up water. Results query whether the well-established and widely used cryogenic vacuum distillation method can be used in a standard unified method of fixed extraction times as it is often done.