 |
| Titel |
Measurement of soil water vapor isotopes for evapotranspiration partitioning |
| VerfasserIn |
Keir Soderberg, Lixin Wang, Stephen Good, Kelly Caylor |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250056656
|
|
|
|
|
|
| Zusammenfassung |
| Evapotranspiration is routinely measured and modeled towards understanding the hydrology
and functioning of ecosystems. Partitioning evapotranspiration into evaporation from soil and
transpiration from leaves remains a challenge, and is particularly important for modeling the
soil moisture in highly seasonal ecosystems. Here we present initial results from the
combination of continuous atmospheric water vapor isotope measurements (δ18O, δ2H) and
new techniques for directly quantifying the isotopic composition of soil water vapor
using portable laser-based isotope analyzers in an open system arrangement. The
study is performed at an eddy covariance flux tower in semi-arid savanna of central
Kenya. The field method is complimented and refined by laboratory experiments
using a soil chamber. The laboratory experiments are based on the mass balance
of both bulk water vapor and water vapor isotopes inside the soil chamber. The
water vapor in the chamber is a mixture of ambient vapor, which is measured before
chamber closing, and evaporated water, which mixes into the ambient vapor once
chamber closes. The air temperature, relative humidity and the isotopic composition
of liquid soil water are also monitored and used in the traditional Craig-Gordon
calculation for comparison with the measured water vapor isotope composition.
Still under improvement, these methods provide a new window into quantifying
the heterogeneity of the soil evaporation isotopic signal at the landscape scale. |
|
|
|
|
|
|