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

人类对五大湖的持续影响是众所周知的。这些影响包括气候变化、污染、营养负荷、发展和入侵物种。然而，五大湖在这些人类影响之前的演变，由于自然气候变化事件，因为它们在最后一个冰河时代结束时形成的了解较少。这项研究将是第一个调查元素地球化学循环在五大湖。这些循环反映了地质时期的生物活动，如生产力和氧含量。这项工作将包括收集上级、休伦湖和伊利的沉积物岩心。将在这些沉积物中测量各种元素和同位素浓度，以评估过去的湖泊状况。该项目还将支持密歇根州立大学和中密歇根大学的研究生和本科生。该团队将与密歇根州K-12学校和当地社区合作，与密歇根州海洋赠款和休伦湖上的雷霆湾国家海洋保护区等组织合作。该项目将收集来自6个五大湖站点的沉积物活塞芯-每个湖的上级，休伦湖，和伊利-调查当地和区域全新世地球化学循环及其对持续人为扰动和气候变化的见解。我们的网站是有针对性的，因为他们跨越梯度的营养条件和水的停留时间，并包括最好的研究和最感兴趣的网站在现代-目前自然缺氧中岛天坑休伦湖，季节性缺氧的中部和东部盆地的伊利湖，和西部和东部停泊地点的上级湖。具体目标包括：（A）自然气候变化如何影响全新世的生产力和生物必需微量元素的行为？(B)自然气候变化如何影响全新世的氧化还原条件？(C)湖内和湖间异质性是否反映了更大的区域环境反馈？(D)成岩作用和其他局部变化在每个地点的代用动力学中起什么作用？这些问题将使用地球化学代理，包括汞同位素，营养物质浓度及其同位素，氧化还原敏感和生物活性微量元素来解决。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

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.