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Authigenic metastable iron sulfide minerals preserve microbial organic carbon in anoxic environments

Title data

Picard, Aude ; Gartman, Amy ; Cosmidis, Julie ; Obst, Martin ; Vidoudez, Charles ; Clarke, David R. ; Girguis, Peter R.:
Authigenic metastable iron sulfide minerals preserve microbial organic carbon in anoxic environments.
In: Chemical Geology. Vol. 530 (December 2019) . - No. 119343.
ISSN 0009-2541
DOI: https://doi.org/10.1016/j.chemgeo.2019.119343

Abstract in another language

The burial of organic carbon (OC) in sedimentary environments promotes long-term carbon sequestration and allows the release of oxygen in the atmosphere. OC preservation in sedimentary environments is commonly enhanced during transport and deposition on the seabed through the association with terrigenous minerals that can serve as physical protectants. Here, we propose an authigenic mechanism for the coupled preservation of labile OC and metastable iron sulfide minerals under anoxic conditions. Sulfate-reducing microorganisms (SRM) are ubiquitous in anoxic environments and produce the majority of free sulfide in marine sediments, leading to the formation of iron sulfide minerals in situ. Using high spatial resolution microscopy, spectroscopy and spectro-microscopy, we show that iron sulfide biominerals precipitated in the presence of SRM incorporate and adsorb organic molecules, leading to the formation of stable organo-mineral aggregates that could persist for years in anoxic environments. OC/iron sulfide assemblages consist of the metastable iron sulfide mineral phases mackinawite and/or greigite, along with labile organic compounds derived from new microbial biomass or from extracellular organic molecules released by SRM. Together these results underscore the role that a major group of anoxic microbes play in OC preservation and illustrate the value of the resulting authigenic metastable iron sulfide minerals mackinawite and greigite in protecting labile organic molecules from degradation over time.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER153675
Keywords: Biomineralization; Iron sulfide minerals; Iron; Sulfur; Organic carbon; Sulfate-reducing microorganisms
Institutions of the University: Research Institutions
Research Institutions > Research Centres
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Heisenberg Professorship - Experimental Biogeochemistry > Heisenberg Professorship - Experimental Biogeochemistry - Univ.-Prof. Dr. Martin Obst
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 27 Jan 2020 09:20
Last Modified: 27 Jan 2020 09:20
URI: https://eref.uni-bayreuth.de/id/eprint/53774