07 Jul 2022
07 Jul 2022
Status: this preprint is currently under review for the journal HESS.

Controls on leaf water hydrogen and oxygen isotopes: A local investigation across seasons and altitude

Jinzhao Liu1,2, Huawu Wu3, Chong Jiang1, Li Guo4, Haiwei Zhang5, and Ying Zhao6 Jinzhao Liu et al.
  • 1State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
  • 2National Observation and Research Station of Earth Critical Zone on the Loess Plateau of Shaanxi, Xi’an, 710061, China
  • 3Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
  • 4State Key Laboratory of Hydraulics and Mountain River Engineering & College of Water Resource and Hydropower, Sichuan University, 610065, Chengdu, China
  • 5Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an, 710054, China
  • 6College of resources and environmental engineering, Ludong University, 264025, Yantai, China

Abstract. The stable oxygen (δ18Oleaf) and hydrogen (δ2Hleaf) isotopes of leaf water act as a bridge that connects hydroclimate to plant-derived organic matter. However, it remains unclear whether the source water (i.e., twig water, soil water, and precipitation) or meteorological parameters (i.e., temperature, relative humidity, and precipitation) are the dominant controls on δ18Oleaf and δ2Hleaf. Here, we reported seasonal analysis of δ18Oleaf and δ2Hleaf together with isotopes from potential source waters and meteorological parameters along an elevation transect on the Chinese Loess Plateau. We found that δ2Hleaf values were more closely correlated with source water isotopes than δ18Oleaf values, whereas δ18Oleaf and δ2Hleaf values were similarly correlated with meteorological parameters. Dual-isotope analysis showed that the δ18Oleaf and δ2Hleaf values were closely correlated because of their similar altitudinal and seasonal responses, and so generated a well-defined isotope line relative to the local meteoric water line (LMWL). We also compared the measured δ18Oleaf and δ2Hleaf values with predicted values by the Craig-Gordon model, and found no significant differences between them. We demonstrate that the first-order control on δ18Oleaf and δ2Hleaf values was the source water, and the second-order control was the enrichment associated with biochemical and environmental factors.

Jinzhao Liu et al.

Status: open (until 01 Sep 2022)

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  • RC1: 'Comment on hess-2022-246', Anonymous Referee #1, 30 Jul 2022 reply

Jinzhao Liu et al.

Jinzhao Liu et al.


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Short summary
What controls on leaf water isotopes? We answered the question from two perspectives: respective and dual isotopes. On the one hand, the δ18O and δ2H values of leaf water responded to isotopes of potential source water (i.e., twig water, soil water, and precipitation) and meteorological parameters (i.e., temperature, RH, and precipitation) differently; On the other hand, dual δ18O and δ2H values of leaf water yielded a significant regression line, associated with altitude and seasonality.