The Acid Rain 2000 Conference in Tsukuba, Japan, held 10-16 December 2000, was the sixth such conference in the series, starting with Columbus, Ohio, USA, in 1975, and including Sandefjord, Norway, in 1980, Muskoka, Canada, in 1985, Glasgow, UK, in 1990, and Goteborg, Sweden, in 1995. This series of International Conferences on the acid rain problem has made a very important contribution to the process of summarizing the state of current understanding and making this information available. In the 6th Conference, approximately 600 papers were presented, including talks and posters. About 300 peer-reviewed papers from the presentation appear in this volume, and will provide readers with a comprehensive review of the history and scientific aspects of the acid rain problem. The papers appear in three volumes: the first containing the plenary and keynote papers and the other two the remaining scientific papers.