1. Department of Fisheries and Oceans, Freshwater Institute, Winnipeg, Manitoba R3T 2N6, Canada, Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada, Department of Fisheries and Oceans, Great Lakes Laboratory for Fisheries and Aquatic Sciences Burlington, Ontario, L7R 4A6, Canada, and National Water Research Institute, Environment Canada, Burlington, Ontario, L7R 4A6 Canada