Tetsu K. Tokunaga

Hydrogeochemical Research Lab

Senior Scientist

Building 074, Room 0302

M/S 74R316C

Phone: 510-486-7176

Fax: 510-486-5686

[email protected]

Curriculum Vitae

Biography

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.

Research Interests

Tetsu Tokunaga’s research combines soil physics with related fields of hydrogeology and biogeochemistry. His research accomplishments in the area of flow and transport include identifying a novel molecular free-path distribution model for gas diffusion in porous media, identifying scale limits for capillary hysteresis, the permeability-imbibition scaling relation, the importance of water film hydraulics in multiphase fluid flow, modeling and measurements of brine film thicknesses under confinement by supercritical CO₂, experimentally identifying uncertainties associated with scaling predictions of capillary pressure-saturation relations for supercritical CO₂-brine in porous media, showing that infiltration paths in talus rocks evolve towards a Boltzmann (geometric) distribution, measuring multiphase fluid equilibrium and flow in low permeability shales, and measuring solute diffusion through adsorbed water films. In field studies, he has expertise in monitoring subsurface flow and transport, particularly through developing novel methods for measuring hydraulic potentials in tandem with spatially resolved fluid sampling.

In the area of contaminant biogeochemistry, he has developed novel applications of the synchrotron X-ray microprobe for tracking transport and redox transformations of selenium, chromium, and uranium in sediments, identified the unsustainability of reduction-based remediation of uranium contamination, showed that unsaturated drainage of contaminated sediments can leach contaminants into groundwater for decades, and identified the role of uranyl vanadates in controlling uranium concentrations in some oxidizing environments.

In studies of terrestrial carbon, he tested the potential acceleration of soil carbon sequestration through gypsum dissolution, and quantified the contribution of deep unsaturated zone respiration to CO₂ fluxes measured at the soil surface.

Additional information can be found at the The Wan-Tokunaga Lab website.