CS27 Paleolimnology and Paleooceanography
Date: Tuesday, June 11, 2002
Location: Poster Session - VCC
Dixit, A, S, Department of Biology, Queen's University, Kington, Ontario, Canada, dixita@biology.queensu.ca
Dixit, S, S, Environment Canada, Hull, Quebec, Canada, Sushil.Dixit@ec.gc.ca
AlpayS, Geological Survey of Canada, Ottawa, Ontario, Canada, salpay@NRCan.gc.ca
Smol, J, P, Department of Biology, Queen's University, Kingston, Ontario, Canada, smolj@biology.queensu.ca
Long-term data are often lacking to assess the patterns of lake acidification and recovery effectively. Fortunately, paleolimnological techniques can be used to infer past changes in lakewater acidity and related variables by means of biological indicators, such as diatom valves and chrysophyte scales preserved in 210Pb-dated sediment cores. Diatom assemblages were analyzed in the surface sediments (0-1 cm) of 50 lakes in northwest Quebec selected among 100 lakes that were sampled by the Geological Survey of Canada (GSC) Metals in the Environment (MITE) Initiative in the vicinity of the Horne smelter (Rouyn-Noranda). Among a diverse set of environmental variables considered in this study, Canonical Correspondence Analysis (CCA) identified lakewater pH as the most significant variable in explaining the variance (28%) in the diatom species. A robust bootstrap weighted averaging model was developed (r2boot=0.83) for inferring lakewater pH. Using this model, temporal variations in pH were reconstructed for two kettle lakes, Lac Perron (N4750'29.4