SS4.06 Speciation, Bioavailability, and Impacts of Atmospheric Trace Metals in Aquatic Systems
Date: Wednesday, June 12, 2002
Time: 2:15:00 PM
Location: Esquimalt
 
Fortin, C, , Laboratoire de radioécologie expérimentale, IPSN, CE Cadarache, Bldg 186, 13108 St-Paul-Lez-Durance, France, claude.fortin@ipsn.fr
Couillard, Y, , Chemicals Evaluation Division, Environment Canada, 351 Saint-Joseph Blvd., Hull, Québec, Canada, yves.couillard@ec.gc.ca
Vigneault, B, , Noranda Technology Centre, 240 Hymus Blvd., Pointe-Claire, Québec, Canada, bernard.vigneault@ntc.noranda.com
CampbellPG, Université du Québec, INRS-ETE, C.P. 7500, Ste-Foy, Québec, Canada, campbell@uquebec.ca
 
FREE CD, CU AND ZN CONCENTRATIONS IN CANADIAN SHIELD LAKES AS DETERMINED BY COMBINED IN SITU DIALYSIS AND COLUMN EQUILIBRATION ION-EXCHANGE
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Using in situ dialysis and a column ion-exchange equilibration method, we measured free metal-ion concentrations (Cd, Cu and Zn) in water samples collected from the littoral zone of 14 lakes in the Rouyn-Noranda area (600 km north west of Montreal, QC). Lakes were selected to represent a wide range of physico-chemical characteristics (hardness, pH, dissolved organic matter – DOM), to determine the influence of these parameters on metal speciation. The proportions of free Cd and Zn to total metal from the 14 selected lakes were surprisingly constant at 80 and 74% respectively, despite the wide pH (4.5 – 8) and DOM (3 – 23 mg C/L) ranges, whereas Cu speciation varied with DOM and pH. Our results were then compared with calculated values obtained using the thermodynamic model WHAM (Windermere Humic Aqueous Model) and a model based on sediment sorption equilibrium. Measured and calculated values were in close agreement for both Cd and Zn. Free measured Cu concentrations were however generally higher than the calculated values, suggesting that WHAM overestimates the increase of Cu complexation by DOM as the pH increases.