Early diagenetic processes generate iron and manganese oxide layers in the sediments of Lake Baikal, Siberia

Torres, N. T. and Och, L. M. and Hauser, P. C. and Furrer, G. and Brandl, H. and Vologina, E. and Sturm, M. and Bürgmann, H. and Müller, B.. (2014) Early diagenetic processes generate iron and manganese oxide layers in the sediments of Lake Baikal, Siberia. Environmental Science : processes & impacts, Vol. 16, H. 4. pp. 879-889.

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Official URL: http://edoc.unibas.ch/dok/A6337828

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Distinct layers of iron(III) and manganese(IV) (Fe/Mn) oxides are found buried within the reducing part of the sediments in Lake Baikal and cause considerable complexity and steep vertical gradients with respect to the redox sequence. For the on-site investigation of the responsible biogeochemical processes, we applied filter tube samplers for the extraction of sediment porewater combined with a portable capillary electrophoresis instrument for the analyses of inorganic cations and anions. On the basis of the new results, the sequence of diagenetic processes leading to the formation, transformation, and dissolution of the Fe/Mn layers was investigated. With two exemplary cores we demonstrate that the dissolution of particulate Fe and Mn is coupled to the anaerobic oxidation of CH4 (AOM) either via the reduction of sulphate (SO42-) and the subsequent generation of Fe(II) by S(-II) oxidation, or directly coupled to Fe reduction. Dissolved Fe(II) diffuses upwards to reduce particulate Mn(IV) thus forming a sharp mineral boundary. An alternative dissolution pathway is indicated by the occurrence of anaerobic nitrification of NH4+ observed at locations with Mn(IV). Furthermore, the reasons and consequences of the non-steady-state sediment pattern and the resulting redox discontinuities are discussed and a suggestion for the burial of active Fe/Mn layers is presented.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Analytische Chemie (Hauser)
UniBasel Contributors:Hauser, Peter C. P. C.
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Royal Society of Chemistry
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:06 Mar 2015 07:44
Deposited On:06 Mar 2015 07:44

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