Tetsu Tokunaga is a Senior Scientist (semi-retired) in the Energy Geosciences Division of Lawrence Berkeley National Laboratory, studying the physicochemical basis of environmental transport processes. While conducting his graduate studies on gas diffusion in porous media at the University of California, Berkeley, he began working at LBNL (1981) as a graduate student on unsaturated flow and transport from uranium mill tailings, and on reactive transport of selenium in contaminated wetland (Kesterson Reservoir). Upon graduation (Ph.D., Soil Science, 1986), he continued at LBNL conducting laboratory and field-based studies on flow and transport problems in soils and geologic media. In addition to his research at LBNL, he taught soil physics at the University of California, Berkeley (1990, 1992). He currently has over 120 publications in peer-reviewed journals.