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| Titel |
Fingerprints of environmental stressors in three selected Slovenian gravel-bed rivers: geochemical and isotopic approach |
| VerfasserIn |
Tjaša Kanduč, David Kocman, Barbara Debeljak, Natasa Mori |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123134
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| Publikation (Nr.) |
 EGU/EGU2016-2334.pdf |
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| Zusammenfassung |
| Rivers are severely impacted by a range of simultaneous processes including water pollution,
flow and channel alteration, over-fishing, invasive species and climate change. Systematic
studies of river water geochemistry provide important information on chemical weathering of
bedrock/soil and natural anthropogenic processes that may control the dissolved
chemical loads, while the isotopic studies of biological components of river systems
(macrophytes, periphyton, heterotrophic biofilm, invertebrates, fish) contribute to the
understanding how the system response to human impacts by means of functional
response.
In this contribution, insights in the fingerprints of various environmental stressors in three
gravel-bed rivers (River Kamniška Bistrica, River Idrijca and River Sava) in Slovenia, using
geochemical and stable isotope approach are discussed. Gravel bed of all three rivers
investigated is composed of carbonates and clastic rocks. The Sava and Kamniška Bistrica
Rivers have alpine high mountain snow-rain regime. The Idrijca River is a boundary river
between the Adriatic and Black Sea catchments and has rain-snow discharge regime with
torrential character. Geochemical methods (ICP-OES, IC, total alkalinity after Gran) and
isotope mass - spectrometric methods (isotopic composition of dissolved inorganic carbon,
particulate organic carbon and isotopic composition of carbon in carbonates) were used to
evaluate biogeochemical processes in rivers. Isotopic composition of carbon and
nitrogen of the moss Fontinalis antipyretica (the whole vegetative shoot) and isotopic
composition of carbon of heterotrophic biofilm was also analyzed in order to better
understand the fluxes and fractionation of carbon and nitrogen across trophic levels.
Geochemical composition of all investigated rivers is HCO3−-Ca2+-Mg2+ with
different Mg2+/Ca2+ ratios as follows: around 0.33 for Kamniška Bistrica and River
Sava in Slovenia and above 0.75 for River Idrijca. In the Kamniška Bistrica River
pollution with nitrates was observed in lower reaches, while the other two rivers in our
studies have good ecological status from chemical point of view. From isotopic
composition of inorganic dissolved carbon (DIC) it can be observed that DICoriginates
from dissolution of carbonates in upper reaches in the Sava and Kamniška Bistrica
Rivers. In the Idrijca River more degraded material is leached from the terrestrial
environment.
Isotopic composition of carbon of F. antipyretica in the River Sava Basin in Slovenia
seasonally ranged from -45‰ to -32.9‰ and isotopic composition of nitrogen from
-0.2‰ to +6.5‰Ṫhe higher isotopic composition of nitrogen of +6.5‰ found in F.
antipyretica was related to agricultural activity in the watershed. The isotopic composition of
carbon in heterotrophic biofilm was from +22.7 to +27.4‰ indicating the flux from
terrestrial (allochtonous) compartment.
The use of water geochemistry and stable C and N isotopes in our studies revealed as
promising approach to better understand the processes and fluxes of carbon and nitrogen
across abiotic and biotic components of undisturbed and impacted river systems. |
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