RENÉ P. SCHWARZENBACH is Professor of Environmental Chemistry at the Swiss Federal Institute for Environmental Science and Technology. PHILIP M. GSCHWEND is Associate Professor of Civil and Environmental Engineering at the Massachusetts Institute of Technology. DIETER M. IMBODEN is Professor of Environmental Physics at the Swiss Federal Institute for Environmental Science and Technology. In addition to numerous other distinctions, Professors Schwarzenbach, Gschwend, and Imboden are the authors of Environmental Organic Chemistry (Wiley-Interscience), which was awarded the AAP/PSP Best New Chemistry Book in 1994.