Design of a Laboratory-controlled, Flow-through System for Measuring Microbial Methane Production in Marine Sediments

Microbially-generated seafloor methane is an important component of the global carbon inventory and may be a viable source of alternative energy. Existing biogeochemical models of microbial methanogenesis, and subsequent anaerobic methane oxidation, rely in part on batch laboratory incubations that do not mimic in situ conditions or account for differences in sediment physical properties. To determine the effects of sediment properties on net methane production, a flow-through sediment column was modified after a previously developed system that was shown to measure the effects of fluid flux on anaerobic methane oxidation and sulfate reduction. Mimicking a cold seep, methane rich advective fluid (as from deep reservoirs) was slowly pumped from the bottom and through the sediment column, and sulfate rich diffusive artificial seawater (as near the sediment-water interface) was supplied at the top. Here, a similar flow-through system was designed for measuring methane production in well-characterized packed sediment with different permeability collected from the Gulf of Mexico. Preliminary runs showed substantial methane production. Future studies will characterize and measure methane production rates in marine sediments collected from other geographic locations.