2018 David Packard Distinguished Lecturer
Cryptic cycles and power laws in the anaerobic seabed bioreactor
Bo Barker Jørgensen
Center for Geomicrobiology, Department Bioscience
Aarhus University, Denmark
Tuesday, May 22, 2018
Pacific Forum—3:00 p.m.
The Geomicrobiology Research Group studies microbial processes that drive sulfur and carbon cycling in marine sediments, from the sediment surface to hundreds of meters subsurface. Based on recent results and data analyses I will discuss how a power law relation between organic matter degradation and sediment age controls sulfate reduction and methanogenesis. This non-intuitive power law explains why 95 percent of methane production in the global seabed is focused in hotspots in continental shelf sediments. The degradation rate is unaffected by the terminal process, which, however, controls the intermediate fermentation products. Cryptic cycles of sulfur and methane within the sediment cause a discrepancy between process rates modeled from geochemical data or measured experimentally with radioactive or stable isotopes. This discrepancy motivates new studies that might lead to unexpected results.
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