Next Article in Journal
Parallelization Performances of PMSS Flow and Dispersion Modeling System over a Huge Urban Area
Previous Article in Journal
Exposures to Carbon Monoxide in a Cookstove Intervention in Northern Ghana
Previous Article in Special Issue
Stable Isotopes in Greenhouse Gases from Soil: A Review of Theory and Application
Article Menu
Issue 7 (July) cover image

Export Article

Open AccessArticle

Modeling Investigation of Diurnal Variations in Water Flux and Its Components with Stable Isotopic Tracers

1
State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
2
Institute of Industrial Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8574, Japan
*
Author to whom correspondence should be addressed.
Atmosphere 2019, 10(7), 403; https://doi.org/10.3390/atmos10070403
Received: 1 June 2019 / Revised: 2 July 2019 / Accepted: 11 July 2019 / Published: 16 July 2019
(This article belongs to the Special Issue Stable Isotopes in Atmospheric Research)
  |  
PDF [3423 KB, uploaded 16 July 2019]
  |  

Abstract

The isotopic compositions of water fluxes provide valuable insights into the hydrological cycle and are widely used to quantify biosphere–atmosphere exchange processes. However, the combination of water isotope approaches with water flux components remains challenging. The Iso-SPAC (coupled heat, water with isotopic tracer in soil–plant–atmosphere-continuum) model is a useful framework for simulating the dynamics of water flux and its components, and for coupling with isotopic fractionation and mixing processes. Here, we traced the isotopic fractionation processes with separate soil evaporation (Ev) and transpiration (Tr), as well as their mixing in evapotranspiration (E) for simulating diurnal variations of isotope compositions in E flux (δE). Three sub modules, namely isotopic steady state (ISS), non-steady-state (NSS), and NSS Péclet, were tested to determine the true value for the isotope compositions of plant transpiration (δTr) and δE. In situ measurements of isotopic water vapor with the Keeling-plot approach for δE and robust eddy covariance data for E agreed with the model output (R2 = 0.52 and 0.98, RMSD = 2.72‰, and 39 W m−2), illustrating the robustness of the Iso-SPAC model. The results illustrate that NSS is a better approximation for estimating diurnal variations in δTr and δE, specifically during the alternating periods of day and night. Leaf stomata conductance regulated by solar radiation controlled the diurnal variations in transpiration fraction (Tr/E). The study emphasized that transpiration and evaporation, respectively, acted to increase and decrease the δ18O of water vapor that was affected by the diurnal trade-off between them. View Full-Text
Keywords: evaporation and transpiration; stable water isotope; non-steady-state; processed-based model; transpiration fraction evaporation and transpiration; stable water isotope; non-steady-state; processed-based model; transpiration fraction
Figures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Wang, P.; Deng, Y.; Wei, Z. Modeling Investigation of Diurnal Variations in Water Flux and Its Components with Stable Isotopic Tracers. Atmosphere 2019, 10, 403.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Atmosphere EISSN 2073-4433 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top