Ancient and Modern Geochemical Signatures in the 13,500-Year Sedimentary Record of Lake Cadagno

Berg, Jasmine S.; Lepine, Mathilde; Laymand, Emile; Han, Xingguo; Vogel, Hendrik; Morlock, Marina A.; Gajendra, Niroshan; Gilli, Adrian; Bernasconi, Stefano M.; Schubert, Carsten J.; Su, Guangyi; Lever, Mark A. (2022). Ancient and Modern Geochemical Signatures in the 13,500-Year Sedimentary Record of Lake Cadagno. Frontiers in Earth Science, 9 Frontiers Media 10.3389/feart.2021.754888

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Although lake sediments are globally important organic carbon sinks and therefore important habitats for deep microbial life, the deep lacustrine biosphere has thus far been little studied compared to its marine counterpart. To investigate the impact of the underexplored deep lacustrine biosphere on the sediment geochemical environment and vice versa, we performed a comprehensive microbiological and geochemical characterization of a sedimentary sequence from Lake Cadagno covering its entire environmental history since formation following glacial retreat. We found that both geochemical gradients and microbial community shifts across the ∼13.5 kyr subsurface sedimentary record reflect redox changes in the lake, going from oxic to anoxic and sulfidic. Most microbial activity occurs within the top 20 cm of sediment, where millimolar sulfate concentrations diffusing in from the bottom water are almost completely consumed. In deeper sediment layers, organic carbon remineralization is much slower but microorganisms nonetheless subsist on fermentation, sulfur cycling, metal reduction, and methanogenesis. The most surprising finding was the presence of a deep, oxidizing groundwater source. This water source generates an inverse redox gradient at the bottom of the sedimentary sequence and could contribute to the remineralization of organic matter sequestered in the energy-limited deep subsurface.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Vogel, Hendrik and Morlock, Marina Alexandra

Subjects:

500 Science > 550 Earth sciences & geology
500 Science > 570 Life sciences; biology

ISSN:

2296-6463

Publisher:

Frontiers Media

Language:

English

Submitter:

Hendrik Vogel

Date Deposited:

14 Feb 2022 15:42

Last Modified:

14 Feb 2022 15:49

Publisher DOI:

10.3389/feart.2021.754888

BORIS DOI:

10.48350/164969

URI:

https://boris.unibe.ch/id/eprint/164969

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