Collaborative Research: Holocene biogeochemical evolution of Earth's largest lake system

Michigan State University, East Lansing MI

Investigators

Abstract

The ongoing human impacts on the Great Lakes are well known. These impacts include climate change, pollution, nutrient loading, development, and invasive species. However, the evolution of the Great Lakes before these human impacts due to natural climate change events since their formation at the end of the last ice age is less understood. This study will be among the first to investigate elemental geochemical cycles in the Great Lakes. These cycles reflect biologic activity such as productivity and oxygen contents over geologic time. This work will involve collecting sediment cores from Lakes Superior, Huron, and Erie. A variety of element and isotope concentrations will be measured in these sediments to assess past lake conditions. This project will support graduate and undergraduate students at both Michigan State University and Central Michigan University as well. The team will conduct outreach to Michigan K-12 schools and local communities working with established organization like Michigan Sea Grant and the Thunder Bay National Marine Sanctuary on Lake Huron. This project will collect piston cores of sediment from 6 Great Lakes sites— 2 from each of Lake’s Superior, Huron, and Erie—to investigate the local and regional Holocene biogeochemical cycling and its insights into ongoing anthropogenic perturbations and climate change. Our sites are targeted because they span a gradient in trophic conditions and water residence times and include among the best studied and highest interest sites in the modern—the currently naturally hypoxic Middle Island Sinkhole of Lake Huron, the seasonally hypoxic Central and Eastern Basins of Lake Erie, and the Western and Eastern Mooring sites of Lake Superior. Specific objectives include: (A) How has natural climate change impacted productivity and the behavior of bioessential trace elements through the Holocene? (B) How has natural climate change impacted redox conditions through the Holocene? (C) Do intra and inter-lake heterogeneity reflect larger regional environmental feedbacks? (D) What role do diagenesis and other local variations play in proxy dynamics at each site? These questions will be addressed using geochemical proxies, including mercury isotopes, nutrients concentrations and their isotopes, and redox-sensitive and biologically active trace elements. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.