Unterschiede
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thesis:plant_available_soil_water_pools [2019/01/28 12:39] – norlowski | thesis:plant_available_soil_water_pools [2020/10/15 11:57] (aktuell) – norlowski | ||
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- | ==== Isotopic determination | + | ==== Intercomparison |
- | == Problemstellung | + | == Background |
- | An increasing number of scientists and disciplines around the world are benefitting from the application of stable water isotope techniques (2H and 18O) –, especially in plant ecology and ecohydrology. | + | An increasing number of scientists and disciplines around the world are benefitting from the application of stable water isotope techniques (δ2H and δ18O), especially in plant ecology and ecohydrology. |
- | A critical issue is that we know little about which soil water extraction method captures which soil water pool (mobile to tightly bounded water). Attempting to unravel plant available soil water pools, Brooks et al. (2) introduced a new soil water concept assuming that two independent (decoupled) soil water pools exist in the soil (the two water world hypothesis). Accordingly, | + | == Aim == |
- | == Ziel der Arbeit == | + | In this study, we will compare different isotopic sampling techniques in plant and soil that involves in situ measurements of δ2H, δ18O, δ17O and different destructive water extraction techniques (e.g. centrifugation, |
- | In this study, we would like to test this hypothesis by isotopically determining the plant available soil water pools by mimicking the pressure plants apply for water uptake. For this purpose, recently developed polymer tensiometers would be used (4). The determined pressure would accordingly be applied for soil water extractions for isotope analyses. | + | {{ : |
+ | Fig. 1: Experimental setup including ecohydrological and isotopic measurement equipment. | ||
- | Against this background, the potential candidate would: | + | Against this background, the potential candidate would: |
- | * Setup a greenhouse | + | * Extend an existing tree pot experiment |
- | * Sample different plant and soil materials for isotope analyses | + | * Compare in-situ (vapour) vs. destructive |
- | * Conduct | + | * Analyze, interpret |
- | * Determine isotopic differences between different pressure levels | + | |
- | * Analyze and interpret | + | |
- | == Herausforderungen == | ||
- | The student/s should be interested in conducting lab work and be familiar with statistical software, such as R or Python. | + | == Challenges == |
- | == Betreuung/Kontakt == | + | The student/s should be interested in conducting field and lab work and be familiar with statistical software, such as R or Python. |
- | This project is in collaboration with Utrecht University and Wageningen University. The greenhouse experiment will be setup at Utrecht University and the lab work will be conducted at University of Freiburg. | + | == Supervision/ |
- | * Natalie Orlowski, University of Freiburg, Germany, Tel. +49761 203 9283, natalie.orlowski@hydrology.uni-freiburg.de | + | Natalie Orlowski: natalie.orlowski@hydrology.uni-freiburg.de; Tel. 0761 - 203-9283 |
- | * Hugo de Boer, Utrecht University, Netherlands, | + | This project is in collaboration with Magali Nehemy (Global Institute for Water Security, Saskatoon, CA) and Paula Martín-Gómez (INRA Bordeaux, FR). |
- | * Martine van der Ploeg, Wageningen University, Netherlands, Tel. +31317483714, | + | |
- | == Sprache | + | == Language |
English | English | ||
- | == Literatur | + | == Literature |
- | - Orlowski, N., Pratt, D. L. & McDonnell, J. J. Intercomparison of soil pore water extraction methods for stable isotope analysis. Hydrol. Process. 30, 3434–3449 | + | - Sprenger M, Seeger S, Blume T, Weiler M. Travel times in the vadose zone: Variability in space and time. Water Resour Res. 52(8): |
- Brooks, J., R., Barnard, H., R., Coulombe, R. & McDonnell, J., J. Ecohydrologic separation of water between trees and streams in a Mediterranean climate. Nature Geosci 3, 100–104 (2010). | - Brooks, J., R., Barnard, H., R., Coulombe, R. & McDonnell, J., J. Ecohydrologic separation of water between trees and streams in a Mediterranean climate. Nature Geosci 3, 100–104 (2010). | ||
+ | - Dawson TE, Ehleringer JR (1993) Isotopic enrichment of water in the ‘woody’ tissues of plants: Implications for plant water source, water uptake, and other studies which use the stable isotopic composition of cellulose. Geochim Cosmochim Acta 57: | ||
+ | - Orlowski, N., Pratt, D. L. & McDonnell, J. J. Intercomparison of soil pore water extraction methods for stable isotope analysis. Hydrol. Process. 30, 3434–3449 (2016). | ||
+ | - Millar C, Pratt D, Schneider DJ, McDonnell JJ. A comparison of extraction systems for plant water stable isotope analysis. Rapid Commun Mass Spectrom. 32(13): | ||
+ | - Martín‐Gómez, | ||
+ | - Nehemy, M. F., Millar, C., Janzen, K., Gaj, M., Pratt, D. L., Laroque, C. P., & McDonnell, J. J.. 17O‐excess as a detector for co‐extracted organics in vapor analyses of plant isotope signatures. Rapid Commun Mass Spectrom. 33(16), 1301-1310 (2019). | ||
- McDonnell, Jeffrey J. 2014. ‘The Two Water Worlds Hypothesis: Ecohydrological Separation of Water between Streams and Trees?’ Wiley Interdisciplinary Reviews: Water 1 (4): 323–29. doi: | - McDonnell, Jeffrey J. 2014. ‘The Two Water Worlds Hypothesis: Ecohydrological Separation of Water between Streams and Trees?’ Wiley Interdisciplinary Reviews: Water 1 (4): 323–29. doi: | ||
- | - Ploeg, M. J. van der, H. P. A. Gooren, G. Bakker, C. W. Hoogendam, C. Huiskes, L. K. Koopal, H. Kruidhof, and G. H. de Rooij. 2010. ‘Polymer Tensiometers with Ceramic Cones: Direct Observations of Matric Pressures in Drying Soils’. Hydrol. Earth Syst. Sci. 14 (10): 1787–99. doi: | ||
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