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Human impacts and eutrophication patterns during the past ~200 years at Lago Grande di Avigliana (N. Italy)

Finsinger, Walter ; Bigler, Christian ; Krähenbühl, Urs ; Lotter, André ; Ammann, Brigitta

In: Journal of Paleolimnology, 2006, vol. 36, no. 1, p. 55-67

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    Titre
    • Human impacts and eutrophication patterns during the past ~200 years at Lago Grande di Avigliana (N. Italy)
    Auteur
    • Finsinger, Walter. Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013, Bern, Switzerland
    • Bigler, Christian. Ecology and Environmental Science, KBC plan 5, Umeå University, SE-901 87, Umeå, Sweden
    • Krähenbühl, Urs. Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012, Bern, Switzerland
    • Lotter, André. Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584 CD, Utrecht, The Netherlands
    • Ammann, Brigitta. Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013, Bern, Switzerland
    Type de document
    • Postprint
    Langue
    • Inglese
    Publié dans
    • Journal of Paleolimnology, 2006, vol. 36, no. 1, p. 55-67. Kluwer Academic Publishers
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:319451
    Summary
    A short sediment core from Lago Grande di Avigliana (Piedmont, Italy), the second most eutrophied lake in Italy, was analysed for pollen and diatoms to reconstruct land-use changes and to estimate baseline conditions for total phosphorus (TP) in the water column. Varve counts on sediment thin-sections and 210Pb, 226Ra, and 137Cs dating provided a reliable chronology for the past ~200 years. The main pollen-inferred land-use changes showed a sharp decrease of hemp retting around AD 1900, as well as a gradual change to less intensive agriculture and increasing abundance of exotic plants since AD ~1970. Diatom-inferred TP reconstructions indicated stable TP concentrations until AD ~1950, revealing baseline mesotrophic conditions (TP <25 µg l−1). After AD ~1950, TP values increased distinctly and continuously, culminating in the late 1960s with concentrations of 150 µg l−1. Subsequently, diatoms implied a linear decrease of TP, with an inferred value of 40 µg l−1 in the surface sediment sample. Comparison with instrumental TP measurements from the water column since AD 1980 showed a rapid recovery and allowed a direct validation of the diatom TP inference. However, although the TP concentration has decreased considerably, baseline conditions have not yet been reached. When compared to the limnological effects of sewage discharges on inferred-TP concentration, our results indicated that agricultural land use played a minor role in the lake's eutrophication