Collaborative research: Banded together: modern water-microbe-mineral feedbacks in the deep Archean lithosphere

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Microbial life is in constant contact with humans and our environment. Interactions between microbial life, humans, and our environment influence essentially every aspect of daily modern life, from the treatment of medical conditions to agricultural innovations. These interactions show how successful microbial life can be under a wide variety of conditions, on short time scales, and at the Earth's surface. However, scientists also have evidence that microbial life is important over long time scales and deep underground. In this project we will investigate the strategies that microbial life uses to survive under difficult circumstances while living deep underground. In particular, we are interested in understanding whether microbial waste products can create new space for growth, new neighborhoods for microbial life, or condemn them to inevitable death. From our scientific observations, we will create models that will help us understand how microbial life works underground. Our results could be useful in understanding how microbial life will affect energy extraction processes, such as hydrologic fracturing ('fracking'), and underground waste disposal for some of our worst waste streams, such as nuclear materials. As part of our project, we will form a partnership with Community and Tribal Colleges of the Great Lakes Region. This partnership will focus on engaging underrepresented groups in the Science, Technology, Engineering, and Mathematics (STEM) fields. Rural Community and Tribal Colleges are primary conduits for post-secondary training and often serve as stepping stones to higher education in Native American communities of the region. We will develop and implement a hands-on summer workshop, 'The Life-Earth Connection', to be offered by our team during two consecutive summers at our field site. The workshops will provide an experiential learning opportunity that highlights the interactions of life, earth, and water through field and laboratory activities. Participants will also interact with peers and scientists in formal and informal settings to build career awareness and a professional network. Through this research project, we seek to discover the mechanisms by which microorganisms interact with physical and geochemical components of the deep subsurface. We are specifically interested in understanding the potential feedbacks that microbial metabolism has on the habitability of fractured-rock aquifer systems. Our overall approach is to conduct a hypothesis-driven study with integrated field-, laboratory-, and modeling components. Our project leverages the experience of a collaborative scientific team that draws broadly on Earth Science disciplines: specifically, geology, hydrogeology, geochemistry, and microbiology. With a field study centered on legacy boreholes and archived cores, we will investigate Neoarchean fractured-rock aquifers of the Canadian Shield. Through this work, we will define: (1) subsurface hydrogeological and geochemical factors that support or inhibit microbial growth; (2) microbial adaptation to limiting factors through community interactions and metabolic innovation; and (3) the positive or negative feedbacks of microbial activity on the geogenic milieu and habitability. Field and laboratory data streams will be integrated, and hypotheses tested, through the development and use of a fracture-scale reactive-transport model.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.