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| Titel |
Variability of the groundwater sulfate concentration in fractured rock slopes: a tool to identify active unstable areas |
| VerfasserIn |
S. Binet, L. Spadini, C. Bertrand, Y. Guglielmi, J. Mudry, C. Scavia |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 13, no. 12 ; Nr. 13, no. 12 (2009-12-08), S.2315-2327 |
| Datensatznummer |
250012067
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| Publikation (Nr.) |
 copernicus.org/hess-13-2315-2009.pdf |
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| Zusammenfassung |
Water chemical analysis of 100 springs from the Orco and the
Tinée valleys (Western Italy and Southern France) and a 7 year
groundwater chemistry monitoring of the 5 main springs were
performed. All these springs drain from crystalline rock slopes.
Some of these drain from currently active gravitational slope
deformations.
All groundwaters flowing through presently unstable slopes show
anomalies in the sulfate concentrations compared to stable aquifers.
Particularly, an increase of sulfate concentrations was observed
repeatedly after each of five consecutive landslides on the La
Clapière slope, thus attesting to the mechanical deformations
are at the origin of this concentration change. Significant changes
in the water chemistry are produced even from slow (mm/year) and low
magnitude deformations of the geological settings.
Pyrite nuclei in open fractures were found to be coated by iron
oxides. This suggests that the increase of dissolved sulfate relates
to oxidative dissolution of Pyrite. Speciation calculations of
Pyrite versus Gypsum confirmed that observed changes in the sulfate
concentrations is predominantly provided from Pyrite. Calculated
amounts of dissolved minerals in the springs water was obtained
through inverse modelling of the major ion water analysis data. It
is shown that the concentration ratio of calculated dissolved Pyrite
versus calculated dissolved gneiss rock allows us to unambiguously
distinguish water from stable and unstable areas. This result opens
an interesting perspective for the follow-up of sliding or friction
dynamic in landslides or in (a) seismic faults. |
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