Sulfur and the organic carbon cycle

 Organic matter (OM) burial in sediments is fundamental to planetary habitability and stability on timescales ranging from billions of years to decades or less. OM burial is tightly linked with biogeochemical processes in the sulfur cycle, which can both respire OM and potentially preserve organic matter through the process of OM sulfurization. We are only beginning to understand the implications of these mechanisms for climate and atmospheric oxygenation. In this talk, I will highlight our recent results from both deep time and modern systems that provide fresh insights into the timescales and drivers of organic sulfur formation, and into the impacts of microbial sulfur cycling on sedimentary OM burial more broadly. In both Mesoproterozoic basins and modern marine O2 deficient zones, we find evidence that OM transformations are driven by microbial sulfur cycling, and that these processes may represent important feedbacks with global climate and redox state. These results have direct applications related to the urgent human need to address climate change and remove billions of tonnes of CO2 from the atmosphere, and I will share some of our efforts to understand the risks and potential for CO2 removal (CDR) via biomass sequestration in anoxic settings.

About this Series: The Department Lecture Series at EAPS at MIT is a series of weekly talks given by leading thinkers in the areas of geology, geophysics, geobiology, geochemistry, atmospheric science, oceanography, climatology, and planetary science. For more information and Zoom password please contact Madelyn Musick: mmusick@mit.edu