1. Center for NanoBioEarth, Department of Geosciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA 24061–0420, USA.
2. School of Earth Sciences and School of Environment and Natural Resources, Ohio State University, Columbus, OH 43210, USA.
3. Department of Civil Engineering and Geological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
4. Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
5. Department of Geology and Geophysics, University of Wisconsin-Madison, Madison, WI 53706–1692, USA.