The research papers in this book were presented as a part of the Sixth International Conference on the Biogeochemistry of Trace Elements held at the University of Guelph, Ontario, Canada from July 29-August 2, 2001. The purpose of this conference was to present current knowledge on the source, pathways, behavior and effects of trace elements in soils, waters, plants and animals. In addition, the book also includes invited research papers from scientists who have done significant research in the area of coal and coal combustion byproducts. All the research papers presented herein have been subjected to peer review. The editors have arranged the articles systematically by topic, beginning with the introductory chapter entitled "The Production and Use of Coal Combustion Products" followed by the sections on Environmental Impacts of Coal Combustion Residues, Trace Elements in Fly Ashes, Transport and Leachability of Metals from Coal and Coal Ash Piles, and the Use of Coal Ash as Agricultural Soil Amendment.