Dr. Freeman’s research is directed toward applying the rich information provided in the carbon, nitrogen and hydrogen isotopic signatures and chemical structures of life-derived molecules to the study of Earth history. For example, she was the first to show that aerobic methanotrophy can be documented in ancient environments with highly 13C-depleted bacterial lipids. Of importance has been her work to understand how physical and chemical environmental conditions that interact with metabolic processes are preserved in isotopic and biomarker signatures. Her work includes study of molecules that record the dynamics of anoxia in ancient ocean basins (using markers for green and purple bacteria), methane cycling on early Earth (using pentacyclic hopanol lipids) and climate-linked changes in atmospheric CO2 (using lipids of nanoplankton and cyanobacteria). Her current work is focused on climate records in terrestrial environments and using bacterial and plant biomarkers to understand carbon and water dynamics on ancient landscapes.
In addition to her research contributions, Dr. Freeman is a pioneer in geobiology education. She has established interdisciplinary training programs and courses to teach biology to geologists and geology to biologists. She chaired development of two interdisciplinary degree programs at Penn State that bridge disciplines of life and Earth sciences: a B.S. program in Geobiology and a Ph.D. program in Biogeochemistry. Dr. Freeman is recognized for her work as teacher and mentor at Penn State, and she has been honored internationally as a Fellow of the Canadian Institute for Advanced Research, the Geological Society of America, the John Simon Guggenheim Memorial Foundation and the Geochemical Society.