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Santa Barbara Basin dynamics

Microbial Diversity of the Sulfate-Methane Transition Zone (former post-doc Husen Zhang and graduate student Ben Harrison) in collaboration with Will Berelson, USC.

Microbial assemblages play an important role in early diagenesis of marine organic matter (OM), coupling its oxidation to the sequential depletion of electon acceptors with depth (oxygen, nitrate, Fe/Mn, sulfate, carbon dioxide). Accordingly, the bioavailability of sedimentary organic carbon decreases over time with increasing burial depth. The sulfate-methane interface (SMI) is defined as the horizon within the sediment column in which sulfate and methane coexist in significant concentrations. At many localities, the SMI has been shown to stimulate subsurface microbial activity, particularly the anaerobic oxidation of methane (AOM). Our lab has been involved in better understanding the Archaeal/Bacterial consortia that catalyze AOM, but we also hope to better characterize other members of the microbial community associated with SMIs. At some continental margin sites the flux of CO2 resulting from microbial respiration at the SMI may exceed methane influx, suggesting that further OM remineralization takes place within the interface, coupled to sulfate reduction independent of AOM. With detailed molecular study of the Santa Barbara Basin SMI we hope to discern which microorganisms are involved in these organic matter transformations.

NSF-OCE: "Collaborative Research:  Anoxic sediment diagenesis at the sulfate-methane interface:  Does a novel microbial syntrophy result in enhanced POC remineralization?"