TEACHING & RESEARCH
Assistant Professor of Geological Sciences
Biogeochemistry of Metals
- Ph.D., 1999, Geology, California Institute of Technology
- M.S., 1995, Geology, California Institute of Technology
- B.S., 1992, Geology and Symbolic Systems, Stanford University
- 2004–2010 Research Scientist, School of Earth and Space Exploration, Arizona State University
- 2002–2004 Postdoctoral Scholar, Department of Geosciences, Virginia Tech
- 1999–2002 Assistant Professor, Department of Geology, Hartwick College
- 1999 Visiting Assistant Professor, Department of Geology, University of Illinois-Urbana
I am a biogeochemist investigating metal chemistry in the earth’s lithosphere, hydrosphere, and biosphere. Specifically I examine stable isotope fractionation of transition and post–transition metals in order to develop new tools for tracing chemical reactions that involve metals.
My primary focus is on fundamental, experimental investigations of metal isotope fractionation mechanisms. In the past ten years multi–collector ICP mass spectrometry has led to the discovery that stable isotopes of most metals fractionate in a wide range of environments all over the Earth. The number of published metal isotope analyses is burgeoning rapidly, and the prospect of much new understanding of metal chemistry in nature is exciting. Few investigators, however, have yet attempted to elucidate the mechanisms that drive metal isotope fractionation. Without careful investigation of molecular–scale mechanisms and systematics of metal isotope effects, we cannot hope to interpret robustly the wealth of information available in nature.
Currently Funded Projects
- NSF Chemical Oceanography "Systematics of zinc isotopes in the oceans: assessing the roles of speciation and surfaces." (Co–investigators Ariel D. Anbar, Arizona State University and Thomas Spiro, University of Washington). The objective of this project is to investigate zinc isotope fractionation mechanisms relevant to zinc cycling within the oceans and between seawater and marine sediment. The work is experimental and involves adsorption and crystal growth experiments. Much of the work is done in a trace metal–clean laboratory, and isotope compositions of samples are measured by multi–collector ICP-MS. The grant supports a graduate student and one or more undergraduate interns.
- NASA Exobiology "Assessing nickel isotope fractionation during abiotic processes." In this project, we are investigating low-temperature, abiotic processes that fractionate stable isotopes of nickel. Nickel isotopes in ancient rocks may be the key to understanding the decline in productivity of methanogens, which led to profound changes in the course of evolution early in Earth’s history. First we must make sure that we understand all the processes that govern Ni isotope systematics, so this project involves experiments, as well as analysis of natural samples, to determine what natural, abiotic processes can or cannot fractionate Ni. The project supports a graduate student, a postdoc, and multiple undergraduate researchers.
- NSF Major Research Instrumentation "Acquisition of a multi–collector ICP–MS for Indiana University." (Co–investigators Lisa Pratt and Ed Ripley, Indiana University) This grant supports the purchase of an instrument to measure very precisely the ratios of stable and radiogenic isotopes of almost any element. An ambitious, multi–disciplinary team of investigators uses the instrument for a wide range of investigations in geological, environmental, and biological contexts. The grant also provides partial support for a lab manager.
Laboratory and Analytical Facilities
Construction of a trace metal clean lab facility was completed in April, 2012. A multi–collector ICP–MS and quadrupole ICP–MS were installed in 2012 with support from the National Science Foundation and from Indiana University’s Office of the Vice Provost for Research, College of Arts and Sciences, Department of Geological Sciences, and School of Public and Environmental Affairs. These instruments enable measurement of metal isotope ratios with sub–parts–per–thousand precision and metal concentrations at the parts–per–billion level.
- Keynote speaker, Indiana Junior Academy of Sciences, November, 2011.
- Mentor for postdoctoral, graduate, and undergraduate advisees of Professor Ariel Anbar, ASU, 2005-2010.
- Reviewer of publications and proposals for Geochimica et Cosmochimica Acta, Chemical Geology, Earth and Planetary Science Letters, Journal of Crystal Growth, Journal of Geoscience Education, National Science Foundation, NASA, Department of Energy.
- Initiator, planner, and/or presenting participant in many public education and outreach events for adults and children, including judging at Intel Science and Engineering Fair in multiple years and classroom visits (2005–2013).