Alumni spotlight

Ryan Lepak holding a Lake Sturgeon

Ryan Lepak, PhD   

Ryan received his B.S. degree in Chemistry from the University of Wisconsin-La Crosse in 2011, with Dr. Kristofer Rolfhus as his mentor. During his time at UW-L he helped the River Studies team on a multi-year research effort to better understand mercury cycling in remote lakes surrounding the upper Lawrentian Great Lakes. This is where his passion for research was seeded. Following graduation Ryan worked at the Upper Midwest Environmental Sciences Center for 6 months before beginning his M.S. work with James Hurley at the University of Wisconsin Madison. During that time Ryan worked with the USGS Mercury Research Lab to understand how invasive zebra and then quagga mussels have altered carbon dynamics and methymercury formation in the nearshore regions of Lake Michigan. During this time Ryan became interested in learning more about a new cutting-edge research technology using naturally occurring mercury isotopes to better understand mercury sources and reactions. This began his Ph.D. work of investigating mercury sources to the Great Lakes with a cohort of University of Wisconsin Madison, USGS and USEPA researchers.

Ryan is now stationed at the USEPA office in Duluth MN as a National Science Foundation postdoctoral scholar. In this position Ryan focuses on three primary research objectives; 1) connecting energy subsidies and contaminants in the Great Lakes to understand contaminant sources to game fish, 2) along with his host institute, Cornell University, looking at the utility of museum-preserved fish specimens for mercury source attribution over complex spatial and temporal frames, 3) working with the nation of Gabon to reduce the severe mercury contamination in subsistence fisheries as a result of mercury use gold mining.

Ryan has published his work in numerous peer-reviewed journals but most notable include entries to Environmental Science and Technology and his recent work in the Proceedings of the National Academy of Sciences of the United States of America. Ryan continues to work with Dr. Rolfhus to bring mercury isotope science to research that began during his undergraduate days to ask what burden mercury brought by French Voyageurs in the 1700’s has on fish harvested today in northern MN.

Environmental Science and Toxicology Cover of Lepak et al.Lepak sampling zooplankton from a seaplane pontoon