EAGER SitS: Emergent Properties during Soil Formation

Soils sustain humankind. These earth materials form as water, air, and dead and living organisms interact with rock material at Earth's surface. Soils form over thousands to millions of years and yet soil can be lost to erosion over human time frames. In this proposed work, innovative sensors and techniques will be used to measure and understand how iron and oxygen are catalyzed by bacteria to interact in soils, affecting the pathways where water flows in the subsurface. The work will focus on soil formation at an NSF-funded observatory in Pennsylvania - a Critical Zone Observatory - where a large effort is ongoing to understand such processes. New scientific knowledge will be developed about how micro-organisms change the chemistry of rock and break it open as it turns into soil, and how this relates to subsurface water flow. At the same time, the new techniques will provide new knowledge of societal relevance about how soil forms, and will also be shown to many other faculty members, students, and colleagues that visit the observatory, as well as members of the public through interactions with a local museum. In addition, the observatory is the site of an annual NSF-funded Geophysics field course where the two techniques to be deployed will be taught to an annual cohort of undergraduate students drawn from under-represented groups and community colleges.

With high-risk experiments using novel deployments, biogeochemical reactions will be explored with respect to how they relate to zones of lateral water flow. Two techniques will be investigated over month- to year-long deployments: the first will measure microbial activity (chronoamperometry) and the second will measure the effects of water-induced changes in volume of rock materials (time-lapse seismic monitoring). Both techniques are still in their infancy because they depend on new sensor technologies and state-of-the-art interpretations. The deployment of these techniques together in a location where many other measurements have already been made will guarantee the highest likelihood of success.

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.