Freshwater Colloquium – Pollution History of Black Carbon (Soot), Toxic Metals and PFAS in Green Bay Over the Past Century

Green Bay, the world’s largest freshwater estuary, and Milwaukee Harbor have experienced significant ecological and environmental changes, driven by increased anthropogenic activities and the introduction of invasive species. Designated by EPA as Areas of Concern (AOCs) in the 1980s, both systems provide natural laboratories for assessing long-term pollution trends. This presentation will explore case studies on the depositional history of black carbon (soot), toxic metals (Cu, Pb, Zn, Cd, Hg, Co, Ni, Cr, and As), and polyfluoroalkyl substances (PFAS) in Green Bay sediments over the past 50-100 years, with comparative insights from Milwaukee Harbor.

Dr. Guo’s major research focus is on aquatic biogeochemistry, with an emphasis on the role of natural organic matter in governing the reactivity, fate and transport of chemical species, including trace metals, radionuclides, nanoparticles, microplastics, PFAS, and other contaminants. He received his Ph.D. degree in Chemical Oceanography from Texas A&M University, College Station. After working as a postdoc and assistant research scientist at Texas A&M-Galveston, Dr. Guo joined University of Alaska Fairbanks in 2000 as a research professor in the International Arctic Research Center and then University of Southern Mississippi in 2005 as a faculty member in the Department of Marine Science. Dr. Guo has been a professor in the School of Freshwater Sciences at the University of Wisconsin-Milwaukee since 2012. Dr. Guo has authored/coauthored over 240 peer-reviewed publications, with an H-index of 70 and over 17,000 citations based on Google Scholar. His research influence is specifically recognized by ScholarGPS®, which ranked him #4 globally in Dissolved Organic Carbon and #5 in Organic Matter based on publications from the prior five years (2022). He received the 2023 UWM Senior Faculty Research Award.

Sam earned her B.S. in Geography with a minor in Chemistry from UW-Whitewater in 2024. She just started the second year of her master’s here at SFS working in Dr. Guo’s lab. Her research consists of studying the historical distribution of heavy metals in Milwaukee Harbor and Green Bay sediments, analyzing the degradation of microplastics and microplastic-derived DOM, as well as examining PFAS molecular weight distribution via ultrafiltration. This year, she has had the opportunity to present her research at numerous conferences, including the Society for Freshwater Sciences annual meeting in San Juan, PR, the ACS Great Lakes regional meeting in Appleton, WI, and at the International Association for Great Lakes Research in Milwaukee, WI.