Factors affecting water chemistry of alpine lakes |
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| Authors: | A Marchetto R Mosello R Psenner G Bendetta A Boggero D Tait G A Tartari |
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| Institution: | (1) C.N.R. Istituto Italiano di Idrobiologia, Largo Tonolli 50, 28048 Verbania Pallanza, Italy;(2) Institut für Zoologie, Universität Innsbruck, Abt. Limnologie, Tecknikerstrasse 25, 6020 Innsbruck, Austria;(3) Laboratorio Biologico Provinciale, via Sottomonte 2, 39100 Laives, BZ, Italy |
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| Abstract: | During a four-year study (1988–1991), 413 lakes in the Central Alps (Italy, Switzerland and Austria) were investigated to quantify their acidification. The ionic content of the lakes was generally low: 68% of them had alkalinity values of less than 200 µeq 1–1 and were regarded as sensitive to acidification. Moreover, 36% of the lakes showed alkalinity values of less than 50 µeq 1–1. Redundancy Analysis was used to relate the hydrochemistry of 187 lakes to their catchment characteristics. Calcite weathering was the main factor influencing lake chemistry. The same analysis, applied to a subset of 101 lakes lying in watersheds exclusively composed of silicic rocks, showed that lake chemistry was influenced by silicate weathering and nitrogen uptake. These processes were found to be mainly related to lake altitude and the fraction of the watershed not covered by vegetation, i.e. controlled by temperature. The importance of these relations to explain the pH shift produced by climatic variation is also discussed. |
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| Keywords: | Alpine lakes hydrochemistry acidification |
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