(Appendix 1-4) Geochemistry, desorption methods, TOC, TC, and mineral content of different settings


Sorption of volatile hydrocarbon gases (VHCs) to marine sediments is a recognized phenomenon that has been investigated in the context of petroleum exploration. However, little is known about the biogeochemistry of sorbed methane and higher VHCs in environments that are not influenced by thermogenic processes. This study evaluated two different extraction protocols for sorbed VHCs, used high pressure equipment to investigate the sorption of methane to pure clay mineral phases, and conducted a geochemical and mineralogical survey of sediment samples from different oceanographic settings and geochemical regimes that are not significantly influenced by thermogenic gas. Extraction of sediments under alkaline conditions yielded higher concentrations of sorbed methane than the established protocol for acidic extraction. Application of alkaline extraction in the environmental survey revealed the presence of substantial amounts of sorbed methane in 374 out of 411 samples (91%). Particularly high amounts, up to 2.1 mmol kg**-1 dry sediment, were recovered from methanogenic sediments. Carbon isotopic compositions of sorbed methane suggested substantial contributions from biogenic sources, both in sulfate-depleted and sulfate-reducing sediments. Carbon isotopic relationships between sorbed and dissolved methane indicate a coupling of the two pools. While our sorption experiments and extraction conditions point to an important role for clay minerals as sorbents, mineralogical analyses of marine sediments suggest that variations in mineral composition are not controlling variations in quantities of sorbed methane. We conclude that the distribution of sorbed methane in sediments is strongly influenced by in situ production.

Supplement to: Ertefai, Tobias F; Heuer, Verena B; Prieto-Mollar, Xavier; Vogt, Christoph; Sylva, Sean P; Seewald, Jeffrey S; Hinrichs, Kai-Uwe (2010): The biogeochemistry of sorbed methane in marine sediments. Geochimica et Cosmochimica Acta, 74, 6033-6048

DOI https://doi.org/10.1594/PANGAEA.746477
Related Identifier IsSupplementTo https://doi.org/10.1016/j.gca.2010.08.006
Related Identifier References https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000114192
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.746477
Creator Ertefai, Tobias F; Heuer, Verena B (ORCID: 0000-0002-1856-116X); Prieto-Mollar, Xavier; Vogt, Christoph ORCID logo; Sylva, Sean P; Seewald, Jeffrey S ORCID logo; Hinrichs, Kai-Uwe ORCID logo
Publisher PANGAEA
Publication Year 2010
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Resource Type Supplementary Publication Series of Datasets; Collection
Format application/zip
Size 4 datasets
Discipline Earth System Research
Spatial Coverage (-81.904W, -12.021S, 14.727E, 72.006N); Japan Trench, seep site 1; Japan Trench, seep site 2; South Pacific Ocean; Juan de Fuca Ridge, North Pacific Ocean; Petroleum mound; Dolgovskoy mound; Batumi seep area; Pechori Mound; Iberia mound; Oil Ridge; Chapopote; Dvurechenskii; Dvurechenskii mud vulcano; Norwegian Sea
Temporal Coverage Begin 2002-03-22T15:00:00Z
Temporal Coverage End 2007-10-22T09:30:00Z