1.Regular Appointments

Assistant Professor, July 1965 - June 1971, Department of Soil Science, University of Saskatchewan, Saskatoon, Canada

Associate Professor, July 1971 - June 1978, Department of Soil Science, University of Saskatchewan, Saskatoon, Canada

Professor, July 1978 to June 2002, Department of Soil Science, University of Saskatchewan, Saskatoon, Canada

Life-Time Professor Emeritus, July 2002 to date, Department of Soil Science, University of Saskatchewan, Saskatoon, Canada

2.Other Appointments on Sabbatical or Leave of Absence

Professor and Head, Department of Soil Science and Director of Soil Research Institute, July 1975 to June 1976, National Chung Hsing University, Taichung, Taiwan (on leave of absence from the University of Saskatchewan)

Visiting Professor, January 1996 - April 1996, Environmental Resources Research Institute, the Pennsylvania State University, University Park, PA, USA (on sabbatical leave from the University of Saskatchewan)

3.Special Appointments by the National Science Council of the Republic of China

National Visiting Research Professor, January 1975 to April 1976, Department of Soil Science, National Chung Hsing University, Taichung, Taiwan (on leave of absence from the University of Saskatchewan)

Research Chair, April 1996-June 1996, Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan (on the sabbatical leave from the University of Saskatchewan)

Research Chair, April 2003-June 2003, Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan

Research Chair, February 2004-November 2004, Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan

4.Honorary Positions

Honorary Professor, Huazhong Agricultural University, Wuhan, China (1992)
Honorary Professor, Guangxi Agricultural University, Nanning, China (1993)
Honorary Professor, Henan Agricultural University, Zhengzhou, China (1996)
Honorary Professor, Nanjing Agricultural University, Nanjing, China (1996)
Honorary Academic Advisor, Laboratory of Material Cycling in Pedosphere, Chinese Academy of Sciences (1996)
Honorary Professor, Lanzhou University, Lanzhou, China (1999)
Honorary Scientist, The Rural Development Administration of the Republic of Korea, Suwon, Korea (2004)

5.Professional and Association Offices

Selected Offices and Committee Activities are Listed Below:
Chair, Division S-2 Soil Chemistry, Soil Science Society of America, 1994-95
Chair, Division S-9, Soil Mineralogy, Soil Science Society of America, 1982-83
Founding Chair, Commission 2.5 Soil Physical/Chemical/Biological Interfacial Reactions, the International Union of Soil Sciences, 2004 to 2006.
Chairman, the Working Group MO "Interactions of Soil Minerals with Organic Components and Microorganisms", the International Society of Soil Science, 1990 to 1998 and the International Union of Soil Sciences, 1998 to 2004
Chair, First Workshop on "Impact of Interactions of Inorganic, Organic, and Microbiological Soil Components on Environmental Quality" of Working Group MO "Interactions of Soil Minerals with Organic Components and Microorganisms" of the International Society of Soil Science, Edmonton, AB, 1992
Chair, Executive Committee, the Second International Symposium "Effect of Mineral–Organic–Microorganism Interactions on Soil and Freshwater Environments", Working Group MO "Interactions of Soil Minerals with Organic Components and Microorganisms" of the International Society of Soil Science, Nancy, France, 1996
Chair, Executive Committee, the Third International Symposium “Soil Mineral-Organic Matter-Microorganism Interactions and Ecosystem Health” of Working Group MO “Interactions of Soil Minerals with Organic Components and Microorganisms” of the International Union of Soil Sciences, Naples-Capri, 2000.
Treasurer, International Association for the Study of Clays, 1993 to 2001
Councillor, The Clay Minerals Society, 1985-88
Canadian National Chapter Leader, International Humic Substances Society, 1992 to 2005 Titular Member, Division VI Chemistry and the Environment, International Union of Pure and Applied Chemistry, 1995 to 2001 and 2006 to date.
Member, Board of Directors, the Soil Science Society of America, 1983-84, 1995-96 Member, Theme Team of Metal Speciation, Canadian Network of Toxicology Centers, 1993-96 Member, Doctoral Prizes Selection Committee - Science, Natural Sciences and Engineering Research Council of Canada, 1996
Member, The Review Panel of the Environmental Quality Research, The Natural History Museum, London, UK, 1999.
Member, Organizing Committee and International Scientific Committee, the 4th International Symposium of Interactions of Soil Minerals with Organic Components and Microorganisms. Working Group MO of the International Union of Soil Sciences, Wuhan, China, 2004. Member, Academic Committee, Chinese Academy of Sciences, 1988-94
Member, Fellows Committee of Soil Science Society of America, 1992-94
Member, Special Awards Committee, the Soil Science Society of America, 1995-96
Member, Marion L. and Chrystie M. Jackson Soil Science Award Committee, Soil Science Society of America, 1990-92
Member, International Soil Science Awards Committee, Soil Science Society of America, 1986 Member, Executive/Organizing Committees, International Conference of Biogeochemistry of Trace Elements, 1994 to 2005.
Member, International Committee, International Conference of Biogeochemistry of Trace Elements, 2000

6.Editorial Board

Special Editor and Member of the Editorial Board, Water Pollution Research Journal of Canada (1983-89, 1993)
Member, Editorial Board, Geoderma (1994 to date)
Member, Editorial Board, Chemosphere (1987 to 1997)
Editor, Journal of Chinese Agricultural Chemistry Society (1975-76)
Member, Editorial Board, The Advances in Environmental Science (1993 to date)
Member, Pedosphere (1990 to date)
Member, International Panel of Referees, International Association of Water Pollution Research and Control (1983-89)
Associate Editor and Member of the Editorial Board, The Soil Science Society of America Journal (1987-93)
Member, Editorial Advisory Board, Trends in Agricultural Sciences-Soil Science (1991-95)
Member, Editorial/Advisory Board, Trends in Soil Science (1996 to date)
Member, Editorial Board, Agro's Annual Review of Crop Ecology (1995 to date)
Associate Editor, Water, Air & Soil Pollution (1998 to 2001)
Member, Editorial Board, Humic Substances in the Environment (1998 to date)
Member, Editorial Board, Soil Science and Plant Nutrition (1998 to date)
Series Editor, IUPAC Book Series “Biophysico-Chemical Processes in Environmental Systems”, John Wiley & Sons, Hoboken, NJ, USA (2006 to date)