The interpretation of the stable isotope signatures of water (2H and 18O) from soils and plants in many research disciplines relies on accurate, high-precision measurements (Wassenaar et al., 2012). Cryogenic water extraction is the most widely used laboratory-based removal technique for soil and plant samples. For soils, the first worldwide round robin laboratory intercomparison showed significant differences in the isotope results from 16 participating labs for two soil types at two water contents (Orlowski et al., 2018). However, for cryogenic extractions from plants the community lacks clear recommendations for standardized water extraction conditions. A recent study by Chen et al. (2020) highlighted the need to perform such interlab comparison and to determine cryogenic extraction related isotope effects on the obtained δ2H and δ18O results.

The aim of this thesis is to perform an interlab comparison between different labs using cryogenic water extraction. Water extractions would be performed by the individual labs on different predefined plant materials with predefined and labs’ own extraction protocols. Obtained isotope samples would be compared for their δ2H and δ18O results.

Laborarbeit, Statistik, Kreativität

Dr. Natalie Orlowski: natalie.orlowski@hydrology.uni-freiburg.de; Tel. +49 (0)761 / 203-9283

Dr. Barbara Herbstritt: barbara.herbstritt@hydrology.uni-freiburg.de; Tel. +49 (0)761 / 203- 3539

Deutsch/Englisch

• Chen, Y., Helliker, B. R., Tang, X., Li, F., Zhou, Y. and Song, X.: Stem water cryogenic extraction biases estimation in deuterium isotope composition of plant source water, PNAS, 117(52), 33345–33350, https://doi.org/10.1073/pnas.2014422117, 2020.
• Orlowski, N., Breuer, L., Angeli, N., Boeckx, P., Brumbt, C., Cook, C. S., Dubbert, M., Dyckmans, J., Gallagher, B., Gralher, B., Herbstritt, B., Hervé-Fernández, P., Hissler, C., Koeniger, P., Legout, A., Macdonald, C. J., Oyarzún, C., Redelstein, R., Seidler, C., Siegwolf, R., Stumpp, C., Thomsen, S., Weiler, M., Werner, C. and McDonnell, J. J.: Inter-laboratory comparison of cryogenic water extraction systems for stable isotope analysis of soil water, Hydrol. Earth Syst. Sci., 22(7), 3619–3637, https://doi.org/10.5194/hess-22-3619-2018, 2018.
• Wassenaar, L. I., Ahmad, M., Aggarwal, P., van Duren, M., Pöltenstein, L., Araguas, L. and Kurttas, T.: Worldwide proficiency test for routine analysis of δ2H and δ18O in water by isotope-ratio mass spectrometry and laser absorption spectroscopy, Rapid Commun. Mass Spectrom., 26(15), 1641–1648, https://doi.org/10.1002/rcm.6270, 2012.

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