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| Titel |
Stable isotopes of water in estimation of groundwater dependence in
peatlands |
| VerfasserIn |
Elina Isokangas, Pekka Rossi, Anna-Kaisa Ronkanen, Hannu Marttila, Kazimierz Różański, Björn Klöve |
| 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 |
250126616
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| Publikation (Nr.) |
 EGU/EGU2016-6365.pdf |
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| Zusammenfassung |
| Peatland hydrology and ecology can be irreversibly affected by anthropogenic actions or
climate change. Especially sensitive are groundwater dependent areas which are difficult to
determine. Environmental tracers such as stable isotopes of water are efficient tools to
identify these dependent areas and study water flow patterns in peatlands. In this study the
groundwater dependence of a Finnish peatland complex situated next to an esker aquifer was
studied. Groundwater seepage areas in the peatland were localized by thermal imaging and
the subsoil structure was determined using ground penetrating radar. Water samples were
collected for stable isotopes of water (δ18O and δ2H), temperature, pH and electrical
conductivity at 133 locations of the studied peatland (depth of 10 cm) at approximately 100 m
intervals during 4 August – 11 August 2014. In addition, 10 vertical profiles were
sampled (10, 30, 60 and 90 cm depth) for the same parameters and for hydraulic
conductivity. The cavity ring-down spectroscopy (CRDS) was applied to measure δ18O
and δ2H values. The local meteoric water line was determined using precipitation
samples from Nuoritta station located 17 km west of the study area and the local
evaporation line was defined using water samples from lake Sarvilampi situated on
the studied peatland complex. Both near-surface spatial survey and depth profiles
of peatland water revealed very wide range in stable isotope composition, from
approximately -13.0 to -6.0 ‰ for δ18O and from -94 to -49 ‰ for δ2H, pointing to
spatially varying influence of groundwater input from near-by esker aquifer. In
addition, position of the data points with respect to the local meteoric water line
showed spatially varying degree of evaporation of peatland water. Stable isotope
signatures of peatland water in combination with thermal images delineated the specific
groundwater dependent areas. By combining the information gained from different types of
observations, the conceptual hydrological model of the studied peatland complex,
including groundwater – surface water interaction, was built in a new, innovative way. |
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