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Mari Titcombe Lee, PhD


Mari Lee (she/her) is the Chief of the Strategic Laboratory Science Branch in the Laboratory and Analytical Services Division of the Water Mission Area.

Mari Lee joined USGS in 2020 as the Branch Chief of the Strategic Laboratory Science Branch, which specializes in the research and development of analytical chemistry methods to meet the needs of the Water Mission Area. During her time at USGS she has served on special assessment teams, as a WMA Project and Function manager, and as the acting Chief of Analytical Services at the National Water Quality Laboratory (2022-2023).

Mari completed her PhD in physical chemistry at the University of Minnesota, co-advised between the departments of Chemistry and Mechanical Engineering. Her thesis research focused on the development of novel mass spectrometry instrumentation to study atmospheric nucleation processes.  The large-scale goal of her work was to better understand the chemistries of nucleating molecular clusters, such that the information could be incorporated into global climate models to reduce uncertainty in aerosol radiative forcing terms.

A passion-project conducted while in graduate school, in collaboration with the UMN School of Public Health, investigated human exposure to particulate matter and PAHs from common cooking practices in rural Tanzania, East Africa.  Mari served as a Peace Corps Volunteer in the country circa the early 2000s and returned to her host community to characterize and attempt to address some of the long-term health impacts of cooking smoke exposure. 

After finishing her PhD, Mari served for three years as a Visiting Professor at Colorado College, in Colorado Springs. There she taught undergraduate courses in chemistry and environmental science for the Environmental Program, and conducted research projects on heavy metal loading in environmental media, and phytoremediation efforts on abandoned mine lands in Saguache County, CO.

Mari also served as a Postdoctoral Research Associate with the Institute for Critical Technology & Applied Science at Virginia Tech. She investigated the aerosolization, transport and fate of enveloped virus and engineered nanomaterials as surrogates for Ebola virus. This project gave her a crash course in microbiology. Her work was republished in a special Covid -19 edition of Environmental Science and Technology due to a “lucky” similarity between her surrogate virus and the Covid-19 viral surface structure.

Immediately prior to joining the USGS, Mari worked for the U.S. EPA in Washington DC, and conducted chemical risk assessments under the Toxic Substances Control Act. Mari served as a technical expert on the fate and transport of chemicals in the environment and human exposure to chemical toxics. During her time at EPA, she evaluated thousands of diverse chemistries new to U.S. commerce through modeling and meta-analysis.