Physical oceanography, pore water chemistry and water column methane turover rates during POLARSTERN cruise ANT-XXIX/4 ...

• Main Authors: Geprägs, Patrizia, Torres, Marta E, Mau, Susan, Kasten, Sabine, Römer, Miriam, Bohrmann, Gerhard
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2016
• Subjects: Antarc*; Antarctic
• Online Access: https://dx.doi.org/10.1594/pangaea.858963; https://doi.pangaea.de/10.1594/PANGAEA.858963

Recent studies have suggested that the marine contribution of methane from shallow regions and melting marine terminating glaciers may have been underestimated. Here we report on methane sources and potential sinks associated with methane seeps in Cumberland Bay, South Georgia's largest fjord system. The average organic carbon content in the upper 8 meters of the sediment is around 0.65 wt.%; this observation combined with Parasound data suggest that the methane gas accumulations probably originate from peat-bearing sediments currently located several tens of meters below the seafloor. Only one of our cores indicates upward advection; instead most of the methane is transported via diffusion. Sulfate and methane flux estimates indicate that a large fraction of methane is consumed by anaerobic oxidation of methane (AOM). Carbon cycling at the sulfate-methane transition (SMT) results in a marked fractionation of the d13C-CH4 from an estimated source value of -65 per mil to a value as low as -96 per mil just ... : Supplement to: Geprägs, Patrizia; Torres, Marta E; Mau, Susan; Kasten, Sabine; Römer, Miriam; Bohrmann, Gerhard (2016): Carbon cycling fed by methane seepage at the shallow Cumberland Bay, South Georgia, sub-Antarctic. Geochemistry, Geophysics, Geosystems, 17(4), 1401-1418 ...