WILLIAM J. MITSCH, PhD, is Distinguished Professor of Natural Resources and Environmental Science at The Ohio State University in Columbus. He holds courtesy appointments in the Department of Civil and Environmental Engineering and the Department of Evolution, Ecology, and Organismal Biology at Ohio State. He is founder and Director of the Olentangy River Wetland Research Park, a 12-ha wetland research facility at the university. He is founder and Editor in Chief of Ecological Engineering-The Journal of Ecotechnology, is on the editorial board of four other ecological journals, and is coauthor or coeditor of twelve other books, including Wetlands (Wiley). SVEN ERIK JORGENSEN, PhD, is Professor of Environmental Chemistry at The Danish University of Pharmaceutical Sciences and at the Agriculture University of Denmark. He has written and edited fifty books, is a member of the editorial board of eleven journals, and is Editor in Chief of Ecological Modelling. He is also Chairman of ILEC's (International Lake Environment Committee) scientific committee.