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Article Dans Une Revue Nature Année : 2023

Long-term organic carbon preservation enhanced by iron and manganese

Oliver Moore
Lisa Curti
Clare Woulds
  • Fonction : Auteur
Peyman Babakhani
Benjamin Mills
William Homoky
Ke-Qing Xiao
Andrew Bray
  • Fonction : Auteur
Ben Fisher
Majid Kazemian
Burkhard Kaulich
  • Fonction : Auteur
Andrew Dale
Caroline Peacock

Résumé

Abstract The balance between degradation and preservation of sedimentary organic carbon (OC) is important for global carbon and oxygen cycles 1 . The relative importance of different mechanisms and environmental conditions contributing to marine sedimentary OC preservation, however, remains unclear 2–8 . Simple organic molecules can be geopolymerized into recalcitrant forms by means of the Maillard reaction 5 , although reaction kinetics at marine sedimentary temperatures are thought to be slow 9,10 . More recent work in terrestrial systems suggests that the reaction can be catalysed by manganese minerals 11–13 , but the potential for the promotion of geopolymerized OC formation at marine sedimentary temperatures is uncertain. Here we present incubation experiments and find that iron and manganese ions and minerals abiotically catalyse the Maillard reaction by up to two orders of magnitude at temperatures relevant to continental margins where most preservation occurs 4 . Furthermore, the chemical signature of the reaction products closely resembles dissolved and total OC found in continental margin sediments globally. With the aid of a pore-water model 14 , we estimate that iron- and manganese-catalysed transformation of simple organic molecules into complex macromolecules might generate on the order of approximately 4.1 Tg C yr −1 for preservation in marine sediments. In the context of perhaps only about 63 Tg C yr −1 variation in sedimentary organic preservation over the past 300 million years 6 , we propose that variable iron and manganese inputs to the ocean could exert a substantial but hitherto unexplored impact on global OC preservation over geological time.

Dates et versions

hal-04450498 , version 1 (10-02-2024)

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Citer

Oliver Moore, Lisa Curti, Clare Woulds, James Bradley, Peyman Babakhani, et al.. Long-term organic carbon preservation enhanced by iron and manganese. Nature, 2023, 621 (7978), pp.312-317. ⟨10.1038/s41586-023-06325-9⟩. ⟨hal-04450498⟩
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