Unterschiede
Hier werden die Unterschiede zwischen zwei Versionen angezeigt.
| Nächste Überarbeitung | Vorhergehende Überarbeitung | ||
| thesis:plantwater_accuracy [2020/02/26 11:51] – angelegt norlowski | thesis:plantwater_accuracy [2021/12/15 08:14] (aktuell) – norlowski | ||
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| Stable isotopes of water (2H, 17O and 18O) are useful tracers for investigating plant water sources, but traditional isotopic measurements via destructive sampling of plant waters are expensive and labor intensive 1,2. Isotope-ratio infrared spectroscopy (IRIS) offers a cheaper alternative and has shown potential to overcome limitations imposed by traditional methods 3,4. However, laser spectroscopic measurements of plant or soil waters can be significantly limited by spectral interferences caused by organic compounds such as methanol or ethanol 5 (Fig. 1), and even small quantities of contaminants (e.g. methanol) can generate a significant deviation from real values (Fig. 2). In this regard, organics can be co-extracted during cryogenic vacuum extraction and vapor equilibration method, which are the most common methods to sample and measure water from soil and plant samples. Recently in situ techniques have been employed to overcome limited temporal observations by increasing sampling frequency and observe dynamic water uptake processes in plants. However, the interference of organic compounds in both liquid and vapor methods hampers our ability to understand plant water uptake dynamics. In an attempt to solve this problem, IRIS manufacturers have developed software applications that identify and flag contaminated samples; however, the possibility to apply a correction to the contaminated samples has not been widely developed for different lasers and type of sample (liquid vs. vapor). | Stable isotopes of water (2H, 17O and 18O) are useful tracers for investigating plant water sources, but traditional isotopic measurements via destructive sampling of plant waters are expensive and labor intensive 1,2. Isotope-ratio infrared spectroscopy (IRIS) offers a cheaper alternative and has shown potential to overcome limitations imposed by traditional methods 3,4. However, laser spectroscopic measurements of plant or soil waters can be significantly limited by spectral interferences caused by organic compounds such as methanol or ethanol 5 (Fig. 1), and even small quantities of contaminants (e.g. methanol) can generate a significant deviation from real values (Fig. 2). In this regard, organics can be co-extracted during cryogenic vacuum extraction and vapor equilibration method, which are the most common methods to sample and measure water from soil and plant samples. Recently in situ techniques have been employed to overcome limited temporal observations by increasing sampling frequency and observe dynamic water uptake processes in plants. However, the interference of organic compounds in both liquid and vapor methods hampers our ability to understand plant water uptake dynamics. In an attempt to solve this problem, IRIS manufacturers have developed software applications that identify and flag contaminated samples; however, the possibility to apply a correction to the contaminated samples has not been widely developed for different lasers and type of sample (liquid vs. vapor). | ||
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| + | Fig. 1: Errors for (a) oxygen and (b) hydrogen stable isotope composition (δ18O and δ2H, respectively, | ||
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| + | Fig. 2. Xylem samples in dual isotope ratio space and respective 17O‐excess (per meg): (A) results for all species showing spectral contamination in dual isotope space; (B) the same samples, but distinguishing between spectrally contaminated (grey) identified visually on the ‘spectral fit residual plot‘, and not contaminated. | ||
| == Aim and research questions == | == Aim and research questions == | ||
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| - West, A. G., Goldsmith, G. R., Brooks, P. D. & Dawson, T. E. Discrepancies between isotope ratio infrared spectroscopy and isotope ratio mass spectrometry for the stable isotope analysis of plant and soil waters. Rapid Commun. Mass Spectrom. 24, 1948–1954 (2010). | - West, A. G., Goldsmith, G. R., Brooks, P. D. & Dawson, T. E. Discrepancies between isotope ratio infrared spectroscopy and isotope ratio mass spectrometry for the stable isotope analysis of plant and soil waters. Rapid Commun. Mass Spectrom. 24, 1948–1954 (2010). | ||
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