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| Titel |
Tracer-based identification of rock glacier thawing in a glacierized Alpine
catchment |
| VerfasserIn |
Michael Engel, Daniele Penna, Werner Tirler, Francesco Comiti |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250154297
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| Publikation (Nr.) |
 EGU/EGU2017-19373.pdf |
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| Zusammenfassung |
| Current warming in high mountains leads to increased melting of snow, glacier
ice and permafrost. In particular rock glaciers, as a creeping form of mountain
permafrost, may release contaminants such as heavy metals into the stream during intense
melting periods in summer. This may have strong impacts on both water quantity and
quality of fresh water resources but might also harm the aquatic fauna in mountain
regions.
In this context, the present study used stable isotopes of water and electrical conductivity
(EC) combined with trace, major and minor elements to identify the influence of permafrost
thawing on the water quality in the glacierized Solda catchment (130 km2) in South Tyrol
(Italy). We carried out a monthly sampling of two springs fed by an active rock glacier at
about 2600 m a.s.l. from July to October 2015. Furthermore, we took monthly water
samples from different stream sections of the Solda River (1110 to m a.s.l.) from
March to November 2015. Meteorological data were measured by an Automatic
Weather Station at 2825 m a.s.l. of the Hydrographic Office (Autonomous Province of
Bozen-Bolzano).
First results show that water from the rock glacier springs and stream water fell along the
global meteoric water line. Spring water was slightly more variable in isotopic ratio (δ2H: -91
to – 105 ) and less variable in dissolved solutes (EC: 380 to 611 μS/cm) than stream water
(δ2H: -96 to – 107 ‰ and EC: 212 to 927 μS/cm). Both spring water and stream water
showed a pronounced drop in EC during July and August, very likely induced by increased
melt water dilution. In both water types, element concentrations of Ca and Mg were highest
(up to 160 and 20 mg/l, respectively). In September, spring water showed higher
concentrations in Cu, As, and Pb than stream water, indicating that these elements partly
exceeded the concentration limit for drinking water. These observations highlight
the important control, which rock glacier thawing may have on water quality of
alpine streams and they underline the need for water quality monitoring at high
elevations.
Keywords: stable isotopes of water; heavy metals, permafrost thawing; alpine rivers;
glacierized catchment |
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