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T3
Spacial isotopic variations in water isotopes and dissolved inorganic carbon along
the pyrenees during the beginning of spring 2013
M. L. Sanchez Montes 1 *
1 Department of Geography, The University of Sheffield, Sheffield
Oxygen (δ 18 O), hydrogen (δ 2 H) and carbon (δ 13 C) stable isotope analyses from 72 rivers
along the Pyrenees have been carried out in order to observe their spatial and temporal
variability. The Pyrenees mountain range has been divided into four areas according to
north, south, west and east to compare the stable isotopic values. Spatial isotopic
fractionation differences along the Pyrenees can be explained by different controls. In
order to do that, here we analyse and compare the isotopic data of the four different areas.
Our results show that, despite their complexity, oxygen and hydrogen isotopic values were
subject to spatial differences among the four areas due to differences in moisture sources
of the precipitation and re-evaporation processes. In contrast, the carbon isotopic values
showed a common respiration and erosion controls for the west and the north and
chemical weathering controls for the south and the east. Furthermore, this study contains
an isotopic data record (δ 2 H and δ 18 O and δ 13 C) to help future investigations regarding
temporal changes in these stable isotopic compositions over this place. As far as it could
be found, this study is the first one to characterize these stable isotopes for the entire
Pyrenees range until the present time. Local isotopic data-record for Lannemezan during
spring 2009 (Lambs et al, 2009) was compared with the data collected in this work in
spring 2013. The isotopic changes of this area showed to have become lighter during the
last 4 years. It is expected that the evolution trajectory of this mountain could be a good
representation of the evolution of mountain ranges situated at higher latitudes, regarding
the context of future global warming scenario (Lopez-Moreno et al. 2008).
Keywords: oxygen; hydrogen; stable isotopes; dissolved inorganic carbon; rivers;
Pyrenees; climate change.
Lambs, L., Brunet, F. and Probst, J.L., 2009, Isotopic characteristics of the Garonne River and its
tributaries, RCM 2543-2550.
Lopez-Moreno, J. I., Beniston, M. And Garcia-Ruiz, J. M., 2008, Environmental change and water
management in the Pyrenees: Facts and future perspectives for Mediterranean mountains, Global and
Planetary Change 61, 300-312.