Reply on RC1

Jinzhao Liu

doi:10.5194/hess-2021-289-ac1

Abstract

Stable oxygen and hydrogen isotopes (δ18O and δ2H) of leaf water which bridges between hydrological processes and plant-derived organic materials that vary spatially and temporally. It is crucially critical to study what controls the δ18O and δ2H values of leaf water for a wide range of applications. Here, we repeatedly sampled soil water, stem water, and leaf water along an elevation transect across seasons on the Chinese Loess Plateau, and analyzed the variations of in the δ18O and δ2H values from precipitation, soil water, stem water, and ultimate leaf water. We found a consistency in the δ18O and δ2H values from in precipitation, soil water, stem water, and leaf water across seasons. , indicating that leaf water can record well the isotopic signals of precipitation well. Importantly, leaf water isotope lines are were generated by the first-order control of source water (soil water and precipitation) associated with seasonality and altitude, and as well as the secondary control of hydroclimate and biochemical factors resulting in weak correlations of the δ18O and δ2H values in leaf water. This study is helpful to better understandimproves our understanding of the generation of leaf water isotopes.

Highlights

The stable isotope compositions of water (δ18O and δ2H) are increasingly used as powerful tracers to follow the movement of water from its input as precipitation, movement through the soil, and to its release as soil evaporation and leaf transpiration (Mook, 2001; Penna and Meerveld, 2019)
The regression lines of the δ18O and δ2H values from soil water, stem water, and leaf water were observed (Fig. 3), suggesting that leaf water isotopes could well inherit the isotopic signals of source waters that originated from stem water, soil water, and precipitation
Precipitation, soil water, stem water, and leaf water were repeatedly sampled to analyze for δ18O and δ2H values associated with season and altitude

Summary

Introduction

The stable isotope compositions of water (δ18O and δ2H) are increasingly used as powerful tracers to follow the movement of water from its input as precipitation, movement through the soil, and to its release as soil evaporation and leaf transpiration (Mook, 2001; Penna and Meerveld, 2019). Leaf water δ18O and δ2H values (δ18Olw and δ2Hlw) are the fundamental parameters required for an in-depth understanding of these plant organic biomarkers in paleoclimate contexts. Soil water isotopes are determined by a mixture of individual precipitation events with distinct isotope signals and are affected by evaporation, both of which lead to isotopic gradients of soil water with depth (Allison et al, 1983; Liu et al, 2015)

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