1. Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1, Water Science and Technology Directorate, Environment Canada, Burlington, Ontario L7R 4A6, Ontario Ministry of the Environment, Toronto, Ontario M9P 3V6, Fresh Water Institute, Department of Fisheries and Oceans, Winnipeg, Manitoba R3T 2N6, Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, and Wellington Laboratories, Guelph, Ontario N1G 3M5, Canada