1. Atmospheric Science & Technology Directorate, Environment Canada, 4905 Dufferin Street, Toronto, Ontario, Canada M3H 5T4, Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario, Canada, M1C 1A4, Water Science & Technology Directorate, Environment Canada, Burlington, Ontario, Canada L7R 4A6, and Centre for Chemicals Management, Lancaster Environment Centre, Lancaster University, Lancaster, UK LA1 4YQ