My primary research interest is the use of sulfur isotope and other geochemical records to reconstruct the coupled biogeochemical cycling of sulfur, carbon, and oxygen across important Earth-life transitions over the course of Earth history. In order to do this, I take both a modern and ancient perspective. I use modern lakes, microbial mats, and coastal environments as natural experimental systems to explore how sulfur isotope and other geochemical signals record chemical, biological, and physical information in sediments. Then, I apply the results to the geological record in order to explore how the sulfur cycle interacts with other biogeochemical cycles (C, P, N, Fe, etc.) to regulate Earth surface oxygen levels during the early evolution of life on Earth and major climate perturbations and associated extinction events in the Phanerozoic.