Quantifying the effect of sediment microbial activity in facilitating silica sequestration during early diagenesis

Reverse weathering is the process that forms clay minerals through reactions that involve biologically produced silica. Carbon dioxide is a byproduct of reverse weathering and an important greenhouse gas. As a result, reverse weathering is considered an important process that has regulated global climate over the earth?s natural history. Prior studies that have examined reverse weathering have focused only on abiotic factors (i.e., factors not affected by biology). This research is the first to examine microbial effects on reverse weathering reactions. The project includes laboratory experiments with well-characterized microbial strains. These experiments will provide understanding of this complicated process in a controlled environment. Follow-up experiments and surveys will be conducted in the northern Gulf of Mexico during two field campaigns led by the scientific team. This project contributes to scientific education and development at many levels. The graduate and postgraduate personnel will learn interdisciplinary approaches and collaborate with an international expert in reverse weathering research. Undergraduate trainees from local community colleges will receive paid internships. The project supports high school education in marine science through a partnership with the Dauphin Island Sea Lab Discovery Hall Program. Scientists involved in this study will also work with a non-profit in Birmingham, Alabama, that brings educational opportunities to underserved and underrepresented students in grades 3-8.

Reverse weathering (RW) affects many biogeochemical cycles in the ocean. RW is now recognized to represent ~40% of global oceanic silica burial. Such RW-driven burial restricts movement of dissolved silica back into the water column where it can fuel diatom growth (consuming carbon dioxide) and potentially transport diatom carbon to the deep ocean where it can be sequestered for centuries. RW also is likely to be a major, but poorly understood, sink term in the oceanic cycles of Li, Al, K, Fe, Ge and may play a role in coastal ocean acidification. Preliminary field data from the Mississippi River plume directly demonstrates a role for sediment microbes in the early phases of RW. Given the simplicity in the biological design of these pilot experiments, collaboration between experts in silica cycling and sediment microbiology is necessary to better understand the role of microbes in RW. Through this research, the scientific team will address the general question: What factors determine whether microbes facilitate or impede formation of early diagenetic silica products within the process of RW? This project supports science education across many levels including: (1) programs for K-12 students offered by the Dauphin Island Sea Lab Discovery Hall Program, (2) STEM research experiences for community college students, (3) graduate student and postdoctoral training and (4) international collaboration.

This project is funded by the Chemical Oceanography and Biological Oceanography Programs in the Division of Ocean Sciences.

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.