Research Interests

I primarily consider myself a geobiologist, although my work is multidisciplinary and involves elements of microbial ecology, biogeochemistry, and geology. In the broadest sense, I am interested in understanding the cycling of bioactive elements on the modern earth, and into the distant geological past. I am particularly interested in understanding how the chemistry of the Earth surface has changed through geologic time, and how this changing chemistry might have influenced the nature and structure of ecosystems and the evolution of life. This work takes us to modern environments including marine sediments, anoxic marine basins, and anoxic lakes. Our work also takes us to rocks deposited long ago. In total, we aim to read the chemical traces preserved in ancient rocks and how these traces can tell us of the nature of ocean and atmospheric chemistry.

We also explore modern microbes to understand how environmental variables like temperature, oxygen content, trace metal availability, or sulfate levels might influence their activity as well as the nature of any metabolic products they might leave behind. In this regard, we have focused much attention on the relationship between oxygen and organism metabolism. For example, what are the minimum oxygen requirement for aerobes and how do these requirements impact their distribution in modern environments and how have they have impacted the evolution or aerobic organisms through time?