Current Research and Scholarly Interests
My research interests involve five main areas: (1) geochemistry of mineral surfaces and their reactivity with aqueous metal complexes, organic matter, and microbial organisms; (2) structure and properties of natural and manufactured nanoparticles; (3) environmental chemistry/geochemistry of heavy metal and actinide contaminants; (4) experimental studies of carbon sequestration through mineral carbonation reactions; and (5) structure-property relationships of silicate liquids and glasses. The first four areas have bearing on the sequestration, transport, and transformations of environmental contaminants (e.g., mercury, lead, arsenic, uranium, and CO2) in aquatic systems, soils, and the atmosphere; the last focuses on the high-temperature geochemistry of silicate magmas and their trace elements. My students and I utilize various types of macroscopic and microscopic measurements, including the very intense x-rays from synchrotron radiation sources, as well as field investigations.
I teach courses at both the undergraduate and graduate levels, including Earth Materials (GES 102), the basic sophomore-level course required of GES majors on minerals and rocks and the processes that form and modify them; Environmental Geochemistry (GES 170/270), a senior-, graduate-level course on the chemistry of the environment; and Physics and Chemistry of Minerals and Mineral Surfaces (GES 261), a graduate-level course on my specialty. I also occasionally teach a sophomore seminar on environment and human health as well as graduate seminars on current topics in environmental geochemistry and mineral surface and aqueous geochemistry.
Elected Fellow, Academia Europaea (2013); Ian Campbell Medal, American Geosciences Institute (2012); Patterson Medal, Geochemical Society for Environmental Geochemistry Research (2007); Roebling Medal, Mineralogical Society of America (2007); director, Stanford-NSF Environmental Molecular Science Institute (2004-2011); member, Science Advisory Committees of the DOE Office of Basic Energy Sciences (2011-present); Environmental Molecular Science Laboratory-PNNL (2003-present); Sincrotrone Trieste-Italian National Synchrotron Laboratory (2005-2011); Center for Advanced Microdevices-LSU (2005-2010); Advanced Light Source-LBNL (1997-2000); Canadian Light Source (1999-2002); Chemistry Division-Los Alamos National Laboratory (1988-2003); fellow, American Association for the Advancement of Science (2000); fellow, Geochemical Society and European Association of Geochemistry (1999); fellow, Geological Society of America (1997); fellow, Mineralogical Society of America (1975); Docteur Honoris Causa degree, Universite Paris 7 (1997); president, Mineralogical Society of America (1996); professor (1988-present) and chair (1998-2007), Stanford Synchrotron Radiation Laboratory Faculty (now Department of Photon Science), SLAC; member, Board of Governors, Gemological Institute of America (1988-2008); chair, Department of Geology, Stanford (1986-1992); co-director, Stanford-NSF Center for Materials Research (1987-1989); chair, Department of Geological & Environmental Sciences (2012-present).