Researchers in my group use chemical concepts and approaches to study geological, chemical and biological processes that shape the Earth's surface environment and how they have changed through time. Study of these processes teaches us about the habitability of the Earth, the history of the environment and life, the effects of human activities on the environment, and the prospects for life beyond Earth. Our efforts center on the development and application of novel analytical techniques, particularly using mass spectrometry.

Recently, we have been among the pioneers in using multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) to precisely measure mass-dependent variations in the isotopic compositions of transition metals, particularly iron and molybdenum. Work by us and others documents that variations of 0.01 - 0.1 %/amu, once undetectable, are actually ubiquitous. Such measurements in natural samples, informed by laboratory experiments and theoretical studies, provide insights into the environmental chemistry of metals and the metal-centered interactions between organisms and their surroundings. Applied to the geologic record, such "metal stable isotope" studies provide information about metal biogeochemical cycles on the ancient Earth, environmental changes that perturbed these cycles, and biological activity in the distant past.

A notable recent example of this research is our use of molybdenum isotopes to study changes in the oxygen content of the oceans through time (Arnold et al., 2004). We plan to continue to explore the biogeochemistry of metals in the middle of the periodic table, using isotopic and other methods. We are especially interested in "metallomic" research that relates the distribution and isotopic composition of metals in nature to the demand for these metals by various metalloenzymes. New state-of-the-art analytical facilities, particularly in the W. M. Keck Foundation Laboratory for Environmental Biogeochemistry, make ASU an exceptional setting to pursue this research.

Front row: Yun Duan, Jennifer Glass, Carina Arrua, Laura Wasylenki

Back row: Gwyneth Gordon, Elise Wilkes, Brian Kendall, Jennifer Morgan, Steve Romaniello, Chris Mead, Ariel Anbar, Greg Brennecka

Not pictured: Mitchell Smith, Achim Herrmann, Amisha Poret-Peterson