TY  - JOUR
AU  - Quade, Maria
AU  - Brüggemann, Nicolas
AU  - Graf, Alexander
AU  - Vanderborght, Jan
AU  - Vereecken, Harry
AU  - Rothfuss, Youri
TI  - Investigation of Kinetic Isotopic Fractionation of Water During Bare Soil Evaporation
JO  - Water resources research
VL  - 54
IS  - 9
SN  - 0043-1397
CY  - [New York]
PB  - Wiley
M1  - FZJ-2018-05543
SP  - 6909-6928
PY  - 2018
AB  - The kinetic fractionation factor (αK) controls to a large extent the isotopic enrichment of surface waters during evaporation (E). In contrast to the well-known vapor-to-liquid isotopic equilibrium fractionation factor, αK has still not yet been properly characterized for soil water evaporation. In this study, we investigated the αK daily dynamics during a series of three laboratory experiments differing in soil water availability and aerodynamic conditions. For this, we applied a commonly-used isotopic evaporation model and tested it in two different approaches. First, a two-end member mixing model (“Keeling plot”) was fitted to the measured isotopic composition of the laboratory air water vapor to obtain αK. In a second approach, αK was obtained from the slope of the “evaporation line” in a dual isotopic coordinate system. For both methods, the isotopic composition of the soil water was determined non-destructively and online by sampling the soil water vapor with gas-permeable microporous tubing. Results highlighted the limitation of the first approach, as the determination of the isotopic composition of E with the Keeling plot was challenging with the laboratory setup. The second approach provided αK values within the range (α_K^(2_H ) = 1.0132 ±0.0013; α_K^(〖18〗_O ) = 1.0149 ±0.0012) reported in the literature and pointed to the prevalence of turbulent water vapor transport under water-saturated soil conditions, but also at soil water content significantly lower than the saturated value. In a third experiment, temporal dynamics of the atmospheric water vapor intrusion in the topmost soil layer could be observed during an isotopic labeling pulse.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000448088100059
DO  - DOI:10.1029/2018WR023159
UR  - https://juser.fz-juelich.de/record/852670
ER  -