 |
| Titel |
Temporal and spatial variability of stable isotopes of the water molecule in the Ebro River basin, Spain |
| VerfasserIn |
Philippe Négrel, Emmanuelle Pételet-Giraud, Romain Millot |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091489
|
| Publikation (Nr.) |
 EGU/EGU2014-5787.pdf |
|
|
|
|
|
| Zusammenfassung |
| Variations in the stable-isotope O and H composition in a catchment’s water balance are
mainly caused by natural variations in the isotopic composition of rainfall, through the
mixing with pre-existing waters and the influence of evaporation. Stable isotopes of water can
be considered as conservative and as not being affected by exchanges with soil or rock. Stable
isotopes were analysed in the surface waters along the course of the Ebro River, in main
tributaries of the Ebro river, in some groundwater, and over a one year survey at the
outlet. The global meteoric-water line is used to represent the meteoric input as
well as the local rainwater characteristics measured in five stations, all surrounding
the Ebro catchment. Mean weighted rain input showed enriched values for four
stations and a depleted one for the latter (large continental circulation of air masses).
The δ18O and δ2H relationships for surface- and ground waters collected in the
Ebro catchment with other rivers draining the French side of the Pyrenees or along
the Mediterranean Sea are compiled. Most of the points clearly plot close to the
global and local meteoric-water lines reflecting a meteoric origin and a lack of
significant evaporation or oxygen isotopes exchanges between water and the rock
matrix.
The tributaries present large variations in their δ18O and δ2H signatures but
only the Guadalope river has an evaporated signal.ghe most depleted values are
observed for the tributaries draining the Pyrenees agreeing with the Cauterets and
Garonne river signatures on the French side. The Aragon, also draining the Pyrenees,
has a more enriched signature that agree with the one observed in the Adour river
on the French side. However, all tributaries have more depleted values than all
mean rain water signal on the Ebro catchment as given by the local rain monitoring
stations. If the Burgos station is considered as representative of long range continental
transport, the depleted values in the tributaries of the Ebro River originate from
depleted rainwater occurring in the Pyrenees. Classical Mediterranean rains yield to
enriched values as demonstrated by the likeness between some rain monitoring
stations and the Herault River (South France). The Ebro River show gδ18O andδ2H
values that fall between that of tributaries and no variation can be related to the
location along the course of the river. Such values reflect the depleted rain inputs,
the Pyrenees inflows and more enriched Mediterranean rain inputs. The survey at
the outlet displays similar range in the δ18O and δ2H, however with some more
enriched values. There is no link with the discharge of the river, nor the Cl content.
The temporal variations at the outlet of the Ebro River reflect the input of depleted
water through Mediterranean rains and enriched ones through Pyrenean waters
inflows.
δ18O and δ2H relationships for rainwater (Burgos, Santander, Zaragoza, Tortosa, Gerona
and Llobregat), for surface- and ground waters collected in the Ebro catchment and for rivers
draining the French side of the Pyrenees or along the Mediterranean Sea in south
France. |
|
|
|
|
|
|