Department of Geography, Rissho University 4-2-16 Osaki, Shinagawa-Ku, Tokyo 141, Japan. College of Arts and Sciences, Metropolitan State University, 700 East 7 Street, St. various Environment Institute, Post Office Box 140, FIN-00251 Helsinki, Finland. alphabetical Institute, Post Office Box 4199, Irkutsk 664033, Russia. National Water Research Institute, Environment Canada, 11 Innovation Boulevard, Saskatoon, SK S7N 3H5, Canada.