Estimation of soil water evaporation from isotope hydrology methods in an agricultural field

These data are from this publication: Oerter, E. J., Perelet, A., Pardyjak, E., & Bowen, G. (2017). Membrane inlet laser spectroscopy to measure H and O stable isotope compositions of soil and sediment pore water with high sample throughput. Rapid Communications in Mass Spectrometry, 31(1), 75-84.

Abstract:
RATIONALE: The fast and accurate measurement of H and O stable isotope compositions (δ2H and δ18O values) of soil and sediment pore water remains an impediment to scaling-up the application of these isotopes in soil and vadose hydrology. Here we describe a method and its calibration to measuring soil and sediment pore water δ2H and δ18O values using a water vapor-permeable probe coupled to an isotope ratio infrared spectroscopy analyzer.
METHODS: We compare the water vapor probe method with a vapor direct equilibration method, and vacuum extraction with liquid water analysis. At a series of four study sites in a managed desert agroecosystem in the eastern Great Basin of North America, we use the water vapor probe to measure soil depth profiles of δ2H and δ18O values.
RESULTS: We demonstrate the accuracy of the method to be equivalent to direct headspace equilibration and vacuum extraction techniques, with increased ease of use in its application, and with analysis throughput rates greater than 7h1. The soil depth H and O stable isotope profiles show that soil properties such as contrasting soil texture and pedogenic soil horizons control the shape of the isotope profiles, which are reflective of local evaporation conditions within the soils.
CONCLUSIONS: We conclude that this water vapor probe method has potential to yield large numbers of H and O stable isotope analyses of soil and sediment waters within shorter timeframes and with increased ease than with currently existing methods.

本数据集来源于以下文献：Oerter, E. J., Perelet, A., Pardyjak, E., & Bowen, G. (2017). 采用膜进样激光光谱法（membrane inlet laser spectroscopy）实现高样品通量测定土壤与沉积物孔隙水氢、氧稳定同位素组成. 《快速质谱通讯》（Rapid Communications in Mass Spectrometry）, 31(1), 75-84.

摘要：

研究依据：快速且精准地测定土壤与沉积物孔隙水中氢、氧稳定同位素组成（δ²H和δ¹⁸O值），仍是制约这类同位素在土壤及包气带水文领域规模化应用的核心瓶颈。本研究介绍一种结合透水汽探针与同位素比值红外光谱分析仪（isotope ratio infrared spectroscopy analyzer）的测定方法，并阐述其校准流程，用于测定土壤与沉积物孔隙水的δ²H和δ¹⁸O值。

方法：本研究将透水汽探针法与蒸汽直接平衡法、真空萃取法与液态水分析方法进行对比。在北美大盆地东部一处人工管理的沙漠农业生态系统的4个研究样地中，我们采用透水汽探针法测定了土壤深度剖面的δ²H和δ¹⁸O值。

结果：本研究证实，该方法的测定精度与顶空直接平衡法、真空萃取法相当，且操作更简便，分析通量高于7样次/小时。土壤深度氢、氧稳定同位素剖面结果显示，土壤质地差异与成土土层等土壤属性决定了同位素剖面的形态，该形态可反映土壤内部的局部蒸发条件。

结论：本研究认为，相较于现有方法，该透水汽探针法可在更短时间内完成更多土壤与沉积物孔隙水的氢、氧稳定同位素分析，且操作更为简便，具备广阔的应用潜力。