1. Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093, Environment Canada, Canadian Wildlife Service, National Wildlife Research Centre, Hull, Quebec, Canada K1A 0H3, Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, British Columbia, Canada V8L 4B2, and Centre for Analytical and Environmental Chemistry, Carleton...