Technical note: A new laboratory approach to extract soil water for stable isotope analysis from large soil samples
<p>A correct soil water extraction represents an initial step in stable water isotope analysis. With this aim, we present a new soil water extraction method based on the principle of complete evaporation and condensation of the soil water in a closed circuit. The proposed device has four extra...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://hess.copernicus.org/articles/29/2863/2025/hess-29-2863-2025.pdf |
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| Summary: | <p>A correct soil water extraction represents an initial step in stable water isotope analysis. With this aim, we present a new soil water extraction method based on the principle of complete evaporation and condensation of the soil water in a closed circuit. The proposed device has four extraction slots and can be used up to two times a day. Owing to its simple design, there is no need for any chemicals, gases, or high-pressure or high-temperature regimes. The experimental tests proved that the extraction itself does not cause any major isotope fractionation effects leading to erroneous results. Extraction of pure-water samples shifts the isotope composition by 0.04 <span class="inline-formula">±</span> 0.06 ‰ and 0.06 <span class="inline-formula">±</span> 0.35 ‰ for <span class="inline-formula"><i>δ</i><sup>18</sup></span>O and <span class="inline-formula"><i>δ</i><sup>2</sup></span>H, respectively. Soil water extraction tests were conducted for five distinct soil types (loamy sand, sandy loam, sandy clay, silt loam, and clay) using 40–150 g of pre-oven-dried soil, which was subsequently rehydrated to 10 % and 20 % water content. The shift in the isotopic composition of these tests ranged between <span class="inline-formula">−</span>0.04 ‰ and 0.07 ‰ for <span class="inline-formula"><i>δ</i><sup>18</sup></span>O and 0.4 ‰ and 1.3 ‰ for <span class="inline-formula"><i>δ</i><sup>2</sup></span>H, with the standard deviations of <span class="inline-formula">±</span> (0.08–0.25) ‰ and <span class="inline-formula">±</span> (0.34–0.58) ‰ for <span class="inline-formula"><i>δ</i><sup>18</sup></span>O and <span class="inline-formula"><i>δ</i><sup>2</sup></span>H, respectively. The results exhibit high accuracy, which makes this method suitable for high-precision studies where unambiguous determination of the water origin is required.</p> |
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| ISSN: | 1027-5606 1607-7938 |