EGU2020-4414
https://doi.org/10.5194/egusphere-egu2020-4414
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Seasonal variability and differences in n-alkane deltaD values between dicotyledonous tree and monocotyledonous grass

Xiaolong Zhang1, Baiqing Xu2, Franziska Günther3, and Gerd Gleixner4
Xiaolong Zhang et al.
  • 1Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China (zxl1986@itpcas.ac.cn)
  • 2CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing, China (baiqing@itpcas.ac.cn)
  • 3Leibniz Centre for Tropical Marine Research, Bremen, Germany (franziska.guenther@leibniz-zmt.de)
  • 4Max Planck Institute for Biogeochemistry, Jena, Germany (gerd.gleixner@bgc-jena.mpg.de)

Understanding seasonal variability in n-alkane δD values (δDwax) among plant forms/lineages and the underlying physiological and biochemical factors that causes it is crucial for δDwax-based quantitative paleoclimate reconstruction. Herein, we present parallel controlled study of Stipa bungeana (monocotyledonous grass) and Quercus aquifolioides (dicotyledonous tree) by conducting semimonthly paired δD analysis of precipitation, soil and leaf water, and n-alkanes over two years. We show that δDwax in both plants inherit precipitation hydrogen isotopic compositions throughout the growing season. However, it is synchronous in S. bungeana and belated in Q. aquifolioides. We reveal previously unrecognized phenomenon that, for trees alkanes with higher concentration percentages utilize lighter deuterium preferentially, whereas grasses do not. We conclude that dicotyledonous trees have a selection mechanism whereby leaf water hydrogen is utilized for n-alkane biosynthesis, whereas monocotyledonous grasses do not. This fundamentally explains δDwax discrepancy between dicotyledonous trees and monocotyledonous grasses, having significant implications for δDwax paleoapplication.

How to cite: Zhang, X., Xu, B., Günther, F., and Gleixner, G.: Seasonal variability and differences in n-alkane deltaD values between dicotyledonous tree and monocotyledonous grass, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4414, https://doi.org/10.5194/egusphere-egu2020-4414, 2020