Title: Vegetation and location of water inflow affect evaporation in a subtropical wetland as indicated by the deuterium excess method: Evaporation Effects Indicated by Deuterium Excess Method

Abstract

Evaporation represents a principal form of water loss from water bodies, but quantifying evaporation with transpiring vegetation is challenging, owing to the difficulties in disentangling evaporation from transpiration. As the two processes have different effects on water isotope signatures (i.e., oxygen and hydrogen stable isotope ratios expressed by δ¹⁸O and δ²H), we used both the δ¹⁸O and δ²H values of water samples to calculate their deuterium excess (d) values, which are proportionate to fraction of evaporation loss (E_f) of water being sampled. Comparing with a single isotope method, the d method holds the advantage that it does not require knowledge of the initial isotope ratios of source water. Limitations of the d method, for example, effects of prior-evaporation of water before entering water bodies, can be checked and corrected. The sampling locations throughout our study site differed in vegetation coverage, water depth, and distance to water inflow (or discharge gate of water inflow), which are three important factors in water management. This sampling design offered us a unique opportunity to quantify the influences of the above three factors on E_f. We found the following: (1) There was a spatiotemporal pattern in δ¹⁸O distribution. (2) The E_f was negatively related tomore » the vegetation coverage, positively related to distance to the water source inflow but nonsignificantly related to water depth. Therefore, vegetation and distance to the water inflow are two important considerations for the control of evaporative water loss, and evaporation calculated by the d method can lead to more informed water management.« less

Authors:

Zhai, Lu  ^[1];

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Wang, Xin ^[2]; Wang, Peng ^[3]; Miralles-Wilhelm, Fernando ^[4]; Sternberg, Leonel da Silveira Lobo ^[2]

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Univ. of Miami, Coral Gables, FL (United States). Dept. of Biology
3. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Science
4. Univ. of Maryland, College Park, MD (United States). Earth System Science Interdisciplinary Center, Dept. of Atmospheric and Oceanic Science

Publication Date:

Mon Mar 04 00:00:00 EST 2019

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1503201

Report Number(s):

LA-UR-19-21229
Journal ID: ISSN 1936-0584

Grant/Contract Number:  

89233218CNA000001

Resource Type:

Accepted Manuscript

Journal Name:

Ecohydrology

Additional Journal Information:

Journal Volume: 12; Journal Issue: 4; Journal ID: ISSN 1936-0584

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; Earth Sciences; Evaporation, Deuterium excess method; Stable isotopes; Vegetation; Isoscape