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| Titel |
Physical and chemical consequences of artificially deepened thermocline in a small humic lake – a paired whole-lake climate change experiment |
| VerfasserIn |
M. Forsius, T. Saloranta, L. Arvola, S. Salo, M. Verta, P. Ala-Opas, M. Rask, J. Vuorenmaa |
| 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 ; 14, no. 12 ; Nr. 14, no. 12 (2010-12-21), S.2629-2642 |
| Datensatznummer |
250012536
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| Publikation (Nr.) |
 copernicus.org/hess-14-2629-2010.pdf |
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| Zusammenfassung |
| Climate change with higher air temperatures and changes in cloud cover,
radiation and wind speed alters the heat balance and stratification patterns
of lakes. A paired whole-lake thermocline manipulation experiment of a small
(0.047 km2) shallow dystrophic lake (Halsjärvi) was carried out in
southern Finland. A thermodynamic model (MyLake) was used for both
predicting the impacts of climate change scenarios and for determining the
manipulation target of the experiment. The model simulations assuming
several climate change scenarios indicated large increases in the whole-lake
monthly mean temperature (+1.4–4.4 °C in April–October for the A2
scenario), and shortening of the length of the ice covered period by 56–89 days.
The thermocline manipulation resulted in large changes in the
thermodynamic properties of the lake, and those were rather well consistent
with the simulated future increases in the heat content during the
summer-autumn season. The manipulation also resulted in changes in the
oxygen stratification, and the expansion of the oxic water layer increased
the spatial extent of the sediment surface oxic-anoxic interfaces. In
addition, the experiment affected several other chemical constituents;
concentrations of organic carbon, TotN, and NH4 showed a statistically
significant decrease, likely due to both changes in hydrological conditions
during the experiment period and increased decomposition and sedimentation.
In comparison with the results of a similar whole-lake manipulation
experiment in a deep, oligotrophic, clear-watered lake in Norway, it is
evident that shallow dystrophic lakes, common in the boreal region, are more
sensitive to physical perturbations. This means that projected climate
change may modify their physical and chemical conditions in the future. |
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