1. Surface and Aqueous Geochemistry Group, Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305-2115, United States
2. Center for
Environmental Implications
of NanoTechnology (CEINT), Duke University, Durham, North Carolina 27708-0287, United States
3. Department of Civil and Environmental
Engineering, Duke University, Durham, North
Carolina 27708, United States
4. Department of Civil and Environmental
Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States .
5. Department of Photon Science
and Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road,
Menlo Park, California 94025, United States